/* $Id$
 *
 */

#ifndef __PJ_PARSER_H__
#define __PJ_PARSER_H__

/**
 * @file scanner.h
 * @brief Text Scanning.
 */

#include <pj/types.h>

PJ_BEGIN_DECL

/**
 * @defgroup PJ_SCAN Text Scanning
 * @ingroup PJ_MISC
 * @brief
 * Text scanning utility.
 */

/**
 * @defgroup PJ_CHARSPEC Character Filter Specification
 * @ingroup PJ_SCAN
 * @brief
 * The type pj_char_spec is a specification of character set used in
 * scanner. Application can define multiple character specs, such as to
 * scan alpha numerics, numbers, tokens, etc.
 * @{
 */

/**
 * This describes the type of individual character specification in
 * #pj_char_spec.
 */
typedef pj_uint8_t pj_char_spec_element_t;

/**
 * The character specification is implemented as array of boolean flags. Each
 * flag indicates the membership of the character in the spec. If the flag
 * at one position is non-zero, then the character at that position belongs
 * to the specification, and vice versa.
 */
typedef pj_char_spec_element_t pj_char_spec[256];
// Note: it's got to be 256 (not 128) to cater for extended character in input.

/**
 * Initialize character spec.
 * @param cs the scanner character specification.
 */
PJ_DECL(void) pj_cs_init( pj_char_spec cs);

/**
 * Set the membership of the specified character to TRUE.
 * @param cs the scanner character specification.
 * @param c the character.
 */
PJ_DECL(void) pj_cs_set( pj_char_spec cs, int c);

/**
 * Add the characters in the specified range '[cstart, cend)' to the 
 * specification (the last character itself ('cend') is not added).
 * @param cs the scanner character specification.
 * @param cstart the first character in the range.
 * @param cend the next character after the last character in the range.
 */
PJ_DECL(void) pj_cs_add_range( pj_char_spec cs, int cstart, int cend);

/**
 * Add alphabetic characters to the specification.
 * @param cs the scanner character specification.
 */
PJ_DECL(void) pj_cs_add_alpha( pj_char_spec cs);

/**
 * Add numeric characters to the specification.
 * @param cs the scanner character specification.
 */
PJ_DECL(void) pj_cs_add_num( pj_char_spec cs);

/**
 * Add the characters in the string to the specification.
 * @param cs the scanner character specification.
 * @param str the string.
 */
PJ_DECL(void) pj_cs_add_str( pj_char_spec cs, const char *str);

/**
 * Delete characters in the specified range from the specification.
 * @param cs the scanner character specification.
 * @param cstart the first character in the range.
 * @param cend the next character after the last character in the range.
 */
PJ_DECL(void) pj_cs_del_range( pj_char_spec cs, int cstart, int cend);

/**
 * Delete characters in the specified string from the specification.
 * @param cs the scanner character specification.
 * @param str the string.
 */
PJ_DECL(void) pj_cs_del_str( pj_char_spec cs, const char *str);

/**
 * Invert specification.
 * @param cs the scanner character specification.
 */
PJ_DECL(void) pj_cs_invert( pj_char_spec cs );

/**
 * Check whether the specified character belongs to the specification.
 * @param cs the scanner character specification.
 * @param c the character to check for matching.
 */
PJ_INLINE(int) pj_cs_match( const pj_char_spec cs, int c )
{
    return cs[c];
}

/**
 * @}
 */

/**
 * @defgroup PJ_SCANNER Text Scanner
 * @ingroup PJ_SCAN
 * @{
 */

/**
 * Flags for scanner.
 */
enum
{
    /** This flags specifies that the scanner should automatically skip
	whitespaces 
     */
    PJ_SCAN_AUTOSKIP_WS = 1,

    /** This flags specifies that the scanner should automatically skip
        SIP header continuation. This flag implies PJ_SCAN_AUTOSKIP_WS.
     */
    PJ_SCAN_AUTOSKIP_WS_HEADER = 3,

    /** Auto-skip new lines.
     */
    PJ_SCAN_AUTOSKIP_NEWLINE = 4,
};


/* Forward decl. */
struct pj_scanner;


/**
 * The callback function type to be called by the scanner when it encounters
 * syntax error.
 * @param scanner   The scanner instance that calls the callback .
 */
typedef void (*pj_syn_err_func_ptr)(struct pj_scanner *scanner);


/**
 * The text scanner structure.
 */
typedef struct pj_scanner
{
    char *begin;        /**< Start of input buffer. */
    char *end;          /**< End of input buffer.   */
    char *curptr;       /**< Current pointer.       */
    int  line;          /**< Current line.          */
    int  col;           /**< Current column.        */
    int  skip_ws;       /**< Skip whitespace flag.  */
    pj_syn_err_func_ptr callback;   /**< Syntax error callback. */
} pj_scanner;


/**
 * This structure can be used by application to store the state of the parser,
 * so that the scanner state can be rollback to this state when necessary.
 */
typedef struct pj_scan_state
{
    char *curptr;       /**< Current scanner's pointer. */
    int   line;         /**< Current line.      */
    int   col;          /**< Current column.    */
} pj_scan_state;


/**
 * Initialize the scanner. Note that the input string buffer must have
 * length at least buflen+1 because the scanner will NULL terminate the
 * string during initialization.
 *
 * @param scanner   The scanner to be initialized.
 * @param bufstart  The input buffer to scan. Note that buffer[buflen] will be 
 *		    filled with NULL char until scanner is destroyed, so
 *		    the actual buffer length must be at least buflen+1.
 * @param buflen    The length of the input buffer, which normally is
 *		    strlen(bufstart).
 * @param options   Zero, or combination of PJ_SCAN_AUTOSKIP_WS or
 *		    PJ_SCAN_AUTOSKIP_WS_HEADER
 * @param callback  Callback to be called when the scanner encounters syntax
 *		    error condition.
 */
PJ_DECL(void) pj_scan_init( pj_scanner *scanner, char *bufstart, int buflen, 
			    unsigned options,
			    pj_syn_err_func_ptr callback );


/** 
 * Call this function when application has finished using the scanner.
 *
 * @param scanner   The scanner.
 */
PJ_DECL(void) pj_scan_fini( pj_scanner *scanner );


/** 
 * Determine whether the EOF condition for the scanner has been met.
 *
 * @param scanner   The scanner.
 *
 * @return Non-zero if scanner is EOF.
 */
PJ_INLINE(int) pj_scan_is_eof( const pj_scanner *scanner)
{
    return scanner->curptr >= scanner->end;
}


/** 
 * Peek strings in current position according to parameter spec, and return
 * the strings in parameter out. The current scanner position will not be
 * moved. If the scanner is already in EOF state, syntax error callback will
 * be called thrown.
 *
 * @param scanner   The scanner.
 * @param spec	    The spec to match input string.
 * @param out	    String to store the result.
 *
 * @return the character right after the peek-ed position or zero if there's
 *	   no more characters.
 */
PJ_DECL(int) pj_scan_peek( pj_scanner *scanner,
			    const pj_char_spec spec, pj_str_t *out);


/** 
 * Peek len characters in current position, and return them in out parameter.
 * Note that whitespaces or newlines will be returned as it is, regardless
 * of PJ_SCAN_AUTOSKIP_WS settings. If the character left is less than len, 
 * syntax error callback will be called.
 *
 * @param scanner   The scanner.
 * @param len	    Length to peek.
 * @param out	    String to store the result.
 *
 * @return the character right after the peek-ed position or zero if there's
 *	   no more characters.
 */
PJ_DECL(int) pj_scan_peek_n( pj_scanner *scanner,
			      pj_size_t len, pj_str_t *out);


/** 
 * Peek strings in current position until spec is matched, and return
 * the strings in parameter out. The current scanner position will not be
 * moved. If the scanner is already in EOF state, syntax error callback will
 * be called.
 *
 * @param scanner   The scanner.
 * @param spec	    The peeking will stop when the input match this spec.
 * @param out	    String to store the result.
 *
 * @return the character right after the peek-ed position.
 */
PJ_DECL(int) pj_scan_peek_until( pj_scanner *scanner,
				  const pj_char_spec spec, 
				  pj_str_t *out);


/** 
 * Get characters from the buffer according to the spec, and return them
 * in out parameter. The scanner will attempt to get as many characters as
 * possible as long as the spec matches. If the first character doesn't
 * match the spec, or scanner is already in EOF when this function is called,
 * an exception will be thrown.
 *
 * @param scanner   The scanner.
 * @param spec	    The spec to match input string.
 * @param out	    String to store the result.
 */
PJ_DECL(void) pj_scan_get( pj_scanner *scanner,
			    const pj_char_spec spec, pj_str_t *out);


/** 
 * Get characters between quotes. If current input doesn't match begin_quote,
 * syntax error will be thrown.
 *
 * @param scanner	The scanner.
 * @param begin_quote	The character to begin the quote.
 * @param end_quote	The character to end the quote.
 * @param out		String to store the result.
 */
PJ_DECL(void) pj_scan_get_quote( pj_scanner *scanner,
				  int begin_quote, int end_quote, 
				  pj_str_t *out);

/** 
 * Get N characters from the scanner.
 *
 * @param scanner   The scanner.
 * @param N	    Number of characters to get.
 * @param out	    String to store the result.
 */
PJ_DECL(void) pj_scan_get_n( pj_scanner *scanner,
			      unsigned N, pj_str_t *out);


/** 
 * Get one character from the scanner.
 *
 * @param scanner   The scanner.
 *
 * @return (unknown)
 */
PJ_DECL(int) pj_scan_get_char( pj_scanner *scanner );


/** 
 * Get a newline from the scanner. A newline is defined as '\\n', or '\\r', or
 * "\\r\\n". If current input is not newline, syntax error will be thrown.
 *
 * @param scanner   The scanner.
 */
PJ_DECL(void) pj_scan_get_newline( pj_scanner *scanner );


/** 
 * Get characters from the scanner and move the scanner position until the
 * current character matches the spec.
 *
 * @param scanner   The scanner.
 * @param spec	    Get until the input match this spec.
 * @param out	    String to store the result.
 */
PJ_DECL(void) pj_scan_get_until( pj_scanner *scanner,
				  const pj_char_spec spec, pj_str_t *out);


/** 
 * Get characters from the scanner and move the scanner position until the
 * current character matches until_char.
 *
 * @param scanner	The scanner.
 * @param until_char    Get until the input match this character.
 * @param out		String to store the result.
 */
PJ_DECL(void) pj_scan_get_until_ch( pj_scanner *scanner, 
				     int until_char, pj_str_t *out);


/** 
 * Get characters from the scanner and move the scanner position until the
 * current character matches until_char.
 *
 * @param scanner	The scanner.
 * @param until_spec	Get until the input match any of these characters.
 * @param out		String to store the result.
 */
PJ_DECL(void) pj_scan_get_until_chr( pj_scanner *scanner,
				      const char *until_spec, pj_str_t *out);

/** 
 * Advance the scanner N characters, and skip whitespace
 * if necessary.
 *
 * @param scanner   The scanner.
 * @param N	    Number of characters to skip.
 * @param skip	    Flag to specify whether whitespace should be skipped
 *		    after skipping the characters.
 */
PJ_DECL(void) pj_scan_advance_n( pj_scanner *scanner,
				  unsigned N, pj_bool_t skip);


/** 
 * Compare string in current position with the specified string.
 * 
 * @param scanner   The scanner.
 * @param s	    The string to compare with.
 * @param len	    Length of the string to compare.
 *
 * @return zero, <0, or >0 (just like strcmp()).
 */
PJ_DECL(int) pj_scan_strcmp( pj_scanner *scanner, const char *s, int len);


/** 
 * Case-less string comparison of current position with the specified
 * string.
 *
 * @param scanner   The scanner.
 * @param s	    The string to compare with.
 * @param len	    Length of the string to compare with.
 *
 * @return zero, <0, or >0 (just like strcmp()).
 */
PJ_DECL(int) pj_scan_stricmp( pj_scanner *scanner, const char *s, int len);


/** 
 * Manually skip whitespaces according to flag that was specified when
 * the scanner was initialized.
 *
 * @param scanner   The scanner.
 */
PJ_DECL(void) pj_scan_skip_whitespace( pj_scanner *scanner );


/** 
 * Save the full scanner state.
 *
 * @param scanner   The scanner.
 * @param state	    Variable to store scanner's state.
 */
PJ_DECL(void) pj_scan_save_state( pj_scanner *scanner, pj_scan_state *state);


/** 
 * Restore the full scanner state.
 * Note that this would not restore the string if application has modified
 * it. This will only restore the scanner scanning position.
 *
 * @param scanner   The scanner.
 * @param state	    State of the scanner.
 */
PJ_DECL(void) pj_scan_restore_state( pj_scanner *scanner, 
				      pj_scan_state *state);

/**
 * @}
 */

#if PJ_FUNCTIONS_ARE_INLINED
#  include "scanner_i.h"
#endif


PJ_END_DECL

#endif