pureikyubu/SRC/Common/Json.h

// Json serialization engine. Json is used to store emulator settings, as well as for the JDI system (Json Debug Interface).

// All errors during deserialization are thrown by exceptions.
// During serializing, in theory, there shouldn't be any mistakes (if we are not enemies to ourselves and have not changed, for example, the Value type to some non-standard one).

#pragma once

#include <tchar.h>
#include <list>
#include <string>
#include <cassert>

class Json
{
	// Foolproof
	static const int MaxDepth = 255;
	static const int MaxStringSize = 0x1000;
	static const int MaxElements = 255;				// Deserialize only

public:
	class Value;

private:

	// Recursive destruction of value and all its descendants
	void DestroyValue(Value* value);

	static TCHAR* CloneStr(const TCHAR* str);
	static TCHAR* CloneAnsiStr(const char* str);

	#pragma region "Serialization Related"

	// Serialize context

	struct SerializeContext
	{
		uint8_t** ptr;
		size_t* actualSize;
		size_t maxSize;
	};

	// Base procedure for generating the text.
	static void EmitChar(SerializeContext* ctx, uint8_t val, bool sizeOnly);

	static void EmitText(SerializeContext* ctx, const char* text, bool sizeOnly);

	// Simple TCHAR to UTF-8 Converter + Escaping
	static void EmitCodePoint(SerializeContext* ctx, int cp, bool sizeOnly);
	static void EmitTcharString(SerializeContext* ctx, TCHAR* str, bool sizeOnly);

	// Indentation

	static void Indent(SerializeContext* ctx, int depth, bool sizeOnly);

	#pragma endregion "Serialization Related"

	#pragma region "De-Serialization Related"

	// Deserialize 

	struct DeserializeContext
	{
		uint8_t* ptr;
		size_t offset;
		size_t maxSize;
	};

	static bool IsWhiteSpace(uint8_t value);
	static bool IsControl(uint8_t value);

	// Json Token

	enum class TokenType : char
	{
		Unknown = '?',
		EndOfStream = 'E',
		ObjectStart = '{',
		ObjectEnd = '}',
		ArrayStart = '[',
		ArrayEnd = ']',
		Colon = ':',
		Comma = ',',
		Int = 'I',
		Float = 'F',
		True = 't',
		False = 'f',
		Null = 'N',
		String = 'S',
	};

	class Token
	{
	public:
		TokenType type = TokenType::Unknown;
		union
		{
			uint64_t AsInt;
			float AsFloat;
			bool AsBool;
			TCHAR* AsString = nullptr;
		} value;
	};

	static bool GetLiteral(DeserializeContext* ctx, Token& token);
	static int FetchCodepoint(DeserializeContext* ctx);
	static bool GetString(DeserializeContext* ctx, Token& token);
	static bool IsAllowed(uint8_t val, char* allowed);
	static bool GetFloat(DeserializeContext* ctx, Token& token);
	static bool GetInt(DeserializeContext* ctx, Token& token);

	static void GetToken(Token& token, DeserializeContext* ctx);

	#pragma endregion "De-Serialization Related"

public:

	// Json Value

	enum class ValueType : char
	{
		Unknown = '?',
		Object = 'O',
		Array = 'A',
		Int = 'I',
		Float = 'F',
		String = 'S',
		Bool = 'B',
		Null = 'N',
	};

	class Value
	{
		char* CloneName(const char* otherName);
		char* CloneTcharName(const TCHAR* otherName);
		void DeserializeObject(DeserializeContext* ctx);
		void DeserializeArray(DeserializeContext* ctx);

	public:
		Value* parent = nullptr;
		ValueType type = ValueType::Unknown;
		// Name of object members. 
		// For simplicity, we do not support Non-Ansi Json value names (although full use of Utf-8 is allowed in the values)
		char* name = nullptr;
		union
		{
			float AsFloat;
			uint64_t AsInt;
			uint8_t AsUint8;
			uint16_t AsUint16;
			uint32_t AsUint32;
			TCHAR* AsString = nullptr;	// Only the String value type requires the release of the stored value.
			bool AsBool;
		} value;
		std::list<Value*> children;

		Value() { }

		Value(Value* _parent)
		{
			this->parent = _parent;
		}

		void Serialize(SerializeContext* ctx, int depth, bool sizeOnly);
		void Deserialize(DeserializeContext* ctx, TCHAR* keyName);

		// Dynamic modification

		Value* AddInt(const char* keyName, int _value);
		Value* AddUInt16(const char* keyName, uint16_t _value);
		Value* AddUInt32(const char* keyName, uint32_t _value);
		Value* AddUInt64(const char* keyName, uint64_t _value);
		Value* AddFloat(const char* keyName, float _value);
		Value* AddNull(const char* keyName);
		Value* AddBool(const char* keyName, bool _value);
		Value* AddString(const char* keyName, const TCHAR* str);
		Value* AddAnsiString(const char* keyName, const char* str);
		Value* ReplaceString(const TCHAR* str);
		Value* AddObject(const char* keyName);
		Value* AddArray(const char* keyName);
		Value* AddValue(const char* keyName, Value* value);
		Value* Add(Value* _parent, Value* other);
		Value* Replace(Value* _parent, Value* other);

		// Access

		Value* ByName(const char* byName);
		Value* ByType(const ValueType byType);
	};

	// Deserialized root

	Value root;

	// Api

	~Json()
	{
		DestroyValue(&root);
	}

	// The process of serialization is that we recursively walk through all the values, passing in each "running" context 
	// which has the pointer to the generated text and the current text size.

	void Serialize(void* text, size_t maxTextSize, size_t& actualTextSize);
	void GetSerializedTextSize(void* text, size_t maxTextSize, size_t& actualTextSize);
	void Deserialize(void* text, size_t textSize);

	// Clone

	void Clone(Json* other);

	// Merge

	void Merge(Json* other);

};