godot/core/variant_parser.h

/*************************************************************************/
/*  variant_parser.h                                                     */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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#ifndef VARIANT_PARSER_H
#define VARIANT_PARSER_H

#include "core/os/file_access.h"
#include "core/resource.h"
#include "core/variant.h"

class VariantParser {
public:
	struct Stream {
	private:
		enum { READAHEAD_SIZE = 2048 };
		CharType readahead_buffer[READAHEAD_SIZE];
		uint32_t readahead_pointer = 0;
		uint32_t readahead_filled = 0;
		bool eof = false;

	protected:
		bool readahead_enabled = true;
		virtual uint32_t _read_buffer(CharType *p_buffer, uint32_t p_num_chars) = 0;
		virtual bool _is_eof() const = 0;

	public:
		CharType saved;

		CharType get_char();
		virtual bool is_utf8() const = 0;
		bool is_eof() const;

		Stream() :
				saved(0) {}
		virtual ~Stream() {}
	};

	struct StreamFile : public Stream {
	protected:
		virtual uint32_t _read_buffer(CharType *p_buffer, uint32_t p_num_chars);
		virtual bool _is_eof() const;

	public:
		FileAccess *f;

		virtual bool is_utf8() const;
		StreamFile(bool p_readahead_enabled = true) {
			f = nullptr;
			readahead_enabled = p_readahead_enabled;
		}
	};

	struct StreamString : public Stream {
	private:
		int pos;

	protected:
		virtual uint32_t _read_buffer(CharType *p_buffer, uint32_t p_num_chars);
		virtual bool _is_eof() const;

	public:
		String s;

		virtual bool is_utf8() const;
		StreamString(bool p_readahead_enabled = true) {
			pos = 0;
			readahead_enabled = p_readahead_enabled;
		}
	};

	typedef Error (*ParseResourceFunc)(void *p_self, Stream *p_stream, Ref<Resource> &r_res, int &line, String &r_err_str);

	struct ResourceParser {
		void *userdata = nullptr;
		ParseResourceFunc func = nullptr;
		ParseResourceFunc ext_func = nullptr;
		ParseResourceFunc sub_func = nullptr;
	};

	enum TokenType {
		TK_CURLY_BRACKET_OPEN,
		TK_CURLY_BRACKET_CLOSE,
		TK_BRACKET_OPEN,
		TK_BRACKET_CLOSE,
		TK_PARENTHESIS_OPEN,
		TK_PARENTHESIS_CLOSE,
		TK_IDENTIFIER,
		TK_STRING,
		TK_NUMBER,
		TK_COLOR,
		TK_COLON,
		TK_COMMA,
		TK_PERIOD,
		TK_EQUAL,
		TK_EOF,
		TK_ERROR,
		TK_MAX
	};

	enum Expecting {

		EXPECT_OBJECT,
		EXPECT_OBJECT_KEY,
		EXPECT_COLON,
		EXPECT_OBJECT_VALUE,
	};

	struct Token {
		TokenType type;
		Variant value;
	};

	struct Tag {
		String name;
		Map<String, Variant> fields;
	};

private:
	static const char *tk_name[TK_MAX];

	template <class T>
	static Error _parse_construct(Stream *p_stream, Vector<T> &r_construct, int &line, String &r_err_str);
	static Error _parse_enginecfg(Stream *p_stream, Vector<String> &strings, int &line, String &r_err_str);
	static Error _parse_dictionary(Dictionary &object, Stream *p_stream, int &line, String &r_err_str, ResourceParser *p_res_parser = nullptr);
	static Error _parse_array(Array &array, Stream *p_stream, int &line, String &r_err_str, ResourceParser *p_res_parser = nullptr);
	static Error _parse_tag(Token &token, Stream *p_stream, int &line, String &r_err_str, Tag &r_tag, ResourceParser *p_res_parser = nullptr, bool p_simple_tag = false);

public:
	static Error parse_tag(Stream *p_stream, int &line, String &r_err_str, Tag &r_tag, ResourceParser *p_res_parser = nullptr, bool p_simple_tag = false);
	static Error parse_tag_assign_eof(Stream *p_stream, int &line, String &r_err_str, Tag &r_tag, String &r_assign, Variant &r_value, ResourceParser *p_res_parser = nullptr, bool p_simple_tag = false);

	static Error parse_value(Token &token, Variant &value, Stream *p_stream, int &line, String &r_err_str, ResourceParser *p_res_parser = nullptr);
	static Error get_token(Stream *p_stream, Token &r_token, int &line, String &r_err_str);
	static Error parse(Stream *p_stream, Variant &r_ret, String &r_err_str, int &r_err_line, ResourceParser *p_res_parser = nullptr);
};

class VariantWriter {
public:
	typedef Error (*StoreStringFunc)(void *ud, const String &p_string);
	typedef String (*EncodeResourceFunc)(void *ud, const RES &p_resource);

	static Error write(const Variant &p_variant, StoreStringFunc p_store_string_func, void *p_store_string_ud, EncodeResourceFunc p_encode_res_func, void *p_encode_res_ud);
	static Error write_to_string(const Variant &p_variant, String &r_string, EncodeResourceFunc p_encode_res_func = nullptr, void *p_encode_res_ud = nullptr);
};

#endif // VARIANT_PARSER_H