Merged the two StringBuilder classes into one

src/ArduinoJson/Memory/StringBuilder.hpp

@@ -0,0 +1,35 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2018
+// MIT License
+
+#pragma once
+
+#include "../Strings/StringInMemoryPool.hpp"
+#include "MemoryPool.hpp"
+
+namespace ARDUINOJSON_NAMESPACE {
+
+class StringBuilder {
+ public:
+  explicit StringBuilder(MemoryPool* parent)
+      : _parent(parent), _start(0), _size(0) {
+    _start = _parent->alloc(1);
+  }
+
+  void append(char c) {
+    _start = _parent->realloc(_start, _size + 1, _size + 2);
+    if (_start) _start[_size++] = c;
+  }
+
+  StringInMemoryPool complete() {
+    if (_start) _start[_size] = 0;
+    return _start;
+  }
+
+ private:
+  MemoryPool* _parent;
+  char* _start;
+  size_t _size;
+};
+
+}  // namespace ARDUINOJSON_NAMESPACE