初始提交: UE5.3项目基础框架

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

@@ -0,0 +1,148 @@
+#pragma once
+
+#include "JsonHandler.h"
+#include "Library.h"
+
+#include <rapidjson/document.h>
+
+#include <cstddef>
+#include <optional>
+#include <span>
+#include <string>
+#include <vector>
+
+namespace rapidjson {
+struct MemoryStream;
+}
+
+namespace CesiumJsonReader {
+
+/**
+ * @brief The result of {@link JsonReader::readJson}.
+ */
+template <typename T> struct ReadJsonResult {
+  /**
+   * @brief The value read from the JSON, or `std::nullopt` on error.
+   */
+  std::optional<T> value;
+
+  /**
+   * @brief Errors that occurred while reading.
+   */
+  std::vector<std::string> errors;
+
+  /**
+   * @brief Warnings that occurred while reading.
+   */
+  std::vector<std::string> warnings;
+};
+
+/**
+ * @brief Reads JSON.
+ */
+class CESIUMJSONREADER_API JsonReader {
+public:
+  /**
+   * @brief Reads JSON from a byte buffer into a statically-typed class.
+   *
+   * @param data The buffer from which to read JSON.
+   * @param handler The handler to receive the top-level JSON object. This
+   * instance must:
+   *   - Implement {@link IJsonHandler}.
+   *   - Contain a `ValueType` type alias indicating the type of the instance to
+   * be read into.
+   *   - Have a `reset` method taking 1) a parent `IJsonHandler` pointer, and 2)
+   * and a pointer to a value of type `ValueType`.
+   * @return The result of reading the JSON.
+   */
+  template <typename T>
+  static ReadJsonResult<typename T::ValueType>
+  readJson(const std::span<const std::byte>& data, T& handler) {
+    ReadJsonResult<typename T::ValueType> result;
+
+    result.value.emplace();
+
+    FinalJsonHandler finalHandler(result.warnings);
+    handler.reset(&finalHandler, &result.value.value());
+
+    JsonReader::internalRead(
+        data,
+        handler,
+        finalHandler,
+        result.errors,
+        result.warnings);
+
+    if (!result.errors.empty()) {
+      result.value.reset();
+    }
+
+    return result;
+  }
+
+  /**
+   * @brief Reads JSON from a `rapidjson::Value` into a statically-typed class.
+   *
+   * @param jsonValue The `rapidjson::Value` from which to read JSON.
+   * @param handler The handler to receive the top-level JSON object. This
+   * instance must:
+   *   - Implement {@link IJsonHandler}.
+   *   - Contain a `ValueType` type alias indicating the type of the instance to
+   * be read into.
+   *   - Have a `reset` method taking 1) a parent `IJsonHandler` pointer, and 2)
+   * and a pointer to a value of type `ValueType`.
+   * @return The result of reading the JSON.
+   */
+  template <typename T>
+  static ReadJsonResult<typename T::ValueType>
+  readJson(const rapidjson::Value& jsonValue, T& handler) {
+    ReadJsonResult<typename T::ValueType> result;
+
+    result.value.emplace();
+
+    FinalJsonHandler finalHandler(result.warnings);
+    handler.reset(&finalHandler, &result.value.value());
+
+    JsonReader::internalRead(
+        jsonValue,
+        handler,
+        finalHandler,
+        result.errors,
+        result.warnings);
+
+    if (!result.errors.empty()) {
+      result.value.reset();
+    }
+
+    return result;
+  }
+
+private:
+  class FinalJsonHandler : public JsonHandler {
+  public:
+    FinalJsonHandler(std::vector<std::string>& warnings);
+    virtual void reportWarning(
+        const std::string& warning,
+        std::vector<std::string>&& context) override;
+    void setInputStream(rapidjson::MemoryStream* pInputStream) noexcept;
+
+  private:
+    std::vector<std::string>& _warnings;
+    rapidjson::MemoryStream* _pInputStream;
+  };
+
+  static void internalRead(
+      const std::span<const std::byte>& data,
+      IJsonHandler& handler,
+      FinalJsonHandler& finalHandler,
+      std::vector<std::string>& errors,
+      std::vector<std::string>& warnings);
+
+  static void internalRead(
+      const rapidjson::Value& jsonValue,
+      IJsonHandler& handler,
+      FinalJsonHandler& finalHandler,
+      std::vector<std::string>& errors,
+      std::vector<std::string>& warnings);
+};
+
+} // namespace CesiumJsonReader