Move VariantImpl definition to VariantImpl.hpp

This new pool replaced the "extension" slot where a secondary variant slot was used to store 8-byte values.

.github/workflows/ci.yml

@@ -93,44 +93,40 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - clang: "3.9"
-            runner: ubuntu-20.04
-            archive: bionic
-          - clang: "4.0"
-            runner: ubuntu-20.04
-            archive: bionic
-          - clang: "5.0"
-            runner: ubuntu-20.04
-            archive: bionic
-          - clang: "6.0"
-            runner: ubuntu-20.04
-            archive: bionic
           - clang: "7"
-            runner: ubuntu-20.04
+            runner: ubuntu-22.04
+            archive: focal
           - clang: "8"
             cxxflags: -fsanitize=leak -fno-sanitize-recover=all
-            runner: ubuntu-20.04
+            runner: ubuntu-22.04
+            archive: focal
           - clang: "9"
             cxxflags: -fsanitize=undefined -fno-sanitize-recover=all
-            runner: ubuntu-20.04
+            runner: ubuntu-22.04
+            archive: focal
           - clang: "10"
             cxxflags: -fsanitize=address -fno-sanitize-recover=all
-            runner: ubuntu-20.04
+            runner: ubuntu-22.04
+            archive: focal
           - clang: "11"
             runner: ubuntu-22.04
           - clang: "12"
             runner: ubuntu-22.04
           - clang: "13"
             runner: ubuntu-22.04
-          - clang: "14"
-            runner: ubuntu-22.04
-          - clang: "15"
-            runner: ubuntu-22.04
-    runs-on: ${{ matrix.runner }}
+          - clang: 14
+          - clang: 15
+          - clang: 16
+          - clang: 17
+          - clang: 18
+          - clang: 19
+    runs-on: ${{ matrix.runner || 'ubuntu-latest' }}
     steps:
       - name: Add archive repositories
         if: matrix.archive
         run: |
+          sudo gpg --keyserver keyserver.ubuntu.com --recv-keys 3B4FE6ACC0B21F32
+          sudo gpg --export 3B4FE6ACC0B21F32 | sudo tee /etc/apt/trusted.gpg.d/ubuntu-keyring.gpg > /dev/null
           sudo add-apt-repository -yn 'deb http://archive.ubuntu.com/ubuntu/ ${{ matrix.archive }} main'
           sudo add-apt-repository -yn 'deb http://archive.ubuntu.com/ubuntu/ ${{ matrix.archive }} universe'
       - name: Install Clang ${{ matrix.clang }}
@@ -138,10 +134,9 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y clang-${{ matrix.clang }}
       - name: Install libc++ ${{ matrix.clang }}
-        if: matrix.clang >= 11
         run: sudo apt-get install -y libc++-${{ matrix.clang }}-dev libc++abi-${{ matrix.clang }}-dev
       - name: Install libunwind ${{ matrix.clang }}
-        if: matrix.clang == 12  # dependency is missing in Ubuntu 22.04
+        if: matrix.clang == 12 # dependency is missing in Ubuntu 22.04
         run: sudo apt-get install -y libunwind-${{ matrix.clang }}-dev
       - name: Checkout
         uses: actions/checkout@v4
@@ -163,7 +158,7 @@ jobs:
   conf_test:
     name: Test configuration on Linux
     needs: [gcc, clang]
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Install
         run: |
@@ -184,19 +179,19 @@ jobs:
 
   conf_test_windows:
     name: Test configuration on Windows
-    runs-on: windows-2019
+    runs-on: windows-2022
     needs: [gcc, clang]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
       - name: 32-bit
         run: |
-          call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars32.bat"
+          call "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvars32.bat"
           cl /Isrc extras/conf_test/x86.cpp
         shell: cmd
       - name: 64-bit
         run: |
-          call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
+          call "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
           cl /Isrc extras/conf_test/x64.cpp
         shell: cmd
 
@@ -257,7 +252,7 @@ jobs:
             board: arduino:avr:uno
           - core: arduino:samd
             board: arduino:samd:mkr1000
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -412,7 +407,7 @@ jobs:
   arm:
     name: GCC for ARM processor
     needs: gcc
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Install
         run: |
@@ -431,7 +426,7 @@ jobs:
   coverage:
     needs: gcc
     name: Coverage
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Install
         run: sudo apt-get install -y lcov ninja-build
@@ -463,7 +458,7 @@ jobs:
   valgrind:
     needs: gcc
     name: Valgrind
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Install
         run: |
@@ -485,24 +480,24 @@ jobs:
   clang-tidy:
     needs: clang
     name: Clang-Tidy
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Install
-        run: sudo apt-get install -y clang-tidy cmake ninja-build
+        run: sudo apt-get install -y clang-tidy libc++-dev libc++abi-dev
       - name: Checkout
         uses: actions/checkout@v4
       - name: Configure
-        run: cmake -G Ninja -DCMAKE_CXX_CLANG_TIDY="clang-tidy-10;--warnings-as-errors=*" -DCMAKE_BUILD_TYPE=Debug .
+        run: cmake -G Ninja -DCMAKE_CXX_CLANG_TIDY="clang-tidy;--warnings-as-errors=*" -DCMAKE_BUILD_TYPE=Debug .
         env:
-          CC: clang-10
-          CXX: clang++-10
+          CC: clang
+          CXX: clang++
       - name: Check
         run: cmake --build . -- -k 0
 
   amalgamate:
     needs: gcc
     name: Amalgamate ArduinoJson.h
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -578,7 +573,7 @@ jobs:
 
   codeql:
     name: CodeQL
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     needs: gcc
 
     permissions:
@@ -587,20 +582,20 @@ jobs:
       security-events: write
 
     steps:
-    - name: Checkout repository
-      uses: actions/checkout@v4
+      - name: Checkout repository
+        uses: actions/checkout@v4
 
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v3
-      with:
-        languages: cpp
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: cpp
 
-    - name: Build
-      run: |
-        cmake -DCMAKE_BUILD_TYPE=Debug .
-        cmake --build .
+      - name: Build
+        run: |
+          cmake -DCMAKE_BUILD_TYPE=Debug .
+          cmake --build .
 
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v3
-      with:
-        category: "/language:cpp"
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3
+        with:
+          category: "/language:cpp"

.github/workflows/release.yml

@@ -8,7 +8,7 @@ on:
 jobs:
   release:
     name: Create release
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Set variables
         id: init

CHANGELOG.md

@@ -1,6 +1,59 @@
 ArduinoJson: change log
 =======================
 
+HEAD
+----
+
+* Optimize storage of static strings
+
+> ### BREAKING CHANGES
+>
+> Static string cannot contain NUL characters anymore (they could since 7.3.0).
+> This is an extremely rare case, so you probably won't be affected.
+>
+> For example, the following code produces different output in 7.3 and 7.4:
+>
+> ```cpp
+> JsonDocument doc;
+> doc["a\0b"] = "c\0d";
+> serializeJson(doc, Serial);
+> // With Arduino 7.3 -> {"a\u0000b":"c\u0000d"}
+> // With Arduino 7.4 -> {"a":"c"}
+> ```
+>
+> `JsonString` contructor now only accepts two arguments, not three.
+> If your code uses `JsonString` to store a string as a pointer, you must remove the size argument.
+>
+> For example, if you have something like this:
+>
+> ```cpp
+> doc["key"] = JsonString(str.c_str(), str.size(), true);
+> ```
+>
+> You must replace with either:
+>
+> ```cpp
+> doc["key"] = JsonString(str.c_str(), true);  // store as pointer, cannot contain NUL characters
+> doc["key"] = JsonString(str.c_str(), str.size()); // store by copy, NUL characters allowed
+> doc["key"] = str; // same as previous line for supported string classes (`String`, `std::string`, etc.)
+> ```
+
+v7.4.2 (2025-06-20)
+------
+
+* Fix truncated strings on Arduino Due (issue #2181)
+
+v7.4.1 (2025-04-11)
+------
+
+* Fix crash with tiny Flash strings (issue #2170)
+
+v7.4.0 (2025-04-09)
+------
+
+* Optimize storage of tiny strings (up to 3 characters)
+* Fix support for `const char[]` (issue #2166)
+
 v7.3.1 (2025-02-27)
 ------
 

CMakeLists.txt

@@ -10,7 +10,7 @@ if(ESP_PLATFORM)
 	return()
 endif()
 
-project(ArduinoJson VERSION 7.3.1)
+project(ArduinoJson VERSION 7.4.2)
 
 if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
 	include(CTest)

README.md

@@ -80,7 +80,7 @@ ArduinoJson is a C++ JSON library for Arduino and IoT (Internet Of Things).
     * Continuously tested on
         * [Visual Studio 2017, 2019, 2022](https://ci.appveyor.com/project/bblanchon/arduinojson/branch/7.x)
         * [GCC 4.8, 5, 6, 7, 8, 9, 10, 11, 12](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22)
-        * [Clang 3.9, 4.0, 5.0, 6.0, 7, 8, 9, 10, 11, 12, 13, 14, 15](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22)
+        * [Clang 7 to 19](https://github.com/bblanchon/ArduinoJson/actions?query=workflow%3A%22Continuous+Integration%22)
     * [Continuously fuzzed with Google OSS Fuzz](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:arduinojson)
     * Passes all default checks of [clang-tidy](https://releases.llvm.org/10.0.0/tools/clang/tools/extra/docs/clang-tidy/)
 * Well documented
@@ -139,11 +139,6 @@ See the [tutorial on arduinojson.org](https://arduinojson.org/v7/doc/serializati
 
 ArduinoJson is thankful to its sponsors. Please give them a visit; they deserve it!
 
-<p>
-  <a href="https://www.programmingelectronics.com/" rel="sponsored">
-    <img src="https://arduinojson.org/images/2021/10/programmingeleactronicsacademy.png" alt="Programming Electronics Academy" width="200">
-  </a>
-</p>
 <p>
   <a href="https://github.com/1technophile" rel="sponsored">
     <img alt="1technophile" src="https://avatars.githubusercontent.com/u/12672732?s=40&v=4">

appveyor.yml

@@ -1,4 +1,4 @@
-version: 7.3.1.{build}
+version: 7.4.2.{build}
 environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2022

extras/conf_test/avr.cpp

@@ -12,7 +12,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 0, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 6, "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 6, "slot size");
 
 void setup() {}
 void loop() {}

extras/conf_test/esp8266.cpp

@@ -10,7 +10,7 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 8, "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 8, "slot size");
 
 void setup() {}
 void loop() {}

extras/conf_test/x64.cpp

@@ -10,7 +10,6 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 16,
-              "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 16, "slot size");
 
 int main() {}

extras/conf_test/x86.cpp

@@ -10,6 +10,6 @@ static_assert(ARDUINOJSON_LITTLE_ENDIAN == 1, "ARDUINOJSON_LITTLE_ENDIAN");
 
 static_assert(ARDUINOJSON_USE_DOUBLE == 1, "ARDUINOJSON_USE_DOUBLE");
 
-static_assert(ArduinoJson::detail::ResourceManager::slotSize == 8, "slot size");
+static_assert(sizeof(ArduinoJson::detail::VariantData) == 8, "slot size");
 
 int main() {}

extras/tests/Deprecated/BasicJsonDocument.cpp

@@ -46,7 +46,7 @@ TEST_CASE("BasicJsonDocument") {
     deserializeJson(doc, "{\"hello\":\"world\"}");
     REQUIRE(doc.as<std::string>() == "{\"hello\":\"world\"}");
     doc.clear();
-    REQUIRE(allocatorLog == "ARAARDDD");
+    REQUIRE(allocatorLog == "AARARDDD");
   }
 
   SECTION("copy") {
@@ -54,7 +54,7 @@ TEST_CASE("BasicJsonDocument") {
     doc["hello"] = "world";
     auto copy = doc;
     REQUIRE(copy.as<std::string>() == "{\"hello\":\"world\"}");
-    REQUIRE(allocatorLog == "AA");
+    REQUIRE(allocatorLog == "AAAA");
   }
 
   SECTION("capacity") {

extras/tests/Helpers/Allocators.hpp

@@ -269,10 +269,16 @@ inline size_t sizeofPoolList(size_t n = ARDUINOJSON_INITIAL_POOL_COUNT) {
   return sizeof(MemoryPool<VariantData>) * n;
 }
 
+template <typename T = ArduinoJson::detail::VariantData>
 inline size_t sizeofPool(
     ArduinoJson::detail::SlotCount n = ARDUINOJSON_POOL_CAPACITY) {
+  return ArduinoJson::detail::MemoryPool<T>::slotsToBytes(n);
+}
+
+inline size_t sizeofStaticStringPool(
+    ArduinoJson::detail::SlotCount n = ARDUINOJSON_POOL_CAPACITY) {
   using namespace ArduinoJson::detail;
-  return MemoryPool<VariantData>::slotsToBytes(n);
+  return MemoryPool<const char*>::slotsToBytes(n);
 }
 
 inline size_t sizeofStringBuffer(size_t iteration = 1) {

extras/tests/JsonArray/add.cpp

@@ -8,7 +8,7 @@
 #include "Allocators.hpp"
 #include "Literals.hpp"
 
-using ArduinoJson::detail::sizeofArray;
+using namespace ArduinoJson::detail;
 
 TEST_CASE("JsonArray::add(T)") {
   SpyingAllocator spy;
@@ -33,7 +33,8 @@ TEST_CASE("JsonArray::add(T)") {
     REQUIRE(array[0].is<double>());
     REQUIRE_FALSE(array[0].is<bool>());
     REQUIRE(spy.log() == AllocatorLog{
-                             Allocate(sizeofPool()),
+                             Allocate(sizeofPool<VariantData>()),
+                             Allocate(sizeofPool<EightByteValue>()),
                          });
   }
 
@@ -56,6 +57,7 @@ TEST_CASE("JsonArray::add(T)") {
     REQUIRE(array[0].is<int>() == false);
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 

extras/tests/JsonDeserializer/array.cpp

@@ -7,7 +7,7 @@
 
 #include "Allocators.hpp"
 
-using ArduinoJson::detail::sizeofArray;
+using namespace ArduinoJson::detail;
 
 TEST_CASE("deserialize JSON array") {
   SpyingAllocator spy;
@@ -92,8 +92,12 @@ TEST_CASE("deserialize JSON array") {
       REQUIRE(arr[0].as<double>() == Approx(4.2123456));
       REQUIRE(arr[1] == -7E89);
       REQUIRE(spy.log() == AllocatorLog{
-                               Allocate(sizeofPool()),
-                               Reallocate(sizeofPool(), sizeofPool(4)),
+                               Allocate(sizeofPool<VariantData>()),
+                               Allocate(sizeofPool<EightByteValue>()),
+                               Reallocate(sizeofPool<VariantData>(),
+                                          sizeofPool<VariantData>(2)),
+                               Reallocate(sizeofPool<EightByteValue>(),
+                                          sizeofPool<EightByteValue>(2)),
                            });
     }
 

extras/tests/JsonDeserializer/destination_types.cpp

@@ -104,6 +104,8 @@ TEST_CASE("deserializeJson(MemberProxy)") {
 
     REQUIRE(err == DeserializationError::Ok);
     REQUIRE(doc.as<std::string>() == "{\"hello\":\"world\",\"value\":[42]}");
-    REQUIRE(spy.log() == AllocatorLog{});
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofStaticStringPool()),
+                         });
   }
 }

extras/tests/JsonDeserializer/errors.cpp

@@ -121,7 +121,7 @@ TEST_CASE("deserializeJson() returns NoMemory if string length overflows") {
   }
 }
 
-TEST_CASE("deserializeJson() returns NoMemory if extension allocation fails") {
+TEST_CASE("deserializeJson() returns NoMemory if 8-bit slot allocation fails") {
   JsonDocument doc(FailingAllocator::instance());
 
   SECTION("uint32_t should pass") {

extras/tests/JsonDeserializer/filter.cpp

@@ -825,7 +825,9 @@ TEST_CASE("shrink filter") {
 
   deserializeJson(doc, "{}", DeserializationOption::Filter(filter));
 
-  REQUIRE(spy.log() == AllocatorLog{
-                           Reallocate(sizeofPool(), sizeofObject(1)),
-                       });
+  REQUIRE(spy.log() ==
+          AllocatorLog{
+              Reallocate(sizeofPool(), sizeofObject(1)),
+              Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(1)),
+          });
 }

extras/tests/JsonDeserializer/input_types.cpp

@@ -26,8 +26,8 @@ TEST_CASE("deserializeJson(char*)") {
   REQUIRE(spy.log() ==
           AllocatorLog{
               Allocate(sizeofStringBuffer()),
-              Reallocate(sizeofStringBuffer(), sizeofString("hello")),
               Allocate(sizeofPool()),
+              Reallocate(sizeofStringBuffer(), sizeofString("hello")),
               Allocate(sizeofStringBuffer()),
               Reallocate(sizeofStringBuffer(), sizeofString("world")),
               Reallocate(sizeofPool(), sizeofObject(1)),

extras/tests/JsonDeserializer/object.cpp

@@ -292,22 +292,23 @@ TEST_CASE("deserialize JSON object") {
     }
 
     SECTION("Repeated key") {
-      DeserializationError err = deserializeJson(doc, "{a:{b:{c:1}},a:2}");
+      DeserializationError err =
+          deserializeJson(doc, "{alfa:{bravo:{charlie:1}},alfa:2}");
 
       REQUIRE(err == DeserializationError::Ok);
-      REQUIRE(doc.as<std::string>() == "{\"a\":2}");
+      REQUIRE(doc.as<std::string>() == "{\"alfa\":2}");
       REQUIRE(spy.log() ==
               AllocatorLog{
                   Allocate(sizeofStringBuffer()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("a")),
                   Allocate(sizeofPool()),
+                  Reallocate(sizeofStringBuffer(), sizeofString("alfa")),
                   Allocate(sizeofStringBuffer()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("b")),
+                  Reallocate(sizeofStringBuffer(), sizeofString("bravo")),
                   Allocate(sizeofStringBuffer()),
-                  Reallocate(sizeofStringBuffer(), sizeofString("c")),
+                  Reallocate(sizeofStringBuffer(), sizeofString("charlie")),
                   Allocate(sizeofStringBuffer()),
-                  Deallocate(sizeofString("b")),
-                  Deallocate(sizeofString("c")),
+                  Deallocate(sizeofString("bravo")),
+                  Deallocate(sizeofString("charlie")),
                   Deallocate(sizeofStringBuffer()),
                   Reallocate(sizeofPool(), sizeofObject(2) + sizeofObject(1)),
               });
@@ -378,7 +379,7 @@ TEST_CASE("deserialize JSON object under memory constraints") {
   }
 
   SECTION("pool allocation fails") {
-    timebomb.setCountdown(2);
+    timebomb.setCountdown(1);
     char input[] = "{\"a\":1}";
 
     DeserializationError err = deserializeJson(doc, input);
@@ -389,11 +390,11 @@ TEST_CASE("deserialize JSON object under memory constraints") {
 
   SECTION("string allocation fails") {
     timebomb.setCountdown(3);
-    char input[] = "{\"a\":\"b\"}";
+    char input[] = "{\"alfa\":\"bravo\"}";
 
     DeserializationError err = deserializeJson(doc, input);
 
     REQUIRE(err == DeserializationError::NoMemory);
-    REQUIRE(doc.as<std::string>() == "{\"a\":null}");
+    REQUIRE(doc.as<std::string>() == "{\"alfa\":null}");
   }
 }

extras/tests/JsonDeserializer/string.cpp

@@ -133,8 +133,8 @@ TEST_CASE("Allocation of the key fails") {
     REQUIRE(spy.log() ==
             AllocatorLog{
                 Allocate(sizeofStringBuffer()),
-                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
                 Allocate(sizeofPool()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
                 AllocateFail(sizeofStringBuffer()),
                 ReallocateFail(sizeofPool(), sizeofObject(1)),
             });
@@ -155,8 +155,8 @@ TEST_CASE("Allocation of the key fails") {
     REQUIRE(spy.log() ==
             AllocatorLog{
                 Allocate(sizeofStringBuffer()),
-                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
                 Allocate(sizeofPool()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
                 AllocateFail(sizeofStringBuffer()),
                 ReallocateFail(sizeofPool(), sizeofObject(1)),
             });

extras/tests/JsonDocument/ElementProxy.cpp

@@ -31,6 +31,7 @@ TEST_CASE("ElementProxy::add()") {
     REQUIRE(doc.as<std::string>() == "[[\"world\"]]");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 

extras/tests/JsonDocument/MemberProxy.cpp

@@ -25,6 +25,7 @@ TEST_CASE("MemberProxy::add()") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":[42]}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 
@@ -34,6 +35,7 @@ TEST_CASE("MemberProxy::add()") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":[\"world\"]}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 
@@ -44,6 +46,7 @@ TEST_CASE("MemberProxy::add()") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":[\"world\"]}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              Allocate(sizeofString("world")),
                          });
   }
@@ -55,8 +58,8 @@ TEST_CASE("MemberProxy::add()") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":[\"world\"]}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              Allocate(sizeofString("world")),
-
                          });
   }
 
@@ -71,6 +74,7 @@ TEST_CASE("MemberProxy::add()") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":[\"world\"]}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              Allocate(sizeofString("world")),
                          });
   }
@@ -399,7 +403,7 @@ TEST_CASE("MemberProxy under memory constraints") {
   }
 
   SECTION("value slot allocation fails") {
-    timebomb.setCountdown(1);
+    timebomb.setCountdown(2);
 
     // fill the pool entirely, but leave one slot for the key
     doc["foo"][ARDUINOJSON_POOL_CAPACITY - 4] = 1;
@@ -412,6 +416,7 @@ TEST_CASE("MemberProxy under memory constraints") {
     REQUIRE(doc.overflowed() == true);
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              AllocateFail(sizeofPool()),
                          });
   }

extras/tests/JsonDocument/add.cpp

@@ -32,6 +32,7 @@ TEST_CASE("JsonDocument::add(T)") {
     REQUIRE(doc.as<std::string>() == "[\"hello\"]");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 

extras/tests/JsonDocument/assignment.cpp

@@ -69,6 +69,8 @@ TEST_CASE("JsonDocument assignment") {
       doc2 = std::move(doc1);
 
       REQUIRE(doc2.as<std::string>() == "{\"hello\":\"world\"}");
+
+      // NOLINTNEXTLINE(clang-analyzer-cplusplus.Move)
       REQUIRE(doc1.as<std::string>() == "null");
     }
     REQUIRE(spyingAllocator.log() == AllocatorLog{

extras/tests/JsonDocument/constructor.cpp

@@ -44,6 +44,8 @@ TEST_CASE("JsonDocument constructor") {
       JsonDocument doc2(std::move(doc1));
 
       REQUIRE(doc2.as<std::string>() == "The size of this string is 32!!");
+
+      // NOLINTNEXTLINE(clang-analyzer-cplusplus.Move)
       REQUIRE(doc1.as<std::string>() == "null");
     }
     REQUIRE(spyingAllocator.log() == AllocatorLog{
@@ -62,6 +64,7 @@ TEST_CASE("JsonDocument constructor") {
     REQUIRE(doc2.as<std::string>() == "{\"hello\":\"world\"}");
     REQUIRE(spyingAllocator.log() == AllocatorLog{
                                          Allocate(sizeofPool()),
+                                         Allocate(sizeofStaticStringPool()),
                                      });
   }
 
@@ -85,6 +88,7 @@ TEST_CASE("JsonDocument constructor") {
     REQUIRE(doc2.as<std::string>() == "[\"hello\"]");
     REQUIRE(spyingAllocator.log() == AllocatorLog{
                                          Allocate(sizeofPool()),
+                                         Allocate(sizeofStaticStringPool()),
                                      });
   }
 

extras/tests/JsonDocument/remove.cpp

@@ -22,10 +22,10 @@ TEST_CASE("JsonDocument::remove()") {
 
   SECTION("string literal") {
     doc["a"] = 1;
-    doc["a\0b"_s] = 2;
+    doc["x"] = 2;
     doc["b"] = 3;
 
-    doc.remove("a\0b");
+    doc.remove("x");
 
     REQUIRE(doc.as<std::string>() == "{\"a\":1,\"b\":3}");
   }

extras/tests/JsonDocument/set.cpp

@@ -37,7 +37,9 @@ TEST_CASE("JsonDocument::set()") {
     doc.set("example");
 
     REQUIRE(doc.as<const char*>() == "example"_s);
-    REQUIRE(spy.log() == AllocatorLog{});
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofStaticStringPool()),
+                         });
   }
 
   SECTION("const char*") {
@@ -87,6 +89,13 @@ TEST_CASE("JsonDocument::set()") {
                          });
   }
 
+  SECTION("Flash tiny string") {  // issue #2170
+    doc.set(F("abc"));
+
+    REQUIRE(doc.as<const char*>() == "abc"_s);
+    REQUIRE(spy.log() == AllocatorLog{});
+  }
+
 #ifdef HAS_VARIABLE_LENGTH_ARRAY
   SECTION("VLA") {
     size_t i = 16;

extras/tests/JsonDocument/shrinkToFit.cpp

@@ -75,7 +75,11 @@ TEST_CASE("JsonDocument::shrinkToFit()") {
     doc.shrinkToFit();
 
     REQUIRE(doc.as<std::string>() == "hello");
-    REQUIRE(spyingAllocator.log() == AllocatorLog{});
+    REQUIRE(spyingAllocator.log() ==
+            AllocatorLog{
+                Allocate(sizeofStaticStringPool()),
+                Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(1)),
+            });
   }
 
   SECTION("owned string") {
@@ -110,7 +114,9 @@ TEST_CASE("JsonDocument::shrinkToFit()") {
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
+                Allocate(sizeofStaticStringPool()),
                 Reallocate(sizeofPool(), sizeofObject(1)),
+                Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(1)),
             });
   }
 
@@ -137,7 +143,9 @@ TEST_CASE("JsonDocument::shrinkToFit()") {
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
+                Allocate(sizeofStaticStringPool()),
                 Reallocate(sizeofPool(), sizeofArray(1)),
+                Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(1)),
             });
   }
 
@@ -164,20 +172,23 @@ TEST_CASE("JsonDocument::shrinkToFit()") {
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
+                Allocate(sizeofStaticStringPool()),
                 Reallocate(sizeofPool(), sizeofObject(1)),
+                Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(2)),
             });
   }
 
   SECTION("owned string in object") {
-    doc["key"] = "abcdefg"_s;
+    doc["key1"_s] = "value"_s;
 
     doc.shrinkToFit();
 
-    REQUIRE(doc.as<std::string>() == "{\"key\":\"abcdefg\"}");
+    REQUIRE(doc.as<std::string>() == "{\"key1\":\"value\"}");
     REQUIRE(spyingAllocator.log() ==
             AllocatorLog{
                 Allocate(sizeofPool()),
-                Allocate(sizeofString("abcdefg")),
+                Allocate(sizeofString("key1")),
+                Allocate(sizeofString("value")),
                 Reallocate(sizeofPool(), sizeofPool(2)),
             });
   }

extras/tests/JsonDocument/subscript.cpp

@@ -25,8 +25,6 @@ TEST_CASE("JsonDocument::operator[]") {
     SECTION("string literal") {
       REQUIRE(doc["abc"] == "ABC");
       REQUIRE(cdoc["abc"] == "ABC");
-      REQUIRE(doc["abc\0d"] == "ABCD");
-      REQUIRE(cdoc["abc\0d"] == "ABCD");
     }
 
     SECTION("std::string") {
@@ -114,6 +112,7 @@ TEST_CASE("JsonDocument::operator[] key storage") {
     REQUIRE(doc.as<std::string>() == "{\"hello\":0}");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 

extras/tests/JsonObject/set.cpp

@@ -26,25 +26,12 @@ TEST_CASE("JsonObject::set()") {
     REQUIRE(obj2["hello"] == "world"_s);
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 
-  SECTION("copy local string value") {
-    obj1["hello"] = "world"_s;
-    spy.clearLog();
-
-    bool success = obj2.set(obj1);
-
-    REQUIRE(success == true);
-    REQUIRE(obj2["hello"] == "world"_s);
-    REQUIRE(spy.log() == AllocatorLog{
-                             Allocate(sizeofPool()),
-                             Allocate(sizeofString("world")),
-                         });
-  }
-
-  SECTION("copy local key") {
-    obj1["hello"_s] = "world";
+  SECTION("copy local string key and value") {
+    obj1["hello"_s] = "world"_s;
     spy.clearLog();
 
     bool success = obj2.set(obj1);
@@ -54,6 +41,7 @@ TEST_CASE("JsonObject::set()") {
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
                              Allocate(sizeofString("hello")),
+                             Allocate(sizeofString("world")),
                          });
   }
 
@@ -100,17 +88,17 @@ TEST_CASE("JsonObject::set()") {
     JsonDocument doc3(&timebomb);
     JsonObject obj3 = doc3.to<JsonObject>();
 
-    obj1["a"_s] = 1;
-    obj1["b"_s] = 2;
+    obj1["alpha"_s] = 1;
+    obj1["beta"_s] = 2;
 
     bool success = obj3.set(obj1);
 
     REQUIRE(success == false);
-    REQUIRE(doc3.as<std::string>() == "{\"a\":1}");
+    REQUIRE(doc3.as<std::string>() == "{\"alpha\":1}");
   }
 
   SECTION("copy fails in the middle of an array") {
-    TimebombAllocator timebomb(1);
+    TimebombAllocator timebomb(2);
     JsonDocument doc3(&timebomb);
     JsonObject obj3 = doc3.to<JsonObject>();
 

extras/tests/JsonObject/subscript.cpp

@@ -102,21 +102,25 @@ TEST_CASE("JsonObject::operator[]") {
     REQUIRE(42 == obj[key]);
   }
 
-  SECTION("should not duplicate const char*") {
+  SECTION("string literals") {
     obj["hello"] = "world";
-    REQUIRE(spy.log() == AllocatorLog{Allocate(sizeofPool())});
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
+                         });
   }
 
   SECTION("should duplicate char* value") {
     obj["hello"] = const_cast<char*>("world");
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              Allocate(sizeofString("world")),
                          });
   }
 
   SECTION("should duplicate char* key") {
-    obj[const_cast<char*>("hello")] = "world";
+    obj[const_cast<char*>("hello")] = 42;
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
                              Allocate(sizeofString("hello")),
@@ -136,12 +140,13 @@ TEST_CASE("JsonObject::operator[]") {
     obj["hello"] = "world"_s;
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                              Allocate(sizeofString("world")),
                          });
   }
 
   SECTION("should duplicate std::string key") {
-    obj["hello"_s] = "world";
+    obj["hello"_s] = 42;
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
                              Allocate(sizeofString("hello")),
@@ -158,7 +163,7 @@ TEST_CASE("JsonObject::operator[]") {
   }
 
   SECTION("should duplicate a non-static JsonString key") {
-    obj[JsonString("hello", false)] = "world";
+    obj[JsonString("hello", false)] = 42;
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
                              Allocate(sizeofString("hello")),
@@ -166,9 +171,10 @@ TEST_CASE("JsonObject::operator[]") {
   }
 
   SECTION("should not duplicate a static JsonString key") {
-    obj[JsonString("hello", true)] = "world";
+    obj[JsonString("hello", true)] = 42;
     REQUIRE(spy.log() == AllocatorLog{
                              Allocate(sizeofPool()),
+                             Allocate(sizeofStaticStringPool()),
                          });
   }
 

extras/tests/JsonVariant/as.cpp

@@ -199,7 +199,7 @@ TEST_CASE("JsonVariant::as()") {
     REQUIRE(variant.as<JsonString>() == "hello");
   }
 
-  SECTION("set(std::string(\"4.2\"))") {
+  SECTION("set(std::string(\"4.2\")) (tiny string optimization)") {
     variant.set("4.2"_s);
 
     REQUIRE(variant.as<bool>() == true);
@@ -211,6 +211,18 @@ TEST_CASE("JsonVariant::as()") {
     REQUIRE(variant.as<JsonString>().isStatic() == false);
   }
 
+  SECTION("set(std::string(\"123.45\"))") {
+    variant.set("123.45"_s);
+
+    REQUIRE(variant.as<bool>() == true);
+    REQUIRE(variant.as<long>() == 123L);
+    REQUIRE(variant.as<double>() == Approx(123.45));
+    REQUIRE(variant.as<const char*>() == "123.45"_s);
+    REQUIRE(variant.as<std::string>() == "123.45"_s);
+    REQUIRE(variant.as<JsonString>() == "123.45");
+    REQUIRE(variant.as<JsonString>().isStatic() == false);
+  }
+
   SECTION("set(\"true\")") {
     variant.set("true");
 

extras/tests/JsonVariant/copy.cpp

@@ -38,13 +38,15 @@ TEST_CASE("JsonVariant::set(JsonVariant)") {
     REQUIRE(var1.as<std::string>() == "{\"value\":[42]}");
   }
 
-  SECTION("stores const char* by reference") {
+  SECTION("stores string literals by pointer") {
     var1.set("hello!!");
     spyingAllocator.clearLog();
 
     var2.set(var1);
 
-    REQUIRE(spyingAllocator.log() == AllocatorLog{});
+    REQUIRE(spyingAllocator.log() == AllocatorLog{
+                                         Allocate(sizeofStaticStringPool()),
+                                     });
   }
 
   SECTION("stores char* by copy") {

extras/tests/JsonVariant/set.cpp

@@ -8,7 +8,7 @@
 #include "Allocators.hpp"
 #include "Literals.hpp"
 
-using ArduinoJson::detail::sizeofObject;
+using namespace ArduinoJson::detail;
 
 enum ErrorCode { ERROR_01 = 1, ERROR_10 = 10 };
 
@@ -23,7 +23,9 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
     REQUIRE(result == true);
     CHECK(variant ==
           "hello"_s);  // linked string cannot contain '\0' at the moment
-    CHECK(spy.log() == AllocatorLog{});
+    CHECK(spy.log() == AllocatorLog{
+                           Allocate(sizeofStaticStringPool()),
+                       });
   }
 
   SECTION("const char*") {
@@ -63,6 +65,18 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
                          });
   }
 
+  SECTION("char* (tiny string optimization)") {
+    char str[16];
+
+    strcpy(str, "abc");
+    bool result = variant.set(str);
+    strcpy(str, "def");
+
+    REQUIRE(result == true);
+    REQUIRE(variant == "abc");  // stores by copy
+    REQUIRE(spy.log() == AllocatorLog{});
+  }
+
   SECTION("(char*)0") {
     bool result = variant.set(static_cast<char*>(0));
 
@@ -137,7 +151,9 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
 
     REQUIRE(result == true);
     REQUIRE(variant == "world");  // stores by pointer
-    REQUIRE(spy.log() == AllocatorLog{});
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofStaticStringPool()),
+                         });
   }
 
   SECTION("non-static JsonString") {
@@ -181,11 +197,11 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
     REQUIRE(result == true);
     REQUIRE(variant.is<double>() == true);
     REQUIRE(variant.as<double>() == 1.2);
-    REQUIRE(spy.log() ==
-            AllocatorLog{
-                Allocate(sizeofPool()),
-                Reallocate(sizeofPool(), sizeofPool(1)),  // one extension slot
-            });
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofPool<EightByteValue>()),
+                             Reallocate(sizeofPool<EightByteValue>(),
+                                        sizeofPool<EightByteValue>(1)),
+                         });
   }
 
   SECTION("int32_t") {
@@ -204,11 +220,11 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
     REQUIRE(result == true);
     REQUIRE(variant.is<int64_t>() == true);
     REQUIRE(variant.as<int64_t>() == -2147483649LL);
-    REQUIRE(spy.log() ==
-            AllocatorLog{
-                Allocate(sizeofPool()),
-                Reallocate(sizeofPool(), sizeofPool(1)),  // one extension slot
-            });
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofPool<EightByteValue>()),
+                             Reallocate(sizeofPool<EightByteValue>(),
+                                        sizeofPool<EightByteValue>(1)),
+                         });
   }
 
   SECTION("uint32_t") {
@@ -227,11 +243,11 @@ TEST_CASE("JsonVariant::set() when there is enough memory") {
     REQUIRE(result == true);
     REQUIRE(variant.is<uint64_t>() == true);
     REQUIRE(variant.as<uint64_t>() == 4294967296);
-    REQUIRE(spy.log() ==
-            AllocatorLog{
-                Allocate(sizeofPool()),
-                Reallocate(sizeofPool(), sizeofPool(1)),  // one extension slot
-            });
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofPool<EightByteValue>()),
+                             Reallocate(sizeofPool<EightByteValue>(),
+                                        sizeofPool<EightByteValue>(1)),
+                         });
   }
 
   SECTION("JsonDocument") {
@@ -253,6 +269,20 @@ TEST_CASE("JsonVariant::set() with not enough memory") {
 
   JsonVariant v = doc.to<JsonVariant>();
 
+  SECTION("string literal") {
+    bool result = v.set("hello world");
+
+    REQUIRE(result == false);
+    REQUIRE(v.isNull());
+  }
+
+  SECTION("static JsonString") {
+    bool result = v.set(JsonString("hello world", true));
+
+    REQUIRE(result == false);
+    REQUIRE(v.isNull());
+  }
+
   SECTION("std::string") {
     bool result = v.set("hello world!!"_s);
 
@@ -348,7 +378,7 @@ TEST_CASE("JsonVariant::set() releases the previous value") {
   }
 
   SECTION("float") {
-    v.set(1.2);
+    v.set(1.2f);
     REQUIRE(spy.log() == AllocatorLog{
                              Deallocate(sizeofString("world")),
                          });
@@ -363,7 +393,7 @@ TEST_CASE("JsonVariant::set() releases the previous value") {
   }
 }
 
-TEST_CASE("JsonVariant::set() reuses extension slot") {
+TEST_CASE("JsonVariant::set() reuses 8-bit slot") {
   SpyingAllocator spy;
   JsonDocument doc(&spy);
   JsonVariant variant = doc.to<JsonVariant>();

extras/tests/JsonVariantConst/subscript.cpp

@@ -57,7 +57,7 @@ TEST_CASE("JsonVariantConst::operator[]") {
     SECTION("string literal") {
       REQUIRE(var["ab"] == "AB"_s);
       REQUIRE(var["abc"] == "ABC"_s);
-      REQUIRE(var["abc\0d"] == "ABCD"_s);
+      REQUIRE(var["abc\0d"] == "ABC"_s);
       REQUIRE(var["def"].isNull());
       REQUIRE(var[0].isNull());
     }

extras/tests/Misc/CMakeLists.txt

@@ -7,6 +7,7 @@ add_executable(MiscTests
 	conflicts.cpp
 	issue1967.cpp
 	issue2129.cpp
+	issue2166.cpp
 	JsonString.cpp
 	NoArduinoHeader.cpp
 	printable.cpp
@@ -28,3 +29,23 @@ set_tests_properties(Misc
 	PROPERTIES
 		LABELS "Catch"
 )
+
+add_executable(Issue2181
+	issue2181.cpp # Cannot be linked with other tests
+)
+
+set_target_properties(Issue2181 PROPERTIES UNITY_BUILD OFF)
+
+add_test(Issue2181 Issue2181)
+
+set_tests_properties(Issue2181
+	PROPERTIES
+		LABELS "Catch"
+)
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+	target_compile_options(Issue2181
+		PRIVATE
+			-Wno-keyword-macro # keyword is hidden by macro definition
+	)
+endif()

extras/tests/Misc/StringAdapters.cpp

@@ -21,7 +21,7 @@ TEST_CASE("adaptString()") {
     auto s = adaptString("bravo\0alpha");
 
     CHECK(s.isNull() == false);
-    CHECK(s.size() == 11);
+    CHECK(s.size() == 5);
     CHECK(s.isStatic() == true);
   }
 
@@ -128,6 +128,7 @@ TEST_CASE("IsString<T>") {
   CHECK(IsString<const __FlashStringHelper*>::value == true);
   CHECK(IsString<const char*>::value == true);
   CHECK(IsString<const char[8]>::value == true);
+  CHECK(IsString<const char[]>::value == true);
   CHECK(IsString<::String>::value == true);
   CHECK(IsString<::StringSumHelper>::value == true);
   CHECK(IsString<const EmptyStruct*>::value == false);

extras/tests/Misc/issue2166.cpp

@@ -0,0 +1,22 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2025, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+struct CCLASS {
+  static const char mszKey[];
+};
+
+TEST_CASE("Issue #2166") {
+  JsonDocument doc;
+  doc[CCLASS::mszKey] = 12;
+  REQUIRE(doc.as<std::string>() == "{\"test3\":12}");
+
+  JsonObject obj = doc.to<JsonObject>();
+  obj[CCLASS::mszKey] = 12;
+  REQUIRE(doc.as<std::string>() == "{\"test3\":12}");
+}
+
+const char CCLASS::mszKey[] = "test3";

extras/tests/Misc/issue2181.cpp

@@ -0,0 +1,15 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2025, Benoit BLANCHON
+// MIT License
+
+#define true 0x1
+#define false 0x0
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+TEST_CASE("Issue #2181") {
+  JsonDocument doc;
+  doc["hello"] = "world";
+  REQUIRE(doc.as<std::string>() == "{\"hello\":\"world\"}");
+}

extras/tests/MsgPackDeserializer/deserializeArray.cpp

@@ -5,8 +5,11 @@
 #include <ArduinoJson.h>
 #include <catch.hpp>
 
+#include "Allocators.hpp"
+
 TEST_CASE("deserialize MsgPack array") {
-  JsonDocument doc;
+  SpyingAllocator spy;
+  JsonDocument doc(&spy);
 
   SECTION("fixarray") {
     SECTION("empty") {
@@ -30,6 +33,24 @@ TEST_CASE("deserialize MsgPack array") {
       REQUIRE(array[0] == 1);
       REQUIRE(array[1] == 2);
     }
+
+    SECTION("tiny strings") {
+      DeserializationError error =
+          deserializeMsgPack(doc, "\x92\xA3xxx\xA3yyy");
+
+      REQUIRE(error == DeserializationError::Ok);
+      REQUIRE(doc.is<JsonArray>());
+      REQUIRE(doc.size() == 2);
+      REQUIRE(doc[0] == "xxx");
+      REQUIRE(doc[1] == "yyy");
+      REQUIRE(spy.log() == AllocatorLog{
+                               Allocate(sizeofPool()),
+                               Allocate(sizeofString("xxx")),
+                               // Buffer is reused for the next string
+                               Deallocate(sizeofString("xxx")),
+                               Reallocate(sizeofPool(), sizeofPool(2)),
+                           });
+    }
   }
 
   SECTION("array 16") {

extras/tests/MsgPackDeserializer/deserializeVariant.cpp

@@ -348,13 +348,14 @@ TEST_CASE("deserializeMsgPack() under memory constaints") {
     SECTION("{}") {
       checkError(0, "\x80", DeserializationError::Ok);
     }
-    SECTION("{H:1}") {
-      checkError(1, "\x81\xA1H\x01", DeserializationError::NoMemory);
-      checkError(2, "\x81\xA1H\x01", DeserializationError::Ok);
+    SECTION("{Hello:1}") {
+      checkError(1, "\x81\xA5Hello\x01", DeserializationError::NoMemory);
+      checkError(2, "\x81\xA5Hello\x01", DeserializationError::Ok);
     }
-    SECTION("{H:1,W:2}") {
-      checkError(2, "\x82\xA1H\x01\xA1W\x02", DeserializationError::NoMemory);
-      checkError(3, "\x82\xA1H\x01\xA1W\x02", DeserializationError::Ok);
+    SECTION("{Hello:1,World:2}") {
+      checkError(2, "\x82\xA5Hello\x01\xA5World\x02",
+                 DeserializationError::NoMemory);
+      checkError(3, "\x82\xA5Hello\x01\xA5World\x02", DeserializationError::Ok);
     }
   }
 
@@ -362,14 +363,16 @@ TEST_CASE("deserializeMsgPack() under memory constaints") {
     SECTION("{}") {
       checkError(0, "\xDE\x00\x00", DeserializationError::Ok);
     }
-    SECTION("{H:1}") {
-      checkError(1, "\xDE\x00\x01\xA1H\x01", DeserializationError::NoMemory);
-      checkError(2, "\xDE\x00\x01\xA1H\x01", DeserializationError::Ok);
-    }
-    SECTION("{H:1,W:2}") {
-      checkError(2, "\xDE\x00\x02\xA1H\x01\xA1W\x02",
+    SECTION("{Hello:1}") {
+      checkError(1, "\xDE\x00\x01\xA5Hello\x01",
                  DeserializationError::NoMemory);
-      checkError(3, "\xDE\x00\x02\xA1H\x01\xA1W\x02", DeserializationError::Ok);
+      checkError(2, "\xDE\x00\x01\xA5Hello\x01", DeserializationError::Ok);
+    }
+    SECTION("{Hello:1,World:2}") {
+      checkError(2, "\xDE\x00\x02\xA5Hello\x01\xA5World\x02",
+                 DeserializationError::NoMemory);
+      checkError(3, "\xDE\x00\x02\xA5Hello\x01\xA5World\x02",
+                 DeserializationError::Ok);
     }
   }
 
@@ -382,8 +385,8 @@ TEST_CASE("deserializeMsgPack() under memory constaints") {
                  DeserializationError::NoMemory);
       checkError(2, "\xDF\x00\x00\x00\x01\xA1H\x01", DeserializationError::Ok);
     }
-    SECTION("{H:1,W:2}") {
-      checkError(2, "\xDF\x00\x00\x00\x02\xA1H\x01\xA1W\x02",
+    SECTION("{Hello:1,World:2}") {
+      checkError(2, "\xDF\x00\x00\x00\x02\xA5Hello\x01\xA5World\x02",
                  DeserializationError::NoMemory);
       checkError(3, "\xDF\x00\x00\x00\x02\xA1H\x01\xA1W\x02",
                  DeserializationError::Ok);

extras/tests/MsgPackDeserializer/destination_types.cpp

@@ -104,6 +104,8 @@ TEST_CASE("deserializeMsgPack(MemberProxy)") {
 
     REQUIRE(err == DeserializationError::Ok);
     REQUIRE(doc.as<std::string>() == "{\"hello\":\"world\",\"value\":[42]}");
-    REQUIRE(spy.log() == AllocatorLog{});
+    REQUIRE(spy.log() == AllocatorLog{
+                             Allocate(sizeofStaticStringPool()),
+                         });
   }
 }

extras/tests/ResourceManager/CMakeLists.txt

@@ -5,9 +5,11 @@
 add_executable(ResourceManagerTests
 	allocVariant.cpp
 	clear.cpp
+	saveStaticString.cpp
 	saveString.cpp
 	shrinkToFit.cpp
 	size.cpp
+	StringBuffer.cpp
 	StringBuilder.cpp
 	swap.cpp
 )

extras/tests/ResourceManager/StringBuffer.cpp

@@ -0,0 +1,50 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2025, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson.hpp>
+#include <catch.hpp>
+
+#include "Allocators.hpp"
+#include "Literals.hpp"
+
+using namespace ArduinoJson::detail;
+
+TEST_CASE("StringBuffer") {
+  SpyingAllocator spy;
+  ResourceManager resources(&spy);
+  StringBuffer sb(&resources);
+  VariantData variant;
+
+  SECTION("Tiny string") {
+    auto ptr = sb.reserve(3);
+    strcpy(ptr, "hi!");
+    sb.save(&variant);
+
+    REQUIRE(variant.type == VariantType::TinyString);
+    REQUIRE(VariantImpl(&variant, &resources).asString() == "hi!");
+  }
+
+  SECTION("Tiny string can't contain NUL") {
+    auto ptr = sb.reserve(3);
+    memcpy(ptr, "a\0b", 3);
+    sb.save(&variant);
+
+    REQUIRE(variant.type == VariantType::OwnedString);
+
+    auto str = VariantImpl(&variant, &resources).asString();
+    REQUIRE(str.size() == 3);
+    REQUIRE(str.c_str()[0] == 'a');
+    REQUIRE(str.c_str()[1] == 0);
+    REQUIRE(str.c_str()[2] == 'b');
+  }
+
+  SECTION("Tiny string can't have 4 characters") {
+    auto ptr = sb.reserve(4);
+    strcpy(ptr, "alfa");
+    sb.save(&variant);
+
+    REQUIRE(variant.type == VariantType::OwnedString);
+    REQUIRE(VariantImpl(&variant, &resources).asString() == "alfa");
+  }
+}

extras/tests/ResourceManager/StringBuilder.cpp

@@ -2,11 +2,12 @@
 // Copyright © 2014-2025, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/StringBuilder.hpp>
+#include <ArduinoJson.hpp>
 #include <catch.hpp>
 
 #include "Allocators.hpp"
 
+using namespace ArduinoJson;
 using namespace ArduinoJson::detail;
 
 TEST_CASE("StringBuilder") {
@@ -16,17 +17,36 @@ TEST_CASE("StringBuilder") {
 
   SECTION("Empty string") {
     StringBuilder str(&resources);
+    VariantData data;
 
     str.startString();
-    str.save();
+    str.save(&data);
 
-    REQUIRE(resources.size() == sizeofString(""));
     REQUIRE(resources.overflowed() == false);
-    REQUIRE(spyingAllocator.log() ==
-            AllocatorLog{
-                Allocate(sizeofStringBuffer()),
-                Reallocate(sizeofStringBuffer(), sizeofString("")),
-            });
+    REQUIRE(spyingAllocator.log() == AllocatorLog{
+                                         Allocate(sizeofStringBuffer()),
+                                     });
+    REQUIRE(data.type == VariantType::TinyString);
+  }
+
+  SECTION("Tiny string") {
+    StringBuilder str(&resources);
+
+    str.startString();
+    str.append("url");
+
+    REQUIRE(str.isValid() == true);
+    REQUIRE(str.str() == "url");
+    REQUIRE(spyingAllocator.log() == AllocatorLog{
+                                         Allocate(sizeofStringBuffer()),
+                                     });
+
+    VariantData data;
+    str.save(&data);
+
+    REQUIRE(resources.overflowed() == false);
+    REQUIRE(data.type == VariantType::TinyString);
+    REQUIRE(VariantImpl(&data, &resources).asString() == "url");
   }
 
   SECTION("Short string fits in first allocation") {
@@ -96,48 +116,74 @@ TEST_CASE("StringBuilder") {
   }
 }
 
-static StringNode* addStringToPool(ResourceManager& resources, const char* s) {
-  StringBuilder str(&resources);
-  str.startString();
-  str.append(s);
-  return str.save();
+static VariantData saveString(StringBuilder& builder, const char* s) {
+  VariantData data;
+  builder.startString();
+  builder.append(s);
+  builder.save(&data);
+  return data;
 }
 
 TEST_CASE("StringBuilder::save() deduplicates strings") {
-  ResourceManager resources;
+  SpyingAllocator spy;
+  ResourceManager resources(&spy);
+  StringBuilder builder(&resources);
 
   SECTION("Basic") {
-    auto s1 = addStringToPool(resources, "hello");
-    auto s2 = addStringToPool(resources, "world");
-    auto s3 = addStringToPool(resources, "hello");
+    auto s1 = saveString(builder, "hello");
+    auto s2 = saveString(builder, "world");
+    auto s3 = saveString(builder, "hello");
 
-    REQUIRE(s1 == s3);
-    REQUIRE(s2 != s3);
-    REQUIRE(s1->references == 2);
-    REQUIRE(s2->references == 1);
-    REQUIRE(s3->references == 2);
-    REQUIRE(resources.size() == sizeofString("hello") + sizeofString("world"));
+    REQUIRE(VariantImpl(&s1, &resources).asString() == "hello");
+    REQUIRE(VariantImpl(&s2, &resources).asString() == "world");
+    REQUIRE(+VariantImpl(&s1, &resources).asString().c_str() ==
+            +VariantImpl(&s3, &resources).asString().c_str());  // same address
+
+    REQUIRE(spy.log() ==
+            AllocatorLog{
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("world")),
+                Allocate(sizeofStringBuffer()),
+            });
   }
 
   SECTION("Requires terminator") {
-    auto s1 = addStringToPool(resources, "hello world");
-    auto s2 = addStringToPool(resources, "hello");
+    auto s1 = saveString(builder, "hello world");
+    auto s2 = saveString(builder, "hello");
 
-    REQUIRE(s2 != s1);
-    REQUIRE(s1->references == 1);
-    REQUIRE(s2->references == 1);
-    REQUIRE(resources.size() ==
-            sizeofString("hello world") + sizeofString("hello"));
+    REQUIRE(VariantImpl(&s1, &resources).asString() == "hello world");
+    REQUIRE(VariantImpl(&s2, &resources).asString() == "hello");
+    REQUIRE(
+        +VariantImpl(&s1, &resources).asString().c_str() !=
+        +VariantImpl(&s2, &resources).asString().c_str());  // different address
+
+    REQUIRE(spy.log() ==
+            AllocatorLog{
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello world")),
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello")),
+            });
   }
 
   SECTION("Don't overrun") {
-    auto s1 = addStringToPool(resources, "hello world");
-    auto s2 = addStringToPool(resources, "wor");
+    auto s1 = saveString(builder, "hello world");
+    auto s2 = saveString(builder, "worl");
 
-    REQUIRE(s2 != s1);
-    REQUIRE(s1->references == 1);
-    REQUIRE(s2->references == 1);
-    REQUIRE(resources.size() ==
-            sizeofString("hello world") + sizeofString("wor"));
+    REQUIRE(VariantImpl(&s1, &resources).asString() == "hello world");
+    REQUIRE(VariantImpl(&s2, &resources).asString() == "worl");
+    REQUIRE(
+        VariantImpl(&s1, &resources).asString().c_str() !=
+        VariantImpl(&s2, &resources).asString().c_str());  // different address
+
+    REQUIRE(spy.log() ==
+            AllocatorLog{
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("hello world")),
+                Allocate(sizeofStringBuffer()),
+                Reallocate(sizeofStringBuffer(), sizeofString("worl")),
+            });
   }
 }

extras/tests/ResourceManager/saveStaticString.cpp

@@ -0,0 +1,47 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2025, Benoit BLANCHON
+// MIT License
+
+#include <ArduinoJson/Memory/ResourceManager.hpp>
+#include <ArduinoJson/Strings/StringAdapters.hpp>
+#include <catch.hpp>
+
+#include "Allocators.hpp"
+
+using namespace ArduinoJson::detail;
+
+TEST_CASE("ResourceManager::saveStaticString() deduplicates strings") {
+  SpyingAllocator spy;
+  ResourceManager resources(&spy);
+
+  auto str1 = "hello";
+  auto str2 = "world";
+
+  auto id1 = resources.saveStaticString(str1);
+  auto id2 = resources.saveStaticString(str2);
+  REQUIRE(id1 != id2);
+
+  auto id3 = resources.saveStaticString(str1);
+  REQUIRE(id1 == id3);
+
+  resources.shrinkToFit();
+  REQUIRE(spy.log() ==
+          AllocatorLog{
+              Allocate(sizeofStaticStringPool()),
+              Reallocate(sizeofStaticStringPool(), sizeofStaticStringPool(2)),
+          });
+  REQUIRE(resources.overflowed() == false);
+}
+
+TEST_CASE("ResourceManager::saveStaticString() when allocation fails") {
+  SpyingAllocator spy(FailingAllocator::instance());
+  ResourceManager resources(&spy);
+
+  auto slotId = resources.saveStaticString("hello");
+
+  REQUIRE(slotId == NULL_SLOT);
+  REQUIRE(resources.overflowed() == true);
+  REQUIRE(spy.log() == AllocatorLog{
+                           AllocateFail(sizeofStaticStringPool()),
+                       });
+}

idf_component.yml

@@ -1,7 +1,7 @@
-version: "7.3.1"
+version: "7.4.2"
 description: >-
   A simple and efficient JSON library for embedded C++.
-  ★ 6849 stars on GitHub!
+  ★ 6953 stars on GitHub!
   Supports serialization, deserialization, MessagePack, streams, filtering, and more.
   Fully tested and documented.
 url: https://arduinojson.org/

library.json

@@ -1,13 +1,13 @@
 {
   "name": "ArduinoJson",
   "keywords": "json, rest, http, web",
-  "description": "A simple and efficient JSON library for embedded C++. ⭐ 6849 stars on GitHub! Supports serialization, deserialization, MessagePack, streams, filtering, and more. Fully tested and documented.",
+  "description": "A simple and efficient JSON library for embedded C++. ⭐ 6953 stars on GitHub! Supports serialization, deserialization, MessagePack, streams, filtering, and more. Fully tested and documented.",
   "homepage": "https://arduinojson.org/?utm_source=meta&utm_medium=library.json",
   "repository": {
     "type": "git",
     "url": "https://github.com/bblanchon/ArduinoJson.git"
   },
-  "version": "7.3.1",
+  "version": "7.4.2",
   "authors": {
     "name": "Benoit Blanchon",
     "url": "https://blog.benoitblanchon.fr"

library.properties

@@ -1,9 +1,9 @@
 name=ArduinoJson
-version=7.3.1
+version=7.4.2
 author=Benoit Blanchon <blog.benoitblanchon.fr>
 maintainer=Benoit Blanchon <blog.benoitblanchon.fr>
 sentence=A simple and efficient JSON library for embedded C++.
-paragraph=⭐ 6849 stars on GitHub! Supports serialization, deserialization, MessagePack, streams, filtering, and more. Fully tested and documented.
+paragraph=⭐ 6953 stars on GitHub! Supports serialization, deserialization, MessagePack, streams, filtering, and more. Fully tested and documented.
 category=Data Processing
 url=https://arduinojson.org/?utm_source=meta&utm_medium=library.properties
 architectures=*

src/ArduinoJson.hpp

@@ -26,6 +26,15 @@
 #  endif
 #endif
 
+// Remove true and false macros defined by some cores, such as Arduino Due's
+// See issues #2181 and arduino/ArduinoCore-sam#50
+#ifdef true
+#  undef true
+#endif
+#ifdef false
+#  undef false
+#endif
+
 #include "ArduinoJson/Array/JsonArray.hpp"
 #include "ArduinoJson/Object/JsonObject.hpp"
 #include "ArduinoJson/Variant/JsonVariantConst.hpp"
@@ -42,7 +51,6 @@
 #include "ArduinoJson/Variant/ConverterImpl.hpp"
 #include "ArduinoJson/Variant/JsonVariantCopier.hpp"
 #include "ArduinoJson/Variant/VariantCompare.hpp"
-#include "ArduinoJson/Variant/VariantImpl.hpp"
 #include "ArduinoJson/Variant/VariantRefBaseImpl.hpp"
 
 #include "ArduinoJson/Json/JsonDeserializer.hpp"

src/ArduinoJson/Array/ArrayData.hpp

@@ -8,59 +8,30 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class ArrayData : public CollectionData {
+class ArrayImpl : public CollectionImpl {
  public:
-  VariantData* addElement(ResourceManager* resources);
+  ArrayImpl() {}
 
-  static VariantData* addElement(ArrayData* array, ResourceManager* resources) {
-    if (!array)
-      return nullptr;
-    return array->addElement(resources);
-  }
+  ArrayImpl(CollectionData* data, ResourceManager* resources)
+      : CollectionImpl(data, resources) {}
+
+  VariantData* addElement();
 
   template <typename T>
-  bool addValue(const T& value, ResourceManager* resources);
+  bool addValue(const T& value);
 
-  template <typename T>
-  static bool addValue(ArrayData* array, const T& value,
-                       ResourceManager* resources) {
-    if (!array)
-      return false;
-    return array->addValue(value, resources);
-  }
+  VariantData* getOrAddElement(size_t index);
 
-  VariantData* getOrAddElement(size_t index, ResourceManager* resources);
+  VariantData* getElement(size_t index) const;
 
-  VariantData* getElement(size_t index, const ResourceManager* resources) const;
+  void removeElement(size_t index);
 
-  static VariantData* getElement(const ArrayData* array, size_t index,
-                                 const ResourceManager* resources) {
-    if (!array)
-      return nullptr;
-    return array->getElement(index, resources);
-  }
-
-  void removeElement(size_t index, ResourceManager* resources);
-
-  static void removeElement(ArrayData* array, size_t index,
-                            ResourceManager* resources) {
-    if (!array)
-      return;
-    array->removeElement(index, resources);
-  }
-
-  void remove(iterator it, ResourceManager* resources) {
-    CollectionData::removeOne(it, resources);
-  }
-
-  static void remove(ArrayData* array, iterator it,
-                     ResourceManager* resources) {
-    if (array)
-      return array->remove(it, resources);
+  void remove(iterator it) {
+    CollectionImpl::removeOne(it);
   }
 
  private:
-  iterator at(size_t index, const ResourceManager* resources) const;
+  iterator at(size_t index) const;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Array/ArrayImpl.hpp

@@ -10,36 +10,37 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-inline ArrayData::iterator ArrayData::at(
-    size_t index, const ResourceManager* resources) const {
-  auto it = createIterator(resources);
+inline ArrayImpl::iterator ArrayImpl::at(size_t index) const {
+  auto it = createIterator();
   while (!it.done() && index) {
-    it.next(resources);
+    it.next(resources_);
     --index;
   }
   return it;
 }
 
-inline VariantData* ArrayData::addElement(ResourceManager* resources) {
-  auto slot = resources->allocVariant();
+inline VariantData* ArrayImpl::addElement() {
+  if (!data_)
+    return nullptr;
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
+  auto slot = resources_->allocVariant();
   if (!slot)
     return nullptr;
-  CollectionData::appendOne(slot, resources);
+  CollectionImpl::appendOne(slot);
   return slot.ptr();
 }
 
-inline VariantData* ArrayData::getOrAddElement(size_t index,
-                                               ResourceManager* resources) {
-  auto it = createIterator(resources);
+inline VariantData* ArrayImpl::getOrAddElement(size_t index) {
+  auto it = createIterator();
   while (!it.done() && index > 0) {
-    it.next(resources);
+    it.next(resources_);
     index--;
   }
   if (it.done())
     index++;
   VariantData* element = it.data();
   while (index > 0) {
-    element = addElement(resources);
+    element = addElement();
     if (!element)
       return nullptr;
     index--;
@@ -47,33 +48,34 @@ inline VariantData* ArrayData::getOrAddElement(size_t index,
   return element;
 }
 
-inline VariantData* ArrayData::getElement(
-    size_t index, const ResourceManager* resources) const {
-  return at(index, resources).data();
+inline VariantData* ArrayImpl::getElement(size_t index) const {
+  return at(index).data();
 }
 
-inline void ArrayData::removeElement(size_t index, ResourceManager* resources) {
-  remove(at(index, resources), resources);
+inline void ArrayImpl::removeElement(size_t index) {
+  remove(at(index));
 }
 
 template <typename T>
-inline bool ArrayData::addValue(const T& value, ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(resources != nullptr);
-  auto slot = resources->allocVariant();
+inline bool ArrayImpl::addValue(const T& value) {
+  if (!data_)
+    return false;
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
+  auto slot = resources_->allocVariant();
   if (!slot)
     return false;
-  JsonVariant variant(slot.ptr(), resources);
+  JsonVariant variant(slot.ptr(), resources_);
   if (!variant.set(value)) {
-    resources->freeVariant(slot);
+    resources_->freeVariant(slot);
     return false;
   }
-  CollectionData::appendOne(slot, resources);
+  CollectionImpl::appendOne(slot);
   return true;
 }
 
 // Returns the size (in bytes) of an array with n elements.
 constexpr size_t sizeofArray(size_t n) {
-  return n * ResourceManager::slotSize;
+  return n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Array/ElementProxy.hpp

@@ -55,17 +55,12 @@ class ElementProxy : public VariantRefBase<ElementProxy<TUpstream>>,
   }
 
   FORCE_INLINE VariantData* getData() const {
-    return VariantData::getElement(
-        VariantAttorney::getData(upstream_), index_,
-        VariantAttorney::getResourceManager(upstream_));
+    return VariantAttorney::getVariantImpl(upstream_).getElement(index_);
   }
 
   VariantData* getOrCreateData() const {
-    auto data = VariantAttorney::getOrCreateData(upstream_);
-    if (!data)
-      return nullptr;
-    return data->getOrAddElement(
-        index_, VariantAttorney::getResourceManager(upstream_));
+    return VariantAttorney::getOrCreateVariantImpl(upstream_).getOrAddElement(
+        index_);
   }
 
   TUpstream upstream_;

src/ArduinoJson/Array/JsonArray.hpp

@@ -20,24 +20,25 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   using iterator = JsonArrayIterator;
 
   // Constructs an unbound reference.
-  JsonArray() : data_(0), resources_(0) {}
+  JsonArray() {}
 
   // INTERNAL USE ONLY
-  JsonArray(detail::ArrayData* data, detail::ResourceManager* resources)
-      : data_(data), resources_(resources) {}
+  JsonArray(detail::VariantData* data, detail::ResourceManager* resources)
+      : impl_(detail::VariantImpl(data, resources).asArray()) {}
+
+  // INTERNAL USE ONLY
+  JsonArray(const detail::ArrayImpl& impl) : impl_(impl) {}
 
   // Returns a JsonVariant pointing to the array.
   // https://arduinojson.org/v7/api/jsonvariant/
   operator JsonVariant() {
-    void* data = data_;  // prevent warning cast-align
-    return JsonVariant(reinterpret_cast<detail::VariantData*>(data),
-                       resources_);
+    return JsonVariant(getData(), getResourceManager());
   }
 
   // Returns a read-only reference to the array.
   // https://arduinojson.org/v7/api/jsonarrayconst/
   operator JsonArrayConst() const {
-    return JsonArrayConst(data_, resources_);
+    return JsonArrayConst(getData(), getResourceManager());
   }
 
   // Appends a new (empty) element to the array.
@@ -55,15 +56,14 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   template <typename T, detail::enable_if_t<
                             detail::is_same<T, JsonVariant>::value, int> = 0>
   JsonVariant add() const {
-    return JsonVariant(detail::ArrayData::addElement(data_, resources_),
-                       resources_);
+    return JsonVariant(impl_.addElement(), impl_.getResourceManager());
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonarray/add/
   template <typename T>
   bool add(const T& value) const {
-    return detail::ArrayData::addValue(data_, value, resources_);
+    return impl_.addValue(value);
   }
 
   // Appends a value to the array.
@@ -71,15 +71,13 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   template <typename T,
             detail::enable_if_t<!detail::is_const<T>::value, int> = 0>
   bool add(T* value) const {
-    return detail::ArrayData::addValue(data_, value, resources_);
+    return impl_.addValue(value);
   }
 
   // Returns an iterator to the first element of the array.
   // https://arduinojson.org/v7/api/jsonarray/begin/
   iterator begin() const {
-    if (!data_)
-      return iterator();
-    return iterator(data_->createIterator(resources_), resources_);
+    return iterator(impl_.createIterator(), impl_.getResourceManager());
   }
 
   // Returns an iterator following the last element of the array.
@@ -91,7 +89,7 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // Copies an array.
   // https://arduinojson.org/v7/api/jsonarray/set/
   bool set(JsonArrayConst src) const {
-    if (!data_)
+    if (isNull())
       return false;
 
     clear();
@@ -106,13 +104,13 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // Removes the element at the specified iterator.
   // https://arduinojson.org/v7/api/jsonarray/remove/
   void remove(iterator it) const {
-    detail::ArrayData::remove(data_, it.iterator_, resources_);
+    impl_.remove(it.iterator_);
   }
 
   // Removes the element at the specified index.
   // https://arduinojson.org/v7/api/jsonarray/remove/
   void remove(size_t index) const {
-    detail::ArrayData::removeElement(data_, index, resources_);
+    impl_.removeElement(index);
   }
 
   // Removes the element at the specified index.
@@ -127,7 +125,7 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // Removes all the elements of the array.
   // https://arduinojson.org/v7/api/jsonarray/clear/
   void clear() const {
-    detail::ArrayData::clear(data_, resources_);
+    impl_.clear();
   }
 
   // Gets or sets the element at the specified index.
@@ -150,31 +148,31 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   }
 
   operator JsonVariantConst() const {
-    return JsonVariantConst(collectionToVariant(data_), resources_);
+    return JsonVariantConst(getData(), getResourceManager());
   }
 
   // Returns true if the reference is unbound.
   // https://arduinojson.org/v7/api/jsonarray/isnull/
   bool isNull() const {
-    return data_ == 0;
+    return impl_.isNull();
   }
 
   // Returns true if the reference is bound.
   // https://arduinojson.org/v7/api/jsonarray/isnull/
   operator bool() const {
-    return data_ != 0;
+    return !isNull();
   }
 
   // Returns the depth (nesting level) of the array.
   // https://arduinojson.org/v7/api/jsonarray/nesting/
   size_t nesting() const {
-    return detail::VariantData::nesting(collectionToVariant(data_), resources_);
+    return impl_.nesting();
   }
 
   // Returns the number of elements in the array.
   // https://arduinojson.org/v7/api/jsonarray/size/
   size_t size() const {
-    return data_ ? data_->size(resources_) : 0;
+    return impl_.size();
   }
 
   // DEPRECATED: use add<JsonVariant>() instead
@@ -201,19 +199,18 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
 
  private:
   detail::ResourceManager* getResourceManager() const {
-    return resources_;
+    return impl_.getResourceManager();
   }
 
   detail::VariantData* getData() const {
-    return collectionToVariant(data_);
+    return impl_.getData();
   }
 
   detail::VariantData* getOrCreateData() const {
-    return collectionToVariant(data_);
+    return impl_.getData();
   }
 
-  detail::ArrayData* data_;
-  detail::ResourceManager* resources_;
+  mutable detail::ArrayImpl impl_;
 };
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE

src/ArduinoJson/Array/JsonArrayConst.hpp

@@ -24,9 +24,7 @@ class JsonArrayConst : public detail::VariantOperators<JsonArrayConst> {
   // Returns an iterator to the first element of the array.
   // https://arduinojson.org/v7/api/jsonarrayconst/begin/
   iterator begin() const {
-    if (!data_)
-      return iterator();
-    return iterator(data_->createIterator(resources_), resources_);
+    return iterator(impl_.createIterator(), impl_.getResourceManager());
   }
 
   // Returns an iterator to the element following the last element of the array.
@@ -36,21 +34,22 @@ class JsonArrayConst : public detail::VariantOperators<JsonArrayConst> {
   }
 
   // Creates an unbound reference.
-  JsonArrayConst() : data_(0), resources_(0) {}
+  JsonArrayConst() {}
 
   // INTERNAL USE ONLY
-  JsonArrayConst(const detail::ArrayData* data,
-                 const detail::ResourceManager* resources)
-      : data_(data), resources_(resources) {}
+  JsonArrayConst(detail::VariantData* data, detail::ResourceManager* resources)
+      : impl_(detail::VariantImpl(data, resources).asArray()) {}
+
+  // INTERNAL USE ONLY
+  JsonArrayConst(const detail::ArrayImpl& impl) : impl_(impl) {}
 
   // Returns the element at the specified index.
   // https://arduinojson.org/v7/api/jsonarrayconst/subscript/
   template <typename T,
             detail::enable_if_t<detail::is_integral<T>::value, int> = 0>
   JsonVariantConst operator[](T index) const {
-    return JsonVariantConst(
-        detail::ArrayData::getElement(data_, size_t(index), resources_),
-        resources_);
+    return JsonVariantConst(impl_.getElement(size_t(index)),
+                            impl_.getResourceManager());
   }
 
   // Returns the element at the specified index.
@@ -65,31 +64,31 @@ class JsonArrayConst : public detail::VariantOperators<JsonArrayConst> {
   }
 
   operator JsonVariantConst() const {
-    return JsonVariantConst(getData(), resources_);
+    return JsonVariantConst(impl_.getData(), impl_.getResourceManager());
   }
 
   // Returns true if the reference is unbound.
   // https://arduinojson.org/v7/api/jsonarrayconst/isnull/
   bool isNull() const {
-    return data_ == 0;
+    return impl_.isNull();
   }
 
   // Returns true if the reference is bound.
   // https://arduinojson.org/v7/api/jsonarrayconst/isnull/
   operator bool() const {
-    return data_ != 0;
+    return !isNull();
   }
 
   // Returns the depth (nesting level) of the array.
   // https://arduinojson.org/v7/api/jsonarrayconst/nesting/
   size_t nesting() const {
-    return detail::VariantData::nesting(getData(), resources_);
+    return impl_.nesting();
   }
 
   // Returns the number of elements in the array.
   // https://arduinojson.org/v7/api/jsonarrayconst/size/
   size_t size() const {
-    return data_ ? data_->size(resources_) : 0;
+    return impl_.size();
   }
 
   // DEPRECATED: always returns zero
@@ -100,11 +99,10 @@ class JsonArrayConst : public detail::VariantOperators<JsonArrayConst> {
 
  private:
   const detail::VariantData* getData() const {
-    return collectionToVariant(data_);
+    return impl_.getData();
   }
 
-  const detail::ArrayData* data_;
-  const detail::ResourceManager* resources_;
+  detail::ArrayImpl impl_;
 };
 
 // Compares the content of two arrays.

src/ArduinoJson/Array/JsonArrayIterator.hpp

@@ -30,7 +30,7 @@ class JsonArrayIterator {
 
  public:
   JsonArrayIterator() {}
-  explicit JsonArrayIterator(detail::ArrayData::iterator iterator,
+  explicit JsonArrayIterator(detail::ArrayImpl::iterator iterator,
                              detail::ResourceManager* resources)
       : iterator_(iterator), resources_(resources) {}
 
@@ -55,7 +55,7 @@ class JsonArrayIterator {
   }
 
  private:
-  detail::ArrayData::iterator iterator_;
+  detail::ArrayImpl::iterator iterator_;
   detail::ResourceManager* resources_;
 };
 
@@ -64,8 +64,8 @@ class JsonArrayConstIterator {
 
  public:
   JsonArrayConstIterator() {}
-  explicit JsonArrayConstIterator(detail::ArrayData::iterator iterator,
-                                  const detail::ResourceManager* resources)
+  explicit JsonArrayConstIterator(detail::ArrayImpl::iterator iterator,
+                                  detail::ResourceManager* resources)
       : iterator_(iterator), resources_(resources) {}
 
   JsonVariantConst operator*() const {
@@ -89,8 +89,8 @@ class JsonArrayConstIterator {
   }
 
  private:
-  detail::ArrayData::iterator iterator_;
-  const detail::ResourceManager* resources_;
+  mutable detail::ArrayImpl::iterator iterator_;
+  mutable detail::ResourceManager* resources_;
 };
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE

src/ArduinoJson/Collection/CollectionData.hpp

@@ -12,11 +12,11 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class VariantData;
+struct VariantData;
 class ResourceManager;
 
 class CollectionIterator {
-  friend class CollectionData;
+  friend class CollectionImpl;
 
  public:
   CollectionIterator() : slot_(nullptr), currentId_(NULL_SLOT) {}
@@ -51,11 +51,11 @@ class CollectionIterator {
   }
 
   VariantData* data() {
-    return reinterpret_cast<VariantData*>(slot_);
+    return slot_;
   }
 
   const VariantData* data() const {
-    return reinterpret_cast<const VariantData*>(slot_);
+    return slot_;
   }
 
  private:
@@ -65,58 +65,68 @@ class CollectionIterator {
   SlotId currentId_, nextId_;
 };
 
-class CollectionData {
-  SlotId head_ = NULL_SLOT;
-  SlotId tail_ = NULL_SLOT;
+struct CollectionData {
+  SlotId head = NULL_SLOT;
+  SlotId tail = NULL_SLOT;
 
- public:
   // Placement new
   static void* operator new(size_t, void* p) noexcept {
     return p;
   }
 
   static void operator delete(void*, void*) noexcept {}
+};
 
+class CollectionImpl {
+ protected:
+  CollectionData* data_;
+  ResourceManager* resources_;
+
+ public:
   using iterator = CollectionIterator;
 
-  iterator createIterator(const ResourceManager* resources) const;
+  CollectionImpl() : data_(nullptr), resources_(nullptr) {}
 
-  size_t size(const ResourceManager*) const;
-  size_t nesting(const ResourceManager*) const;
+  CollectionImpl(CollectionData* data, ResourceManager* resources)
+      : data_(data), resources_(resources) {}
 
-  void clear(ResourceManager* resources);
-
-  static void clear(CollectionData* collection, ResourceManager* resources) {
-    if (!collection)
-      return;
-    collection->clear(resources);
+  explicit operator bool() const {
+    return data_ != nullptr;
   }
 
+  bool isNull() const {
+    return data_ == nullptr;
+  }
+
+  VariantData* getData() const {
+    void* data = data_;  // prevent warning cast-align
+    return reinterpret_cast<VariantData*>(data);
+  }
+
+  ResourceManager* getResourceManager() const {
+    return resources_;
+  }
+
+  iterator createIterator() const;
+
+  size_t size() const;
+  size_t nesting() const;
+
+  void clear();
+
   SlotId head() const {
-    return head_;
+    return data_->head;
   }
 
  protected:
-  void appendOne(Slot<VariantData> slot, const ResourceManager* resources);
-  void appendPair(Slot<VariantData> key, Slot<VariantData> value,
-                  const ResourceManager* resources);
+  void appendOne(Slot<VariantData> slot);
+  void appendPair(Slot<VariantData> key, Slot<VariantData> value);
 
-  void removeOne(iterator it, ResourceManager* resources);
-  void removePair(iterator it, ResourceManager* resources);
+  void removeOne(iterator it);
+  void removePair(iterator it);
 
  private:
-  Slot<VariantData> getPreviousSlot(VariantData*, const ResourceManager*) const;
+  Slot<VariantData> getPreviousSlot(VariantData*) const;
 };
 
-inline const VariantData* collectionToVariant(
-    const CollectionData* collection) {
-  const void* data = collection;  // prevent warning cast-align
-  return reinterpret_cast<const VariantData*>(data);
-}
-
-inline VariantData* collectionToVariant(CollectionData* collection) {
-  void* data = collection;  // prevent warning cast-align
-  return reinterpret_cast<VariantData*>(data);
-}
-
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Collection/CollectionImpl.hpp

@@ -14,7 +14,7 @@ ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 inline CollectionIterator::CollectionIterator(VariantData* slot, SlotId slotId)
     : slot_(slot), currentId_(slotId) {
-  nextId_ = slot_ ? slot_->next() : NULL_SLOT;
+  nextId_ = slot_ ? slot_->next : NULL_SLOT;
 }
 
 inline void CollectionIterator::next(const ResourceManager* resources) {
@@ -22,114 +22,123 @@ inline void CollectionIterator::next(const ResourceManager* resources) {
   slot_ = resources->getVariant(nextId_);
   currentId_ = nextId_;
   if (slot_)
-    nextId_ = slot_->next();
+    nextId_ = slot_->next;
 }
 
-inline CollectionData::iterator CollectionData::createIterator(
-    const ResourceManager* resources) const {
-  return iterator(resources->getVariant(head_), head_);
+inline CollectionImpl::iterator CollectionImpl::createIterator() const {
+  if (!data_)
+    return iterator();
+  return iterator(resources_->getVariant(data_->head), data_->head);
 }
 
-inline void CollectionData::appendOne(Slot<VariantData> slot,
-                                      const ResourceManager* resources) {
-  if (tail_ != NULL_SLOT) {
-    auto tail = resources->getVariant(tail_);
-    tail->setNext(slot.id());
-    tail_ = slot.id();
+inline void CollectionImpl::appendOne(Slot<VariantData> slot) {
+  ARDUINOJSON_ASSERT(data_ != nullptr);
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
+
+  if (data_->tail != NULL_SLOT) {
+    auto tail = resources_->getVariant(data_->tail);
+    tail->next = slot.id();
+    data_->tail = slot.id();
   } else {
-    head_ = slot.id();
-    tail_ = slot.id();
+    data_->head = slot.id();
+    data_->tail = slot.id();
   }
 }
 
-inline void CollectionData::appendPair(Slot<VariantData> key,
-                                       Slot<VariantData> value,
-                                       const ResourceManager* resources) {
-  key->setNext(value.id());
+inline void CollectionImpl::appendPair(Slot<VariantData> key,
+                                       Slot<VariantData> value) {
+  ARDUINOJSON_ASSERT(data_ != nullptr);
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
 
-  if (tail_ != NULL_SLOT) {
-    auto tail = resources->getVariant(tail_);
-    tail->setNext(key.id());
-    tail_ = value.id();
+  key->next = value.id();
+
+  if (data_->tail != NULL_SLOT) {
+    auto tail = resources_->getVariant(data_->tail);
+    tail->next = key.id();
+    data_->tail = value.id();
   } else {
-    head_ = key.id();
-    tail_ = value.id();
+    data_->head = key.id();
+    data_->tail = value.id();
   }
 }
 
-inline void CollectionData::clear(ResourceManager* resources) {
-  auto next = head_;
+inline void CollectionImpl::clear() {
+  if (!data_)
+    return;
+  auto next = data_->head;
   while (next != NULL_SLOT) {
     auto currId = next;
-    auto slot = resources->getVariant(next);
-    next = slot->next();
-    resources->freeVariant({slot, currId});
+    auto slot = resources_->getVariant(next);
+    next = slot->next;
+    resources_->freeVariant({slot, currId});
   }
 
-  head_ = NULL_SLOT;
-  tail_ = NULL_SLOT;
+  data_->head = NULL_SLOT;
+  data_->tail = NULL_SLOT;
 }
 
-inline Slot<VariantData> CollectionData::getPreviousSlot(
-    VariantData* target, const ResourceManager* resources) const {
+inline Slot<VariantData> CollectionImpl::getPreviousSlot(
+    VariantData* target) const {
   auto prev = Slot<VariantData>();
-  auto currentId = head_;
+  auto currentId = data_->head;
   while (currentId != NULL_SLOT) {
-    auto currentSlot = resources->getVariant(currentId);
+    auto currentSlot = resources_->getVariant(currentId);
     if (currentSlot == target)
       break;
     prev = Slot<VariantData>(currentSlot, currentId);
-    currentId = currentSlot->next();
+    currentId = currentSlot->next;
   }
   return prev;
 }
 
-inline void CollectionData::removeOne(iterator it, ResourceManager* resources) {
+inline void CollectionImpl::removeOne(iterator it) {
   if (it.done())
     return;
   auto curr = it.slot_;
-  auto prev = getPreviousSlot(curr, resources);
-  auto next = curr->next();
+  auto prev = getPreviousSlot(curr);
+  auto next = curr->next;
   if (prev)
-    prev->setNext(next);
+    prev->next = next;
   else
-    head_ = next;
+    data_->head = next;
   if (next == NULL_SLOT)
-    tail_ = prev.id();
-  resources->freeVariant({it.slot_, it.currentId_});
+    data_->tail = prev.id();
+  resources_->freeVariant({it.slot_, it.currentId_});
 }
 
-inline void CollectionData::removePair(ObjectData::iterator it,
-                                       ResourceManager* resources) {
+inline void CollectionImpl::removePair(ObjectImpl::iterator it) {
   if (it.done())
     return;
 
   auto keySlot = it.slot_;
 
   auto valueId = it.nextId_;
-  auto valueSlot = resources->getVariant(valueId);
+  auto valueSlot = resources_->getVariant(valueId);
 
   // remove value slot
-  keySlot->setNext(valueSlot->next());
-  resources->freeVariant({valueSlot, valueId});
+  keySlot->next = valueSlot->next;
+  resources_->freeVariant({valueSlot, valueId});
 
   // remove key slot
-  removeOne(it, resources);
+  removeOne(it);
 }
 
-inline size_t CollectionData::nesting(const ResourceManager* resources) const {
+inline size_t CollectionImpl::nesting() const {
+  if (!data_)
+    return 0;
   size_t maxChildNesting = 0;
-  for (auto it = createIterator(resources); !it.done(); it.next(resources)) {
-    size_t childNesting = it->nesting(resources);
+  for (auto it = createIterator(); !it.done(); it.next(resources_)) {
+    VariantImpl variant(it.data(), resources_);
+    size_t childNesting = variant.nesting();
     if (childNesting > maxChildNesting)
       maxChildNesting = childNesting;
   }
   return maxChildNesting + 1;
 }
 
-inline size_t CollectionData::size(const ResourceManager* resources) const {
+inline size_t CollectionImpl::size() const {
   size_t count = 0;
-  for (auto it = createIterator(resources); !it.done(); it.next(resources))
+  for (auto it = createIterator(); !it.done(); it.next(resources_))
     count++;
   return count;
 }

src/ArduinoJson/Configuration.hpp

@@ -274,9 +274,9 @@
 #endif
 
 #if ARDUINOJSON_USE_LONG_LONG || ARDUINOJSON_USE_DOUBLE
-#  define ARDUINOJSON_USE_EXTENSIONS 1
+#  define ARDUINOJSON_USE_8_BYTE_POOL 1
 #else
-#  define ARDUINOJSON_USE_EXTENSIONS 0
+#  define ARDUINOJSON_USE_8_BYTE_POOL 0
 #endif
 
 #if defined(nullptr)

src/ArduinoJson/Deserialization/deserialize.hpp

@@ -50,7 +50,7 @@ DeserializationError doDeserialize(TDestination&& dst, TReader reader,
   auto resources = VariantAttorney::getResourceManager(dst);
   dst.clear();
   auto err = TDeserializer<TReader>(resources, reader)
-                 .parse(*data, options.filter, options.nestingLimit);
+                 .parse(data, options.filter, options.nestingLimit);
   shrinkJsonDocument(dst);
   return err;
 }

src/ArduinoJson/Document/JsonDocument.hpp

@@ -88,7 +88,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // https://arduinojson.org/v7/api/jsondocument/clear/
   void clear() {
     resources_.clear();
-    data_.reset();
+    data_.type = detail::VariantType::Null;
   }
 
   // Returns true if the root is of the specified type.
@@ -120,13 +120,13 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Returns the depth (nesting level) of the array.
   // https://arduinojson.org/v7/api/jsondocument/nesting/
   size_t nesting() const {
-    return data_.nesting(&resources_);
+    return getVariantImpl().nesting();
   }
 
   // Returns the number of elements in the root array or object.
   // https://arduinojson.org/v7/api/jsondocument/size/
   size_t size() const {
-    return data_.size(&resources_);
+    return getVariantImpl().size();
   }
 
   // Copies the specified document.
@@ -165,7 +165,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   template <typename TChar>
   ARDUINOJSON_DEPRECATED("use doc[\"key\"].is<T>() instead")
   bool containsKey(TChar* key) const {
-    return data_.getMember(detail::adaptString(key), &resources_) != 0;
+    return getVariantImpl().getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -174,7 +174,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use doc[key].is<T>() instead")
   bool containsKey(const TString& key) const {
-    return data_.getMember(detail::adaptString(key), &resources_) != 0;
+    return getVariantImpl().getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -212,7 +212,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
     return JsonVariantConst(
-        data_.getMember(detail::adaptString(key), &resources_), &resources_);
+        getVariantImpl().getMember(detail::adaptString(key)), &resources_);
   }
 
   // Gets a root object's member.
@@ -223,7 +223,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
                                 int> = 0>
   JsonVariantConst operator[](TChar* key) const {
     return JsonVariantConst(
-        data_.getMember(detail::adaptString(key), &resources_), &resources_);
+        getVariantImpl().getMember(detail::adaptString(key)), &resources_);
   }
 
   // Gets or sets a root array's element.
@@ -237,7 +237,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Gets a root array's member.
   // https://arduinojson.org/v7/api/jsondocument/subscript/
   JsonVariantConst operator[](size_t index) const {
-    return JsonVariantConst(data_.getElement(index, &resources_), &resources_);
+    return JsonVariantConst(getVariantImpl().getElement(index), &resources_);
   }
 
   // Gets or sets a root object's member.
@@ -267,14 +267,14 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   template <typename T, detail::enable_if_t<
                             detail::is_same<T, JsonVariant>::value, int> = 0>
   JsonVariant add() {
-    return JsonVariant(data_.addElement(&resources_), &resources_);
+    return JsonVariant(getVariantImpl().addElement(), &resources_);
   }
 
   // Appends a value to the root array.
   // https://arduinojson.org/v7/api/jsondocument/add/
   template <typename TValue>
   bool add(const TValue& value) {
-    return data_.addValue(value, &resources_);
+    return getVariantImpl().addValue(value);
   }
 
   // Appends a value to the root array.
@@ -282,7 +282,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   template <typename TChar,
             detail::enable_if_t<!detail::is_const<TChar>::value, int> = 0>
   bool add(TChar* value) {
-    return data_.addValue(value, &resources_);
+    return getVariantImpl().addValue(value);
   }
 
   // Removes an element of the root array.
@@ -290,8 +290,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   template <typename T,
             detail::enable_if_t<detail::is_integral<T>::value, int> = 0>
   void remove(T index) {
-    detail::VariantData::removeElement(getData(), size_t(index),
-                                       getResourceManager());
+    getVariantImpl().removeElement(size_t(index));
   }
 
   // Removes a member of the root object.
@@ -301,8 +300,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
                                     !detail::is_const<TChar>::value,
                                 int> = 0>
   void remove(TChar* key) {
-    detail::VariantData::removeMember(getData(), detail::adaptString(key),
-                                      getResourceManager());
+    getVariantImpl().removeMember(detail::adaptString(key));
   }
 
   // Removes a member of the root object.
@@ -310,8 +308,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   template <typename TString,
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   void remove(const TString& key) {
-    detail::VariantData::removeMember(getData(), detail::adaptString(key),
-                                      getResourceManager());
+    getVariantImpl().removeMember(detail::adaptString(key));
   }
 
   // Removes a member of the root object or an element of the root array.
@@ -391,6 +388,10 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   }
 
  private:
+  detail::VariantImpl getVariantImpl() const {
+    return detail::VariantImpl(&data_, &resources_);
+  }
+
   JsonVariant getVariant() {
     return JsonVariant(&data_, &resources_);
   }
@@ -415,8 +416,8 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
     return &data_;
   }
 
-  detail::ResourceManager resources_;
-  detail::VariantData data_;
+  mutable detail::ResourceManager resources_;
+  mutable detail::VariantData data_;
 };
 
 inline void convertToJson(const JsonDocument& src, JsonVariant dst) {

src/ArduinoJson/Json/JsonDeserializer.hpp

@@ -28,13 +28,13 @@ class JsonDeserializer {
         resources_(resources) {}
 
   template <typename TFilter>
-  DeserializationError parse(VariantData& variant, TFilter filter,
+  DeserializationError parse(VariantData* variant, TFilter filter,
                              DeserializationOption::NestingLimit nestingLimit) {
     DeserializationError::Code err;
 
     err = parseVariant(variant, filter, nestingLimit);
 
-    if (!err && latch_.last() != 0 && variant.isFloat()) {
+    if (!err && latch_.last() != 0 && variant->isFloat()) {
       // We don't detect trailing characters earlier, so we need to check now
       return DeserializationError::InvalidInput;
     }
@@ -60,7 +60,7 @@ class JsonDeserializer {
 
   template <typename TFilter>
   DeserializationError::Code parseVariant(
-      VariantData& variant, TFilter filter,
+      VariantData* variant, TFilter filter,
       DeserializationOption::NestingLimit nestingLimit) {
     DeserializationError::Code err;
 
@@ -71,13 +71,15 @@ class JsonDeserializer {
     switch (current()) {
       case '[':
         if (filter.allowArray())
-          return parseArray(variant.toArray(), filter, nestingLimit);
+          return parseArray(VariantImpl(variant, resources_).toArray(), filter,
+                            nestingLimit);
         else
           return skipArray(nestingLimit);
 
       case '{':
         if (filter.allowObject())
-          return parseObject(variant.toObject(), filter, nestingLimit);
+          return parseObject(VariantImpl(variant, resources_).toObject(),
+                             filter, nestingLimit);
         else
           return skipObject(nestingLimit);
 
@@ -90,12 +92,12 @@ class JsonDeserializer {
 
       case 't':
         if (filter.allowValue())
-          variant.setBoolean(true);
+          variant->setBoolean(true);
         return skipKeyword("true");
 
       case 'f':
         if (filter.allowValue())
-          variant.setBoolean(false);
+          variant->setBoolean(false);
         return skipKeyword("false");
 
       case 'n':
@@ -146,7 +148,7 @@ class JsonDeserializer {
 
   template <typename TFilter>
   DeserializationError::Code parseArray(
-      ArrayData& array, TFilter filter,
+      ArrayImpl array, TFilter filter,
       DeserializationOption::NestingLimit nestingLimit) {
     DeserializationError::Code err;
 
@@ -172,12 +174,12 @@ class JsonDeserializer {
     for (;;) {
       if (elementFilter.allow()) {
         // Allocate slot in array
-        VariantData* value = array.addElement(resources_);
+        VariantData* value = array.addElement();
         if (!value)
           return DeserializationError::NoMemory;
 
         // 1 - Parse value
-        err = parseVariant(*value, elementFilter, nestingLimit.decrement());
+        err = parseVariant(value, elementFilter, nestingLimit.decrement());
         if (err)
           return err;
       } else {
@@ -232,7 +234,7 @@ class JsonDeserializer {
 
   template <typename TFilter>
   DeserializationError::Code parseObject(
-      ObjectData& object, TFilter filter,
+      ObjectImpl object, TFilter filter,
       DeserializationOption::NestingLimit nestingLimit) {
     DeserializationError::Code err;
 
@@ -273,21 +275,19 @@ class JsonDeserializer {
       TFilter memberFilter = filter[key];
 
       if (memberFilter.allow()) {
-        auto member = object.getMember(adaptString(key), resources_);
+        auto member = object.getMember(adaptString(key));
         if (!member) {
-          // Save key in memory pool.
-          auto savedKey = stringBuilder_.save();
-
-          // Allocate slot in object
-          member = object.addMember(savedKey, resources_);
-          if (!member)
+          auto keyVariant = object.addPair(&member);
+          if (!keyVariant)
             return DeserializationError::NoMemory;
+
+          stringBuilder_.save(keyVariant);
         } else {
-          member->clear(resources_);
+          VariantImpl(member, resources_).clear();
         }
 
         // Parse value
-        err = parseVariant(*member, memberFilter, nestingLimit.decrement());
+        err = parseVariant(member, memberFilter, nestingLimit.decrement());
         if (err)
           return err;
       } else {
@@ -381,7 +381,7 @@ class JsonDeserializer {
     }
   }
 
-  DeserializationError::Code parseStringValue(VariantData& variant) {
+  DeserializationError::Code parseStringValue(VariantData* variant) {
     DeserializationError::Code err;
 
     stringBuilder_.startString();
@@ -390,7 +390,7 @@ class JsonDeserializer {
     if (err)
       return err;
 
-    variant.setOwnedString(stringBuilder_.save());
+    stringBuilder_.save(variant);
 
     return DeserializationError::Ok;
   }
@@ -506,7 +506,7 @@ class JsonDeserializer {
     return DeserializationError::Ok;
   }
 
-  DeserializationError::Code parseNumericValue(VariantData& result) {
+  DeserializationError::Code parseNumericValue(VariantData* result) {
     uint8_t n = 0;
 
     char c = current();
@@ -520,26 +520,28 @@ class JsonDeserializer {
     auto number = parseNumber(buffer_);
     switch (number.type()) {
       case NumberType::UnsignedInteger:
-        if (result.setInteger(number.asUnsignedInteger(), resources_))
+        if (VariantImpl(result, resources_)
+                .setInteger(number.asUnsignedInteger()))
           return DeserializationError::Ok;
         else
           return DeserializationError::NoMemory;
 
       case NumberType::SignedInteger:
-        if (result.setInteger(number.asSignedInteger(), resources_))
+        if (VariantImpl(result, resources_)
+                .setInteger(number.asSignedInteger()))
           return DeserializationError::Ok;
         else
           return DeserializationError::NoMemory;
 
       case NumberType::Float:
-        if (result.setFloat(number.asFloat(), resources_))
+        if (VariantImpl(result, resources_).setFloat(number.asFloat()))
           return DeserializationError::Ok;
         else
           return DeserializationError::NoMemory;
 
 #if ARDUINOJSON_USE_DOUBLE
       case NumberType::Double:
-        if (result.setFloat(number.asDouble(), resources_))
+        if (VariantImpl(result, resources_).setFloat(number.asDouble()))
           return DeserializationError::Ok;
         else
           return DeserializationError::NoMemory;

src/ArduinoJson/Json/JsonSerializer.hpp

@@ -16,10 +16,10 @@ class JsonSerializer : public VariantDataVisitor<size_t> {
  public:
   static const bool producesText = true;
 
-  JsonSerializer(TWriter writer, const ResourceManager* resources)
+  JsonSerializer(TWriter writer, ResourceManager* resources)
       : formatter_(writer), resources_(resources) {}
 
-  size_t visit(const ArrayData& array) {
+  size_t visit(const ArrayImpl& array) {
     write('[');
 
     auto slotId = array.head();
@@ -27,9 +27,9 @@ class JsonSerializer : public VariantDataVisitor<size_t> {
     while (slotId != NULL_SLOT) {
       auto slot = resources_->getVariant(slotId);
 
-      slot->accept(*this, resources_);
+      VariantImpl(slot, resources_).accept(*this);
 
-      slotId = slot->next();
+      slotId = slot->next;
 
       if (slotId != NULL_SLOT)
         write(',');
@@ -39,7 +39,7 @@ class JsonSerializer : public VariantDataVisitor<size_t> {
     return bytesWritten();
   }
 
-  size_t visit(const ObjectData& object) {
+  size_t visit(const ObjectImpl& object) {
     write('{');
 
     auto slotId = object.head();
@@ -48,9 +48,9 @@ class JsonSerializer : public VariantDataVisitor<size_t> {
 
     while (slotId != NULL_SLOT) {
       auto slot = resources_->getVariant(slotId);
-      slot->accept(*this, resources_);
+      VariantImpl(slot, resources_).accept(*this);
 
-      slotId = slot->next();
+      slotId = slot->next;
 
       if (slotId != NULL_SLOT)
         write(isKey ? ':' : ',');
@@ -120,7 +120,7 @@ class JsonSerializer : public VariantDataVisitor<size_t> {
   TextFormatter<TWriter> formatter_;
 
  protected:
-  const ResourceManager* resources_;
+  ResourceManager* resources_;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Json/PrettyJsonSerializer.hpp

@@ -16,17 +16,17 @@ class PrettyJsonSerializer : public JsonSerializer<TWriter> {
   using base = JsonSerializer<TWriter>;
 
  public:
-  PrettyJsonSerializer(TWriter writer, const ResourceManager* resources)
+  PrettyJsonSerializer(TWriter writer, ResourceManager* resources)
       : base(writer, resources), nesting_(0) {}
 
-  size_t visit(const ArrayData& array) {
-    auto it = array.createIterator(base::resources_);
+  size_t visit(const ArrayImpl& array) {
+    auto it = array.createIterator();
     if (!it.done()) {
       base::write("[\r\n");
       nesting_++;
       while (!it.done()) {
         indent();
-        it->accept(*this, base::resources_);
+        VariantImpl(it.data(), base::resources_).accept(*this);
 
         it.next(base::resources_);
         base::write(it.done() ? "\r\n" : ",\r\n");
@@ -40,8 +40,8 @@ class PrettyJsonSerializer : public JsonSerializer<TWriter> {
     return this->bytesWritten();
   }
 
-  size_t visit(const ObjectData& object) {
-    auto it = object.createIterator(base::resources_);
+  size_t visit(const ObjectImpl& object) {
+    auto it = object.createIterator();
     if (!it.done()) {
       base::write("{\r\n");
       nesting_++;
@@ -49,7 +49,7 @@ class PrettyJsonSerializer : public JsonSerializer<TWriter> {
       while (!it.done()) {
         if (isKey)
           indent();
-        it->accept(*this, base::resources_);
+        VariantImpl(it.data(), base::resources_).accept(*this);
         it.next(base::resources_);
         if (isKey)
           base::write(": ");

src/ArduinoJson/Memory/MemoryPool.hpp

@@ -34,6 +34,11 @@ class Slot {
     return ptr_;
   }
 
+  T& operator*() const {
+    ARDUINOJSON_ASSERT(ptr_ != nullptr);
+    return *ptr_;
+  }
+
   T* operator->() const {
     ARDUINOJSON_ASSERT(ptr_ != nullptr);
     return ptr_;
@@ -76,6 +81,14 @@ class MemoryPool {
     return slots_ + id;
   }
 
+  SlotId find(const T& value) const {
+    for (SlotId i = 0; i < usage_; i++) {
+      if (slots_[i] == value)
+        return i;
+    }
+    return NULL_SLOT;
+  }
+
   void clear() {
     usage_ = 0;
   }

src/ArduinoJson/Memory/MemoryPoolList.hpp

@@ -114,6 +114,15 @@ class MemoryPoolList {
     return pools_[poolIndex].getSlot(indexInPool);
   }
 
+  SlotId find(const T& value) const {
+    for (PoolCount i = 0; i < count_; i++) {
+      SlotId id = pools_[i].find(value);
+      if (id != NULL_SLOT)
+        return SlotId(i * ARDUINOJSON_POOL_CAPACITY + id);
+    }
+    return NULL_SLOT;
+  }
+
   void clear(Allocator* allocator) {
     for (PoolCount i = 0; i < count_; i++)
       pools_[i].destroy(allocator);

src/ArduinoJson/Memory/ResourceManager.hpp

@@ -14,26 +14,21 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class VariantData;
+struct VariantData;
 class VariantWithId;
 
 class ResourceManager {
-  union SlotData {
-    VariantData variant;
-#if ARDUINOJSON_USE_EXTENSIONS
-    VariantExtension extension;
-#endif
-  };
-
  public:
-  constexpr static size_t slotSize = sizeof(SlotData);
-
   ResourceManager(Allocator* allocator = DefaultAllocator::instance())
       : allocator_(allocator), overflowed_(false) {}
 
   ~ResourceManager() {
     stringPool_.clear(allocator_);
     variantPools_.clear(allocator_);
+    staticStringsPools_.clear(allocator_);
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    eightBytePools_.clear(allocator_);
+#endif
   }
 
   ResourceManager(const ResourceManager&) = delete;
@@ -42,6 +37,10 @@ class ResourceManager {
   friend void swap(ResourceManager& a, ResourceManager& b) {
     swap(a.stringPool_, b.stringPool_);
     swap(a.variantPools_, b.variantPools_);
+    swap(a.staticStringsPools_, b.staticStringsPools_);
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    swap(a.eightBytePools_, b.eightBytePools_);
+#endif
     swap_(a.allocator_, b.allocator_);
     swap_(a.overflowed_, b.overflowed_);
   }
@@ -62,10 +61,10 @@ class ResourceManager {
   void freeVariant(Slot<VariantData> slot);
   VariantData* getVariant(SlotId id) const;
 
-#if ARDUINOJSON_USE_EXTENSIONS
-  Slot<VariantExtension> allocExtension();
-  void freeExtension(SlotId slot);
-  VariantExtension* getExtension(SlotId id) const;
+#if ARDUINOJSON_USE_8_BYTE_POOL
+  Slot<EightByteValue> allocEightByte();
+  void freeEightByte(SlotId slot);
+  EightByteValue* getEightByte(SlotId id) const;
 #endif
 
   template <typename TAdaptedString>
@@ -111,21 +110,51 @@ class ResourceManager {
     stringPool_.dereference(s, allocator_);
   }
 
+  SlotId saveStaticString(const char* s) {
+    auto existingSlotId = staticStringsPools_.find(s);
+    if (existingSlotId != NULL_SLOT)
+      return existingSlotId;
+
+    auto slot = staticStringsPools_.allocSlot(allocator_);
+    if (slot)
+      *slot = s;
+    else
+      overflowed_ = true;
+
+    return slot.id();
+  }
+
+  const char* getStaticString(SlotId id) const {
+    return *staticStringsPools_.getSlot(id);
+  }
+
   void clear() {
-    variantPools_.clear(allocator_);
     overflowed_ = false;
+    variantPools_.clear(allocator_);
     stringPool_.clear(allocator_);
+    staticStringsPools_.clear(allocator_);
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    eightBytePools_.clear(allocator_);
+#endif
   }
 
   void shrinkToFit() {
     variantPools_.shrinkToFit(allocator_);
+    staticStringsPools_.shrinkToFit(allocator_);
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    eightBytePools_.shrinkToFit(allocator_);
+#endif
   }
 
  private:
   Allocator* allocator_;
   bool overflowed_;
   StringPool stringPool_;
-  MemoryPoolList<SlotData> variantPools_;
+  MemoryPoolList<VariantData> variantPools_;
+  MemoryPoolList<const char*> staticStringsPools_;
+#if ARDUINOJSON_USE_8_BYTE_POOL
+  MemoryPoolList<EightByteValue> eightBytePools_;
+#endif
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Memory/ResourceManagerImpl.hpp

@@ -4,48 +4,48 @@
 
 #pragma once
 
-#include <ArduinoJson/Collection/CollectionData.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Polyfills/alias_cast.hpp>
-#include <ArduinoJson/Variant/VariantData.hpp>
+#include <ArduinoJson/Variant/VariantImpl.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 inline Slot<VariantData> ResourceManager::allocVariant() {
-  auto p = variantPools_.allocSlot(allocator_);
-  if (!p) {
+  auto slot = variantPools_.allocSlot(allocator_);
+  if (!slot) {
     overflowed_ = true;
     return {};
   }
-  return {new (&p->variant) VariantData, p.id()};
+  new (slot.ptr()) VariantData();
+  return slot;
 }
 
-inline void ResourceManager::freeVariant(Slot<VariantData> variant) {
-  variant->clear(this);
-  variantPools_.freeSlot({alias_cast<SlotData*>(variant.ptr()), variant.id()});
+inline void ResourceManager::freeVariant(Slot<VariantData> slot) {
+  VariantImpl(slot.ptr(), this).clear();
+  variantPools_.freeSlot(slot);
 }
 
 inline VariantData* ResourceManager::getVariant(SlotId id) const {
   return reinterpret_cast<VariantData*>(variantPools_.getSlot(id));
 }
 
-#if ARDUINOJSON_USE_EXTENSIONS
-inline Slot<VariantExtension> ResourceManager::allocExtension() {
-  auto p = variantPools_.allocSlot(allocator_);
-  if (!p) {
+#if ARDUINOJSON_USE_8_BYTE_POOL
+inline Slot<EightByteValue> ResourceManager::allocEightByte() {
+  auto slot = eightBytePools_.allocSlot(allocator_);
+  if (!slot) {
     overflowed_ = true;
     return {};
   }
-  return {&p->extension, p.id()};
+  return slot;
 }
 
-inline void ResourceManager::freeExtension(SlotId id) {
-  auto p = getExtension(id);
-  variantPools_.freeSlot({reinterpret_cast<SlotData*>(p), id});
+inline void ResourceManager::freeEightByte(SlotId id) {
+  auto p = getEightByte(id);
+  eightBytePools_.freeSlot({p, id});
 }
 
-inline VariantExtension* ResourceManager::getExtension(SlotId id) const {
-  return &variantPools_.getSlot(id)->extension;
+inline EightByteValue* ResourceManager::getEightByte(SlotId id) const {
+  return eightBytePools_.getSlot(id);
 }
 #endif
 

src/ArduinoJson/Memory/StringBuffer.hpp

@@ -32,7 +32,26 @@ class StringBuffer {
     return node_->data;
   }
 
-  StringNode* save() {
+  JsonString str() const {
+    ARDUINOJSON_ASSERT(node_ != nullptr);
+    return JsonString(node_->data, node_->length);
+  }
+
+  void save(VariantData* data) {
+    ARDUINOJSON_ASSERT(node_ != nullptr);
+    const char* s = node_->data;
+    if (isTinyString(s, size_))
+      data->setTinyString(adaptString(s, size_));
+    else
+      data->setOwnedString(commitStringNode());
+  }
+
+  void saveRaw(VariantData* data) {
+    data->setRawString(commitStringNode());
+  }
+
+ private:
+  StringNode* commitStringNode() {
     ARDUINOJSON_ASSERT(node_ != nullptr);
     node_->data[size_] = 0;
     auto node = resources_->getString(adaptString(node_->data, size_));
@@ -52,13 +71,6 @@ class StringBuffer {
     return node;
   }
 
-  JsonString str() const {
-    ARDUINOJSON_ASSERT(node_ != nullptr);
-
-    return JsonString(node_->data, node_->length);
-  }
-
- private:
   ResourceManager* resources_;
   StringNode* node_ = nullptr;
   size_t size_ = 0;

src/ArduinoJson/Memory/StringBuilder.hpp

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <ArduinoJson/Memory/ResourceManager.hpp>
+#include <ArduinoJson/Strings/JsonString.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
@@ -25,10 +26,18 @@ class StringBuilder {
       node_ = resources_->createString(initialCapacity);
   }
 
-  StringNode* save() {
+  void save(VariantData* variant) {
+    ARDUINOJSON_ASSERT(variant != nullptr);
     ARDUINOJSON_ASSERT(node_ != nullptr);
-    node_->data[size_] = 0;
-    StringNode* node = resources_->getString(adaptString(node_->data, size_));
+
+    char* p = node_->data;
+    if (isTinyString(p, size_)) {
+      variant->setTinyString(adaptString(p, size_));
+      return;
+    }
+
+    p[size_] = 0;
+    StringNode* node = resources_->getString(adaptString(p, size_));
     if (!node) {
       node = resources_->resizeString(node_, size_);
       ARDUINOJSON_ASSERT(node != nullptr);  // realloc to smaller can't fail
@@ -37,7 +46,7 @@ class StringBuilder {
     } else {
       node->references++;
     }
-    return node;
+    variant->setOwnedString(node);
   }
 
   void append(const char* s) {

src/ArduinoJson/MsgPack/MsgPackBinary.hpp

@@ -29,7 +29,7 @@ struct Converter<MsgPackBinary> : private detail::VariantAttorney {
     if (!data)
       return;
     auto resources = getResourceManager(dst);
-    data->clear(resources);
+    detail::VariantImpl(data, resources).clear();
     if (src.data()) {
       size_t headerSize = src.size() >= 0x10000 ? 5
                           : src.size() >= 0x100 ? 3
@@ -66,10 +66,8 @@ struct Converter<MsgPackBinary> : private detail::VariantAttorney {
   }
 
   static MsgPackBinary fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    if (!data)
-      return {};
-    auto rawstr = data->asRawString();
+    auto variant = VariantAttorney::getVariantImpl(src);
+    auto rawstr = variant.asRawString();
     auto p = reinterpret_cast<const uint8_t*>(rawstr.c_str());
     auto n = rawstr.size();
     if (n >= 2 && p[0] == 0xc4) {  // bin 8

src/ArduinoJson/MsgPack/MsgPackDeserializer.hpp

@@ -24,10 +24,10 @@ class MsgPackDeserializer {
         foundSomething_(false) {}
 
   template <typename TFilter>
-  DeserializationError parse(VariantData& variant, TFilter filter,
+  DeserializationError parse(VariantData* variant, TFilter filter,
                              DeserializationOption::NestingLimit nestingLimit) {
     DeserializationError::Code err;
-    err = parseVariant(&variant, filter, nestingLimit);
+    err = parseVariant(variant, filter, nestingLimit);
     return foundSomething_ ? err : DeserializationError::EmptyInput;
   }
 
@@ -91,7 +91,7 @@ class MsgPackDeserializer {
 
     if (code <= 0x7f || code >= 0xe0) {  // fixint
       if (allowValue)
-        variant->setInteger(static_cast<int8_t>(code), resources_);
+        VariantImpl(variant, resources_).setInteger(static_cast<int8_t>(code));
       return DeserializationError::Ok;
     }
 
@@ -231,14 +231,14 @@ class MsgPackDeserializer {
     if (isSigned) {
       auto truncatedValue = static_cast<JsonInteger>(signedValue);
       if (truncatedValue == signedValue) {
-        if (!variant->setInteger(truncatedValue, resources_))
+        if (!VariantImpl(variant, resources_).setInteger(truncatedValue))
           return DeserializationError::NoMemory;
       }
       // else set null on overflow
     } else {
       auto truncatedValue = static_cast<JsonUInt>(unsignedValue);
       if (truncatedValue == unsignedValue)
-        if (!variant->setInteger(truncatedValue, resources_))
+        if (!VariantImpl(variant, resources_).setInteger(truncatedValue))
           return DeserializationError::NoMemory;
       // else set null on overflow
     }
@@ -257,7 +257,7 @@ class MsgPackDeserializer {
       return err;
 
     fixEndianness(value);
-    variant->setFloat(value, resources_);
+    VariantImpl(variant, resources_).setFloat(value);
 
     return DeserializationError::Ok;
   }
@@ -273,7 +273,7 @@ class MsgPackDeserializer {
       return err;
 
     fixEndianness(value);
-    if (variant->setFloat(value, resources_))
+    if (VariantImpl(variant, resources_).setFloat(value))
       return DeserializationError::Ok;
     else
       return DeserializationError::NoMemory;
@@ -293,7 +293,7 @@ class MsgPackDeserializer {
 
     doubleToFloat(i, o);
     fixEndianness(value);
-    variant->setFloat(value, resources_);
+    VariantImpl(variant, resources_).setFloat(value);
 
     return DeserializationError::Ok;
   }
@@ -305,7 +305,7 @@ class MsgPackDeserializer {
     if (err)
       return err;
 
-    variant->setOwnedString(stringBuffer_.save());
+    stringBuffer_.save(variant);
     return DeserializationError::Ok;
   }
 
@@ -334,7 +334,7 @@ class MsgPackDeserializer {
     if (err)
       return err;
 
-    variant->setRawString(stringBuffer_.save());
+    stringBuffer_.saveRaw(variant);
     return DeserializationError::Ok;
   }
 
@@ -349,12 +349,10 @@ class MsgPackDeserializer {
 
     bool allowArray = filter.allowArray();
 
-    ArrayData* array;
+    ArrayImpl array;
     if (allowArray) {
       ARDUINOJSON_ASSERT(variant != 0);
-      array = &variant->toArray();
-    } else {
-      array = 0;
+      array = VariantImpl(variant, resources_).toArray();
     }
 
     TFilter elementFilter = filter[0U];
@@ -363,8 +361,7 @@ class MsgPackDeserializer {
       VariantData* value;
 
       if (elementFilter.allow()) {
-        ARDUINOJSON_ASSERT(array != 0);
-        value = array->addElement(resources_);
+        value = array.addElement();
         if (!value)
           return DeserializationError::NoMemory;
       } else {
@@ -388,12 +385,10 @@ class MsgPackDeserializer {
     if (nestingLimit.reached())
       return DeserializationError::TooDeep;
 
-    ObjectData* object;
+    ObjectImpl object;
     if (filter.allowObject()) {
       ARDUINOJSON_ASSERT(variant != 0);
-      object = &variant->toObject();
-    } else {
-      object = 0;
+      object = VariantImpl(variant, resources_).toObject();
     }
 
     for (; n; --n) {
@@ -403,19 +398,14 @@ class MsgPackDeserializer {
 
       JsonString key = stringBuffer_.str();
       TFilter memberFilter = filter[key.c_str()];
-      VariantData* member;
+      VariantData* member = 0;
 
       if (memberFilter.allow()) {
-        ARDUINOJSON_ASSERT(object != 0);
-
-        // Save key in memory pool.
-        auto savedKey = stringBuffer_.save();
-
-        member = object->addMember(savedKey, resources_);
-        if (!member)
+        auto keyVariant = object.addPair(&member);
+        if (!keyVariant)
           return DeserializationError::NoMemory;
-      } else {
-        member = 0;
+
+        stringBuffer_.save(keyVariant);
       }
 
       err = parseVariant(member, memberFilter, nestingLimit.decrement());

src/ArduinoJson/MsgPack/MsgPackExtension.hpp

@@ -31,11 +31,11 @@ class MsgPackExtension {
 template <>
 struct Converter<MsgPackExtension> : private detail::VariantAttorney {
   static void toJson(MsgPackExtension src, JsonVariant dst) {
-    auto data = VariantAttorney::getData(dst);
+    auto data = getData(dst);
     if (!data)
       return;
     auto resources = getResourceManager(dst);
-    data->clear(resources);
+    detail::VariantImpl(data, resources).clear();
     if (src.data()) {
       uint8_t format, sizeBytes;
       if (src.size() >= 0x10000) {
@@ -80,10 +80,8 @@ struct Converter<MsgPackExtension> : private detail::VariantAttorney {
   }
 
   static MsgPackExtension fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    if (!data)
-      return {};
-    auto rawstr = data->asRawString();
+    auto variant = VariantAttorney::getVariantImpl(src);
+    auto rawstr = variant.asRawString();
     if (rawstr.size() == 0)
       return {};
     auto p = reinterpret_cast<const uint8_t*>(rawstr.c_str());

src/ArduinoJson/MsgPack/MsgPackSerializer.hpp

@@ -19,7 +19,7 @@ class MsgPackSerializer : public VariantDataVisitor<size_t> {
  public:
   static const bool producesText = false;
 
-  MsgPackSerializer(TWriter writer, const ResourceManager* resources)
+  MsgPackSerializer(TWriter writer, ResourceManager* resources)
       : writer_(writer), resources_(resources) {}
 
   template <typename T>
@@ -47,8 +47,8 @@ class MsgPackSerializer : public VariantDataVisitor<size_t> {
     return bytesWritten();
   }
 
-  size_t visit(const ArrayData& array) {
-    size_t n = array.size(resources_);
+  size_t visit(const ArrayImpl& array) {
+    size_t n = array.size();
     if (n < 0x10) {
       writeByte(uint8_t(0x90 + n));
     } else if (n < 0x10000) {
@@ -62,15 +62,15 @@ class MsgPackSerializer : public VariantDataVisitor<size_t> {
     auto slotId = array.head();
     while (slotId != NULL_SLOT) {
       auto slot = resources_->getVariant(slotId);
-      slot->accept(*this, resources_);
-      slotId = slot->next();
+      VariantImpl(slot, resources_).accept(*this);
+      slotId = slot->next;
     }
 
     return bytesWritten();
   }
 
-  size_t visit(const ObjectData& object) {
-    size_t n = object.size(resources_);
+  size_t visit(const ObjectImpl& object) {
+    size_t n = object.size();
     if (n < 0x10) {
       writeByte(uint8_t(0x80 + n));
     } else if (n < 0x10000) {
@@ -84,8 +84,8 @@ class MsgPackSerializer : public VariantDataVisitor<size_t> {
     auto slotId = object.head();
     while (slotId != NULL_SLOT) {
       auto slot = resources_->getVariant(slotId);
-      slot->accept(*this, resources_);
-      slotId = slot->next();
+      VariantImpl(slot, resources_).accept(*this);
+      slotId = slot->next;
     }
 
     return bytesWritten();
@@ -209,7 +209,7 @@ class MsgPackSerializer : public VariantDataVisitor<size_t> {
   }
 
   CountingDecorator<TWriter> writer_;
-  const ResourceManager* resources_;
+  ResourceManager* resources_;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Object/JsonObject.hpp

@@ -20,56 +20,55 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   using iterator = JsonObjectIterator;
 
   // Creates an unbound reference.
-  JsonObject() : data_(0), resources_(0) {}
+  JsonObject() {}
 
   // INTERNAL USE ONLY
-  JsonObject(detail::ObjectData* data, detail::ResourceManager* resource)
-      : data_(data), resources_(resource) {}
+  JsonObject(const detail::ObjectImpl& impl) : impl_(impl) {}
+
+  // INTERNAL USE ONLY
+  JsonObject(detail::VariantData* data, detail::ResourceManager* resource)
+      : impl_(detail::VariantImpl(data, resource).asObject()) {}
 
   operator JsonVariant() const {
-    void* data = data_;  // prevent warning cast-align
-    return JsonVariant(reinterpret_cast<detail::VariantData*>(data),
-                       resources_);
+    return JsonVariant(getData(), getResourceManager());
   }
 
   operator JsonObjectConst() const {
-    return JsonObjectConst(data_, resources_);
+    return JsonObjectConst(getData(), getResourceManager());
   }
 
   operator JsonVariantConst() const {
-    return JsonVariantConst(collectionToVariant(data_), resources_);
+    return JsonVariantConst(getData(), getResourceManager());
   }
 
   // Returns true if the reference is unbound.
   // https://arduinojson.org/v7/api/jsonobject/isnull/
   bool isNull() const {
-    return data_ == 0;
+    return impl_.isNull();
   }
 
   // Returns true if the reference is bound.
   // https://arduinojson.org/v7/api/jsonobject/isnull/
   operator bool() const {
-    return data_ != 0;
+    return !isNull();
   }
 
   // Returns the depth (nesting level) of the object.
   // https://arduinojson.org/v7/api/jsonobject/nesting/
   size_t nesting() const {
-    return detail::VariantData::nesting(collectionToVariant(data_), resources_);
+    return impl_.nesting();
   }
 
   // Returns the number of members in the object.
   // https://arduinojson.org/v7/api/jsonobject/size/
   size_t size() const {
-    return data_ ? data_->size(resources_) : 0;
+    return impl_.size();
   }
 
   // Returns an iterator to the first key-value pair of the object.
   // https://arduinojson.org/v7/api/jsonobject/begin/
   iterator begin() const {
-    if (!data_)
-      return iterator();
-    return iterator(data_->createIterator(resources_), resources_);
+    return iterator(impl_.createIterator(), impl_.getResourceManager());
   }
 
   // Returns an iterator following the last key-value pair of the object.
@@ -81,13 +80,13 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // Removes all the members of the object.
   // https://arduinojson.org/v7/api/jsonobject/clear/
   void clear() const {
-    detail::ObjectData::clear(data_, resources_);
+    impl_.clear();
   }
 
   // Copies an object.
   // https://arduinojson.org/v7/api/jsonobject/set/
   bool set(JsonObjectConst src) {
-    if (!data_ || !src.data_)
+    if (isNull() || src.isNull())
       return false;
 
     clear();
@@ -131,7 +130,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // Removes the member at the specified iterator.
   // https://arduinojson.org/v7/api/jsonobject/remove/
   FORCE_INLINE void remove(iterator it) const {
-    detail::ObjectData::remove(data_, it.iterator_, resources_);
+    impl_.remove(it.iterator_);
   }
 
   // Removes the member with the specified key.
@@ -139,8 +138,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   template <typename TString,
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   void remove(const TString& key) const {
-    detail::ObjectData::removeMember(data_, detail::adaptString(key),
-                                     resources_);
+    impl_.removeMember(detail::adaptString(key));
   }
 
   // Removes the member with the specified key.
@@ -156,8 +154,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // https://arduinojson.org/v7/api/jsonobject/remove/
   template <typename TChar>
   FORCE_INLINE void remove(TChar* key) const {
-    detail::ObjectData::removeMember(data_, detail::adaptString(key),
-                                     resources_);
+    impl_.removeMember(detail::adaptString(key));
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -166,8 +163,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[key].is<T>() instead")
   bool containsKey(const TString& key) const {
-    return detail::ObjectData::getMember(data_, detail::adaptString(key),
-                                         resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj["key"].is<T>() instead
@@ -178,8 +174,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
                                 int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[\"key\"].is<T>() instead")
   bool containsKey(TChar* key) const {
-    return detail::ObjectData::getMember(data_, detail::adaptString(key),
-                                         resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -227,19 +222,18 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
 
  private:
   detail::ResourceManager* getResourceManager() const {
-    return resources_;
+    return impl_.getResourceManager();
   }
 
   detail::VariantData* getData() const {
-    return detail::collectionToVariant(data_);
+    return impl_.getData();
   }
 
   detail::VariantData* getOrCreateData() const {
-    return detail::collectionToVariant(data_);
+    return impl_.getData();
   }
 
-  detail::ObjectData* data_;
-  detail::ResourceManager* resources_;
+  mutable detail::ObjectImpl impl_;
 };
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE

src/ArduinoJson/Object/JsonObjectConst.hpp

@@ -19,47 +19,47 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   using iterator = JsonObjectConstIterator;
 
   // Creates an unbound reference.
-  JsonObjectConst() : data_(0), resources_(0) {}
+  JsonObjectConst() {}
 
   // INTERNAL USE ONLY
-  JsonObjectConst(const detail::ObjectData* data,
-                  const detail::ResourceManager* resources)
-      : data_(data), resources_(resources) {}
+  JsonObjectConst(detail::VariantData* data, detail::ResourceManager* resources)
+      : impl_(detail::VariantImpl(data, resources).asObject()) {}
+
+  // INTERNAL USE ONLY
+  JsonObjectConst(const detail::ObjectImpl& impl) : impl_(impl) {}
 
   operator JsonVariantConst() const {
-    return JsonVariantConst(getData(), resources_);
+    return JsonVariantConst(impl_.getData(), impl_.getResourceManager());
   }
 
   // Returns true if the reference is unbound.
   // https://arduinojson.org/v7/api/jsonobjectconst/isnull/
   bool isNull() const {
-    return data_ == 0;
+    return impl_.isNull();
   }
 
   // Returns true if the reference is bound.
   // https://arduinojson.org/v7/api/jsonobjectconst/isnull/
   operator bool() const {
-    return data_ != 0;
+    return !isNull();
   }
 
   // Returns the depth (nesting level) of the object.
   // https://arduinojson.org/v7/api/jsonobjectconst/nesting/
   size_t nesting() const {
-    return detail::VariantData::nesting(getData(), resources_);
+    return impl_.nesting();
   }
 
   // Returns the number of members in the object.
   // https://arduinojson.org/v7/api/jsonobjectconst/size/
   size_t size() const {
-    return data_ ? data_->size(resources_) : 0;
+    return impl_.size();
   }
 
   // Returns an iterator to the first key-value pair of the object.
   // https://arduinojson.org/v7/api/jsonobjectconst/begin/
   iterator begin() const {
-    if (!data_)
-      return iterator();
-    return iterator(data_->createIterator(resources_), resources_);
+    return iterator(impl_.createIterator(), impl_.getResourceManager());
   }
 
   // Returns an iterator following the last key-value pair of the object.
@@ -74,8 +74,7 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[key].is<T>() instead")
   bool containsKey(const TString& key) const {
-    return detail::ObjectData::getMember(data_, detail::adaptString(key),
-                                         resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj["key"].is<T>() instead
@@ -83,8 +82,7 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   template <typename TChar>
   ARDUINOJSON_DEPRECATED("use obj[\"key\"].is<T>() instead")
   bool containsKey(TChar* key) const {
-    return detail::ObjectData::getMember(data_, detail::adaptString(key),
-                                         resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -101,9 +99,8 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   template <typename TString,
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
-    return JsonVariantConst(detail::ObjectData::getMember(
-                                data_, detail::adaptString(key), resources_),
-                            resources_);
+    return JsonVariantConst(impl_.getMember(detail::adaptString(key)),
+                            impl_.getResourceManager());
   }
 
   // Gets the member with specified key.
@@ -113,9 +110,8 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
                                     !detail::is_const<TChar>::value,
                                 int> = 0>
   JsonVariantConst operator[](TChar* key) const {
-    return JsonVariantConst(detail::ObjectData::getMember(
-                                data_, detail::adaptString(key), resources_),
-                            resources_);
+    return JsonVariantConst(impl_.getMember(detail::adaptString(key)),
+                            impl_.getResourceManager());
   }
 
   // Gets the member with specified key.
@@ -137,11 +133,10 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
 
  private:
   const detail::VariantData* getData() const {
-    return collectionToVariant(data_);
+    return impl_.getData();
   }
 
-  const detail::ObjectData* data_;
-  const detail::ResourceManager* resources_;
+  detail::ObjectImpl impl_;
 };
 
 inline bool operator==(JsonObjectConst lhs, JsonObjectConst rhs) {

src/ArduinoJson/Object/JsonObjectIterator.hpp

@@ -14,7 +14,7 @@ class JsonObjectIterator {
  public:
   JsonObjectIterator() {}
 
-  explicit JsonObjectIterator(detail::ObjectData::iterator iterator,
+  explicit JsonObjectIterator(detail::ObjectImpl::iterator iterator,
                               detail::ResourceManager* resources)
       : iterator_(iterator), resources_(resources) {}
 
@@ -40,7 +40,7 @@ class JsonObjectIterator {
   }
 
  private:
-  detail::ObjectData::iterator iterator_;
+  detail::ObjectImpl::iterator iterator_;
   detail::ResourceManager* resources_;
 };
 
@@ -50,8 +50,8 @@ class JsonObjectConstIterator {
  public:
   JsonObjectConstIterator() {}
 
-  explicit JsonObjectConstIterator(detail::ObjectData::iterator iterator,
-                                   const detail::ResourceManager* resources)
+  explicit JsonObjectConstIterator(detail::ObjectImpl::iterator iterator,
+                                   detail::ResourceManager* resources)
       : iterator_(iterator), resources_(resources) {}
 
   JsonPairConst operator*() const {
@@ -76,8 +76,8 @@ class JsonObjectConstIterator {
   }
 
  private:
-  detail::ObjectData::iterator iterator_;
-  const detail::ResourceManager* resources_;
+  detail::ObjectImpl::iterator iterator_;
+  detail::ResourceManager* resources_;
 };
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE

src/ArduinoJson/Object/JsonPair.hpp

@@ -15,10 +15,11 @@ ARDUINOJSON_BEGIN_PUBLIC_NAMESPACE
 class JsonPair {
  public:
   // INTERNAL USE ONLY
-  JsonPair(detail::ObjectData::iterator iterator,
+  JsonPair(detail::ObjectImpl::iterator iterator,
            detail::ResourceManager* resources) {
     if (!iterator.done()) {
-      key_ = iterator->asString();
+      detail::VariantImpl variant(iterator.data(), resources);
+      key_ = variant.asString();
       iterator.next(resources);
       value_ = JsonVariant(iterator.data(), resources);
     }
@@ -43,10 +44,11 @@ class JsonPair {
 // https://arduinojson.org/v7/api/jsonobjectconst/begin_end/
 class JsonPairConst {
  public:
-  JsonPairConst(detail::ObjectData::iterator iterator,
-                const detail::ResourceManager* resources) {
+  JsonPairConst(detail::ObjectImpl::iterator iterator,
+                detail::ResourceManager* resources) {
     if (!iterator.done()) {
-      key_ = iterator->asString();
+      detail::VariantImpl variant(iterator.data(), resources);
+      key_ = variant.asString();
       iterator.next(resources);
       value_ = JsonVariantConst(iterator.data(), resources);
     }

src/ArduinoJson/Object/MemberProxy.hpp

@@ -56,17 +56,12 @@ class MemberProxy
   }
 
   VariantData* getData() const {
-    return VariantData::getMember(
-        VariantAttorney::getData(upstream_), key_,
-        VariantAttorney::getResourceManager(upstream_));
+    return VariantAttorney::getVariantImpl(upstream_).getMember(key_);
   }
 
   VariantData* getOrCreateData() const {
-    auto data = VariantAttorney::getOrCreateData(upstream_);
-    if (!data)
-      return nullptr;
-    return data->getOrAddMember(key_,
-                                VariantAttorney::getResourceManager(upstream_));
+    return VariantAttorney::getOrCreateVariantImpl(upstream_).getOrAddMember(
+        key_);
   }
 
  private:

src/ArduinoJson/Object/ObjectData.hpp

@@ -8,61 +8,40 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class ObjectData : public CollectionData {
+class VariantImpl;
+
+class ObjectImpl : public CollectionImpl {
  public:
-  template <typename TAdaptedString>  // also works with StringNode*
-  VariantData* addMember(TAdaptedString key, ResourceManager* resources);
+  ObjectImpl() {}
+
+  ObjectImpl(CollectionData* data, ResourceManager* resources)
+      : CollectionImpl(data, resources) {}
 
   template <typename TAdaptedString>
-  VariantData* getOrAddMember(TAdaptedString key, ResourceManager* resources);
+  VariantData* addMember(TAdaptedString key);
+
+  VariantData* addPair(VariantData** value);
 
   template <typename TAdaptedString>
-  VariantData* getMember(TAdaptedString key,
-                         const ResourceManager* resources) const;
+  VariantData* getOrAddMember(TAdaptedString key);
 
   template <typename TAdaptedString>
-  static VariantData* getMember(const ObjectData* object, TAdaptedString key,
-                                const ResourceManager* resources) {
-    if (!object)
-      return nullptr;
-    return object->getMember(key, resources);
-  }
+  VariantData* getMember(TAdaptedString key) const;
 
   template <typename TAdaptedString>
-  void removeMember(TAdaptedString key, ResourceManager* resources);
+  void removeMember(TAdaptedString key);
 
-  template <typename TAdaptedString>
-  static void removeMember(ObjectData* obj, TAdaptedString key,
-                           ResourceManager* resources) {
-    if (!obj)
-      return;
-    obj->removeMember(key, resources);
+  void remove(iterator it) {
+    CollectionImpl::removePair(it);
   }
 
-  void remove(iterator it, ResourceManager* resources) {
-    CollectionData::removePair(it, resources);
-  }
-
-  static void remove(ObjectData* obj, ObjectData::iterator it,
-                     ResourceManager* resources) {
-    if (!obj)
-      return;
-    obj->remove(it, resources);
-  }
-
-  size_t size(const ResourceManager* resources) const {
-    return CollectionData::size(resources) / 2;
-  }
-
-  static size_t size(const ObjectData* obj, const ResourceManager* resources) {
-    if (!obj)
-      return 0;
-    return obj->size(resources);
+  size_t size() const {
+    return CollectionImpl::size() / 2;
   }
 
  private:
   template <typename TAdaptedString>
-  iterator findKey(TAdaptedString key, const ResourceManager* resources) const;
+  iterator findKey(TAdaptedString key) const;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Object/ObjectImpl.hpp

@@ -11,32 +11,30 @@
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 template <typename TAdaptedString>
-inline VariantData* ObjectData::getMember(
-    TAdaptedString key, const ResourceManager* resources) const {
-  auto it = findKey(key, resources);
+inline VariantData* ObjectImpl::getMember(TAdaptedString key) const {
+  auto it = findKey(key);
   if (it.done())
     return nullptr;
-  it.next(resources);
+  it.next(resources_);
   return it.data();
 }
 
 template <typename TAdaptedString>
-VariantData* ObjectData::getOrAddMember(TAdaptedString key,
-                                        ResourceManager* resources) {
-  auto data = getMember(key, resources);
+VariantData* ObjectImpl::getOrAddMember(TAdaptedString key) {
+  auto data = getMember(key);
   if (data)
     return data;
-  return addMember(key, resources);
+  return addMember(key);
 }
 
 template <typename TAdaptedString>
-inline ObjectData::iterator ObjectData::findKey(
-    TAdaptedString key, const ResourceManager* resources) const {
+inline ObjectImpl::iterator ObjectImpl::findKey(TAdaptedString key) const {
   if (key.isNull())
     return iterator();
   bool isKey = true;
-  for (auto it = createIterator(resources); !it.done(); it.next(resources)) {
-    if (isKey && stringEquals(key, adaptString(it->asString())))
+  for (auto it = createIterator(); !it.done(); it.next(resources_)) {
+    VariantImpl variant(it.data(), resources_);
+    if (isKey && stringEquals(key, adaptString(variant.asString())))
       return it;
     isKey = !isKey;
   }
@@ -44,33 +42,55 @@ inline ObjectData::iterator ObjectData::findKey(
 }
 
 template <typename TAdaptedString>
-inline void ObjectData::removeMember(TAdaptedString key,
-                                     ResourceManager* resources) {
-  remove(findKey(key, resources), resources);
+inline void ObjectImpl::removeMember(TAdaptedString key) {
+  remove(findKey(key));
 }
 
 template <typename TAdaptedString>
-inline VariantData* ObjectData::addMember(TAdaptedString key,
-                                          ResourceManager* resources) {
-  auto keySlot = resources->allocVariant();
+inline VariantData* ObjectImpl::addMember(TAdaptedString key) {
+  if (!data_)
+    return nullptr;
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
+
+  auto keySlot = resources_->allocVariant();
   if (!keySlot)
     return nullptr;
 
-  auto valueSlot = resources->allocVariant();
+  auto valueSlot = resources_->allocVariant();
   if (!valueSlot)
     return nullptr;
 
-  if (!keySlot->setString(key, resources))
+  VariantImpl keyImpl(keySlot.ptr(), resources_);
+  if (!keyImpl.setString(key))
     return nullptr;
 
-  CollectionData::appendPair(keySlot, valueSlot, resources);
+  CollectionImpl::appendPair(keySlot, valueSlot);
 
   return valueSlot.ptr();
 }
 
+inline VariantData* ObjectImpl::addPair(VariantData** value) {
+  if (!data_)
+    return nullptr;
+  ARDUINOJSON_ASSERT(resources_ != nullptr);
+
+  auto keySlot = resources_->allocVariant();
+  if (!keySlot)
+    return nullptr;
+
+  auto valueSlot = resources_->allocVariant();
+  if (!valueSlot)
+    return nullptr;
+  *value = valueSlot.ptr();
+
+  CollectionImpl::appendPair(keySlot, valueSlot);
+
+  return keySlot.ptr();
+}
+
 // Returns the size (in bytes) of an object with n members.
 constexpr size_t sizeofObject(size_t n) {
-  return 2 * n * ResourceManager::slotSize;
+  return 2 * n * sizeof(VariantData);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Serialization/measure.hpp

@@ -14,7 +14,7 @@ size_t measure(ArduinoJson::JsonVariantConst source) {
   auto data = VariantAttorney::getData(source);
   auto resources = VariantAttorney::getResourceManager(source);
   TSerializer<DummyWriter> serializer(dp, resources);
-  return VariantData::accept(data, resources, serializer);
+  return VariantImpl(data, resources).accept(serializer);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Serialization/serialize.hpp

@@ -13,7 +13,7 @@ size_t doSerialize(ArduinoJson::JsonVariantConst source, TWriter writer) {
   auto data = VariantAttorney::getData(source);
   auto resources = VariantAttorney::getResourceManager(source);
   TSerializer<TWriter> serializer(writer, resources);
-  return VariantData::accept(data, resources, serializer);
+  return VariantImpl(data, resources).accept(serializer);
 }
 
 template <template <typename> class TSerializer, typename TDestination>

src/ArduinoJson/Strings/Adapters/RamString.hpp

@@ -76,12 +76,23 @@ struct StringAdapter<TChar*, enable_if_t<IsChar<TChar>::value>> {
   }
 };
 
+template <typename TChar>
+struct StringAdapter<TChar[], enable_if_t<IsChar<TChar>::value>> {
+  using AdaptedString = RamString;
+
+  static AdaptedString adapt(const TChar* p) {
+    auto str = reinterpret_cast<const char*>(p);
+    return AdaptedString(str, str ? ::strlen(str) : 0);
+  }
+};
+
 template <size_t N>
 struct StringAdapter<const char (&)[N]> {
   using AdaptedString = RamString;
 
-  static AdaptedString adapt(const char (&p)[N]) {
-    return RamString(p, N - 1, true);
+  static AdaptedString adapt(const char* p) {
+    ARDUINOJSON_ASSERT(p);
+    return RamString(p, ::strlen(p), true);
   }
 };
 

src/ArduinoJson/Strings/JsonString.hpp

@@ -28,8 +28,7 @@ class JsonString {
             detail::enable_if_t<detail::is_integral<TSize>::value &&
                                     !detail::is_same<TSize, bool>::value,
                                 int> = 0>
-  JsonString(const char* data, TSize sz, bool isStatic = false)
-      : str_(data, size_t(sz), isStatic) {}
+  JsonString(const char* data, TSize sz) : str_(data, size_t(sz), false) {}
 
   // Returns a pointer to the characters.
   const char* c_str() const {

src/ArduinoJson/Variant/ConverterImpl.hpp

@@ -60,25 +60,18 @@ struct Converter<T, detail::enable_if_t<detail::is_integral<T>::value &&
     : private detail::VariantAttorney {
   static bool toJson(T src, JsonVariant dst) {
     ARDUINOJSON_ASSERT_INTEGER_TYPE_IS_SUPPORTED(T);
-    auto data = getData(dst);
-    if (!data)
-      return false;
-    auto resources = getResourceManager(dst);
-    data->clear(resources);
-    return data->setInteger(src, resources);
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    return variant.setInteger(src);
   }
 
   static T fromJson(JsonVariantConst src) {
     ARDUINOJSON_ASSERT_INTEGER_TYPE_IS_SUPPORTED(T);
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data ? data->template asIntegral<T>(resources) : T();
+    return getVariantImpl(src).template asIntegral<T>();
   }
 
   static bool checkJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data && data->template isInteger<T>(resources);
+    return getVariantImpl(src).template isInteger<T>();
   }
 };
 
@@ -90,40 +83,29 @@ struct Converter<T, detail::enable_if_t<detail::is_enum<T>::value>>
   }
 
   static T fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data ? static_cast<T>(data->template asIntegral<int>(resources))
-                : T();
+    return static_cast<T>(getVariantImpl(src).template asIntegral<int>());
   }
 
   static bool checkJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data && data->template isInteger<int>(resources);
+    return getVariantImpl(src).template isInteger<int>();
   }
 };
 
 template <>
 struct Converter<bool> : private detail::VariantAttorney {
   static bool toJson(bool src, JsonVariant dst) {
-    auto data = getData(dst);
-    if (!data)
-      return false;
-    auto resources = getResourceManager(dst);
-    data->clear(resources);
-    data->setBoolean(src);
-    return true;
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    return variant.setBoolean(src);
   }
 
   static bool fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data ? data->asBoolean(resources) : false;
+    return getVariantImpl(src).asBoolean();
   }
 
   static bool checkJson(JsonVariantConst src) {
     auto data = getData(src);
-    return data && data->isBoolean();
+    return data && data->type == detail::VariantType::Boolean;
   }
 };
 
@@ -131,18 +113,13 @@ template <typename T>
 struct Converter<T, detail::enable_if_t<detail::is_floating_point<T>::value>>
     : private detail::VariantAttorney {
   static bool toJson(T src, JsonVariant dst) {
-    auto data = getData(dst);
-    if (!data)
-      return false;
-    auto resources = getResourceManager(dst);
-    data->clear(resources);
-    return data->setFloat(src, resources);
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    return variant.setFloat(src);
   }
 
   static T fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return data ? data->template asFloat<T>(resources) : 0;
+    return getVariantImpl(src).template asFloat<T>();
   }
 
   static bool checkJson(JsonVariantConst src) {
@@ -154,13 +131,13 @@ struct Converter<T, detail::enable_if_t<detail::is_floating_point<T>::value>>
 template <>
 struct Converter<const char*> : private detail::VariantAttorney {
   static void toJson(const char* src, JsonVariant dst) {
-    detail::VariantData::setString(getData(dst), detail::adaptString(src),
-                                   getResourceManager(dst));
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    variant.setString(detail::adaptString(src));
   }
 
   static const char* fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    return data ? data->asString().c_str() : 0;
+    return getVariantImpl(src).asString().c_str();
   }
 
   static bool checkJson(JsonVariantConst src) {
@@ -172,13 +149,13 @@ struct Converter<const char*> : private detail::VariantAttorney {
 template <>
 struct Converter<JsonString> : private detail::VariantAttorney {
   static void toJson(JsonString src, JsonVariant dst) {
-    detail::VariantData::setString(getData(dst), detail::adaptString(src),
-                                   getResourceManager(dst));
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    variant.setString(detail::adaptString(src));
   }
 
   static JsonString fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    return data ? data->asString() : JsonString();
+    return getVariantImpl(src).asString();
   }
 
   static bool checkJson(JsonVariantConst src) {
@@ -190,10 +167,9 @@ struct Converter<JsonString> : private detail::VariantAttorney {
 template <typename T>
 inline detail::enable_if_t<detail::IsString<T>::value> convertToJson(
     const T& src, JsonVariant dst) {
-  using namespace detail;
-  auto data = VariantAttorney::getData(dst);
-  auto resources = VariantAttorney::getResourceManager(dst);
-  detail::VariantData::setString(data, adaptString(src), resources);
+  auto variant = detail::VariantAttorney::getVariantImpl(dst);
+  variant.clear();
+  variant.setString(detail::adaptString(src));
 }
 
 // SerializedValue<std::string>
@@ -202,22 +178,23 @@ inline detail::enable_if_t<detail::IsString<T>::value> convertToJson(
 template <typename T>
 struct Converter<SerializedValue<T>> : private detail::VariantAttorney {
   static void toJson(SerializedValue<T> src, JsonVariant dst) {
-    detail::VariantData::setRawString(getData(dst), src,
-                                      getResourceManager(dst));
+    auto variant = getVariantImpl(dst);
+    variant.clear();
+    variant.setRawString(src);
   }
 };
 
 template <>
 struct Converter<detail::nullptr_t> : private detail::VariantAttorney {
   static void toJson(detail::nullptr_t, JsonVariant dst) {
-    detail::VariantData::clear(getData(dst), getResourceManager(dst));
+    getVariantImpl(dst).clear();
   }
   static detail::nullptr_t fromJson(JsonVariantConst) {
     return nullptr;
   }
   static bool checkJson(JsonVariantConst src) {
     auto data = getData(src);
-    return data == 0 || data->isNull();
+    return data == 0 || data->type == detail::VariantType::Null;
   }
 };
 
@@ -230,9 +207,9 @@ class StringBuilderPrint : public Print {
     copier_.startString();
   }
 
-  StringNode* save() {
+  void save(VariantData* data) {
     ARDUINOJSON_ASSERT(!overflowed());
-    return copier_.save();
+    copier_.save(data);
   }
 
   size_t write(uint8_t c) {
@@ -263,12 +240,12 @@ inline void convertToJson(const ::Printable& src, JsonVariant dst) {
   auto data = detail::VariantAttorney::getData(dst);
   if (!resources || !data)
     return;
-  data->clear(resources);
+  detail::VariantImpl(data, resources).clear();
   detail::StringBuilderPrint print(resources);
   src.printTo(print);
   if (print.overflowed())
     return;
-  data->setOwnedString(print.save());
+  print.save(data);
 }
 
 #endif
@@ -329,14 +306,12 @@ struct Converter<JsonArrayConst> : private detail::VariantAttorney {
   }
 
   static JsonArrayConst fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto array = data ? data->asArray() : nullptr;
-    return JsonArrayConst(array, getResourceManager(src));
+    return JsonArrayConst(getData(src), getResourceManager(src));
   }
 
   static bool checkJson(JsonVariantConst src) {
     auto data = getData(src);
-    return data && data->isArray();
+    return data && data->type == detail::VariantType::Array;
   }
 };
 
@@ -350,14 +325,12 @@ struct Converter<JsonArray> : private detail::VariantAttorney {
   }
 
   static JsonArray fromJson(JsonVariant src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return JsonArray(data != 0 ? data->asArray() : 0, resources);
+    return JsonArray(getData(src), getResourceManager(src));
   }
 
   static bool checkJson(JsonVariant src) {
     auto data = getData(src);
-    return data && data->isArray();
+    return data && data->type == detail::VariantType::Array;
   }
 };
 
@@ -371,14 +344,12 @@ struct Converter<JsonObjectConst> : private detail::VariantAttorney {
   }
 
   static JsonObjectConst fromJson(JsonVariantConst src) {
-    auto data = getData(src);
-    auto object = data != 0 ? data->asObject() : nullptr;
-    return JsonObjectConst(object, getResourceManager(src));
+    return JsonObjectConst(getData(src), getResourceManager(src));
   }
 
   static bool checkJson(JsonVariantConst src) {
     auto data = getData(src);
-    return data && data->isObject();
+    return data && data->type == detail::VariantType::Object;
   }
 };
 
@@ -392,14 +363,12 @@ struct Converter<JsonObject> : private detail::VariantAttorney {
   }
 
   static JsonObject fromJson(JsonVariant src) {
-    auto data = getData(src);
-    auto resources = getResourceManager(src);
-    return JsonObject(data != 0 ? data->asObject() : 0, resources);
+    return JsonObject(getData(src), getResourceManager(src));
   }
 
   static bool checkJson(JsonVariant src) {
     auto data = getData(src);
-    return data && data->isObject();
+    return data && data->type == detail::VariantType::Object;
   }
 };
 

src/ArduinoJson/Variant/JsonVariant.hpp

@@ -16,27 +16,29 @@ class JsonVariant : public detail::VariantRefBase<JsonVariant>,
 
  public:
   // Creates an unbound reference.
-  JsonVariant() : data_(0), resources_(0) {}
+  JsonVariant() {}
 
   // INTERNAL USE ONLY
   JsonVariant(detail::VariantData* data, detail::ResourceManager* resources)
-      : data_(data), resources_(resources) {}
+      : impl_(data, resources) {}
+
+  // INTERNAL USE ONLY
+  JsonVariant(detail::VariantImpl impl) : impl_(impl) {}
 
  private:
   detail::ResourceManager* getResourceManager() const {
-    return resources_;
+    return impl_.getResourceManager();
   }
 
   detail::VariantData* getData() const {
-    return data_;
+    return impl_.getData();
   }
 
   detail::VariantData* getOrCreateData() const {
-    return data_;
+    return impl_.getData();
   }
 
-  detail::VariantData* data_;
-  detail::ResourceManager* resources_;
+  mutable detail::VariantImpl impl_;
 };
 
 namespace detail {

src/ArduinoJson/Variant/JsonVariantConst.hpp

@@ -35,34 +35,34 @@ class JsonVariantConst : public detail::VariantTag,
 
  public:
   // Creates an unbound reference.
-  JsonVariantConst() : data_(nullptr), resources_(nullptr) {}
+  JsonVariantConst() {}
 
   // INTERNAL USE ONLY
-  explicit JsonVariantConst(const detail::VariantData* data,
-                            const detail::ResourceManager* resources)
-      : data_(data), resources_(resources) {}
+  explicit JsonVariantConst(detail::VariantData* data,
+                            detail::ResourceManager* resources)
+      : impl_(data, resources) {}
 
   // Returns true if the value is null or the reference is unbound.
   // https://arduinojson.org/v7/api/jsonvariantconst/isnull/
   bool isNull() const {
-    return detail::VariantData::isNull(data_);
+    return impl_.isNull();
   }
 
   // Returns true if the reference is unbound.
   bool isUnbound() const {
-    return !data_;
+    return impl_.getData() == nullptr;
   }
 
   // Returns the depth (nesting level) of the value.
   // https://arduinojson.org/v7/api/jsonvariantconst/nesting/
   size_t nesting() const {
-    return detail::VariantData::nesting(data_, resources_);
+    return impl_.nesting();
   }
 
   // Returns the size of the array or object.
   // https://arduinojson.org/v7/api/jsonvariantconst/size/
   size_t size() const {
-    return detail::VariantData::size(data_, resources_);
+    return impl_.size();
   }
 
   // Casts the value to the specified type.
@@ -104,9 +104,8 @@ class JsonVariantConst : public detail::VariantTag,
   template <typename T,
             detail::enable_if_t<detail::is_integral<T>::value, int> = 0>
   JsonVariantConst operator[](T index) const {
-    return JsonVariantConst(
-        detail::VariantData::getElement(data_, size_t(index), resources_),
-        resources_);
+    return JsonVariantConst(impl_.getElement(size_t(index)),
+                            impl_.getResourceManager());
   }
 
   // Gets object's member with specified key.
@@ -114,9 +113,8 @@ class JsonVariantConst : public detail::VariantTag,
   template <typename TString,
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
-    return JsonVariantConst(detail::VariantData::getMember(
-                                data_, detail::adaptString(key), resources_),
-                            resources_);
+    return JsonVariantConst(impl_.getMember(detail::adaptString(key)),
+                            impl_.getResourceManager());
   }
 
   // Gets object's member with specified key.
@@ -126,9 +124,8 @@ class JsonVariantConst : public detail::VariantTag,
                                     !detail::is_const<TChar>::value,
                                 int> = 0>
   JsonVariantConst operator[](TChar* key) const {
-    return JsonVariantConst(detail::VariantData::getMember(
-                                data_, detail::adaptString(key), resources_),
-                            resources_);
+    return JsonVariantConst(impl_.getMember(detail::adaptString(key)),
+                            impl_.getResourceManager());
   }
 
   // Gets object's member with specified key or the array's element at the
@@ -149,8 +146,7 @@ class JsonVariantConst : public detail::VariantTag,
             detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use var[key].is<T>() instead")
   bool containsKey(const TString& key) const {
-    return detail::VariantData::getMember(getData(), detail::adaptString(key),
-                                          resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj["key"].is<T>() instead
@@ -161,8 +157,7 @@ class JsonVariantConst : public detail::VariantTag,
                                 int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[\"key\"].is<T>() instead")
   bool containsKey(TChar* key) const {
-    return detail::VariantData::getMember(getData(), detail::adaptString(key),
-                                          resources_) != 0;
+    return impl_.getMember(detail::adaptString(key)) != 0;
   }
 
   // DEPRECATED: use obj[key].is<T>() instead
@@ -181,17 +176,16 @@ class JsonVariantConst : public detail::VariantTag,
   }
 
  protected:
-  const detail::VariantData* getData() const {
-    return data_;
+  detail::VariantData* getData() const {
+    return impl_.getData();
   }
 
-  const detail::ResourceManager* getResourceManager() const {
-    return resources_;
+  detail::ResourceManager* getResourceManager() const {
+    return impl_.getResourceManager();
   }
 
  private:
-  const detail::VariantData* data_;
-  const detail::ResourceManager* resources_;
+  mutable detail::VariantImpl impl_;
 };
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE

src/ArduinoJson/Variant/JsonVariantVisitor.hpp

@@ -26,15 +26,14 @@ class VisitorAdapter {
  public:
   using result_type = typename TVisitor::result_type;
 
-  VisitorAdapter(TVisitor& visitor, const ResourceManager* resources)
-      : visitor_(&visitor), resources_(resources) {}
+  VisitorAdapter(TVisitor& visitor) : visitor_(&visitor) {}
 
-  result_type visit(const ArrayData& value) {
-    return visitor_->visit(JsonArrayConst(&value, resources_));
+  result_type visit(const ArrayImpl& array) {
+    return visitor_->visit(JsonArrayConst(array));
   }
 
-  result_type visit(const ObjectData& value) {
-    return visitor_->visit(JsonObjectConst(&value, resources_));
+  result_type visit(const ObjectImpl& object) {
+    return visitor_->visit(JsonObjectConst(object));
   }
 
   template <typename T>
@@ -44,18 +43,15 @@ class VisitorAdapter {
 
  private:
   TVisitor* visitor_;
-  const ResourceManager* resources_;
 };
 
 template <typename TVisitor>
 typename TVisitor::result_type accept(JsonVariantConst variant,
                                       TVisitor& visit) {
   auto data = VariantAttorney::getData(variant);
-  if (!data)
-    return visit.visit(nullptr);
   auto resources = VariantAttorney::getResourceManager(variant);
-  VisitorAdapter<TVisitor> adapter(visit, resources);
-  return data->accept(adapter, resources);
+  VisitorAdapter<TVisitor> adapter(visit);
+  return VariantImpl(data, resources).accept(adapter);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Variant/VariantAttorney.hpp

@@ -6,7 +6,7 @@
 
 #include <ArduinoJson/Polyfills/attributes.hpp>
 #include <ArduinoJson/Polyfills/type_traits.hpp>
-#include <ArduinoJson/Variant/VariantData.hpp>
+#include <ArduinoJson/Variant/VariantImpl.hpp>
 #include <ArduinoJson/Variant/VariantTo.hpp>
 #include "JsonVariantConst.hpp"
 
@@ -26,6 +26,16 @@ class VariantAttorney {
     return client.getData();
   }
 
+  template <typename TClient>
+  static VariantImpl getVariantImpl(TClient& client) {
+    return VariantImpl(client.getData(), client.getResourceManager());
+  }
+
+  template <typename TClient>
+  static VariantImpl getOrCreateVariantImpl(TClient& client) {
+    return VariantImpl(client.getOrCreateData(), client.getResourceManager());
+  }
+
   template <typename TClient>
   static VariantData* getOrCreateData(TClient& client) {
     return client.getOrCreateData();

src/ArduinoJson/Variant/VariantContent.hpp

@@ -16,14 +16,15 @@ ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 enum class VariantTypeBits : uint8_t {
   OwnedStringBit = 0x01,  // 0000 0001
   NumberBit = 0x08,       // 0000 1000
-#if ARDUINOJSON_USE_EXTENSIONS
-  ExtensionBit = 0x10,  // 0001 0000
+#if ARDUINOJSON_USE_8_BYTE_POOL
+  EightByteBit = 0x10,  // 0001 0000
 #endif
   CollectionMask = 0x60,
 };
 
 enum class VariantType : uint8_t {
   Null = 0,             // 0000 0000
+  TinyString = 0x02,    // 0000 0010
   RawString = 0x03,     // 0000 0011
   LinkedString = 0x04,  // 0000 0100
   OwnedString = 0x05,   // 0000 0101
@@ -46,6 +47,8 @@ inline bool operator&(VariantType type, VariantTypeBits bit) {
   return (uint8_t(type) & uint8_t(bit)) != 0;
 }
 
+const size_t tinyStringMaxLength = 3;
+
 union VariantContent {
   VariantContent() {}
 
@@ -53,18 +56,14 @@ union VariantContent {
   bool asBoolean;
   uint32_t asUint32;
   int32_t asInt32;
-#if ARDUINOJSON_USE_EXTENSIONS
   SlotId asSlotId;
-#endif
-  ArrayData asArray;
-  ObjectData asObject;
   CollectionData asCollection;
-  const char* asLinkedString;
   struct StringNode* asOwnedString;
+  char asTinyString[tinyStringMaxLength + 1];
 };
 
-#if ARDUINOJSON_USE_EXTENSIONS
-union VariantExtension {
+#if ARDUINOJSON_USE_8_BYTE_POOL
+union EightByteValue {
 #  if ARDUINOJSON_USE_LONG_LONG
   uint64_t asUint64;
   int64_t asInt64;
@@ -73,6 +72,9 @@ union VariantExtension {
   double asDouble;
 #  endif
 };
+
+static_assert(sizeof(EightByteValue) == 8,
+              "sizeof(EightByteValue) must be 8 bytes");
 #endif
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Variant/VariantData.hpp

@@ -4,12 +4,7 @@
 
 #pragma once
 
-#include <ArduinoJson/Memory/MemoryPool.hpp>
 #include <ArduinoJson/Memory/StringNode.hpp>
-#include <ArduinoJson/Misc/SerializedValue.hpp>
-#include <ArduinoJson/Numbers/convertNumber.hpp>
-#include <ArduinoJson/Strings/JsonString.hpp>
-#include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <ArduinoJson/Variant/VariantContent.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
@@ -17,12 +12,21 @@ ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 template <typename T>
 T parseNumber(const char* s);
 
-class VariantData {
-  VariantContent content_;  // must be first to allow cast from array to variant
-  VariantType type_;
-  SlotId next_;
+template <typename T>
+static bool isTinyString(const T& s, size_t n) {
+  if (n > tinyStringMaxLength)
+    return false;
+  bool containsNul = false;
+  for (uint8_t i = 0; i < uint8_t(n); i++)
+    containsNul |= !s[i];
+  return !containsNul;
+}
+
+struct VariantData {
+  VariantContent content;  // must be first to allow cast from array to variant
+  VariantType type = VariantType::Null;
+  SlotId next = NULL_SLOT;
 
- public:
   // Placement new
   static void* operator new(size_t, void* p) noexcept {
     return p;
@@ -30,545 +34,50 @@ class VariantData {
 
   static void operator delete(void*, void*) noexcept {}
 
-  VariantData() : type_(VariantType::Null), next_(NULL_SLOT) {}
-
-  SlotId next() const {
-    return next_;
-  }
-
-  void setNext(SlotId slot) {
-    next_ = slot;
-  }
-
-  template <typename TVisitor>
-  typename TVisitor::result_type accept(
-      TVisitor& visit, const ResourceManager* resources) const {
-#if ARDUINOJSON_USE_EXTENSIONS
-    auto extension = getExtension(resources);
-#else
-    (void)resources;  // silence warning
-#endif
-    switch (type_) {
-      case VariantType::Float:
-        return visit.visit(content_.asFloat);
-
-#if ARDUINOJSON_USE_DOUBLE
-      case VariantType::Double:
-        return visit.visit(extension->asDouble);
-#endif
-
-      case VariantType::Array:
-        return visit.visit(content_.asArray);
-
-      case VariantType::Object:
-        return visit.visit(content_.asObject);
-
-      case VariantType::LinkedString:
-        return visit.visit(JsonString(content_.asLinkedString, true));
-
-      case VariantType::OwnedString:
-        return visit.visit(JsonString(content_.asOwnedString->data,
-                                      content_.asOwnedString->length));
-
-      case VariantType::RawString:
-        return visit.visit(RawString(content_.asOwnedString->data,
-                                     content_.asOwnedString->length));
-
-      case VariantType::Int32:
-        return visit.visit(static_cast<JsonInteger>(content_.asInt32));
-
-      case VariantType::Uint32:
-        return visit.visit(static_cast<JsonUInt>(content_.asUint32));
-
-#if ARDUINOJSON_USE_LONG_LONG
-      case VariantType::Int64:
-        return visit.visit(extension->asInt64);
-
-      case VariantType::Uint64:
-        return visit.visit(extension->asUint64);
-#endif
-
-      case VariantType::Boolean:
-        return visit.visit(content_.asBoolean != 0);
-
-      default:
-        return visit.visit(nullptr);
-    }
-  }
-
-  template <typename TVisitor>
-  static typename TVisitor::result_type accept(const VariantData* var,
-                                               const ResourceManager* resources,
-                                               TVisitor& visit) {
-    if (var != 0)
-      return var->accept(visit, resources);
-    else
-      return visit.visit(nullptr);
-  }
-
-  VariantData* addElement(ResourceManager* resources) {
-    auto array = isNull() ? &toArray() : asArray();
-    return detail::ArrayData::addElement(array, resources);
-  }
-
-  static VariantData* addElement(VariantData* var, ResourceManager* resources) {
-    if (!var)
-      return nullptr;
-    return var->addElement(resources);
-  }
-
-  template <typename T>
-  bool addValue(const T& value, ResourceManager* resources) {
-    auto array = isNull() ? &toArray() : asArray();
-    return detail::ArrayData::addValue(array, value, resources);
-  }
-
-  template <typename T>
-  static bool addValue(VariantData* var, const T& value,
-                       ResourceManager* resources) {
-    if (!var)
-      return false;
-    return var->addValue(value, resources);
-  }
-
-  bool asBoolean(const ResourceManager* resources) const {
-#if ARDUINOJSON_USE_EXTENSIONS
-    auto extension = getExtension(resources);
-#else
-    (void)resources;  // silence warning
-#endif
-    switch (type_) {
-      case VariantType::Boolean:
-        return content_.asBoolean;
-      case VariantType::Uint32:
-      case VariantType::Int32:
-        return content_.asUint32 != 0;
-      case VariantType::Float:
-        return content_.asFloat != 0;
-#if ARDUINOJSON_USE_DOUBLE
-      case VariantType::Double:
-        return extension->asDouble != 0;
-#endif
-      case VariantType::Null:
-        return false;
-#if ARDUINOJSON_USE_LONG_LONG
-      case VariantType::Uint64:
-      case VariantType::Int64:
-        return extension->asUint64 != 0;
-#endif
-      default:
-        return true;
-    }
-  }
-
-  ArrayData* asArray() {
-    return isArray() ? &content_.asArray : 0;
-  }
-
-  const ArrayData* asArray() const {
-    return const_cast<VariantData*>(this)->asArray();
-  }
-
-  CollectionData* asCollection() {
-    return isCollection() ? &content_.asCollection : 0;
-  }
-
-  const CollectionData* asCollection() const {
-    return const_cast<VariantData*>(this)->asCollection();
-  }
-
-  template <typename T>
-  T asFloat(const ResourceManager* resources) const {
-    static_assert(is_floating_point<T>::value, "T must be a floating point");
-#if ARDUINOJSON_USE_EXTENSIONS
-    auto extension = getExtension(resources);
-#else
-    (void)resources;  // silence warning
-#endif
-    const char* str = nullptr;
-    switch (type_) {
-      case VariantType::Boolean:
-        return static_cast<T>(content_.asBoolean);
-      case VariantType::Uint32:
-        return static_cast<T>(content_.asUint32);
-      case VariantType::Int32:
-        return static_cast<T>(content_.asInt32);
-#if ARDUINOJSON_USE_LONG_LONG
-      case VariantType::Uint64:
-        return static_cast<T>(extension->asUint64);
-      case VariantType::Int64:
-        return static_cast<T>(extension->asInt64);
-#endif
-      case VariantType::LinkedString:
-        str = content_.asLinkedString;
-        break;
-      case VariantType::OwnedString:
-        str = content_.asOwnedString->data;
-        break;
-      case VariantType::Float:
-        return static_cast<T>(content_.asFloat);
-#if ARDUINOJSON_USE_DOUBLE
-      case VariantType::Double:
-        return static_cast<T>(extension->asDouble);
-#endif
-      default:
-        return 0.0;
-    }
-
-    ARDUINOJSON_ASSERT(str != nullptr);
-    return parseNumber<T>(str);
-  }
-
-  template <typename T>
-  T asIntegral(const ResourceManager* resources) const {
-    static_assert(is_integral<T>::value, "T must be an integral type");
-#if ARDUINOJSON_USE_EXTENSIONS
-    auto extension = getExtension(resources);
-#else
-    (void)resources;  // silence warning
-#endif
-    const char* str = nullptr;
-    switch (type_) {
-      case VariantType::Boolean:
-        return content_.asBoolean;
-      case VariantType::Uint32:
-        return convertNumber<T>(content_.asUint32);
-      case VariantType::Int32:
-        return convertNumber<T>(content_.asInt32);
-#if ARDUINOJSON_USE_LONG_LONG
-      case VariantType::Uint64:
-        return convertNumber<T>(extension->asUint64);
-      case VariantType::Int64:
-        return convertNumber<T>(extension->asInt64);
-#endif
-      case VariantType::LinkedString:
-        str = content_.asLinkedString;
-        break;
-      case VariantType::OwnedString:
-        str = content_.asOwnedString->data;
-        break;
-      case VariantType::Float:
-        return convertNumber<T>(content_.asFloat);
-#if ARDUINOJSON_USE_DOUBLE
-      case VariantType::Double:
-        return convertNumber<T>(extension->asDouble);
-#endif
-      default:
-        return 0;
-    }
-
-    ARDUINOJSON_ASSERT(str != nullptr);
-    return parseNumber<T>(str);
-  }
-
-  ObjectData* asObject() {
-    return isObject() ? &content_.asObject : 0;
-  }
-
-  const ObjectData* asObject() const {
-    return const_cast<VariantData*>(this)->asObject();
-  }
-
-  JsonString asRawString() const {
-    switch (type_) {
-      case VariantType::RawString:
-        return JsonString(content_.asOwnedString->data,
-                          content_.asOwnedString->length);
-      default:
-        return JsonString();
-    }
-  }
-
-  JsonString asString() const {
-    switch (type_) {
-      case VariantType::LinkedString:
-        return JsonString(content_.asLinkedString, true);
-      case VariantType::OwnedString:
-        return JsonString(content_.asOwnedString->data,
-                          content_.asOwnedString->length);
-      default:
-        return JsonString();
-    }
-  }
-
-#if ARDUINOJSON_USE_EXTENSIONS
-  const VariantExtension* getExtension(const ResourceManager* resources) const;
-#endif
-
-  VariantData* getElement(size_t index,
-                          const ResourceManager* resources) const {
-    return ArrayData::getElement(asArray(), index, resources);
-  }
-
-  static VariantData* getElement(const VariantData* var, size_t index,
-                                 const ResourceManager* resources) {
-    return var != 0 ? var->getElement(index, resources) : 0;
-  }
-
-  template <typename TAdaptedString>
-  VariantData* getMember(TAdaptedString key,
-                         const ResourceManager* resources) const {
-    return ObjectData::getMember(asObject(), key, resources);
-  }
-
-  template <typename TAdaptedString>
-  static VariantData* getMember(const VariantData* var, TAdaptedString key,
-                                const ResourceManager* resources) {
-    if (!var)
-      return 0;
-    return var->getMember(key, resources);
-  }
-
-  VariantData* getOrAddElement(size_t index, ResourceManager* resources) {
-    auto array = isNull() ? &toArray() : asArray();
-    if (!array)
-      return nullptr;
-    return array->getOrAddElement(index, resources);
-  }
-
-  template <typename TAdaptedString>
-  VariantData* getOrAddMember(TAdaptedString key, ResourceManager* resources) {
-    if (key.isNull())
-      return nullptr;
-    auto obj = isNull() ? &toObject() : asObject();
-    if (!obj)
-      return nullptr;
-    return obj->getOrAddMember(key, resources);
-  }
-
-  bool isArray() const {
-    return type_ == VariantType::Array;
-  }
-
-  bool isBoolean() const {
-    return type_ == VariantType::Boolean;
-  }
-
-  bool isCollection() const {
-    return type_ & VariantTypeBits::CollectionMask;
-  }
-
-  bool isFloat() const {
-    return type_ & VariantTypeBits::NumberBit;
-  }
-
-  template <typename T>
-  bool isInteger(const ResourceManager* resources) const {
-#if ARDUINOJSON_USE_LONG_LONG
-    auto extension = getExtension(resources);
-#else
-    (void)resources;  // silence warning
-#endif
-    switch (type_) {
-      case VariantType::Uint32:
-        return canConvertNumber<T>(content_.asUint32);
-
-      case VariantType::Int32:
-        return canConvertNumber<T>(content_.asInt32);
-
-#if ARDUINOJSON_USE_LONG_LONG
-      case VariantType::Uint64:
-        return canConvertNumber<T>(extension->asUint64);
-
-      case VariantType::Int64:
-        return canConvertNumber<T>(extension->asInt64);
-#endif
-
-      default:
-        return false;
-    }
-  }
-
-  bool isNull() const {
-    return type_ == VariantType::Null;
-  }
-
-  static bool isNull(const VariantData* var) {
-    if (!var)
-      return true;
-    return var->isNull();
-  }
-
-  bool isObject() const {
-    return type_ == VariantType::Object;
-  }
-
-  bool isString() const {
-    return type_ == VariantType::LinkedString ||
-           type_ == VariantType::OwnedString;
-  }
-
-  size_t nesting(const ResourceManager* resources) const {
-    auto collection = asCollection();
-    if (collection)
-      return collection->nesting(resources);
-    else
-      return 0;
-  }
-
-  static size_t nesting(const VariantData* var,
-                        const ResourceManager* resources) {
-    if (!var)
-      return 0;
-    return var->nesting(resources);
-  }
-
-  void removeElement(size_t index, ResourceManager* resources) {
-    ArrayData::removeElement(asArray(), index, resources);
-  }
-
-  static void removeElement(VariantData* var, size_t index,
-                            ResourceManager* resources) {
-    if (!var)
-      return;
-    var->removeElement(index, resources);
-  }
-
-  template <typename TAdaptedString>
-  void removeMember(TAdaptedString key, ResourceManager* resources) {
-    ObjectData::removeMember(asObject(), key, resources);
-  }
-
-  template <typename TAdaptedString>
-  static void removeMember(VariantData* var, TAdaptedString key,
-                           ResourceManager* resources) {
-    if (!var)
-      return;
-    var->removeMember(key, resources);
-  }
-
-  void reset() {  // TODO: remove
-    type_ = VariantType::Null;
-  }
-
   void setBoolean(bool value) {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    type_ = VariantType::Boolean;
-    content_.asBoolean = value;
-  }
-
-  template <typename T>
-  enable_if_t<sizeof(T) == 4, bool> setFloat(T value, ResourceManager*) {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    type_ = VariantType::Float;
-    content_.asFloat = value;
-    return true;
-  }
-
-  template <typename T>
-  enable_if_t<sizeof(T) == 8, bool> setFloat(T value, ResourceManager*);
-
-  template <typename T>
-  enable_if_t<is_signed<T>::value, bool> setInteger(T value,
-                                                    ResourceManager* resources);
-
-  template <typename T>
-  enable_if_t<is_unsigned<T>::value, bool> setInteger(
-      T value, ResourceManager* resources);
-
-  void setRawString(StringNode* s) {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    ARDUINOJSON_ASSERT(s);
-    type_ = VariantType::RawString;
-    content_.asOwnedString = s;
-  }
-
-  template <typename T>
-  void setRawString(SerializedValue<T> value, ResourceManager* resources);
-
-  template <typename T>
-  static void setRawString(VariantData* var, SerializedValue<T> value,
-                           ResourceManager* resources) {
-    if (!var)
-      return;
-    var->clear(resources);
-    var->setRawString(value, resources);
+    ARDUINOJSON_ASSERT(type == VariantType::Null);
+    type = VariantType::Boolean;
+    content.asBoolean = value;
   }
 
   template <typename TAdaptedString>
-  bool setString(TAdaptedString value, ResourceManager* resources);
+  void setTinyString(const TAdaptedString& s) {
+    ARDUINOJSON_ASSERT(type == VariantType::Null);
+    ARDUINOJSON_ASSERT(s.size() <= tinyStringMaxLength);
 
-  bool setString(StringNode* s, ResourceManager*) {
-    setOwnedString(s);
-    return true;
-  }
+    type = VariantType::TinyString;
 
-  template <typename TAdaptedString>
-  static void setString(VariantData* var, TAdaptedString value,
-                        ResourceManager* resources) {
-    if (!var)
-      return;
-    var->clear(resources);
-    var->setString(value, resources);
-  }
+    auto n = uint8_t(s.size());
+    for (uint8_t i = 0; i < n; i++) {
+      char c = s[i];
+      ARDUINOJSON_ASSERT(c != 0);  // no NUL in tiny string
+      content.asTinyString[i] = c;
+    }
 
-  void setLinkedString(const char* s) {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    ARDUINOJSON_ASSERT(s);
-    type_ = VariantType::LinkedString;
-    content_.asLinkedString = s;
+    content.asTinyString[n] = 0;
   }
 
   void setOwnedString(StringNode* s) {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
+    ARDUINOJSON_ASSERT(type == VariantType::Null);
     ARDUINOJSON_ASSERT(s);
-    type_ = VariantType::OwnedString;
-    content_.asOwnedString = s;
+    type = VariantType::OwnedString;
+    content.asOwnedString = s;
   }
 
-  size_t size(const ResourceManager* resources) const {
-    if (isObject())
-      return content_.asObject.size(resources);
-
-    if (isArray())
-      return content_.asArray.size(resources);
-
-    return 0;
+  void setRawString(StringNode* s) {
+    ARDUINOJSON_ASSERT(type == VariantType::Null);
+    ARDUINOJSON_ASSERT(s);
+    type = VariantType::RawString;
+    content.asOwnedString = s;
   }
 
-  static size_t size(const VariantData* var, const ResourceManager* resources) {
-    return var != 0 ? var->size(resources) : 0;
+  bool isFloat() const {
+    return type & VariantTypeBits::NumberBit;
   }
 
-  ArrayData& toArray() {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    type_ = VariantType::Array;
-    new (&content_.asArray) ArrayData();
-    return content_.asArray;
-  }
-
-  static ArrayData* toArray(VariantData* var, ResourceManager* resources) {
-    if (!var)
-      return 0;
-    var->clear(resources);
-    return &var->toArray();
-  }
-
-  ObjectData& toObject() {
-    ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-    type_ = VariantType::Object;
-    new (&content_.asObject) ObjectData();
-    return content_.asObject;
-  }
-
-  static ObjectData* toObject(VariantData* var, ResourceManager* resources) {
-    if (!var)
-      return 0;
-    var->clear(resources);
-    return &var->toObject();
-  }
-
-  VariantType type() const {
-    return type_;
-  }
-
-  // Release the resources used by this variant and set it to null.
-  void clear(ResourceManager* resources);
-
-  static void clear(VariantData* var, ResourceManager* resources) {
-    if (!var)
-      return;
-    var->clear(resources);
+  bool isString() const {
+    return type == VariantType::LinkedString ||
+           type == VariantType::OwnedString || type == VariantType::TinyString;
   }
 };
 

src/ArduinoJson/Variant/VariantImpl.hpp

@@ -5,137 +5,570 @@
 #pragma once
 
 #include <ArduinoJson/Memory/ResourceManager.hpp>
+#include <ArduinoJson/Misc/SerializedValue.hpp>
+#include <ArduinoJson/Numbers/convertNumber.hpp>
+#include <ArduinoJson/Strings/JsonString.hpp>
+#include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <ArduinoJson/Variant/VariantData.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
+class VariantImpl {
+ public:
+  VariantImpl() : data_(nullptr), resources_(nullptr) {}
+
+  VariantImpl(VariantData* data, ResourceManager* resources)
+      : data_(data), resources_(resources) {}
+
+  VariantData* getData() const {
+    return data_;
+  }
+
+  ResourceManager* getResourceManager() const {
+    return resources_;
+  }
+
+  template <typename TVisitor>
+  typename TVisitor::result_type accept(TVisitor& visit) {
+    if (!data_)
+      return visit.visit(nullptr);
+
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    auto eightByteValue = getEightByte();
+#endif
+    switch (data_->type) {
+      case VariantType::Float:
+        return visit.visit(data_->content.asFloat);
+
+#if ARDUINOJSON_USE_DOUBLE
+      case VariantType::Double:
+        return visit.visit(eightByteValue->asDouble);
+#endif
+
+      case VariantType::Array:
+        return visit.visit(asArray());
+
+      case VariantType::Object:
+        return visit.visit(asObject());
+
+      case VariantType::TinyString:
+        return visit.visit(JsonString(data_->content.asTinyString));
+
+      case VariantType::LinkedString:
+        return visit.visit(JsonString(asLinkedString(), true));
+
+      case VariantType::OwnedString:
+        return visit.visit(JsonString(data_->content.asOwnedString->data,
+                                      data_->content.asOwnedString->length));
+
+      case VariantType::RawString:
+        return visit.visit(RawString(data_->content.asOwnedString->data,
+                                     data_->content.asOwnedString->length));
+
+      case VariantType::Int32:
+        return visit.visit(static_cast<JsonInteger>(data_->content.asInt32));
+
+      case VariantType::Uint32:
+        return visit.visit(static_cast<JsonUInt>(data_->content.asUint32));
+
+#if ARDUINOJSON_USE_LONG_LONG
+      case VariantType::Int64:
+        return visit.visit(eightByteValue->asInt64);
+
+      case VariantType::Uint64:
+        return visit.visit(eightByteValue->asUint64);
+#endif
+
+      case VariantType::Boolean:
+        return visit.visit(data_->content.asBoolean != 0);
+
+      default:
+        return visit.visit(nullptr);
+    }
+  }
+
+  VariantData* addElement() {
+    auto array = isNull() ? toArray() : asArray();
+    return array.addElement();
+  }
+
+  template <typename T>
+  bool addValue(const T& value) {
+    auto array = isNull() ? toArray() : asArray();
+    return array.addValue(value);
+  }
+
+  bool asBoolean() const {
+    if (!data_)
+      return false;
+
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    auto eightByteValue = getEightByte();
+#endif
+    switch (data_->type) {
+      case VariantType::Boolean:
+        return data_->content.asBoolean;
+      case VariantType::Uint32:
+      case VariantType::Int32:
+        return data_->content.asUint32 != 0;
+      case VariantType::Float:
+        return data_->content.asFloat != 0;
+#if ARDUINOJSON_USE_DOUBLE
+      case VariantType::Double:
+        return eightByteValue->asDouble != 0;
+#endif
+      case VariantType::Null:
+        return false;
+#if ARDUINOJSON_USE_LONG_LONG
+      case VariantType::Uint64:
+      case VariantType::Int64:
+        return eightByteValue->asUint64 != 0;
+#endif
+      default:
+        return true;
+    }
+  }
+
+  ArrayImpl asArray() {
+    return ArrayImpl(isArray() ? &data_->content.asCollection : nullptr,
+                     resources_);
+  }
+
+  CollectionImpl asCollection() {
+    return CollectionImpl(
+        isCollection() ? &data_->content.asCollection : nullptr, resources_);
+  }
+
+  template <typename T>
+  T asFloat() const {
+    if (!data_)
+      return 0.0;
+
+    static_assert(is_floating_point<T>::value, "T must be a floating point");
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    auto eightByteValue = getEightByte();
+#endif
+    const char* str = nullptr;
+    switch (data_->type) {
+      case VariantType::Boolean:
+        return static_cast<T>(data_->content.asBoolean);
+      case VariantType::Uint32:
+        return static_cast<T>(data_->content.asUint32);
+      case VariantType::Int32:
+        return static_cast<T>(data_->content.asInt32);
+#if ARDUINOJSON_USE_LONG_LONG
+      case VariantType::Uint64:
+        return static_cast<T>(eightByteValue->asUint64);
+      case VariantType::Int64:
+        return static_cast<T>(eightByteValue->asInt64);
+#endif
+      case VariantType::TinyString:
+        str = data_->content.asTinyString;
+        break;
+      case VariantType::LinkedString:
+        str = asLinkedString();
+        break;
+      case VariantType::OwnedString:
+        str = data_->content.asOwnedString->data;
+        break;
+      case VariantType::Float:
+        return static_cast<T>(data_->content.asFloat);
+#if ARDUINOJSON_USE_DOUBLE
+      case VariantType::Double:
+        return static_cast<T>(eightByteValue->asDouble);
+#endif
+      default:
+        return 0.0;
+    }
+
+    ARDUINOJSON_ASSERT(str != nullptr);
+    return parseNumber<T>(str);
+  }
+
+  template <typename T>
+  T asIntegral() const {
+    if (!data_)
+      return 0;
+
+    static_assert(is_integral<T>::value, "T must be an integral type");
+#if ARDUINOJSON_USE_8_BYTE_POOL
+    auto eightByteValue = getEightByte();
+#endif
+    const char* str = nullptr;
+    switch (data_->type) {
+      case VariantType::Boolean:
+        return data_->content.asBoolean;
+      case VariantType::Uint32:
+        return convertNumber<T>(data_->content.asUint32);
+      case VariantType::Int32:
+        return convertNumber<T>(data_->content.asInt32);
+#if ARDUINOJSON_USE_LONG_LONG
+      case VariantType::Uint64:
+        return convertNumber<T>(eightByteValue->asUint64);
+      case VariantType::Int64:
+        return convertNumber<T>(eightByteValue->asInt64);
+#endif
+      case VariantType::TinyString:
+        str = data_->content.asTinyString;
+        break;
+      case VariantType::LinkedString:
+        str = asLinkedString();
+        break;
+      case VariantType::OwnedString:
+        str = data_->content.asOwnedString->data;
+        break;
+      case VariantType::Float:
+        return convertNumber<T>(data_->content.asFloat);
+#if ARDUINOJSON_USE_DOUBLE
+      case VariantType::Double:
+        return convertNumber<T>(eightByteValue->asDouble);
+#endif
+      default:
+        return 0;
+    }
+
+    ARDUINOJSON_ASSERT(str != nullptr);
+    return parseNumber<T>(str);
+  }
+
+  ObjectImpl asObject() {
+    return ObjectImpl(isObject() ? &data_->content.asCollection : nullptr,
+                      resources_);
+  }
+
+  JsonString asRawString() const {
+    switch (type()) {
+      case VariantType::RawString:
+        return JsonString(data_->content.asOwnedString->data,
+                          data_->content.asOwnedString->length);
+      default:
+        return JsonString();
+    }
+  }
+
+  const char* asLinkedString() const {
+    ARDUINOJSON_ASSERT(type() == VariantType::LinkedString);
+    return resources_->getStaticString(data_->content.asSlotId);
+  }
+
+  JsonString asString() const {
+    switch (type()) {
+      case VariantType::TinyString:
+        return JsonString(data_->content.asTinyString);
+      case VariantType::LinkedString:
+        return JsonString(asLinkedString(), true);
+      case VariantType::OwnedString:
+        return JsonString(data_->content.asOwnedString->data,
+                          data_->content.asOwnedString->length);
+      default:
+        return JsonString();
+    }
+  }
+
+#if ARDUINOJSON_USE_8_BYTE_POOL
+  const EightByteValue* getEightByte() const {
+    return type() & VariantTypeBits::EightByteBit
+               ? resources_->getEightByte(data_->content.asSlotId)
+               : 0;
+  }
+#endif
+
+  VariantData* getElement(size_t index) {
+    return asArray().getElement(index);
+  }
+
+  template <typename TAdaptedString>
+  VariantData* getMember(TAdaptedString key) {
+    return asObject().getMember(key);
+  }
+
+  VariantData* getOrAddElement(size_t index) {
+    auto array = isNull() ? toArray() : asArray();
+    return array.getOrAddElement(index);
+  }
+
+  template <typename TAdaptedString>
+  VariantData* getOrAddMember(TAdaptedString key) {
+    if (key.isNull())
+      return nullptr;
+    auto obj = isNull() ? toObject() : asObject();
+    return obj.getOrAddMember(key);
+  }
+
+  bool isArray() const {
+    return type() == VariantType::Array;
+  }
+
+  bool isBoolean() const {
+    return type() == VariantType::Boolean;
+  }
+
+  bool isCollection() const {
+    return type() & VariantTypeBits::CollectionMask;
+  }
+
+  bool isFloat() const {
+    return data_ && data_->isFloat();
+  }
+
+  template <typename T>
+  bool isInteger() const {
+    if (!data_)
+      return false;
+
+#if ARDUINOJSON_USE_LONG_LONG
+    auto eightByteValue = getEightByte();
+#endif
+    switch (data_->type) {
+      case VariantType::Uint32:
+        return canConvertNumber<T>(data_->content.asUint32);
+
+      case VariantType::Int32:
+        return canConvertNumber<T>(data_->content.asInt32);
+
+#if ARDUINOJSON_USE_LONG_LONG
+      case VariantType::Uint64:
+        return canConvertNumber<T>(eightByteValue->asUint64);
+
+      case VariantType::Int64:
+        return canConvertNumber<T>(eightByteValue->asInt64);
+#endif
+
+      default:
+        return false;
+    }
+  }
+
+  bool isNull() const {
+    return type() == VariantType::Null;
+  }
+
+  bool isObject() const {
+    return type() == VariantType::Object;
+  }
+
+  bool isString() const {
+    return data_ && data_->isString();
+  }
+
+  size_t nesting() {
+    return asCollection().nesting();
+  }
+
+  void removeElement(size_t index) {
+    asArray().removeElement(index);
+  }
+
+  template <typename TAdaptedString>
+  void removeMember(TAdaptedString key) {
+    asObject().removeMember(key);
+  }
+
+  bool setBoolean(bool value) {
+    if (!data_)
+      return false;
+    data_->setBoolean(value);
+    return true;
+  }
+
+  template <typename T>
+  enable_if_t<sizeof(T) == 4, bool> setFloat(T value) {
+    ARDUINOJSON_ASSERT(type() == VariantType::Null);  // must call clear() first
+    if (!data_)
+      return false;
+    data_->type = VariantType::Float;
+    data_->content.asFloat = value;
+    return true;
+  }
+
+  template <typename T>
+  enable_if_t<sizeof(T) == 8, bool> setFloat(T value) {
+    ARDUINOJSON_ASSERT(isNull());  // must call clear() first
+
+    if (!data_)
+      return false;
+
+    float valueAsFloat = static_cast<float>(value);
+
+#if ARDUINOJSON_USE_DOUBLE
+    if (value == valueAsFloat) {
+      data_->type = VariantType::Float;
+      data_->content.asFloat = valueAsFloat;
+    } else {
+      auto slot = resources_->allocEightByte();
+      if (!slot)
+        return false;
+      data_->type = VariantType::Double;
+      data_->content.asSlotId = slot.id();
+      slot->asDouble = value;
+    }
+#else
+    data_->type = VariantType::Float;
+    data_->content.asFloat = valueAsFloat;
+#endif
+    return true;
+  }
+
+  template <typename T>
+  enable_if_t<is_signed<T>::value, bool> setInteger(T value) {
+    ARDUINOJSON_ASSERT(isNull());  // must call clear() first
+
+    if (!data_)
+      return false;
+
+    if (canConvertNumber<int32_t>(value)) {
+      data_->type = VariantType::Int32;
+      data_->content.asInt32 = static_cast<int32_t>(value);
+    }
+#if ARDUINOJSON_USE_LONG_LONG
+    else {
+      auto slot = resources_->allocEightByte();
+      if (!slot)
+        return false;
+      data_->type = VariantType::Int64;
+      data_->content.asSlotId = slot.id();
+      slot->asInt64 = value;
+    }
+#endif
+    return true;
+  }
+
+  template <typename T>
+  enable_if_t<is_unsigned<T>::value, bool> setInteger(T value) {
+    ARDUINOJSON_ASSERT(isNull());  // must call clear() first
+
+    if (!data_)
+      return false;
+
+    if (canConvertNumber<uint32_t>(value)) {
+      data_->type = VariantType::Uint32;
+      data_->content.asUint32 = static_cast<uint32_t>(value);
+    }
+#if ARDUINOJSON_USE_LONG_LONG
+    else {
+      auto slot = resources_->allocEightByte();
+      if (!slot)
+        return false;
+      data_->type = VariantType::Uint64;
+      data_->content.asSlotId = slot.id();
+      slot->asUint64 = value;
+    }
+#endif
+    return true;
+  }
+
+  template <typename T>
+  void setRawString(SerializedValue<T> value);
+
+  template <typename TAdaptedString>
+  bool setString(TAdaptedString value);
+
+  bool setLinkedString(const char* s);
+
+  size_t size() {
+    if (isObject())
+      return asObject().size();
+
+    if (isArray())
+      return asArray().size();
+
+    return 0;
+  }
+
+  ArrayImpl toArray() {
+    ARDUINOJSON_ASSERT(type() == VariantType::Null);  // must call clear() first
+    if (!data_)
+      return ArrayImpl();
+    data_->type = VariantType::Array;
+    return ArrayImpl(new (&data_->content.asCollection) CollectionData(),
+                     resources_);
+  }
+
+  ObjectImpl toObject() {
+    ARDUINOJSON_ASSERT(type() == VariantType::Null);  // must call clear() first
+    if (!data_)
+      return ObjectImpl();
+    data_->type = VariantType::Object;
+    return ObjectImpl(new (&data_->content.asCollection) CollectionData(),
+                      resources_);
+  }
+
+  VariantType type() const {
+    return data_ ? data_->type : VariantType::Null;
+  }
+
+  // Release the resources used by this variant and set it to null.
+  void clear();
+
+ private:
+  VariantData* data_;
+  ResourceManager* resources_;
+};
+
 template <typename T>
-inline void VariantData::setRawString(SerializedValue<T> value,
-                                      ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-  auto dup = resources->saveString(adaptString(value.data(), value.size()));
+inline void VariantImpl::setRawString(SerializedValue<T> value) {
+  if (!data_)
+    return;
+  auto dup = resources_->saveString(adaptString(value.data(), value.size()));
   if (dup)
-    setRawString(dup);
+    data_->setRawString(dup);
+}
+
+inline bool VariantImpl::setLinkedString(const char* s) {
+  ARDUINOJSON_ASSERT(isNull());  // must call clear() first
+  ARDUINOJSON_ASSERT(s);
+
+  auto slotId = resources_->saveStaticString(s);
+  if (slotId == NULL_SLOT)
+    return false;
+
+  data_->type = VariantType::LinkedString;
+  data_->content.asSlotId = slotId;
+  return true;
 }
 
 template <typename TAdaptedString>
-inline bool VariantData::setString(TAdaptedString value,
-                                   ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
+inline bool VariantImpl::setString(TAdaptedString value) {
+  ARDUINOJSON_ASSERT(isNull());  // must call clear() first
+
+  if (!data_)
+    return false;
 
   if (value.isNull())
     return false;
 
-  if (value.isStatic()) {
-    setLinkedString(value.data());
+  if (value.isStatic())
+    return setLinkedString(value.data());
+
+  if (isTinyString(value, value.size())) {
+    data_->setTinyString(value);
     return true;
   }
 
-  auto dup = resources->saveString(value);
+  auto dup = resources_->saveString(value);
   if (dup) {
-    setOwnedString(dup);
+    data_->setOwnedString(dup);
     return true;
   }
 
   return false;
 }
 
-inline void VariantData::clear(ResourceManager* resources) {
-  if (type_ & VariantTypeBits::OwnedStringBit)
-    resources->dereferenceString(content_.asOwnedString->data);
+inline void VariantImpl::clear() {
+  if (!data_)
+    return;
 
-#if ARDUINOJSON_USE_EXTENSIONS
-  if (type_ & VariantTypeBits::ExtensionBit)
-    resources->freeExtension(content_.asSlotId);
+  if (data_->type & VariantTypeBits::OwnedStringBit)
+    resources_->dereferenceString(data_->content.asOwnedString->data);
+
+#if ARDUINOJSON_USE_8_BYTE_POOL
+  if (data_->type & VariantTypeBits::EightByteBit)
+    resources_->freeEightByte(data_->content.asSlotId);
 #endif
 
-  auto collection = asCollection();
-  if (collection)
-    collection->clear(resources);
+  asCollection().clear();
 
-  type_ = VariantType::Null;
-}
-
-#if ARDUINOJSON_USE_EXTENSIONS
-inline const VariantExtension* VariantData::getExtension(
-    const ResourceManager* resources) const {
-  return type_ & VariantTypeBits::ExtensionBit
-             ? resources->getExtension(content_.asSlotId)
-             : nullptr;
-}
-#endif
-
-template <typename T>
-enable_if_t<sizeof(T) == 8, bool> VariantData::setFloat(
-    T value, ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-  (void)resources;                                 // silence warning
-
-  float valueAsFloat = static_cast<float>(value);
-
-#if ARDUINOJSON_USE_DOUBLE
-  if (value == valueAsFloat) {
-    type_ = VariantType::Float;
-    content_.asFloat = valueAsFloat;
-  } else {
-    auto extension = resources->allocExtension();
-    if (!extension)
-      return false;
-    type_ = VariantType::Double;
-    content_.asSlotId = extension.id();
-    extension->asDouble = value;
-  }
-#else
-  type_ = VariantType::Float;
-  content_.asFloat = valueAsFloat;
-#endif
-  return true;
-}
-
-template <typename T>
-enable_if_t<is_signed<T>::value, bool> VariantData::setInteger(
-    T value, ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-  (void)resources;                                 // silence warning
-
-  if (canConvertNumber<int32_t>(value)) {
-    type_ = VariantType::Int32;
-    content_.asInt32 = static_cast<int32_t>(value);
-  }
-#if ARDUINOJSON_USE_LONG_LONG
-  else {
-    auto extension = resources->allocExtension();
-    if (!extension)
-      return false;
-    type_ = VariantType::Int64;
-    content_.asSlotId = extension.id();
-    extension->asInt64 = value;
-  }
-#endif
-  return true;
-}
-
-template <typename T>
-enable_if_t<is_unsigned<T>::value, bool> VariantData::setInteger(
-    T value, ResourceManager* resources) {
-  ARDUINOJSON_ASSERT(type_ == VariantType::Null);  // must call clear() first
-  (void)resources;                                 // silence warning
-
-  if (canConvertNumber<uint32_t>(value)) {
-    type_ = VariantType::Uint32;
-    content_.asUint32 = static_cast<uint32_t>(value);
-  }
-#if ARDUINOJSON_USE_LONG_LONG
-  else {
-    auto extension = resources->allocExtension();
-    if (!extension)
-      return false;
-    type_ = VariantType::Uint64;
-    content_.asSlotId = extension.id();
-    extension->asUint64 = value;
-  }
-#endif
-  return true;
+  data_->type = VariantType::Null;
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Variant/VariantRefBase.hpp

@@ -29,13 +29,13 @@ class VariantRefBase : public VariantTag {
   // Sets the value to null.
   // https://arduinojson.org/v7/api/jsonvariant/clear/
   void clear() const {
-    VariantData::clear(getOrCreateData(), getResourceManager());
+    getOrCreateVariantImpl().clear();
   }
 
   // Returns true if the value is null or the reference is unbound.
   // https://arduinojson.org/v7/api/jsonvariant/isnull/
   bool isNull() const {
-    return VariantData::isNull(getData());
+    return getVariantImpl().isNull();
   }
 
   // Returns true if the reference is unbound.
@@ -93,13 +93,13 @@ class VariantRefBase : public VariantTag {
   // Returns the size of the array or object.
   // https://arduinojson.org/v7/api/jsonvariant/size/
   size_t size() const {
-    return VariantData::size(getData(), getResourceManager());
+    return getVariantImpl().size();
   }
 
   // Returns the depth (nesting level) of the value.
   // https://arduinojson.org/v7/api/jsonvariant/nesting/
   size_t nesting() const {
-    return VariantData::nesting(getData(), getResourceManager());
+    return getVariantImpl().nesting();
   }
 
   // Appends a new (empty) element to the array.
@@ -120,38 +120,34 @@ class VariantRefBase : public VariantTag {
   // https://arduinojson.org/v7/api/jsonvariant/add/
   template <typename T>
   bool add(const T& value) const {
-    return detail::VariantData::addValue(getOrCreateData(), value,
-                                         getResourceManager());
+    return getOrCreateVariantImpl().addValue(value);
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonvariant/add/
   template <typename T, enable_if_t<!is_const<T>::value, int> = 0>
   bool add(T* value) const {
-    return detail::VariantData::addValue(getOrCreateData(), value,
-                                         getResourceManager());
+    return getOrCreateVariantImpl().addValue(value);
   }
 
   // Removes an element of the array.
   // https://arduinojson.org/v7/api/jsonvariant/remove/
   void remove(size_t index) const {
-    VariantData::removeElement(getData(), index, getResourceManager());
+    getVariantImpl().removeElement(index);
   }
 
   // Removes a member of the object.
   // https://arduinojson.org/v7/api/jsonvariant/remove/
   template <typename TChar, enable_if_t<IsString<TChar*>::value, int> = 0>
   void remove(TChar* key) const {
-    VariantData::removeMember(getData(), adaptString(key),
-                              getResourceManager());
+    getVariantImpl().removeMember(adaptString(key));
   }
 
   // Removes a member of the object.
   // https://arduinojson.org/v7/api/jsonvariant/remove/
   template <typename TString, enable_if_t<IsString<TString>::value, int> = 0>
   void remove(const TString& key) const {
-    VariantData::removeMember(getData(), adaptString(key),
-                              getResourceManager());
+    getVariantImpl().removeMember(adaptString(key));
   }
 
   // Removes a member of the object or an element of the array.
@@ -275,6 +271,14 @@ class VariantRefBase : public VariantTag {
     return VariantAttorney::getOrCreateData(derived());
   }
 
+  VariantImpl getVariantImpl() const {
+    return VariantImpl(getData(), getResourceManager());
+  }
+
+  VariantImpl getOrCreateVariantImpl() const {
+    return VariantImpl(getOrCreateData(), getResourceManager());
+  }
+
   FORCE_INLINE ArduinoJson::JsonVariant getVariant() const;
 
   FORCE_INLINE ArduinoJson::JsonVariantConst getVariantConst() const {

src/ArduinoJson/Variant/VariantRefBaseImpl.hpp

@@ -69,23 +69,20 @@ inline void convertToJson(const VariantRefBase<TDerived>& src,
 template <typename TDerived>
 template <typename T, enable_if_t<is_same<T, JsonVariant>::value, int>>
 inline T VariantRefBase<TDerived>::add() const {
-  return JsonVariant(
-      detail::VariantData::addElement(getOrCreateData(), getResourceManager()),
-      getResourceManager());
+  return JsonVariant(getOrCreateVariantImpl().addElement(),
+                     getResourceManager());
 }
 
 template <typename TDerived>
 template <typename TString, enable_if_t<IsString<TString>::value, int>>
 inline bool VariantRefBase<TDerived>::containsKey(const TString& key) const {
-  return VariantData::getMember(getData(), adaptString(key),
-                                getResourceManager()) != 0;
+  return getVariantImpl().getMember(adaptString(key)) != 0;
 }
 
 template <typename TDerived>
 template <typename TChar, enable_if_t<IsString<TChar*>::value, int>>
 inline bool VariantRefBase<TDerived>::containsKey(TChar* key) const {
-  return VariantData::getMember(getData(), adaptString(key),
-                                getResourceManager()) != 0;
+  return getVariantImpl().getMember(adaptString(key)) != 0;
 }
 
 template <typename TDerived>
@@ -150,26 +147,25 @@ inline bool VariantRefBase<TDerived>::doSet(const T& value, true_type) const {
 template <typename TDerived>
 template <typename T, enable_if_t<is_same<T, JsonArray>::value, int>>
 inline JsonArray VariantRefBase<TDerived>::to() const {
-  return JsonArray(
-      VariantData::toArray(getOrCreateData(), getResourceManager()),
-      getResourceManager());
+  auto variant = getOrCreateVariantImpl();
+  variant.clear();
+  return JsonArray(variant.toArray());
 }
 
 template <typename TDerived>
 template <typename T, enable_if_t<is_same<T, JsonObject>::value, int>>
 JsonObject VariantRefBase<TDerived>::to() const {
-  return JsonObject(
-      VariantData::toObject(getOrCreateData(), getResourceManager()),
-      getResourceManager());
+  auto variant = getOrCreateVariantImpl();
+  variant.clear();
+  return JsonObject(variant.toObject());
 }
 
 template <typename TDerived>
 template <typename T, enable_if_t<is_same<T, JsonVariant>::value, int>>
 JsonVariant VariantRefBase<TDerived>::to() const {
-  auto data = getOrCreateData();
-  auto resources = getResourceManager();
-  detail::VariantData::clear(data, resources);
-  return JsonVariant(data, resources);
+  detail::VariantImpl impl(getOrCreateData(), getResourceManager());
+  impl.clear();
+  return JsonVariant(impl);
 }
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/version.hpp

@@ -4,8 +4,8 @@
 
 #pragma once
 
-#define ARDUINOJSON_VERSION "7.3.1"
+#define ARDUINOJSON_VERSION "7.4.2"
 #define ARDUINOJSON_VERSION_MAJOR 7
-#define ARDUINOJSON_VERSION_MINOR 3
-#define ARDUINOJSON_VERSION_REVISION 1
-#define ARDUINOJSON_VERSION_MACRO V731
+#define ARDUINOJSON_VERSION_MINOR 4
+#define ARDUINOJSON_VERSION_REVISION 2
+#define ARDUINOJSON_VERSION_MACRO V742