/*
 * Copyright (C) 2020 Weber Yann
 * 
 * This file is part of pyrpn.
 * 
 * pyrpn is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * pyrpn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with pyrpn.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __rpn_parse__h__
#define __rpn_parse__h__

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include "config.h"
#include "rpn_lib.h"

/**@file rpn_parse.h
 * @brief RPN expression parsing headers
 * @ingroup rpn_tokenize
 *
 * Contains headers of @ref rpn_tokenize and @ref rpn_parse .
 */
/**@defgroup rpn_tokenize Expression tokenization
 * @brief Parsing an expression into a @ref rpn_tokenized_t
 * 
 * The tokenized form ( see @ref rpn_tokenized_t ) of an expression is usefull
 * for @ref mutation.
 *
 * The tokenizing process is done in a way allowing compilation process to
 * fetch tokens while parsing the expression (see @ref rpn_tok).
 * @ingroup rpn_compile
 */
/**@defgroup rpn_parse Token parsing functions
 * @brief Internal parsing functions
 * @ingroup rpn_tokenize
 */

/**@brief Shortcut for loop on all operations list */
#define foreach_rpn_ops(IDX) for(IDX=0; IDX<rpn_op_sz(); IDX++)

/**@brief Check if a tokenizer is in error state
 * @param tokenizer Pointer on a @ref rpn_tokenizer_s
 * @return false if no error else true
 * @note test if first chr of @ref rpn_tokenizer_s::err_reason is "\0"
 */
#define rpn_tokenizer_error(tokenizer) (*((tokenizer)->err_reason))

/**@brief Shortcut for struct @ref rpn_op_s */
typedef struct rpn_op_s rpn_op_t;
/**@brief Shortcut for struct @ref rpn_token_type_e */
typedef enum rpn_token_type_e rpn_token_type_t;
/**@brief Shortcut for struct @ref rpn_token_s */
typedef struct rpn_token_s rpn_token_t;
/**@brief Shortcut for struct @ref rpn_tokenized_s */
typedef struct rpn_tokenized_s rpn_tokenized_t;
/**@brief Shortcut for struct @ref rpn_tokenizer_s */
typedef struct rpn_tokenizer_s rpn_tokenizer_t;

/**@brief Handles operation identification informations storage
 * @ingroup rpn_tokenize
 */
struct rpn_op_s
{
	/**@brief Pointer on function pointer */
	const void **fun;
	/**@brief Function code size */
	const unsigned long *fun_sz;
	/**@brief Caracter representing operation ('\0' if None)*/
	char chr;
	/**@brief String representing operation */
	char *str;
};

/**@brief Defines @ref rpn_token_s types
 * @ingroup rpn_tokenize */
enum rpn_token_type_e {
	/**@brief The token is an operation */
	RPN_op,
	/**@brief The token is an argument */
	RPN_arg,
	/**@brief The token is a value */
	RPN_val
};

/**@brief Represent an expression token (value, argument or operation)
 * @ingroup rpn_tokenize */
struct rpn_token_s
{
	/**@brief Token type */
	rpn_token_type_t type;

	/**@brief Token data depending on @ref type */
	union {
		/**@brief Token data for @ref RPN_op tokens */
		struct {
			/**@brief Indicate the operation index in @ref rpn_ops */
			unsigned char op_n;
			/**@brief Pointer on operation informations */
			const rpn_op_t *op;
		};
		/**@brief Indicate the argument number */
		unsigned long int arg_n;
		/**@brief Indicate the constant value */
		unsigned long int value;
	};
};
//} __attribute__((aligned));

/**@brief Represent a tokenized expression
 *
 * A list of @ref rpn_token_s and argc
 * @ingroup rpn_tokenize */
struct rpn_tokenized_s
{
	/**@brief Number of expected arguments */
	size_t argc;
	/**@brief The number of token in the expression */
	size_t tokens_sz;
	/**@brief List of tokens */
	rpn_token_t *tokens;
};

/**@brief Handles data will tokenizing
 *
 * Store compilation state, allowing to return new token as soon as they
 * become ready.
 * @ingroup rpn_tokenize */
struct rpn_tokenizer_s
{
	/**@brief Source expression */
	const char *orig;
	/**@brief Expression work buffer */
	char *buff;
	/**@brief Current expression buffer */
	char *cur;
	/**@brief Current chr number (for error generation & debugging) */
	size_t chr_no;

	/**@brief The tokenized representation of the expression
	 * @note Should point on @ref rpn_expr_t::toks */
	rpn_tokenized_t *toks;
	/**@brief The number of allocated rpn_token_t in toks */
	size_t allocated_toks;

	/**@brief Tokenization error */
	char err_reason[64];
};

/**@brief Define all operations
 *
 * Stores operation identification informations
 * @ingroup rpn_tokenize */
extern const rpn_op_t rpn_ops[];

/**@brief Initialize a tokenizer and a tokenized representation
 * @param tokenizer Pointer on a new tokenizer
 * @param dst Pointer on a tokenized struct to store generated tokens
 * @param expr Pointer on the RPN expression to tokenize
 * @param argc Number of argument accepted by expression
 * @return 0 if no error else -1 and set @ref rpn_tokenizer_s::err_reason
 * @warning no NULL checks for the moment...
 * @ingroup rpn_tokenize
 */
int rpn_tokenizer_start(rpn_tokenizer_t *tokenizer, rpn_tokenized_t *dst,
	const char* expr, size_t argc);

/**@brief Return the next token
 * @param tokenizer Pointer on tokenizing task informations
 * @return The a pointer on next @ref rpn_token_s in @ref rpn_tokenizer_s::toks
 * or NULL if end of expression or error
 * @note When NULL is returned all ressources are freed, no need to 
 * call @ref rpn_tokenizer_free
 * @ingroup rpn_tokenize
 */
rpn_token_t* rpn_tok(rpn_tokenizer_t *tokenizer);

/**@brief Free ressources of a tokenizer
 * @param tokenizer Pointer on the tokenizer we want to deallocate
 * @note This method must be used to abord a tokenizing process with no
 * error or end of expression encountered
 * @ingroup rpn_tokenize
 */
void rpn_tokenizer_free(rpn_tokenizer_t *tokenizer);

/**@brief Tokenize a '\0' terminated string
 * @param token A '\0' terminated string
 * @param dst Pointer on information destination
 * @param error Pointer on an error reason buffer
 * @return 0 if dst set and token recognized else -1 and set error buffer
 * @warning assert token is not empty
 * @ingroup rpn_tokenize
 */
int rpn_tokenize(const char *token, rpn_token_t *dst, char error[64]);

/**@brief Represented a tokenized expression in a string
 * @param tokens Tokenized expression
 * @param long_op If true uses @ref rpn_op_s::str else @ref rpn_op_s::chr
 * @return A newly allocated char* that should be deallocated using free()
 * @ingroup rpn_tokenize
 */
char* rpn_tokenized_expr(rpn_tokenized_t *tokens, char long_op);

/**@brief Returns NULL or a pointer on corresponding operation infos
 * @param token The token we want to match
 * @return NULL or operation informations
 * @ingroup rpn_parse
 */
const rpn_op_t* rpn_match_token(const char* token);
/**@brief Return -1 or an index corresponding to @ref rpn_ops
 * @param token The token we want to match
 * @return NULL or operation informations
 * @ingroup rpn_parse
 */
int rpn_match_token_i(const char* token);

/**@brief Get an integer from a token 
 * @param token The token to decode
 * @param result A pointer on the result
 * @return -1 if given token is not a decimal number else 0 is returned
 * and result is set
 * @ingroup rpn_parse
 */
int rpn_match_number(const char* token, unsigned long *result);

/**@brief Get operations list size
 * @return number of operations in @ref rpn_ops
 */
size_t rpn_op_sz();

/**@page rpn_lang RPN expression syntax
 * @brief Howto write an expression
 *
 * \section rpn_lang_syntax General syntax
 * An expression is composed of tokens separated by 1 or multiple separation
 * characters (space, newline or tabs).
 * 
 * There is 3 types of token (see @ref rpn_token_type_e ) : @ref rpn_lang_op ,
 * @ref rpn_lang_arg and @ref rpn_lang_value .
 *
 * \section rpn_lang_tokens RPN tokens
 * \subsection rpn_lang_arg Arguments
 * Expression can be parametric : arguments are given at evaluation and
 * replaced in expression.
 *
 * In RPN epxressions arguments are desgined by a number (starting from 0)
 * and preffixed by 'A' char.
 *
 * For example an expression evaluating to the sum of their two arguments
 * will be written : "A0 A1 +"
 *
 * \subsection rpn_lang_value Constant values
 * Constant values can be expressed in different bases (the Python syntax) :
 * - 42
 * - 0x2a or 0x2A
 * - 0o52
 * - 0b101010
 *
 * \subsection rpn_lang_op Operations
 * Operations have two form : a short (1 character long) and a long (a string).
 * 
 * Each valid operations are declared in @ref rpn_ops variable (see 
 * @ref rpn_parse.c for details).
 *
 * The @ref python_module expose a function pyrpn.get_ops() ( @see pyrpn_ops )
 * returning a dict with long operations as key and short as value.
 * \subsubsection rpn_lan_op_internal Internal mechanism
 * Operations are done using a loopstack : operands are poped from stack, and
 * the result is pushed onto it.
 *
 * Operations implementation are wrote in x86_64 linux assembly code ( see
 * @ref rpn_lib.asm ). Each operations has a corresponding exported symbol
 * (declared in @ref rpn_lib.h ) pointing compiled code. This code will be
 * copied in a memory map in order to compile (@ref rpn_cmap ) an evaluation
 * function.
 */
/**@page rpn_lang_ext Language extension
 * @brief Howto add new operations
 *
 * @section rpn_lang_ext_op Add an operation
 *
 * In order to add a new operation you have to do three things :
 *
 * @subsection rpn_lang_ext_asm Write the operation code
 *
 * You have to write the operation code in @ref rpn_lib.asm and to expose
 * the corresponding symbols (the code label and the code portion size).
 *
 * The macro part_sz allows to do most of the work by :
 * - defining a symbol NAME_sz pointing on the code portion size
 * - export the symbols NAME and NAME_sz
 * 
 * @warning The part_sz macro HAS TO be placed at the end of the corresponding
 * code_portion
 *
 * @subsection rpn_lang_ext_head Import the symbols in C headers
 * 
 * The @ref rpn_lib.h header is designed to contain all extern assembly symbols
 * (pointer on compiled code and on size).
 *
 * To add a new operation you have to "import" the symbols defined in
 * @ref rpn_lib.asm using the @ref CODE_PART macro
 *
 * @subsection rpn_lang_ext_code Declare corresponding short and long tokens
 *
 * The @ref rpn_compile will match short or long operations and corresponding
 * pre-compiled code.
 *
 * The association between short (char) long (char*) and pre-compiled code is
 * done in the @ref rpn_ops variable.
 * @note The __op macro allow simple operation declaration.
 */

#endif