Added StaticJsonBuffer::clear()

CHANGELOG.md

@@ -5,6 +5,7 @@ HEAD
 ----
 
 * Made `JsonBuffer` non-copyable (PR #524 by @luisrayas3)
+* Added `StaticJsonBuffer::clear()`
 
 v5.10.1
 -------

src/ArduinoJson/StaticJsonBuffer.hpp

@@ -54,19 +54,29 @@ class StaticJsonBufferBase : public JsonBufferBase<StaticJsonBufferBase> {
   StaticJsonBufferBase(char* buffer, size_t capa)
       : _buffer(buffer), _capacity(capa), _size(0) {}
 
+  // Gets the capacity of the buffer in bytes
   size_t capacity() const {
     return _capacity;
   }
+
+  // Gets the current usage of the buffer in bytes
   size_t size() const {
     return _size;
   }
 
+  // Allocates the specified amount of bytes in the buffer
   virtual void* alloc(size_t bytes) {
     alignNextAlloc();
     if (!canAlloc(bytes)) return NULL;
     return doAlloc(bytes);
   }
 
+  // Resets the size to zero.
+  // USE WITH CAUTION: this invalidates all previously allocated data
+  void clear() {
+    _size = 0;
+  }
+
   String startString() {
     return String(this);
   }

test/StaticJsonBuffer/CMakeLists.txt

@@ -11,6 +11,7 @@ add_executable(StaticJsonBufferTests
 	createObject.cpp
 	parseArray.cpp
 	parseObject.cpp
+	size.cpp
 	startString.cpp
 )
 

test/StaticJsonBuffer/alloc.cpp

@@ -17,52 +17,39 @@ static bool isAligned(void *ptr) {
 TEST_CASE("StaticJsonBuffer::alloc()") {
   StaticJsonBuffer<64> buffer;
 
-  SECTION("CapacityMatchTemplateParameter") {
+  SECTION("Returns different addresses") {
-    REQUIRE(64 == buffer.capacity());
+    void *p1 = buffer.alloc(1);
+    void *p2 = buffer.alloc(1);
+    REQUIRE(p1 != p2);
   }
 
-  SECTION("InitialSizeIsZero") {
+  SECTION("Returns non-NULL when using full capacity") {
-    REQUIRE(0 == buffer.size());
-  }
-
-  SECTION("GrowsAfterAlloc") {
-    buffer.alloc(1);
-    REQUIRE(1U <= buffer.size());
-    buffer.alloc(1);
-    REQUIRE(2U <= buffer.size());
-  }
-
-  SECTION("DoesntGrowWhenFull") {
-    buffer.alloc(64);
-    buffer.alloc(1);
-    REQUIRE(64 == buffer.size());
-  }
-
-  SECTION("DoesntGrowWhenTooSmall") {
-    buffer.alloc(65);
-    REQUIRE(0 == buffer.size());
-  }
-
-  SECTION("ReturnsNonNull") {
     void *p = buffer.alloc(64);
     REQUIRE(0 != p);
   }
 
-  SECTION("ReturnsNullWhenFull") {
+  SECTION("Returns NULL when full") {
     buffer.alloc(64);
     void *p = buffer.alloc(1);
     REQUIRE(0 == p);
   }
 
-  SECTION("ReturnsNullWhenTooSmall") {
+  SECTION("Returns NULL when buffer is too small") {
     void *p = buffer.alloc(65);
     REQUIRE(0 == p);
   }
 
-  SECTION("Alignment") {
+  SECTION("Returns aligned pointers") {
     for (size_t size = 1; size <= sizeof(void *); size++) {
       void *p = buffer.alloc(1);
       REQUIRE(isAligned(p));
     }
   }
+
+  SECTION("Returns same address after clear()") {
+    void *p1 = buffer.alloc(1);
+    buffer.clear();
+    void *p2 = buffer.alloc(1);
+    REQUIRE(p1 == p2);
+  }
 }

test/StaticJsonBuffer/size.cpp

@@ -0,0 +1,45 @@
+// Copyright Benoit Blanchon 2014-2017
+// MIT License
+//
+// Arduino JSON library
+// https://bblanchon.github.io/ArduinoJson/
+// If you like this project, please add a star!
+
+#include <ArduinoJson.h>
+#include <catch.hpp>
+
+TEST_CASE("StaticJsonBuffer::size()") {
+  StaticJsonBuffer<64> buffer;
+
+  SECTION("Capacity equals template parameter") {
+    REQUIRE(64 == buffer.capacity());
+  }
+
+  SECTION("Initial size is 0") {
+    REQUIRE(0 == buffer.size());
+  }
+
+  SECTION("Increases after alloc()") {
+    buffer.alloc(1);
+    REQUIRE(1U <= buffer.size());
+    buffer.alloc(1);
+    REQUIRE(2U <= buffer.size());
+  }
+
+  SECTION("Doesn't grow when buffer is full") {
+    buffer.alloc(64);
+    buffer.alloc(1);
+    REQUIRE(64 == buffer.size());
+  }
+
+  SECTION("Does't grow when buffer is too small for alloc") {
+    buffer.alloc(65);
+    REQUIRE(0 == buffer.size());
+  }
+
+  SECTION("Goes back to zero after clear()") {
+    buffer.alloc(1);
+    buffer.clear();
+    REQUIRE(0 == buffer.size());
+  }
+}