re2c实例

#include <stdio.h>
#include "demo_def.h"

#define T_BEGIN 0
#define T_NUMBER 1
#define T_LOWER_CHAR 2
#define T_UPPER_CHAR 3
#define T_EXIT 4
#define T_UNKNOWN 5
#define T_INPUT_ERROR 6
#define T_END 7
#define T_WHITESPACE 8

typedef struct _scanner {
  char *yy_cursor;
  int yy_state;
  char *yy_limit;
  char *yy_marker;
} Scanner;

Scanner scanner_globals;

#define YYCTYPE char
#define YYFILL(n)
#define STATE(name)  yyc##name
#define BEGIN(state) YYSETCONDITION(STATE(state))
#define LANG_SCNG(v) (scanner_globals.v)
#define SCNG    LANG_SCNG

#define YYGETCONDITION()  SCNG(yy_state)
#define YYSETCONDITION(s) SCNG(yy_state) = s
#define YYCURSOR  SCNG(yy_cursor)
#define YYLIMIT   SCNG(yy_limit)
#define YYMARKER  SCNG(yy_marker)

int scan(){
    /*!re2c

      <INITIAL>"<?php" {BEGIN(ST_IN_SCRIPTING); return T_BEGIN;}
      <ST_IN_SCRIPTING>[0-9]+ {return T_NUMBER;}
      <ST_IN_SCRIPTING>[ \n\t\r]+ {return T_WHITESPACE;}
      <ST_IN_SCRIPTING>"exit" { return T_EXIT; }
      <ST_IN_SCRIPTING>[a-z]+ {return T_LOWER_CHAR;}
      <ST_IN_SCRIPTING>[A-Z]+ {return T_UPPER_CHAR;}
      <ST_IN_SCRIPTING>"?>" {return T_END;}

      <ST_IN_SCRIPTING>[^] {return T_UNKNOWN;}
      <*>[^] {return T_INPUT_ERROR;}
     */
}

void print_token(int token) {
    switch (token) {
        case T_BEGIN: printf("%s\n", "T_BEGIN");break;
        case T_NUMBER: printf("%s\n", "T_NUMBER");break;
        case T_LOWER_CHAR: printf("%s\n", "T_LOWER_CHAR");break;
        case T_UPPER_CHAR: printf("%s\n", "T_UPPER_CHAR");break;
        case T_EXIT: printf("%s\n", "T_EXIT");break;
        case T_UNKNOWN: printf("%s\n", "T_UNKNOWN");break;
        case T_INPUT_ERROR: printf("%s\n", "T_INPUT_ERROR");break;
        case T_END: printf("%s\n", "T_END");break;
    }
}

int main(int argc, char* argv[])
{
    int token;
    BEGIN(INITIAL); //  全局初始化，需要放在scan调用之前
    scanner_globals.yy_cursor = argv[];    //将输入的第一个参数作为要解析的字符串

    while() {
        if(*YYCURSOR == '\0') break;
        token = scan();
        print_token(token);
    }

    return ;
}

编译，运行，结果

[root@bhu les5]# re2c -o demo.c -c -t demo_def.h demo.l

[root@bhu les5]# gcc -o demo demo.c -g

[root@bhu les5]# ./demo "<?php 3ee344SDEFeee@#?>"

T_BEGIN

T_NUMBER

T_LOWER_CHAR

T_NUMBER

T_UPPER_CHAR

T_LOWER_CHAR

T_UNKNOWN

T_UNKNOWN

T_END