《flex与bison》读书笔记--ch01 flex和bison简介（上）

        说起flex，大多数人第一感觉是adobe的 Flex，包括百度、Google也是这么认为，看来Flex确实是热火朝天啊，等有空了也玩下Adobe的Flex。为了不和Adobe的产品混淆，这里统统用flex来指快速文法分析器。

 --------------------------------------------------------------

       flex和bison是用来生成程序的工具，它们所生成的程序能够处理结构化输入。

       词法分析和语法分析

       词法分析（lexical analysis，或scanning）把输入分割成一个个有意义的词块，称为记号（token）。用编译原理课本中的话来说，词法分析的过程就是识别单词的过程，输入的是字符串，输出的是单词。

       语法分析（syntax analysis，或parsing）确定这些记号是如何彼此关联的。用编译原理课本中的话来说，语法分析的过程就是识别句子的过程，输入的是单词，输出的是句子。

       正则表达式和词法分析

       词法分析通常所做的就是在输入中寻找字符的模式（pattern）。一种简洁明了的模式描述方式就是正则表达式（regular expression，常简写为regex或regexp）。编辑器ed和vi以及搜索程序grep就是用这种方式来描述其所要查找的文本。flex程序主要由一系列带有指令的正则表达式组成，这些指令确定了正则表达式匹配后响应的动作（action）。由flex生成的词法分析器可以读取输入，匹配输入与所有的正则表达式并且执行每次匹配后适当的关联动作。flex会把所有的正则表达式翻译成一种高效的内部格式，这使它几乎可以同时处理所有需要匹配的模式，因此它的速度可以成百倍地提高。这种内部格式使用确定性有穷自动机（Deterministic Finite Automation，DFA）。对于DFA，他们的处理速度与模式的个数和复杂度无关。

       

/* wc程序 */%{    int chars = 0;    int words = 0;    int lines = 0;}%%%[a-zA-Z]+    { words++; chars += strlen(yytext);}\n                { chars++; lines++;}.                  { chars++;}%%main(int argc, char **argv){     yylex();     printf("%8d%8d%8d\n", lines, words, chars);}

       flex程序包含3个部分，各部分之间通过仅有%%的行来分割。

       第1部分：包含声明和选项设置。在这部分，%{和}%之间的代码会被原样照抄到生成的C文件的开头部分。在这个例子里面，它只是用来设定了行数、单词数和字符数的变量。

       第2部分：一系列的模式和动作。这部分中，每个模式处在一行的开头处，接着是模式匹配时所需要执行的C代码。这儿的C代码使用{}括住的一行或者多行语句。（模式必须在行首出现，因为flex认为以空白开始的行都是代码而把它们照抄到生成的C程序中。）

       第3部分：会被拷贝到生成的词法分析器里面的C代码，它们一般是一些与动作代码相关的例程。这个主程序负责调用flex提供的词法分析例程yylex（），并输出结果。在没有任何其他改变的情况下，词法分析器将读取标准输入。

       将上面的代码存为wc.l并执行：flex -o wc.c wc.l 后生成wc.c文件，其内容如下：

#line 2 "wc.c"#line 4 "wc.c"#define  YY_INT_ALIGNED short int/* A lexical scanner generated by flex */#define FLEX_SCANNER#define YY_FLEX_MAJOR_VERSION 2#define YY_FLEX_MINOR_VERSION 5#define YY_FLEX_SUBMINOR_VERSION 37#if YY_FLEX_SUBMINOR_VERSION > 0#define FLEX_BETA#endif/* First, we deal with  platform-specific or compiler-specific issues. *//* begin standard C headers. */#include <stdio.h>#include <string.h>#include <errno.h>#include <stdlib.h>/* end standard C headers. *//* flex integer type definitions */#ifndef FLEXINT_H#define FLEXINT_H/* C99 systems have <inttypes.h>. Non-C99 systems may or may not. */#if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L/* C99 says to define __STDC_LIMIT_MACROS before including stdint.h, * if you want the limit (max/min) macros for int types. */#ifndef __STDC_LIMIT_MACROS#define __STDC_LIMIT_MACROS 1#endif#include <inttypes.h>typedef int8_t flex_int8_t;typedef uint8_t flex_uint8_t;typedef int16_t flex_int16_t;typedef uint16_t flex_uint16_t;typedef int32_t flex_int32_t;typedef uint32_t flex_uint32_t;#elsetypedef signed char flex_int8_t;typedef short int flex_int16_t;typedef int flex_int32_t;typedef unsigned char flex_uint8_t;typedef unsigned short int flex_uint16_t;typedef unsigned int flex_uint32_t;/* Limits of integral types. */#ifndef INT8_MIN#define INT8_MIN               (-128)#endif#ifndef INT16_MIN#define INT16_MIN              (-32767-1)#endif#ifndef INT32_MIN#define INT32_MIN              (-2147483647-1)#endif#ifndef INT8_MAX#define INT8_MAX               (127)#endif#ifndef INT16_MAX#define INT16_MAX              (32767)#endif#ifndef INT32_MAX#define INT32_MAX              (2147483647)#endif#ifndef UINT8_MAX#define UINT8_MAX              (255U)#endif#ifndef UINT16_MAX#define UINT16_MAX             (65535U)#endif#ifndef UINT32_MAX#define UINT32_MAX             (4294967295U)#endif#endif /* ! C99 */#endif /* ! FLEXINT_H */#ifdef __cplusplus/* The "const" storage-class-modifier is valid. */#define YY_USE_CONST#else   /* ! __cplusplus *//* C99 requires __STDC__ to be defined as 1. */#if defined (__STDC__)#define YY_USE_CONST#endif  /* defined (__STDC__) */#endif  /* ! __cplusplus */#ifdef YY_USE_CONST#define yyconst const#else#define yyconst#endif/* Returned upon end-of-file. */#define YY_NULL 0/* Promotes a possibly negative, possibly signed char to an unsigned * integer for use as an array index.  If the signed char is negative, * we want to instead treat it as an 8-bit unsigned char, hence the * double cast. */#define YY_SC_TO_UI(c) ((unsigned int) (unsigned char) c)/* Enter a start condition.  This macro really ought to take a parameter, * but we do it the disgusting crufty way forced on us by the ()-less * definition of BEGIN. */#define BEGIN (yy_start) = 1 + 2 */* Translate the current start state into a value that can be later handed * to BEGIN to return to the state.  The YYSTATE alias is for lex * compatibility. */#define YY_START (((yy_start) - 1) / 2)#define YYSTATE YY_START/* Action number for EOF rule of a given start state. */#define YY_STATE_EOF(state) (YY_END_OF_BUFFER + state + 1)/* Special action meaning "start processing a new file". */#define YY_NEW_FILE yyrestart(yyin  )#define YY_END_OF_BUFFER_CHAR 0/* Size of default input buffer. */#ifndef YY_BUF_SIZE#define YY_BUF_SIZE 16384#endif/* The state buf must be large enough to hold one state per character in the main buffer. */#define YY_STATE_BUF_SIZE   ((YY_BUF_SIZE + 2) * sizeof(yy_state_type))#ifndef YY_TYPEDEF_YY_BUFFER_STATE#define YY_TYPEDEF_YY_BUFFER_STATEtypedef struct yy_buffer_state *YY_BUFFER_STATE;#endif#ifndef YY_TYPEDEF_YY_SIZE_T#define YY_TYPEDEF_YY_SIZE_Ttypedef size_t yy_size_t;#endifextern yy_size_t yyleng;extern FILE *yyin, *yyout;#define EOB_ACT_CONTINUE_SCAN 0#define EOB_ACT_END_OF_FILE 1#define EOB_ACT_LAST_MATCH 2    #define YY_LESS_LINENO(n)/* Return all but the first "n" matched characters back to the input stream. */#define yyless(n) \        do \                { \                /* Undo effects of setting up yytext. */ \        int yyless_macro_arg = (n); \        YY_LESS_LINENO(yyless_macro_arg);\                *yy_cp = (yy_hold_char); \                YY_RESTORE_YY_MORE_OFFSET \                (yy_c_buf_p) = yy_cp = yy_bp + yyless_macro_arg - YY_MORE_ADJ; \                YY_DO_BEFORE_ACTION; /* set up yytext again */ \                } \        while ( 0 )#define unput(c) yyunput( c, (yytext_ptr)  )#ifndef YY_STRUCT_YY_BUFFER_STATE#define YY_STRUCT_YY_BUFFER_STATEstruct yy_buffer_state        {        FILE *yy_input_file;        char *yy_ch_buf;                /* input buffer */        char *yy_buf_pos;               /* current position in input buffer */        /* Size of input buffer in bytes, not including room for EOB         * characters.         */        yy_size_t yy_buf_size;        /* Number of characters read into yy_ch_buf, not including EOB         * characters.         */        yy_size_t yy_n_chars;        /* Whether we "own" the buffer - i.e., we know we created it,         * and can realloc() it to grow it, and should free() it to         * delete it.         */        int yy_is_our_buffer;        /* Whether this is an "interactive" input source; if so, and         * if we're using stdio for input, then we want to use getc()         * instead of fread(), to make sure we stop fetching input after         * each newline.         */        int yy_is_interactive;        /* Whether we're considered to be at the beginning of a line.         * If so, '^' rules will be active on the next match, otherwise         * not.         */        int yy_at_bol;    int yy_bs_lineno; /**< The line count. */    int yy_bs_column; /**< The column count. */        /* Whether to try to fill the input buffer when we reach the         * end of it.         */        int yy_fill_buffer;        int yy_buffer_status;#define YY_BUFFER_NEW 0#define YY_BUFFER_NORMAL 1        /* When an EOF's been seen but there's still some text to process         * then we mark the buffer as YY_EOF_PENDING, to indicate that we         * shouldn't try reading from the input source any more.  We might         * still have a bunch of tokens to match, though, because of         * possible backing-up.         *         * When we actually see the EOF, we change the status to "new"         * (via yyrestart()), so that the user can continue scanning by         * just pointing yyin at a new input file.         */#define YY_BUFFER_EOF_PENDING 2        };#endif /* !YY_STRUCT_YY_BUFFER_STATE *//* Stack of input buffers. */static size_t yy_buffer_stack_top = 0; /**< index of top of stack. */static size_t yy_buffer_stack_max = 0; /**< capacity of stack. */static YY_BUFFER_STATE * yy_buffer_stack = 0; /**< Stack as an array. *//* We provide macros for accessing buffer states in case in the * future we want to put the buffer states in a more general * "scanner state". * * Returns the top of the stack, or NULL. */#define YY_CURRENT_BUFFER ( (yy_buffer_stack) \                          ? (yy_buffer_stack)[(yy_buffer_stack_top)] \                          : NULL)/* Same as previous macro, but useful when we know that the buffer stack is not * NULL or when we need an lvalue. For internal use only. */#define YY_CURRENT_BUFFER_LVALUE (yy_buffer_stack)[(yy_buffer_stack_top)]/* yy_hold_char holds the character lost when yytext is formed. */static char yy_hold_char;static yy_size_t yy_n_chars;            /* number of characters read into yy_ch_buf */yy_size_t yyleng;/* Points to current character in buffer. */static char *yy_c_buf_p = (char *) 0;static int yy_init = 0;         /* whether we need to initialize */static int yy_start = 0;        /* start state number *//* Flag which is used to allow yywrap()'s to do buffer switches * instead of setting up a fresh yyin.  A bit of a hack ... */static int yy_did_buffer_switch_on_eof;void yyrestart (FILE *input_file  );void yy_switch_to_buffer (YY_BUFFER_STATE new_buffer  );YY_BUFFER_STATE yy_create_buffer (FILE *file,int size  );void yy_delete_buffer (YY_BUFFER_STATE b  );void yy_flush_buffer (YY_BUFFER_STATE b  );void yypush_buffer_state (YY_BUFFER_STATE new_buffer  );void yypop_buffer_state (void );static void yyensure_buffer_stack (void );static void yy_load_buffer_state (void );static void yy_init_buffer (YY_BUFFER_STATE b,FILE *file  );#define YY_FLUSH_BUFFER yy_flush_buffer(YY_CURRENT_BUFFER )YY_BUFFER_STATE yy_scan_buffer (char *base,yy_size_t size  );YY_BUFFER_STATE yy_scan_string (yyconst char *yy_str  );YY_BUFFER_STATE yy_scan_bytes (yyconst char *bytes,yy_size_t len  );void *yyalloc (yy_size_t  );void *yyrealloc (void *,yy_size_t  );void yyfree (void *  );#define yy_new_buffer yy_create_buffer#define yy_set_interactive(is_interactive) \        { \        if ( ! YY_CURRENT_BUFFER ){ \        yyensure_buffer_stack (); \                YY_CURRENT_BUFFER_LVALUE =    \            yy_create_buffer(yyin,YY_BUF_SIZE ); \        } \        YY_CURRENT_BUFFER_LVALUE->yy_is_interactive = is_interactive; \        }#define yy_set_bol(at_bol) \        { \        if ( ! YY_CURRENT_BUFFER ){\        yyensure_buffer_stack (); \                YY_CURRENT_BUFFER_LVALUE =    \            yy_create_buffer(yyin,YY_BUF_SIZE ); \        } \        YY_CURRENT_BUFFER_LVALUE->yy_at_bol = at_bol; \        }#define YY_AT_BOL() (YY_CURRENT_BUFFER_LVALUE->yy_at_bol)/* Begin user sect3 */typedef unsigned char YY_CHAR;FILE *yyin = (FILE *) 0, *yyout = (FILE *) 0;typedef int yy_state_type;extern int yylineno;int yylineno = 1;extern char *yytext;#define yytext_ptr yytextstatic yy_state_type yy_get_previous_state (void );static yy_state_type yy_try_NUL_trans (yy_state_type current_state  );static int yy_get_next_buffer (void );static void yy_fatal_error (yyconst char msg[]  );/* Done after the current pattern has been matched and before the * corresponding action - sets up yytext. */#define YY_DO_BEFORE_ACTION \        (yytext_ptr) = yy_bp; \        yyleng = (size_t) (yy_cp - yy_bp); \        (yy_hold_char) = *yy_cp; \        *yy_cp = '\0'; \        (yy_c_buf_p) = yy_cp;#define YY_NUM_RULES 4#define YY_END_OF_BUFFER 5/* This struct is not used in this scanner,   but its presence is necessary. */struct yy_trans_info        {        flex_int32_t yy_verify;        flex_int32_t yy_nxt;        };static yyconst flex_int16_t yy_accept[9] =    {   0,        0,    0,    5,    3,    2,    1,    1,    0    } ;static yyconst flex_int32_t yy_ec[256] =    {   0,        1,    1,    1,    1,    1,    1,    1,    1,    1,    2,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    3,    3,    3,    3,    3,    3,        3,    3,    3,    3,    3,    3,    3,    3,    3,    3,        3,    3,    3,    3,    3,    3,    3,    3,    3,    3,        1,    1,    1,    1,    1,    1,    3,    3,    3,    3,        3,    3,    3,    3,    3,    3,    3,    3,    3,    3,        3,    3,    3,    3,    3,    3,    3,    3,    3,    3,        3,    3,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1,    1,    1,    1,    1,    1,        1,    1,    1,    1,    1    } ;static yyconst flex_int32_t yy_meta[4] =    {   0,        1,    1,    2    } ;static yyconst flex_int16_t yy_base[10] =    {   0,        0,    0,    5,    6,    6,    0,    0,    6,    2    } ;static yyconst flex_int16_t yy_def[10] =    {   0,        8,    1,    8,    8,    8,    9,    9,    0,    8    } ;static yyconst flex_int16_t yy_nxt[10] =    {   0,        4,    5,    6,    7,    8,    3,    8,    8,    8    } ;static yyconst flex_int16_t yy_chk[10] =    {   0,        1,    1,    1,    9,    3,    8,    8,    8,    8    } ;static yy_state_type yy_last_accepting_state;static char *yy_last_accepting_cpos;extern int yy_flex_debug;int yy_flex_debug = 0;/* The intent behind this definition is that it'll catch * any uses of REJECT which flex missed. */#define REJECT reject_used_but_not_detected#define yymore() yymore_used_but_not_detected#define YY_MORE_ADJ 0#define YY_RESTORE_YY_MORE_OFFSETchar *yytext;#line 1 "wc.l"/* wc */#line 3 "wc.l"    int chars = 0;    int words = 0;    int lines = 0;#line 456 "wc.c"#define INITIAL 0#ifndef YY_NO_UNISTD_H/* Special case for "unistd.h", since it is non-ANSI. We include it way * down here because we want the user's section 1 to have been scanned first. * The user has a chance to override it with an option. */#include <unistd.h>#endif#ifndef YY_EXTRA_TYPE#define YY_EXTRA_TYPE void *#endifstatic int yy_init_globals (void );/* Accessor methods to globals.   These are made visible to non-reentrant scanners for convenience. */int yylex_destroy (void );int yyget_debug (void );void yyset_debug (int debug_flag  );YY_EXTRA_TYPE yyget_extra (void );void yyset_extra (YY_EXTRA_TYPE user_defined  );FILE *yyget_in (void );void yyset_in  (FILE * in_str  );FILE *yyget_out (void );void yyset_out  (FILE * out_str  );yy_size_t yyget_leng (void );char *yyget_text (void );int yyget_lineno (void );void yyset_lineno (int line_number  );/* Macros after this point can all be overridden by user definitions in * section 1. */#ifndef YY_SKIP_YYWRAP#ifdef __cplusplusextern "C" int yywrap (void );#elseextern int yywrap (void );#endif#endif    static void yyunput (int c,char *buf_ptr  );#ifndef yytext_ptrstatic void yy_flex_strncpy (char *,yyconst char *,int );#endif#ifdef YY_NEED_STRLENstatic int yy_flex_strlen (yyconst char * );#endif#ifndef YY_NO_INPUT#ifdef __cplusplusstatic int yyinput (void );#elsestatic int input (void );#endif#endif/* Amount of stuff to slurp up with each read. */#ifndef YY_READ_BUF_SIZE#define YY_READ_BUF_SIZE 8192#endif/* Copy whatever the last rule matched to the standard output. */#ifndef ECHO/* This used to be an fputs(), but since the string might contain NUL's, * we now use fwrite(). */#define ECHO do { if (fwrite( yytext, yyleng, 1, yyout )) {} } while (0)#endif/* Gets input and stuffs it into "buf".  number of characters read, or YY_NULL, * is returned in "result". */#ifndef YY_INPUT#define YY_INPUT(buf,result,max_size) \        if ( YY_CURRENT_BUFFER_LVALUE->yy_is_interactive ) \                { \                int c = '*'; \                size_t n; \                for ( n = 0; n < max_size && \                             (c = getc( yyin )) != EOF && c != '\n'; ++n ) \                        buf[n] = (char) c; \                if ( c == '\n' ) \                        buf[n++] = (char) c; \                if ( c == EOF && ferror( yyin ) ) \                        YY_FATAL_ERROR( "input in flex scanner failed" ); \                result = n; \                } \        else \                { \                errno=0; \                while ( (result = fread(buf, 1, max_size, yyin))==0 && ferror(yyin)) \                        { \                        if( errno != EINTR) \                                { \                                YY_FATAL_ERROR( "input in flex scanner failed" ); \                                break; \                                } \                        errno=0; \                        clearerr(yyin); \                        } \                }\\#endif/* No semi-colon after return; correct usage is to write "yyterminate();" - * we don't want an extra ';' after the "return" because that will cause * some compilers to complain about unreachable statements. */#ifndef yyterminate#define yyterminate() return YY_NULL#endif/* Number of entries by which start-condition stack grows. */#ifndef YY_START_STACK_INCR#define YY_START_STACK_INCR 25#endif/* Report a fatal error. */#ifndef YY_FATAL_ERROR#define YY_FATAL_ERROR(msg) yy_fatal_error( msg )#endif/* end tables serialization structures and prototypes *//* Default declaration of generated scanner - a define so the user can * easily add parameters. */#ifndef YY_DECL#define YY_DECL_IS_OURS 1extern int yylex (void);#define YY_DECL int yylex (void)#endif /* !YY_DECL *//* Code executed at the beginning of each rule, after yytext and yyleng * have been set up. */#ifndef YY_USER_ACTION#define YY_USER_ACTION#endif/* Code executed at the end of each rule. */#ifndef YY_BREAK#define YY_BREAK break;#endif#define YY_RULE_SETUP \        YY_USER_ACTION/** The main scanner function which does all the work. */YY_DECL{        register yy_state_type yy_current_state;        register char *yy_cp, *yy_bp;        register int yy_act;#line 8 "wc.l"#line 641 "wc.c"        if ( !(yy_init) )                {                (yy_init) = 1;#ifdef YY_USER_INIT                YY_USER_INIT;#endif                if ( ! (yy_start) )                        (yy_start) = 1; /* first start state */                if ( ! yyin )                        yyin = stdin;                if ( ! yyout )                        yyout = stdout;                if ( ! YY_CURRENT_BUFFER ) {                        yyensure_buffer_stack ();                        YY_CURRENT_BUFFER_LVALUE =                                yy_create_buffer(yyin,YY_BUF_SIZE );                }                yy_load_buffer_state( );                }        while ( 1 )             /* loops until end-of-file is reached */                {                yy_cp = (yy_c_buf_p);                /* Support of yytext. */                *yy_cp = (yy_hold_char);                /* yy_bp points to the position in yy_ch_buf of the start of                 * the current run.                 */                yy_bp = yy_cp;                yy_current_state = (yy_start);yy_match:                do                        {                        register YY_CHAR yy_c = yy_ec[YY_SC_TO_UI(*yy_cp)];                        if ( yy_accept[yy_current_state] )                                {                                (yy_last_accepting_state) = yy_current_state;                                (yy_last_accepting_cpos) = yy_cp;                                }                        while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )                                {                                yy_current_state = (int) yy_def[yy_current_state];                                if ( yy_current_state >= 9 )                                        yy_c = yy_meta[(unsigned int) yy_c];                                }                        yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];                        ++yy_cp;                        }                while ( yy_base[yy_current_state] != 6 );yy_find_action:                yy_act = yy_accept[yy_current_state];                if ( yy_act == 0 )                        { /* have to back up */                        yy_cp = (yy_last_accepting_cpos);                        yy_current_state = (yy_last_accepting_state);                        yy_act = yy_accept[yy_current_state];                        }                YY_DO_BEFORE_ACTION;do_action:      /* This label is used only to access EOF actions. */                switch ( yy_act )        { /* beginning of action switch */                        case 0: /* must back up */                        /* undo the effects of YY_DO_BEFORE_ACTION */                        *yy_cp = (yy_hold_char);                        yy_cp = (yy_last_accepting_cpos);                        yy_current_state = (yy_last_accepting_state);                        goto yy_find_action;case 1:YY_RULE_SETUP#line 10 "wc.l"{words++; chars += strlen(yytext);}        YY_BREAKcase 2:/* rule 2 can match eol */YY_RULE_SETUP#line 11 "wc.l"{chars++; lines++;}        YY_BREAKcase 3:YY_RULE_SETUP#line 12 "wc.l"{chars++;}        YY_BREAKcase 4:YY_RULE_SETUP#line 14 "wc.l"ECHO;        YY_BREAK#line 745 "wc.c"case YY_STATE_EOF(INITIAL):        yyterminate();        case YY_END_OF_BUFFER:                {                /* Amount of text matched not including the EOB char. */                int yy_amount_of_matched_text = (int) (yy_cp - (yytext_ptr)) - 1;                /* Undo the effects of YY_DO_BEFORE_ACTION. */                *yy_cp = (yy_hold_char);                YY_RESTORE_YY_MORE_OFFSET                if ( YY_CURRENT_BUFFER_LVALUE->yy_buffer_status == YY_BUFFER_NEW )                        {                        /* We're scanning a new file or input source.  It's                         * possible that this happened because the user                         * just pointed yyin at a new source and called                         * yylex().  If so, then we have to assure                         * consistency between YY_CURRENT_BUFFER and our                         * globals.  Here is the right place to do so, because                         * this is the first action (other than possibly a                         * back-up) that will match for the new input source.                         */                        (yy_n_chars) = YY_CURRENT_BUFFER_LVALUE->yy_n_chars;                        YY_CURRENT_BUFFER_LVALUE->yy_input_file = yyin;                        YY_CURRENT_BUFFER_LVALUE->yy_buffer_status = YY_BUFFER_NORMAL;                        }                /* Note that here we test for yy_c_buf_p "<=" to the position                 * of the first EOB in the buffer, since yy_c_buf_p will                 * already have been incremented past the NUL character                 * (since all states make transitions on EOB to the                 * end-of-buffer state).  Contrast this with the test                 * in input().                 */                if ( (yy_c_buf_p) <= &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] )                        { /* This was really a NUL. */                        yy_state_type yy_next_state;                        (yy_c_buf_p) = (yytext_ptr) + yy_amount_of_matched_text;                        yy_current_state = yy_get_previous_state(  );                        /* Okay, we're now positioned to make the NUL                         * transition.  We couldn't have                         * yy_get_previous_state() go ahead and do it                         * for us because it doesn't know how to deal                         * with the possibility of jamming (and we don't                         * want to build jamming into it because then it                         * will run more slowly).                         */                        yy_next_state = yy_try_NUL_trans( yy_current_state );                        yy_bp = (yytext_ptr) + YY_MORE_ADJ;                        if ( yy_next_state )                                {                                /* Consume the NUL. */                                yy_cp = ++(yy_c_buf_p);                                yy_current_state = yy_next_state;                                goto yy_match;                                }                        else                                {                                yy_cp = (yy_c_buf_p);                                goto yy_find_action;                                }                        }                else switch ( yy_get_next_buffer(  ) )                        {                        case EOB_ACT_END_OF_FILE:                                {                                (yy_did_buffer_switch_on_eof) = 0;                                if ( yywrap( ) )                                        {                                        /* Note: because we've taken care in                                         * yy_get_next_buffer() to have set up                                         * yytext, we can now set up                                         * yy_c_buf_p so that if some total                                         * hoser (like flex itself) wants to                                         * call the scanner after we return the                                         * YY_NULL, it'll still work - another                                         * YY_NULL will get returned.                                         */                                        (yy_c_buf_p) = (yytext_ptr) + YY_MORE_ADJ;                                        yy_act = YY_STATE_EOF(YY_START);                                        goto do_action;                                        }                                else                                        {                                        if ( ! (yy_did_buffer_switch_on_eof) )                                                YY_NEW_FILE;                                        }                                break;                                }                        case EOB_ACT_CONTINUE_SCAN:                                (yy_c_buf_p) =                                        (yytext_ptr) + yy_amount_of_matched_text;                                yy_current_state = yy_get_previous_state(  );                                yy_cp = (yy_c_buf_p);                                yy_bp = (yytext_ptr) + YY_MORE_ADJ;                                goto yy_match;                        case EOB_ACT_LAST_MATCH:                                (yy_c_buf_p) =                                &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)];                                yy_current_state = yy_get_previous_state(  );                                yy_cp = (yy_c_buf_p);                                yy_bp = (yytext_ptr) + YY_MORE_ADJ;                                goto yy_find_action;                        }                break;                }        default:                YY_FATAL_ERROR(                        "fatal flex scanner internal error--no action found" );        } /* end of action switch */                } /* end of scanning one token */} /* end of yylex *//* yy_get_next_buffer - try to read in a new buffer * * Returns a code representing an action: *      EOB_ACT_LAST_MATCH - *      EOB_ACT_CONTINUE_SCAN - continue scanning from current position *      EOB_ACT_END_OF_FILE - end of file */static int yy_get_next_buffer (void){        register char *dest = YY_CURRENT_BUFFER_LVALUE->yy_ch_buf;        register char *source = (yytext_ptr);        register int number_to_move, i;        int ret_val;        if ( (yy_c_buf_p) > &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars) + 1] )                YY_FATAL_ERROR(                "fatal flex scanner internal error--end of buffer missed" );        if ( YY_CURRENT_BUFFER_LVALUE->yy_fill_buffer == 0 )                { /* Don't try to fill the buffer, so this is an EOF. */                if ( (yy_c_buf_p) - (yytext_ptr) - YY_MORE_ADJ == 1 )                        {                        /* We matched a single character, the EOB, so                         * treat this as a final EOF.                         */                        return EOB_ACT_END_OF_FILE;                        }                else                        {                        /* We matched some text prior to the EOB, first                         * process it.                         */                        return EOB_ACT_LAST_MATCH;                        }                }        /* Try to read more data. */        /* First move last chars to start of buffer. */        number_to_move = (int) ((yy_c_buf_p) - (yytext_ptr)) - 1;        for ( i = 0; i < number_to_move; ++i )                *(dest++) = *(source++);        if ( YY_CURRENT_BUFFER_LVALUE->yy_buffer_status == YY_BUFFER_EOF_PENDING )                /* don't do the read, it's not guaranteed to return an EOF,                 * just force an EOF                 */                YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars) = 0;        else                {                        yy_size_t num_to_read =                        YY_CURRENT_BUFFER_LVALUE->yy_buf_size - number_to_move - 1;                while ( num_to_read <= 0 )                        { /* Not enough room in the buffer - grow it. */                        /* just a shorter name for the current buffer */                        YY_BUFFER_STATE b = YY_CURRENT_BUFFER_LVALUE;                        int yy_c_buf_p_offset =                                (int) ((yy_c_buf_p) - b->yy_ch_buf);                        if ( b->yy_is_our_buffer )                                {                                yy_size_t new_size = b->yy_buf_size * 2;                                if ( new_size <= 0 )                                        b->yy_buf_size += b->yy_buf_size / 8;                                else                                        b->yy_buf_size *= 2;                                b->yy_ch_buf = (char *)                                        /* Include room in for 2 EOB chars. */                                        yyrealloc((void *) b->yy_ch_buf,b->yy_buf_size + 2  );                                }                        else                                /* Can't grow it, we don't own it. */                                b->yy_ch_buf = 0;                        if ( ! b->yy_ch_buf )                                YY_FATAL_ERROR(                                "fatal error - scanner input buffer overflow" );                        (yy_c_buf_p) = &b->yy_ch_buf[yy_c_buf_p_offset];                        num_to_read = YY_CURRENT_BUFFER_LVALUE->yy_buf_size -                                                number_to_move - 1;                        }                if ( num_to_read > YY_READ_BUF_SIZE )                        num_to_read = YY_READ_BUF_SIZE;                /* Read in more data. */                YY_INPUT( (&YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[number_to_move]),                        (yy_n_chars), num_to_read );                YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);                }        if ( (yy_n_chars) == 0 )                {                if ( number_to_move == YY_MORE_ADJ )                        {                        ret_val = EOB_ACT_END_OF_FILE;                        yyrestart(yyin  );                        }                else                        {                        ret_val = EOB_ACT_LAST_MATCH;                        YY_CURRENT_BUFFER_LVALUE->yy_buffer_status =                                YY_BUFFER_EOF_PENDING;                        }                }        else                ret_val = EOB_ACT_CONTINUE_SCAN;        if ((yy_size_t) ((yy_n_chars) + number_to_move) > YY_CURRENT_BUFFER_LVALUE->yy_buf_size) {                /* Extend the array by 50%, plus the number we really need. */                yy_size_t new_size = (yy_n_chars) + number_to_move + ((yy_n_chars) >> 1);                YY_CURRENT_BUFFER_LVALUE->yy_ch_buf = (char *) yyrealloc((void *) YY_CURRENT_BUFFER_LVALUE->yy_ch_buf,new_size  );                if ( ! YY_CURRENT_BUFFER_LVALUE->yy_ch_buf )                        YY_FATAL_ERROR( "out of dynamic memory in yy_get_next_buffer()" );        }        (yy_n_chars) += number_to_move;        YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] = YY_END_OF_BUFFER_CHAR;        YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars) + 1] = YY_END_OF_BUFFER_CHAR;        (yytext_ptr) = &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[0];        return ret_val;}/* yy_get_previous_state - get the state just before the EOB char was reached */    static yy_state_type yy_get_previous_state (void){        register yy_state_type yy_current_state;        register char *yy_cp;        yy_current_state = (yy_start);        for ( yy_cp = (yytext_ptr) + YY_MORE_ADJ; yy_cp < (yy_c_buf_p); ++yy_cp )                {                register YY_CHAR yy_c = (*yy_cp ? yy_ec[YY_SC_TO_UI(*yy_cp)] : 1);                if ( yy_accept[yy_current_state] )                        {                        (yy_last_accepting_state) = yy_current_state;                        (yy_last_accepting_cpos) = yy_cp;                        }                while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )                        {                        yy_current_state = (int) yy_def[yy_current_state];                        if ( yy_current_state >= 9 )                                yy_c = yy_meta[(unsigned int) yy_c];                        }                yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];                }        return yy_current_state;}/* yy_try_NUL_trans - try to make a transition on the NUL character * * synopsis *      next_state = yy_try_NUL_trans( current_state ); */    static yy_state_type yy_try_NUL_trans  (yy_state_type yy_current_state ){        register int yy_is_jam;        register char *yy_cp = (yy_c_buf_p);        register YY_CHAR yy_c = 1;        if ( yy_accept[yy_current_state] )                {                (yy_last_accepting_state) = yy_current_state;                (yy_last_accepting_cpos) = yy_cp;                }        while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )                {                yy_current_state = (int) yy_def[yy_current_state];                if ( yy_current_state >= 9 )                        yy_c = yy_meta[(unsigned int) yy_c];                }        yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];        yy_is_jam = (yy_current_state == 8);                return yy_is_jam ? 0 : yy_current_state;}    static void yyunput (int c, register char * yy_bp ){        register char *yy_cp;    yy_cp = (yy_c_buf_p);        /* undo effects of setting up yytext */        *yy_cp = (yy_hold_char);        if ( yy_cp < YY_CURRENT_BUFFER_LVALUE->yy_ch_buf + 2 )                { /* need to shift things up to make room */                /* +2 for EOB chars. */                register yy_size_t number_to_move = (yy_n_chars) + 2;                register char *dest = &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[                                        YY_CURRENT_BUFFER_LVALUE->yy_buf_size + 2];                register char *source =                                &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[number_to_move];                while ( source > YY_CURRENT_BUFFER_LVALUE->yy_ch_buf )                        *--dest = *--source;                yy_cp += (int) (dest - source);                yy_bp += (int) (dest - source);                YY_CURRENT_BUFFER_LVALUE->yy_n_chars =                        (yy_n_chars) = YY_CURRENT_BUFFER_LVALUE->yy_buf_size;                if ( yy_cp < YY_CURRENT_BUFFER_LVALUE->yy_ch_buf + 2 )                        YY_FATAL_ERROR( "flex scanner push-back overflow" );                }        *--yy_cp = (char) c;        (yytext_ptr) = yy_bp;        (yy_hold_char) = *yy_cp;        (yy_c_buf_p) = yy_cp;}#ifndef YY_NO_INPUT#ifdef __cplusplus    static int yyinput (void)#else    static int input  (void)#endif{        int c;        *(yy_c_buf_p) = (yy_hold_char);        if ( *(yy_c_buf_p) == YY_END_OF_BUFFER_CHAR )                {                /* yy_c_buf_p now points to the character we want to return.                 * If this occurs *before* the EOB characters, then it's a                 * valid NUL; if not, then we've hit the end of the buffer.                 */                if ( (yy_c_buf_p) < &YY_CURRENT_BUFFER_LVALUE->yy_ch_buf[(yy_n_chars)] )                        /* This was really a NUL. */                        *(yy_c_buf_p) = '\0';                else                        { /* need more input */                        yy_size_t offset = (yy_c_buf_p) - (yytext_ptr);                        ++(yy_c_buf_p);                        switch ( yy_get_next_buffer(  ) )                                {                                case EOB_ACT_LAST_MATCH:                                        /* This happens because yy_g_n_b()                                         * sees that we've accumulated a                                         * token and flags that we need to                                         * try matching the token before                                         * proceeding.  But for input(),                                         * there's no matching to consider.                                         * So convert the EOB_ACT_LAST_MATCH                                         * to EOB_ACT_END_OF_FILE.                                         */                                        /* Reset buffer status. */                                        yyrestart(yyin );                                        /*FALLTHROUGH*/                                case EOB_ACT_END_OF_FILE:                                        {                                        if ( yywrap( ) )                                                return EOF;                                        if ( ! (yy_did_buffer_switch_on_eof) )                                                YY_NEW_FILE;#ifdef __cplusplus                                        return yyinput();#else                                        return input();#endif                                        }                                case EOB_ACT_CONTINUE_SCAN:                                        (yy_c_buf_p) = (yytext_ptr) + offset;                                        break;                                }                        }                }        c = *(unsigned char *) (yy_c_buf_p);    /* cast for 8-bit char's */        *(yy_c_buf_p) = '\0';   /* preserve yytext */        (yy_hold_char) = *++(yy_c_buf_p);        return c;}#endif  /* ifndef YY_NO_INPUT *//** Immediately switch to a different input stream. * @param input_file A readable stream. * * @note This function does not reset the start condition to @c INITIAL . */    void yyrestart  (FILE * input_file ){        if ( ! YY_CURRENT_BUFFER ){        yyensure_buffer_stack ();                YY_CURRENT_BUFFER_LVALUE =            yy_create_buffer(yyin,YY_BUF_SIZE );        }        yy_init_buffer(YY_CURRENT_BUFFER,input_file );        yy_load_buffer_state( );}/** Switch to a different input buffer. * @param new_buffer The new input buffer. * */    void yy_switch_to_buffer  (YY_BUFFER_STATE  new_buffer ){        /* TODO. We should be able to replace this entire function body         * with         *              yypop_buffer_state();         *              yypush_buffer_state(new_buffer);     */        yyensure_buffer_stack ();        if ( YY_CURRENT_BUFFER == new_buffer )                return;        if ( YY_CURRENT_BUFFER )                {                /* Flush out information for old buffer. */                *(yy_c_buf_p) = (yy_hold_char);                YY_CURRENT_BUFFER_LVALUE->yy_buf_pos = (yy_c_buf_p);                YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);                }        YY_CURRENT_BUFFER_LVALUE = new_buffer;        yy_load_buffer_state( );        /* We don't actually know whether we did this switch during         * EOF (yywrap()) processing, but the only time this flag         * is looked at is after yywrap() is called, so it's safe         * to go ahead and always set it.         */        (yy_did_buffer_switch_on_eof) = 1;}static void yy_load_buffer_state  (void){        (yy_n_chars) = YY_CURRENT_BUFFER_LVALUE->yy_n_chars;        (yytext_ptr) = (yy_c_buf_p) = YY_CURRENT_BUFFER_LVALUE->yy_buf_pos;        yyin = YY_CURRENT_BUFFER_LVALUE->yy_input_file;        (yy_hold_char) = *(yy_c_buf_p);}/** Allocate and initialize an input buffer state. * @param file A readable stream. * @param size The character buffer size in bytes. When in doubt, use @c YY_BUF_SIZE. * * @return the allocated buffer state. */    YY_BUFFER_STATE yy_create_buffer  (FILE * file, int  size ){        YY_BUFFER_STATE b;        b = (YY_BUFFER_STATE) yyalloc(sizeof( struct yy_buffer_state )  );        if ( ! b )                YY_FATAL_ERROR( "out of dynamic memory in yy_create_buffer()" );        b->yy_buf_size = size;        /* yy_ch_buf has to be 2 characters longer than the size given because         * we need to put in 2 end-of-buffer characters.         */        b->yy_ch_buf = (char *) yyalloc(b->yy_buf_size + 2  );        if ( ! b->yy_ch_buf )                YY_FATAL_ERROR( "out of dynamic memory in yy_create_buffer()" );        b->yy_is_our_buffer = 1;        yy_init_buffer(b,file );        return b;}/** Destroy the buffer. * @param b a buffer created with yy_create_buffer() * */    void yy_delete_buffer (YY_BUFFER_STATE  b ){        if ( ! b )                return;        if ( b == YY_CURRENT_BUFFER ) /* Not sure if we should pop here. */                YY_CURRENT_BUFFER_LVALUE = (YY_BUFFER_STATE) 0;        if ( b->yy_is_our_buffer )                yyfree((void *) b->yy_ch_buf  );        yyfree((void *) b  );}/* Initializes or reinitializes a buffer. * This function is sometimes called more than once on the same buffer, * such as during a yyrestart() or at EOF. */    static void yy_init_buffer  (YY_BUFFER_STATE  b, FILE * file ){        int oerrno = errno;        yy_flush_buffer(b );        b->yy_input_file = file;        b->yy_fill_buffer = 1;    /* If b is the current buffer, then yy_init_buffer was _probably_     * called from yyrestart() or through yy_get_next_buffer.     * In that case, we don't want to reset the lineno or column.     */    if (b != YY_CURRENT_BUFFER){        b->yy_bs_lineno = 1;        b->yy_bs_column = 0;    }        b->yy_is_interactive = file ? (isatty( fileno(file) ) > 0) : 0;        errno = oerrno;}/** Discard all buffered characters. On the next scan, YY_INPUT will be called. * @param b the buffer state to be flushed, usually @c YY_CURRENT_BUFFER. * */    void yy_flush_buffer (YY_BUFFER_STATE  b ){        if ( ! b )                return;        b->yy_n_chars = 0;        /* We always need two end-of-buffer characters.  The first causes         * a transition to the end-of-buffer state.  The second causes         * a jam in that state.         */        b->yy_ch_buf[0] = YY_END_OF_BUFFER_CHAR;        b->yy_ch_buf[1] = YY_END_OF_BUFFER_CHAR;        b->yy_buf_pos = &b->yy_ch_buf[0];        b->yy_at_bol = 1;        b->yy_buffer_status = YY_BUFFER_NEW;        if ( b == YY_CURRENT_BUFFER )                yy_load_buffer_state( );}/** Pushes the new state onto the stack. The new state becomes *  the current state. This function will allocate the stack *  if necessary. *  @param new_buffer The new state. * */void yypush_buffer_state (YY_BUFFER_STATE new_buffer ){        if (new_buffer == NULL)                return;        yyensure_buffer_stack();        /* This block is copied from yy_switch_to_buffer. */        if ( YY_CURRENT_BUFFER )                {                /* Flush out information for old buffer. */                *(yy_c_buf_p) = (yy_hold_char);                YY_CURRENT_BUFFER_LVALUE->yy_buf_pos = (yy_c_buf_p);                YY_CURRENT_BUFFER_LVALUE->yy_n_chars = (yy_n_chars);                }        /* Only push if top exists. Otherwise, replace top. */        if (YY_CURRENT_BUFFER)                (yy_buffer_stack_top)++;        YY_CURRENT_BUFFER_LVALUE = new_buffer;        /* copied from yy_switch_to_buffer. */        yy_load_buffer_state( );        (yy_did_buffer_switch_on_eof) = 1;}/** Removes and deletes the top of the stack, if present. *  The next element becomes the new top. * */void yypop_buffer_state (void){        if (!YY_CURRENT_BUFFER)                return;        yy_delete_buffer(YY_CURRENT_BUFFER );        YY_CURRENT_BUFFER_LVALUE = NULL;        if ((yy_buffer_stack_top) > 0)                --(yy_buffer_stack_top);        if (YY_CURRENT_BUFFER) {                yy_load_buffer_state( );                (yy_did_buffer_switch_on_eof) = 1;        }}/* Allocates the stack if it does not exist. *  Guarantees space for at least one push. */static void yyensure_buffer_stack (void){        yy_size_t num_to_alloc;        if (!(yy_buffer_stack)) {                /* First allocation is just for 2 elements, since we don't know if this                 * scanner will even need a stack. We use 2 instead of 1 to avoid an                 * immediate realloc on the next call.         */                num_to_alloc = 1;                (yy_buffer_stack) = (struct yy_buffer_state**)yyalloc                                                                (num_to_alloc * sizeof(struct yy_buffer_state*)                                                                );                if ( ! (yy_buffer_stack) )                        YY_FATAL_ERROR( "out of dynamic memory in yyensure_buffer_stack()" );                memset((yy_buffer_stack), 0, num_to_alloc * sizeof(struct yy_buffer_state*));                (yy_buffer_stack_max) = num_to_alloc;                (yy_buffer_stack_top) = 0;                return;        }        if ((yy_buffer_stack_top) >= ((yy_buffer_stack_max)) - 1){                /* Increase the buffer to prepare for a possible push. */                int grow_size = 8 /* arbitrary grow size */;                num_to_alloc = (yy_buffer_stack_max) + grow_size;                (yy_buffer_stack) = (struct yy_buffer_state**)yyrealloc                                                                ((yy_buffer_stack),                                                                num_to_alloc * sizeof(struct yy_buffer_state*)                                                                );                if ( ! (yy_buffer_stack) )                        YY_FATAL_ERROR( "out of dynamic memory in yyensure_buffer_stack()" );                /* zero only the new slots.*/                memset((yy_buffer_stack) + (yy_buffer_stack_max), 0, grow_size * sizeof(struct yy_buffer_state*));                (yy_buffer_stack_max) = num_to_alloc;        }}/** Setup the input buffer state to scan directly from a user-specified character buffer. * @param base the character buffer * @param size the size in bytes of the character buffer * * @return the newly allocated buffer state object. */YY_BUFFER_STATE yy_scan_buffer  (char * base, yy_size_t  size ){        YY_BUFFER_STATE b;        if ( size < 2 ||             base[size-2] != YY_END_OF_BUFFER_CHAR ||             base[size-1] != YY_END_OF_BUFFER_CHAR )                /* They forgot to leave room for the EOB's. */                return 0;        b = (YY_BUFFER_STATE) yyalloc(sizeof( struct yy_buffer_state )  );        if ( ! b )                YY_FATAL_ERROR( "out of dynamic memory in yy_scan_buffer()" );        b->yy_buf_size = size - 2;      /* "- 2" to take care of EOB's */        b->yy_buf_pos = b->yy_ch_buf = base;        b->yy_is_our_buffer = 0;        b->yy_input_file = 0;        b->yy_n_chars = b->yy_buf_size;        b->yy_is_interactive = 0;        b->yy_at_bol = 1;        b->yy_fill_buffer = 0;        b->yy_buffer_status = YY_BUFFER_NEW;        yy_switch_to_buffer(b  );        return b;}/** Setup the input buffer state to scan a string. The next call to yylex() will * scan from a @e copy of @a str. * @param yystr a NUL-terminated string to scan * * @return the newly allocated buffer state object. * @note If you want to scan bytes that may contain NUL values, then use *       yy_scan_bytes() instead. */YY_BUFFER_STATE yy_scan_string (yyconst char * yystr ){        return yy_scan_bytes(yystr,strlen(yystr) );}/** Setup the input buffer state to scan the given bytes. The next call to yylex() will * scan from a @e copy of @a bytes. * @param yybytes the byte buffer to scan * @param _yybytes_len the number of bytes in the buffer pointed to by @a bytes. * * @return the newly allocated buffer state object. */YY_BUFFER_STATE yy_scan_bytes  (yyconst char * yybytes, yy_size_t  _yybytes_len ){        YY_BUFFER_STATE b;        char *buf;        yy_size_t n;        int i;        /* Get memory for full buffer, including space for trailing EOB's. */        n = _yybytes_len + 2;        buf = (char *) yyalloc(n  );        if ( ! buf )                YY_FATAL_ERROR( "out of dynamic memory in yy_scan_bytes()" );        for ( i = 0; i < _yybytes_len; ++i )                buf[i] = yybytes[i];        buf[_yybytes_len] = buf[_yybytes_len+1] = YY_END_OF_BUFFER_CHAR;        b = yy_scan_buffer(buf,n );        if ( ! b )                YY_FATAL_ERROR( "bad buffer in yy_scan_bytes()" );        /* It's okay to grow etc. this buffer, and we should throw it         * away when we're done.         */        b->yy_is_our_buffer = 1;        return b;}#ifndef YY_EXIT_FAILURE#define YY_EXIT_FAILURE 2#endifstatic void yy_fatal_error (yyconst char* msg ){        (void) fprintf( stderr, "%s\n", msg );        exit( YY_EXIT_FAILURE );}/* Redefine yyless() so it works in section 3 code. */#undef yyless#define yyless(n) \        do \                { \                /* Undo effects of setting up yytext. */ \        int yyless_macro_arg = (n); \        YY_LESS_LINENO(yyless_macro_arg);\                yytext[yyleng] = (yy_hold_char); \                (yy_c_buf_p) = yytext + yyless_macro_arg; \                (yy_hold_char) = *(yy_c_buf_p); \                *(yy_c_buf_p) = '\0'; \                yyleng = yyless_macro_arg; \                } \        while ( 0 )/* Accessor  methods (get/set functions) to struct members. *//** Get the current line number. * */int yyget_lineno  (void){    return yylineno;}/** Get the input stream. * */FILE *yyget_in  (void){        return yyin;}/** Get the output stream. * */FILE *yyget_out  (void){        return yyout;}/** Get the length of the current token. * */yy_size_t yyget_leng  (void){        return yyleng;}/** Get the current token. * */char *yyget_text  (void){        return yytext;}/** Set the current line number. * @param line_number * */void yyset_lineno (int  line_number ){    yylineno = line_number;}/** Set the input stream. This does not discard the current * input buffer. * @param in_str A readable stream. * * @see yy_switch_to_buffer */void yyset_in (FILE *  in_str ){        yyin = in_str ;}void yyset_out (FILE *  out_str ){        yyout = out_str ;}int yyget_debug  (void){        return yy_flex_debug;}void yyset_debug (int  bdebug ){        yy_flex_debug = bdebug ;}static int yy_init_globals (void){        /* Initialization is the same as for the non-reentrant scanner.     * This function is called from yylex_destroy(), so don't allocate here.     */    (yy_buffer_stack) = 0;    (yy_buffer_stack_top) = 0;    (yy_buffer_stack_max) = 0;    (yy_c_buf_p) = (char *) 0;    (yy_init) = 0;    (yy_start) = 0;/* Defined in main.c */#ifdef YY_STDINIT    yyin = stdin;    yyout = stdout;#else    yyin = (FILE *) 0;    yyout = (FILE *) 0;#endif    /* For future reference: Set errno on error, since we are called by     * yylex_init()     */    return 0;}/* yylex_destroy is for both reentrant and non-reentrant scanners. */int yylex_destroy  (void){    /* Pop the buffer stack, destroying each element. */        while(YY_CURRENT_BUFFER){                yy_delete_buffer(YY_CURRENT_BUFFER  );                YY_CURRENT_BUFFER_LVALUE = NULL;                yypop_buffer_state();        }        /* Destroy the stack itself. */        yyfree((yy_buffer_stack) );        (yy_buffer_stack) = NULL;    /* Reset the globals. This is important in a non-reentrant scanner so the next time     * yylex() is called, initialization will occur. */    yy_init_globals( );    return 0;}/* * Internal utility routines. */#ifndef yytext_ptrstatic void yy_flex_strncpy (char* s1, yyconst char * s2, int n ){        register int i;        for ( i = 0; i < n; ++i )                s1[i] = s2[i];}#endif#ifdef YY_NEED_STRLENstatic int yy_flex_strlen (yyconst char * s ){        register int n;        for ( n = 0; s[n]; ++n )                ;        return n;}#endifvoid *yyalloc (yy_size_t  size ){        return (void *) malloc( size );}void *yyrealloc  (void * ptr, yy_size_t  size ){        /* The cast to (char *) in the following accommodates both         * implementations that use char* generic pointers, and those         * that use void* generic pointers.  It works with the latter         * because both ANSI C and C++ allow castless assignment from         * any pointer type to void*, and deal with argument conversions         * as though doing an assignment.         */        return (void *) realloc( (char *) ptr, size );}void yyfree (void * ptr ){        free( (char *) ptr );   /* see yyrealloc() for (char *) cast */}#define YYTABLES_NAME "yytables"#line 14 "wc.l"main(int argc, char** argv){    yylex();    printf("%8d%8d%8d\n", lines, words, chars);}

       最后编译：gcc -o wc wc.c -lfl 生成可执行程序wc。

       执行：./wc < wc.c

       输出：  1748 6555 44017