请大仙们帮小弟我看看这是什么代码呀，这是小弟我从libcue里面拿出来的，神奇的VC竟然可以编译

%{
/*
 * Copyright (c) 2004, 2005, 2006, 2007, Svend Sorensen
 * Copyright (c) 2009, 2010 Jochen Keil
 * For license terms, see the file COPYING in this distribution.
 */

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

#include "config.h"

#include "cd.h"
#include "time.h"

#ifdef YY_BUF_SIZE
#undef YY_BUF_SIZE
#endif
#define YY_BUF_SIZE 16384

#define YYDEBUG 1

char fnamebuf[PARSER_BUFFER];

/* debugging */
//int yydebug = 1;

extern int yylineno;
extern FILE* yyin;

static Cd *cd = NULL;
static Track *track = NULL;
static Track *prev_track = NULL;
static Cdtext *cdtext = NULL;
static Rem *rem = NULL;
static char *prev_filename = NULL;    /* last file in or before last track */
static char *cur_filename = NULL;    /* last file in the last track */
static char *new_filename = NULL;    /* last file in this track */

/* lexer interface */
typedef struct yy_buffer_state* YY_BUFFER_STATE;

int yylex(void);
void yyerror(const char*);
YY_BUFFER_STATE yy_scan_string(const char*);
YY_BUFFER_STATE yy_create_buffer(FILE*, int);
void yy_switch_to_buffer(YY_BUFFER_STATE);
void yy_delete_buffer(YY_BUFFER_STATE);

/* parser interface */
int yyparse(void);
Cd *cue_parse_file(FILE *fp);
Cd *cue_parse_string(const char*);
%}

%start cuefile

%union {
    long ival;
    char *sval;
}

%token <ival> NUMBER
%token <sval> STRING

/* global (header) */
%token CATALOG
%token CDTEXTFILE

%token FFILE
%token BINARY
%token MOTOROLA
%token AIFF
%token WAVE
%token MP3

/* track */
%token TRACK

%token <ival> AUDIO
%token <ival> MODE1_2048
%token <ival> MODE1_2352
%token <ival> MODE2_2336
%token <ival> MODE2_2048
%token <ival> MODE2_2342
%token <ival> MODE2_2332
%token <ival> MODE2_2352

/* ISRC is with CD_TEXT */
%token TRACK_ISRC

%token FLAGS
%token <ival> PRE
%token <ival> DCP
%token <ival> FOUR_CH
%token <ival> SCMS

%token PREGAP
%token INDEX
%token POSTGAP

/* CD-TEXT */
%token <ival> TITLE
%token <ival> PERFORMER
%token <ival> SONGWRITER
%token <ival> COMPOSER
%token <ival> ARRANGER
%token <ival> MESSAGE
%token <ival> DISC_ID
%token <ival> GENRE
%token <ival> TOC_INFO1
%token <ival> TOC_INFO2
%token <ival> UPC_EAN
%token <ival> ISRC
%token <ival> SIZE_INFO

%type <ival> track_mode
%type <ival> track_flag
%type <ival> time
%type <ival> cdtext_item

/* REM */
%type <ival> rem_item
%token <ival> DATE
%token <ival> REPLAYGAIN_ALBUM_GAIN
%token <ival> REPLAYGAIN_ALBUM_PEAK
%token <ival> REPLAYGAIN_TRACK_GAIN
%token <ival> REPLAYGAIN_TRACK_PEAK
%%

cuefile
    : new_cd global_statements track_list
    ;

new_cd
    : /* empty */ {
        cd = cd_init();
        cdtext = cd_get_cdtext(cd);
        rem = cd_get_rem(cd);
    }
    ;

global_statements
    : /* empty */
    | global_statements global_statement
    ;

global_statement
    : CATALOG STRING '\n' { cd_set_catalog(cd, $2); }
    | CDTEXTFILE STRING '\n' { cd_set_cdtextfile(cd, $2); }
    | cdtext
    | rem
    | track_data
    | error '\n'
    ;

track_data
    : FFILE STRING file_format '\n' {
        if (NULL != new_filename) {
            yyerror("too many files specified\n");
        }
        new_filename = strncpy(fnamebuf, $2, sizeof(fnamebuf));
        new_filename[strlen(new_filename)] = '\0';
    }
    ;

track_list
    : track
    | track_list track
    ;

track
    : new_track track_def track_statements
    ;

file_format
    : BINARY
    | MOTOROLA
    | AIFF
    | WAVE
    | MP3
    ;

new_track
    : /*empty */ {
        /* save previous track, to later set length */
        prev_track = track;

        track = cd_add_track(cd);
        cdtext = track_get_cdtext(track);
        rem = track_get_rem(track);

        cur_filename = new_filename;
        if (NULL != cur_filename)
            prev_filename = cur_filename;

        if (NULL == prev_filename)
            yyerror("no file specified for track");
        else
            track_set_filename(track, prev_filename);

        new_filename = NULL;
    }
    ;

track_def
    : TRACK NUMBER track_mode '\n' {
        track_set_mode(track, $3);
    }
    ;

track_mode
    : AUDIO
    | MODE1_2048
    | MODE1_2352
    | MODE2_2336
    | MODE2_2048
    | MODE2_2342
    | MODE2_2332
    | MODE2_2352
    ;

track_statements
    : track_statement
    | track_statements track_statement
    ;

track_statement
    : cdtext
    | rem
    | FLAGS track_flags '\n'
    | TRACK_ISRC STRING '\n' { track_set_isrc(track, $2); }
    | PREGAP time '\n' { track_set_zero_pre(track, $2); }
    | INDEX NUMBER time '\n' {
        int i = track_get_nindex(track);
        long prev_length;

        if (0 == i) {
            /* first index */
            track_set_start(track, $3);

            if (NULL != prev_track && NULL == cur_filename) {
                /* track shares file with previous track */
                prev_length = $3 - track_get_start(prev_track);
                track_set_length(prev_track, prev_length);
            }
        }

        for (; i <= $2; i++)
            track_add_index(track, \
            track_get_zero_pre(track) + $3 \
            - track_get_start(track));
    }
    | POSTGAP time '\n' { track_set_zero_post(track, $2); }
    | track_data
    | error '\n'
    ;

track_flags
    : /* empty */
    | track_flags track_flag { track_set_flag(track, $2); }
    ;

track_flag
    : PRE
    | DCP
    | FOUR_CH
    | SCMS
    ;

cdtext
    : cdtext_item STRING '\n' { cdtext_set ($1, $2, cdtext); }
    ;

cdtext_item
    : TITLE
    | PERFORMER
    | SONGWRITER
    | COMPOSER
    | ARRANGER
    | MESSAGE
    | DISC_ID
    | GENRE
    | TOC_INFO1
    | TOC_INFO2
    | UPC_EAN
    | ISRC
    | SIZE_INFO
    ;

time
    : NUMBER
    | NUMBER ':' NUMBER ':' NUMBER { $$ = time_msf_to_frame($1, $3, $5); }
    ;

rem
    : rem_item STRING '\n' { rem_set($1, $2, rem); }
    ;

rem_item
    : DATE
    | REPLAYGAIN_ALBUM_GAIN
    | REPLAYGAIN_ALBUM_PEAK
    | REPLAYGAIN_TRACK_GAIN
    | REPLAYGAIN_TRACK_PEAK
    ;
%%

/* lexer interface */

void yyerror (const char *s)
{
    fprintf(stderr, "%d: %s\n", yylineno, s);
}

Cd *cue_parse_file(FILE *fp)
{
    YY_BUFFER_STATE buffer = NULL;

    yyin = fp;

    buffer = yy_create_buffer(yyin, YY_BUF_SIZE);

    yy_switch_to_buffer(buffer);

    if (0 == yyparse())
    {
        yy_delete_buffer(buffer);
        return cd;
    }

    yy_delete_buffer(buffer);
    return NULL;
}

Cd *cue_parse_string(const char* string)
{
    YY_BUFFER_STATE buffer = NULL;

    buffer = yy_scan_string(string);

    if (0 == yyparse())
    {
        yy_delete_buffer(buffer);
        return cd;
    }

    yy_delete_buffer(buffer);
    if(cd) 
        cd_delete(cd);

    return NULL;
}