Add ShrinkToFit() to StringBuffer and MemoryBuffer

include/rapidjson/memorybuffer.h

@@ -49,6 +49,7 @@ struct GenericMemoryBuffer {
     void Flush() {}
 
     void Clear() { stack_.Clear(); }
+    void ShrinkToFit() { stack_.ShrinkToFit(); }
     Ch* Push(size_t count) { return stack_.template Push<Ch>(count); }
     void Pop(size_t count) { stack_.template Pop<Ch>(count); }
 

include/rapidjson/stringbuffer.h

@@ -42,6 +42,12 @@ struct GenericStringBuffer {
     void Flush() {}
 
     void Clear() { stack_.Clear(); }
+    void ShrinkToFit() {
+        // Push and pop a null terminator. This is safe.
+        *stack_.template Push<Ch>() = '\0';
+        stack_.ShrinkToFit();
+        stack_.template Pop<Ch>(1);
+    }
     Ch* Push(size_t count) { return stack_.template Push<Ch>(count); }
     void Pop(size_t count) { stack_.template Pop<Ch>(count); }
 

test/unittest/writertest.cpp

@@ -31,6 +31,7 @@ TEST(Writer, Compact) {
     StringStream s("{ \"hello\" : \"world\", \"t\" : true , \"f\" : false, \"n\": null, \"i\":123, \"pi\": 3.1416, \"a\":[1, 2, 3] } ");
     StringBuffer buffer;
     Writer<StringBuffer> writer(buffer);
+    buffer.ShrinkToFit();
     Reader reader;
     reader.Parse<0>(s, writer);
     EXPECT_STREQ("{\"hello\":\"world\",\"t\":true,\"f\":false,\"n\":null,\"i\":123,\"pi\":3.1416,\"a\":[1,2,3]}", buffer.GetString());