Parsing Lex&;Yacc解析器输出值?
因此,对于我正在进行的项目,我使用Lex和Yacc解析FTP配置文件。配置文件如下所示:Parsing Lex&;Yacc解析器输出值?,parsing,yacc,lex,Parsing,Yacc,Lex,因此,对于我正在进行的项目,我使用Lex和Yacc解析FTP配置文件。配置文件如下所示: global { num_daemons = 10 etc = /etc/ftpd }; host "ftp-1.foobar.com" { ftproot = /var/ftp/server1 max_out_bandwidth = 20.7 }; host "ftp-2.foobar.com" { ftproot = /var/ftp/server2
global {
num_daemons = 10
etc = /etc/ftpd
};
host "ftp-1.foobar.com" {
ftproot = /var/ftp/server1
max_out_bandwidth = 20.7
};
host "ftp-2.foobar.com" {
ftproot = /var/ftp/server2
exclude = /var/ftp/server2/private
};
host "ftp-3.foobar.com" {
ftproot = /var/ftp/server3
};
现在,我的问题是,我如何以可用的方式获得这些信息?比方说,我想把地址之类的东西放在主机令牌之后,放进一个结构中。我该怎么做?另外,我如何简单地将解析后的值打印到命令行?另外,要运行它,我是否只需在编译的c程序中对配置文件和管道进行cat?提前感谢您的帮助
这是我的密码:
%{
// tokens.l
#include <stdio.h>
#include <stdlib.h>
#include "y.tab.h"
int yyparse();
%}
%option noyywrap
%x OPTION
%x OPTID
%%
<INITIAL>global { return GLOBAL; }
<INITIAL>host { return HOST; }
<INITIAL>"[a-zA-z1-9./-]+" { return NAME; }
<INITIAL>\{ { return CURLY_OPEN; BEGIN OPTION; }
<INITIAL>\n { return EOLN; }
<INITIAL><<EOF>> { return EOFTOK; }
<OPTION>[a-zA-z1-9./-_]+ { return ID_NAME; BEGIN OPTID; }
<OPTION>[\t] {}
<OPTION>[\};] { return OPTION_CLOSE; BEGIN INITIAL;}
<OPTID>[a-zA-z1-9./-]+ { return ID_STRING; BEGIN OPTION; }
<OPTID>[0-9.]+ { return ID_NUM; BEGIN OPTION; }
<OPTID>[\n] { return EOLN; }
%%
int main(int argc, char **argv) {
// Where I am confused..
}
%{
//代币
#包括
#包括
#包括“y.tab.h”
int-yyparse();
%}
%选项No yywrap
%x选项
%x选项
%%
全局{返回全局;}
主机{返回主机;}
“[a-zA-z1-9./-]+”{返回名称;}
\{{return CURLY_OPEN;BEGIN选项;}
\n{return EOLN;}
{返回EOFTOK;}
[a-zA-z1-9./-+{return ID_NAME;BEGIN OPTID;}
[\t]{}
[\};]{return OPTION\u CLOSE;BEGIN INITIAL;}
[a-zA-z1-9./-]+{返回ID_字符串;开始选项;}
[0-9.]+{return ID_NUM;BEGIN OPTION;}
[\n]{return EOLN;}
%%
int main(int argc,字符**argv){
//我感到困惑的地方。。
}
和我的yacc文件:
%{
// parse.y
#include <stdio.h>
#include <stdlib.h>
int yyerror(char *);
int yylex(void);
%}
%token ERROR EOLN EOFTOK
%token OPTION_CLOSE GLOBAL HOST NAME ID_NAME ID_STRING ID_NUM CURLY_OPEN
%%
input
: lines EOFTOK { YYACCEPT; }
;
lines
:
| lines line
;
line
: option
| opident
| OPTION_CLOSE
;
option
: GLOBAL CURLY_OPEN
| HOST NAME CURLY_OPEN
;
opident
: ID_NAME '=' ID_STRING
| ID_NAME '=' ID_NUM
;
%%
int yyerror(char *msg) {}
%{
//parse.y
#包括
#包括
int yyerror(字符*);
int yylex(无效);
%}
%令牌错误EOLN EOFTOK
%令牌选项\u关闭全局主机名ID\u名称ID\u字符串ID\u NUM CURLY\u打开
%%
输入
:行EOFTOK{YYACCEPT;}
;
线
:
|线
;
线
:选项
|见解
|选项(u关闭)
;
选项
:全局卷曲打开
|主机名CURLY_OPEN
;
见解
:ID\u NAME'='ID\u字符串
|ID\u NAME'='ID\u NUM
;
%%
int yyerror(char*msg){}
通常,在调用解析器之前,可以访问并设置变量,如键/值对的链接列表:
typedef struct sNode {
char *key;
char *val;
struct sNode *next;
} tNode;
tNode *lookupHead = NULL;
然后,在Yacc代码中,类似于:
opident
: ID_NAME '=' ID_STRING { addLookupStr (lookupHead, $1, $3); }
| ID_NAME '=' ID_NUM { other function call here }
;
void addLookupStr (char *newkey, char *newval) {
// Check for duplicate keys, then attempt to add. All premature returns
// should also be logging errors and setting error flags as needed.
tNode *curr = lookupHead;
while (curr != NULL) {
if (strcmp (curr->key, newkey) == 0)
return;
curr = curr->next;
}
if ((curr = malloc (sizeof (tNode))) == NULL)
return;
if ((curr->key = strdup (newkey)) == NULL) {
free (curr);
return;
}
if ((curr->val = strdup (newval)) == NULL) {
free (curr->newkey);
free (curr);
return;
}
// All possibly-failing ops complete, insert at head of list.
curr->next = lookupHead;
lookupHead = curr;
}
这将基本上在找到规则时执行该代码(用规则中的项替换$
变量,$1
是ID\u NAME
标记的值,$2
是=
等等)
该函数类似于:
opident
: ID_NAME '=' ID_STRING { addLookupStr (lookupHead, $1, $3); }
| ID_NAME '=' ID_NUM { other function call here }
;
void addLookupStr (char *newkey, char *newval) {
// Check for duplicate keys, then attempt to add. All premature returns
// should also be logging errors and setting error flags as needed.
tNode *curr = lookupHead;
while (curr != NULL) {
if (strcmp (curr->key, newkey) == 0)
return;
curr = curr->next;
}
if ((curr = malloc (sizeof (tNode))) == NULL)
return;
if ((curr->key = strdup (newkey)) == NULL) {
free (curr);
return;
}
if ((curr->val = strdup (newval)) == NULL) {
free (curr->newkey);
free (curr);
return;
}
// All possibly-failing ops complete, insert at head of list.
curr->next = lookupHead;
lookupHead = curr;
}