我编写了一个使用flex和bison来解析文件的程序。 yylval通过flex正确返回，当我尝试在我的野牛代码中打印$ 1值时，它还会打印$ 2，$ 3 .. 我怎么能摆脱这个。我附上了我的弹性和野牛代码。
setuplog.l
%{
#include <stdio.h>
#include "setuplog.tab.h"
#include <string.h>
int yyline=1;
%}
time ([0-9]+\:[0-9]+\:[0-9]+\.[0-9]+)
date ([0-9]+\/[0-9]+\/[0-9]+)
identifier [_A-Za-z0-9=\.:\\()&#'-]+
%%
"(["{identifier}"])" {
return(DATA);
}
{identifier}"!" {
yylval=yytext;
printf("FRM LEXER ID = %s %s\n",yytext,yylval);
return(IDENTIFIER);
}
"[" {
printf("OPEN\n");
return(OPEN_TOK);
}
"]" {
printf("CLOSE\n");
return(CLOSE_TOK);
}
">>>" {
return (START_TOK);
}
"<<<" {
printf("END TOKEN\n");
return (END_TOK);
}
"!!!" {
return(ERROR_TOK);
}
"!" {
return(WARN_TOK);
}
"Boot" {
return(BOOT_TOK);
}
\n {
yyline++;
}
{time} {
yylval=yytext;
printf("FRM LEXER TIME= %s %s\n",yytext,yylval);
return(TIME);
}
{date} {
yylval=yytext;
printf("FRM LEXER DATE= %s %s\n",yytext,yylval);
return(DATE);
}
{identifier} {
yylval=yytext;
printf("FRM LEXER ID = %s %s\n",yytext,yylval);
return(IDENTIFIER);
}
%%
int yywrap(void)
{
return 1;
}
setuplog.y
%{
#include <stdio.h>
#include <string.h>
#define YYSTYPE char*
extern int yyline;
int set_count=1;
FILE *fp;
extern char* yytext;
%}
%token OPEN_TOK
%token CLOSE_TOK
%token START_TOK
%token END_TOK
%token ERROR_TOK
%token WARN_TOK
%token BOOT_TOK
%token TIME
%token DATE
%token DATA
%token IDENTIFIER
%start session
%%
session : boot_data section_start
{
printf("SESSION\n");
fprintf(fp,"\n\nNO.OF LINES PARSED = %d\n",yyline);
}
;
boot_data : head_desc statement head_desc head_desc
{
printf("BOOT_DATA\n");
}
;
head_desc :OPEN_TOK statement CLOSE_TOK
{
printf("NON BOOT DATA--%s\n",$2);
$$=$2;
}
| OPEN_TOK BOOT_TOK statement CLOSE_TOK
{
printf("HEAD_DESCRIPTION\n$2=%s\nyytext=%s\n\n",$2,yytext);
$$=$3;
fprintf(fp,"\n[Boot %s\n",$3);
}
;
statement : word
{
printf("WORD\n");
$$=$1;
}
|statement word
{
printf("STATEMENTS\n");
$$=$1;
printf("STATEMENT VALUE== %s\n\n",$$);
}
;
word : TIME
{
printf("TIME\n");
$$=$1;
}
|DATE
{
printf("DATE\n");
$$=$1;
}
|DATA
{
}
| IDENTIFIER
{
printf("IDENTIFIER\n");
$$=$1;
}
;
section_start : section_details
{
printf("SINGLE SECTIONS\n");
}
|section_start section_details
{
printf("MULTIPLE SECTIONS\n");
}
|section_start head_desc section_details
;
section_details :
{
fprintf(fp,"\n%d:\n",set_count);
}
section_head section_body section_end
{
printf("SECTION DETAILS\n");
set_count++;
}
;
section_head : START_TOK head_desc START_TOK statement DATE TIME
{
printf("SECTION HEAD...\n\n%s===\n\n%s\n",$2,$4);
fprintf(fp,"%s\n",$2);
}
;
section_body :log_entry
{
}
|section_body log_entry
{
}
;
log_entry : entry_prefix time_stamp body_statements
{
}
;
time_stamp:DATE TIME
{
printf("DATE AND TIME\n");
}
|
{
}
;
body_statements : statement
{
}
|head_desc
{
}
;
entry_prefix : ERROR_TOK
{
fprintf(fp,"%s","Error Message\n");
}
|WARN_TOK
{
fprintf(fp,"%s","Warning Message\n");
}
|
{
printf("INFORMATION MESSAGE\n");
}
;
section_end :END_TOK statement
{
}
END_TOK head_desc
{
printf("SECTION END...\n\n%s===\n\n%s\n",$2,$5);
fprintf(fp,"%s\n",$2);
}
;
%%
yyerror(char *str)
{
printf("Parse error: %s at line %d ,",str,yyline);
yywhere();
}
yywhere()
{
int colon=0;
int i;
if(yytext)
{
for(i=0;i<50;i++) if(!yytext[i] || yytext[i] == '\n') break;
if(i)
{
if(!colon)
{
printf(" near: \"%s\"\n", yytext);
colon = 1;
}
}
printf("\n");
}
}
int main(void)
{
int i =remove("output.txt");
fp=fopen("output.txt","a+");
yyparse();
fclose(fp);
}
答案 0 :(得分：2)