JsonArray::remove() and JsonObject::remove() now release the memory of strings

src/ArduinoJson/Memory/StringBuilder.hpp

@@ -11,25 +11,43 @@ namespace ARDUINOJSON_NAMESPACE {
 
 class StringBuilder {
  public:
-  explicit StringBuilder(MemoryPool* parent)
-      : _parent(parent), _start(0), _size(0) {
-    _start = _parent->alloc(1);
+  typedef StringInMemoryPool StringType;
+
+  explicit StringBuilder(MemoryPool* parent) : _parent(parent), _size(0) {
+    _slot = _parent->allocExpandableString();
+  }
+
+  void append(const char* s) {
+    while (*s) append(*s++);
+  }
+
+  void append(const char* s, size_t n) {
+    while (n-- > 0) append(*s++);
   }
 
   void append(char c) {
-    _start = _parent->realloc(_start, _size + 1, _size + 2);
-    if (_start) _start[_size++] = c;
+    if (!_slot) return;
+
+    if (_size >= _slot->size) {
+      _slot = _parent->expandString(_slot);
+      if (!_slot) return;
+    }
+
+    _slot->value[_size++] = c;
   }
 
-  StringInMemoryPool complete() {
-    if (_start) _start[_size] = 0;
-    return _start;
+  StringType complete() {
+    append('\0');
+    if (_slot) {
+      _parent->freezeString(_slot, _size);
+    }
+    return _slot;
   }
 
  private:
   MemoryPool* _parent;
-  char* _start;
   size_t _size;
+  StringSlot* _slot;
 };
 
 }  // namespace ARDUINOJSON_NAMESPACE