Don't add partial objects when allocation fails

Fixes #2081

src/ArduinoJson/Array/ArrayData.hpp

@@ -20,6 +20,17 @@ class ArrayData : public CollectionData {
     return array->addElement(resources);
   }
 
+  template <typename T>
+  bool addValue(T&& value, ResourceManager* resources);
+
+  template <typename T>
+  static bool addValue(ArrayData* array, T&& value,
+                       ResourceManager* resources) {
+    if (!array)
+      return false;
+    return array->addValue(value, resources);
+  }
+
   VariantData* getOrAddElement(size_t index, ResourceManager* resources);
 
   VariantData* getElement(size_t index, const ResourceManager* resources) const;

src/ArduinoJson/Array/ArrayImpl.hpp

@@ -47,4 +47,19 @@ inline void ArrayData::removeElement(size_t index, ResourceManager* resources) {
   remove(at(index, resources), resources);
 }
 
+template <typename T>
+inline bool ArrayData::addValue(T&& value, ResourceManager* resources) {
+  ARDUINOJSON_ASSERT(resources != nullptr);
+  auto slot = resources->allocSlot();
+  if (!slot)
+    return false;
+  JsonVariant variant(slot->data(), resources);
+  if (!variant.set(detail::forward<T>(value))) {
+    resources->freeSlot(slot);
+    return false;
+  }
+  addSlot(slot, resources);
+  return true;
+}
+
 ARDUINOJSON_END_PRIVATE_NAMESPACE

src/ArduinoJson/Array/JsonArray.hpp

@@ -61,14 +61,14 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // https://arduinojson.org/v7/api/jsonarray/add/
   template <typename T>
   bool add(const T& value) const {
-    return add<JsonVariant>().set(value);
+    return detail::ArrayData::addValue(data_, value, resources_);
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonarray/add/
   template <typename T>
   bool add(T* value) const {
-    return add<JsonVariant>().set(value);
+    return detail::ArrayData::addValue(data_, value, resources_);
   }
 
   // Returns an iterator to the first element of the array.

src/ArduinoJson/Collection/CollectionData.hpp

@@ -111,6 +111,8 @@ class CollectionData {
     return head_;
   }
 
+  void addSlot(SlotWithId slot, ResourceManager* resources);
+
  protected:
   iterator addSlot(ResourceManager*);
 

src/ArduinoJson/Collection/CollectionImpl.hpp

@@ -63,6 +63,18 @@ inline CollectionData::iterator CollectionData::addSlot(
   return iterator(slot, slot.id());
 }
 
+inline void CollectionData::addSlot(SlotWithId slot,
+                                    ResourceManager* resources) {
+  if (tail_ != NULL_SLOT) {
+    auto tail = resources->getSlot(tail_);
+    tail->setNext(slot.id());
+    tail_ = slot.id();
+  } else {
+    head_ = slot.id();
+    tail_ = slot.id();
+  }
+}
+
 inline void CollectionData::clear(ResourceManager* resources) {
   auto next = head_;
   while (next != NULL_SLOT) {

src/ArduinoJson/Document/JsonDocument.hpp

@@ -256,14 +256,14 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // https://arduinojson.org/v7/api/jsondocument/add/
   template <typename TValue>
   bool add(const TValue& value) {
-    return add<JsonVariant>().set(value);
+    return data_.addValue(value, &resources_);
   }
 
   // Appends a value to the root array.
   // https://arduinojson.org/v7/api/jsondocument/add/
   template <typename TChar>
   bool add(TChar* value) {
-    return add<JsonVariant>().set(value);
+    return data_.addValue(value, &resources_);
   }
 
   // Removes an element of the root array.

src/ArduinoJson/Variant/VariantData.hpp

@@ -82,6 +82,21 @@ class VariantData {
     return var->addElement(resources);
   }
 
+  template <typename T>
+  bool addValue(T&& value, ResourceManager* resources) {
+    auto array = isNull() ? &toArray() : asArray();
+    return detail::ArrayData::addValue(array, detail::forward<T>(value),
+                                       resources);
+  }
+
+  template <typename T>
+  static bool addValue(VariantData* var, T&& value,
+                       ResourceManager* resources) {
+    if (!var)
+      return false;
+    return var->addValue(value, resources);
+  }
+
   bool asBoolean() const {
     switch (type()) {
       case VALUE_IS_BOOLEAN:

src/ArduinoJson/Variant/VariantRefBase.hpp

@@ -117,14 +117,16 @@ class VariantRefBase : public VariantTag {
   // https://arduinojson.org/v7/api/jsonvariant/add/
   template <typename T>
   bool add(const T& value) const {
-    return add<JsonVariant>().set(value);
+    return detail::VariantData::addValue(getOrCreateData(), value,
+                                         getResourceManager());
   }
 
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonvariant/add/
   template <typename T>
   bool add(T* value) const {
-    return add<JsonVariant>().set(value);
+    return detail::VariantData::addValue(getOrCreateData(), value,
+                                         getResourceManager());
   }
 
   // Removes an element of the array.