Replace add() with add<T>() (add(T) is still supported)

CHANGELOG.md

@@ -27,3 +27,4 @@ HEAD
 * Add `deserializeJson(JsonVariant, ...)` and `deserializeMsgPack(JsonVariant, ...)` (#1226)
 * Call `shrinkToFit()` in `deserializeJson()` and `deserializeMsgPack()`
 * `serializeJson()` and `serializeMsgPack()` replace the content of `std::string` and `String` instead of appending to it
+* Replace `add()` with `add<T>()` (`add(T)` is still supported)

extras/tests/JsonArray/add.cpp

@@ -9,7 +9,7 @@
 
 using ArduinoJson::detail::sizeofArray;
 
-TEST_CASE("JsonArray::add()") {
+TEST_CASE("JsonArray::add(T)") {
   SpyingAllocator spy;
   JsonDocument doc(&spy);
   JsonArray array = doc.to<JsonArray>();
@@ -154,3 +154,28 @@ TEST_CASE("JsonArray::add()") {
                          });
   }
 }
+
+TEST_CASE("JsonArray::add<T>()") {
+  JsonDocument doc;
+  JsonArray array = doc.to<JsonArray>();
+
+  SECTION("add<JsonArray>()") {
+    JsonArray nestedArray = array.add<JsonArray>();
+    nestedArray.add(1);
+    nestedArray.add(2);
+    REQUIRE(doc.as<std::string>() == "[[1,2]]");
+  }
+
+  SECTION("add<JsonObject>()") {
+    JsonObject nestedObject = array.add<JsonObject>();
+    nestedObject["a"] = 1;
+    nestedObject["b"] = 2;
+    REQUIRE(doc.as<std::string>() == "[{\"a\":1,\"b\":2}]");
+  }
+
+  SECTION("add<JsonVariant>()") {
+    JsonVariant nestedVariant = array.add<JsonVariant>();
+    nestedVariant.set(42);
+    REQUIRE(doc.as<std::string>() == "[42]");
+  }
+}

extras/tests/JsonDocument/ElementProxy.cpp

@@ -9,7 +9,7 @@ typedef ArduinoJson::detail::ElementProxy<JsonDocument&> ElementProxy;
 
 TEST_CASE("ElementProxy::add()") {
   JsonDocument doc;
-  doc.add();
+  doc.add<JsonVariant>();
   ElementProxy ep = doc[0];
 
   SECTION("add(int)") {
@@ -35,7 +35,7 @@ TEST_CASE("ElementProxy::add()") {
 
 TEST_CASE("ElementProxy::clear()") {
   JsonDocument doc;
-  doc.add();
+  doc.add<JsonVariant>();
   ElementProxy ep = doc[0];
 
   SECTION("size goes back to zero") {
@@ -95,7 +95,7 @@ TEST_CASE("ElementProxy::operator==()") {
 
 TEST_CASE("ElementProxy::remove()") {
   JsonDocument doc;
-  doc.add();
+  doc.add<JsonVariant>();
   ElementProxy ep = doc[0];
 
   SECTION("remove(int)") {
@@ -168,7 +168,7 @@ TEST_CASE("ElementProxy::set()") {
 
 TEST_CASE("ElementProxy::size()") {
   JsonDocument doc;
-  doc.add();
+  doc.add<JsonVariant>();
   ElementProxy ep = doc[0];
 
   SECTION("returns 0") {

extras/tests/JsonDocument/add.cpp

@@ -12,7 +12,7 @@
 
 using ArduinoJson::detail::sizeofArray;
 
-TEST_CASE("JsonDocument::add()") {
+TEST_CASE("JsonDocument::add(T)") {
   SpyingAllocator spy;
   JsonDocument doc(&spy);
 
@@ -79,3 +79,26 @@ TEST_CASE("JsonDocument::add()") {
                          });
   }
 }
+
+TEST_CASE("JsonDocument::add<T>()") {
+  JsonDocument doc;
+
+  SECTION("JsonArray") {
+    JsonArray array = doc.add<JsonArray>();
+    array.add(1);
+    array.add(2);
+    REQUIRE(doc.as<std::string>() == "[[1,2]]");
+  }
+
+  SECTION("JsonObject") {
+    JsonObject object = doc.add<JsonObject>();
+    object["hello"] = "world";
+    REQUIRE(doc.as<std::string>() == "[{\"hello\":\"world\"}]");
+  }
+
+  SECTION("JsonVariant") {
+    JsonVariant variant = doc.add<JsonVariant>();
+    variant.set(42);
+    REQUIRE(doc.as<std::string>() == "[42]");
+  }
+}

extras/tests/JsonVariant/add.cpp

@@ -6,7 +6,7 @@
 #include <stdint.h>
 #include <catch.hpp>
 
-TEST_CASE("JsonVariant::add()") {
+TEST_CASE("JsonVariant::add(T)") {
   JsonDocument doc;
   JsonVariant var = doc.to<JsonVariant>();
 
@@ -44,3 +44,27 @@ TEST_CASE("JsonVariant::add()") {
     REQUIRE(var.as<std::string>() == "{\"val\":123}");
   }
 }
+
+TEST_CASE("JsonVariant::add<T>()") {
+  JsonDocument doc;
+  JsonVariant var = doc.to<JsonVariant>();
+
+  SECTION("JsonArray") {
+    JsonArray array = var.add<JsonArray>();
+    array.add(1);
+    array.add(2);
+    REQUIRE(doc.as<std::string>() == "[[1,2]]");
+  }
+
+  SECTION("JsonObject") {
+    JsonObject object = var.add<JsonObject>();
+    object["hello"] = "world";
+    REQUIRE(doc.as<std::string>() == "[{\"hello\":\"world\"}]");
+  }
+
+  SECTION("JsonVariant") {
+    JsonVariant variant = var.add<JsonVariant>();
+    variant.set(42);
+    REQUIRE(doc.as<std::string>() == "[42]");
+  }
+}

extras/tests/JsonVariant/compare.cpp

@@ -10,7 +10,7 @@
 
 TEST_CASE("Compare JsonVariant with value") {
   JsonDocument doc;
-  JsonVariant a = doc.add();
+  JsonVariant a = doc.add<JsonVariant>();
 
   SECTION("null vs (char*)0") {
     char* b = 0;
@@ -38,8 +38,8 @@ TEST_CASE("Compare JsonVariant with value") {
 
 TEST_CASE("Compare JsonVariant with JsonVariant") {
   JsonDocument doc;
-  JsonVariant a = doc.add();
-  JsonVariant b = doc.add();
+  JsonVariant a = doc.add<JsonVariant>();
+  JsonVariant b = doc.add<JsonVariant>();
 
   SECTION("'abc' vs 'abc'") {
     a.set("abc");

src/ArduinoJson/Array/JsonArray.hpp

@@ -41,10 +41,21 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
     return JsonArrayConst(data_, resources_);
   }
 
+  // Appends a new (empty) element to the array.
+  // Returns a reference to the new element.
+  // https://arduinojson.org/v6/api/jsonarray/add/
+  template <typename T>
+  typename detail::enable_if<!detail::is_same<T, JsonVariant>::value, T>::type
+  add() const {
+    return add<JsonVariant>().to<T>();
+  }
+
   // Appends a new (null) element to the array.
   // Returns a reference to the new element.
   // https://arduinojson.org/v6/api/jsonarray/add/
-  JsonVariant add() const {
+  template <typename T>
+  typename detail::enable_if<detail::is_same<T, JsonVariant>::value, T>::type
+  add() const {
     return JsonVariant(detail::ArrayData::addElement(data_, resources_),
                        resources_);
   }
@@ -53,14 +64,14 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // https://arduinojson.org/v6/api/jsonarray/add/
   template <typename T>
   FORCE_INLINE bool add(const T& value) const {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v6/api/jsonarray/add/
   template <typename T>
   FORCE_INLINE bool add(T* value) const {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Returns an iterator to the first element of the array.
@@ -126,7 +137,7 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // Creates an array and appends it to the array.
   // https://arduinojson.org/v6/api/jsonarray/createnestedarray/
   FORCE_INLINE JsonArray createNestedArray() const {
-    return add().to<JsonArray>();
+    return add<JsonArray>();
   }
 
   operator JsonVariantConst() const {

src/ArduinoJson/Array/JsonArrayImpl.hpp

@@ -10,7 +10,7 @@
 ARDUINOJSON_BEGIN_PUBLIC_NAMESPACE
 
 inline JsonObject JsonArray::createNestedObject() const {
-  return add().to<JsonObject>();
+  return add<JsonObject>();
 }
 
 ARDUINOJSON_END_PUBLIC_NAMESPACE
@@ -19,12 +19,12 @@ ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 template <typename TDerived>
 inline JsonArray VariantRefBase<TDerived>::createNestedArray() const {
-  return add().template to<JsonArray>();
+  return add<JsonArray>();
 }
 
 template <typename TDerived>
 inline JsonObject VariantRefBase<TDerived>::createNestedObject() const {
-  return add().template to<JsonObject>();
+  return add<JsonObject>();
 }
 
 template <typename TDerived>

src/ArduinoJson/Array/Utilities.hpp

@@ -34,7 +34,7 @@ inline typename detail::enable_if<
 copyArray(const T* src, size_t len, const TDestination& dst) {
   bool ok = true;
   for (size_t i = 0; i < len; i++) {
-    ok &= copyArray(src[i], dst.add());
+    ok &= copyArray(src[i], dst.template add<JsonVariant>());
   }
   return ok;
 }

src/ArduinoJson/Document/JsonDocument.hpp

@@ -161,7 +161,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Creates an array and appends it to the root array.
   // https://arduinojson.org/v6/api/jsondocument/createnestedarray/
   JsonArray createNestedArray() {
-    return add().to<JsonArray>();
+    return add<JsonArray>();
   }
 
   // Creates an array and adds it to the root object.
@@ -181,7 +181,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Creates an object and appends it to the root array.
   // https://arduinojson.org/v6/api/jsondocument/createnestedobject/
   JsonObject createNestedObject() {
-    return add().to<JsonObject>();
+    return add<JsonObject>();
   }
 
   // Creates an object and adds it to the root object.
@@ -264,10 +264,21 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
     return JsonVariantConst(data_.getElement(index, &resources_), &resources_);
   }
 
+  // Appends a new (empty) element to the root array.
+  // Returns a reference to the new element.
+  // https://arduinojson.org/v6/api/jsondocument/add/
+  template <typename T>
+  typename detail::enable_if<!detail::is_same<T, JsonVariant>::value, T>::type
+  add() {
+    return add<JsonVariant>().to<T>();
+  }
+
   // Appends a new (null) element to the root array.
   // Returns a reference to the new element.
   // https://arduinojson.org/v6/api/jsondocument/add/
-  FORCE_INLINE JsonVariant add() {
+  template <typename T>
+  typename detail::enable_if<detail::is_same<T, JsonVariant>::value, T>::type
+  add() {
     return JsonVariant(data_.addElement(&resources_), &resources_);
   }
 
@@ -275,14 +286,14 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // https://arduinojson.org/v6/api/jsondocument/add/
   template <typename TValue>
   FORCE_INLINE bool add(const TValue& value) {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Appends a value to the root array.
   // https://arduinojson.org/v6/api/jsondocument/add/
   template <typename TChar>
   FORCE_INLINE bool add(TChar* value) {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Removes an element of the root array.

src/ArduinoJson/Variant/JsonVariant.hpp

@@ -87,7 +87,9 @@ ARDUINOJSON_END_PUBLIC_NAMESPACE
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 template <typename TDerived>
-inline JsonVariant VariantRefBase<TDerived>::add() const {
+template <typename T>
+inline typename enable_if<is_same<T, JsonVariant>::value, T>::type
+VariantRefBase<TDerived>::add() const {
   return JsonVariant(
       detail::VariantData::addElement(getOrCreateData(), getResourceManager()),
       getResourceManager());

src/ArduinoJson/Variant/VariantRefBase.hpp

@@ -136,23 +136,32 @@ class VariantRefBase : public VariantTag {
     return VariantData::nesting(getData(), getResourceManager());
   }
 
+  // Appends a new (empty) element to the array.
+  // Returns a reference to the new element.
+  // https://arduinojson.org/v6/api/jsonvariant/add/
+  template <typename T>
+  typename enable_if<!is_same<T, JsonVariant>::value, T>::type add() const {
+    return add<JsonVariant>().template to<T>();
+  }
+
   // Appends a new (null) element to the array.
   // Returns a reference to the new element.
   // https://arduinojson.org/v6/api/jsonvariant/add/
-  FORCE_INLINE JsonVariant add() const;
+  template <typename T>
+  typename enable_if<is_same<T, JsonVariant>::value, T>::type add() const;
 
   // Appends a value to the array.
   // https://arduinojson.org/v6/api/jsonvariant/add/
   template <typename T>
   FORCE_INLINE bool add(const T& value) const {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v6/api/jsonvariant/add/
   template <typename T>
   FORCE_INLINE bool add(T* value) const {
-    return add().set(value);
+    return add<JsonVariant>().set(value);
   }
 
   // Removes an element of the array.
@@ -261,7 +270,6 @@ class VariantRefBase : public VariantTag {
     return VariantAttorney::getOrCreateData(derived());
   }
 
- private:
   FORCE_INLINE ArduinoJson::JsonVariant getVariant() const;
 
   FORCE_INLINE ArduinoJson::JsonVariantConst getVariantConst() const {