初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumJsonReader/DictionaryJsonHandler.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include "CesiumUtility/Assert.h"
+#include "IntegerJsonHandler.h"
+#include "Library.h"
+#include "ObjectJsonHandler.h"
+
+#include <map>
+#include <unordered_map>
+
+namespace CesiumJsonReader {
+/**
+ * @brief Reads the keys and values of a JSON object into a
+ * `std::map<std::string, T>` or an `std::unordered_map<std::string, T>`.
+ *
+ * @tparam T The type of values in the map.
+ * @tparam THandler The type of the \ref IJsonHandler to handle the map values.
+ */
+template <typename T, typename THandler>
+class CESIUMJSONREADER_API DictionaryJsonHandler : public ObjectJsonHandler {
+public:
+  /**
+   * @brief Creates a new \ref DictionaryJsonHandler, passing the specified
+   * arguments to the constructor of THandler.
+   */
+  template <typename... Ts>
+  DictionaryJsonHandler(Ts&&... args) noexcept
+      : ObjectJsonHandler(), _item(std::forward<Ts>(args)...) {}
+
+  /**
+   * @brief Resets the parent of this \ref IJsonHandler and sets the destination
+   * pointer of this handler to an `std::unordered_map<std::string, T>`.
+   *
+   * @warning Technically, there is no reason why you can't call `reset` twice
+   * on the same \ref DictionaryJsonHandler, once with an `std::map` and once
+   * with an `std::unordered_map`. In practice, if a pointer to an
+   * `std::unordered_map` is present, it will always be used as the destination
+   * and the pointer to an `std::map` will be ignored.
+   */
+  void reset(
+      IJsonHandler* pParent,
+      std::unordered_map<std::string, T>* pDictionary) {
+    ObjectJsonHandler::reset(pParent);
+    this->_pDictionary1 = pDictionary;
+  }
+
+  /**
+   * @brief Resets the parent of this \ref IJsonHandler and sets the destination
+   * pointer of this handler to an `std::map<std::string, T>`.
+   */
+  void reset(IJsonHandler* pParent, std::map<std::string, T>* pDictionary) {
+    ObjectJsonHandler::reset(pParent);
+    this->_pDictionary2 = pDictionary;
+  }
+
+  /** @copydoc IJsonHandler::readObjectKey */
+  virtual IJsonHandler* readObjectKey(const std::string_view& str) override {
+    CESIUM_ASSERT(this->_pDictionary1 || this->_pDictionary2);
+
+    if (this->_pDictionary1) {
+      auto it = this->_pDictionary1->emplace(str, T()).first;
+
+      return this->property(it->first.c_str(), this->_item, it->second);
+    }
+
+    auto it = this->_pDictionary2->emplace(str, T()).first;
+
+    return this->property(it->first.c_str(), this->_item, it->second);
+  }
+
+private:
+  std::unordered_map<std::string, T>* _pDictionary1 = nullptr;
+  std::map<std::string, T>* _pDictionary2 = nullptr;
+  THandler _item;
+};
+} // namespace CesiumJsonReader