core/ngx_regex.h头文件分析
本章我们主要讲述一下nginx中表达式匹配(ngx_regex)的实现。
1. ngx_regex_t数据结构
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#ifndef _NGX_REGEX_H_INCLUDED_
#define _NGX_REGEX_H_INCLUDED_
#include <ngx_config.h>
#include <ngx_core.h>
#include <pcre.h>
#define NGX_REGEX_NO_MATCHED PCRE_ERROR_NOMATCH /* -1 */
#define NGX_REGEX_CASELESS PCRE_CASELESS
typedef struct {
pcre *code;
pcre_extra *extra;
} ngx_regex_t;这里ngx_regex_t只是对pcre的一个再次封装。其中：
-
code: 代表一个编译后的正则表达式
-
extra: 用作pcre的辅助数据，一般是通过
pcre_study()学习到的，可以加快后面的后续的匹配过程
2. 数据结构
typedef struct {
ngx_str_t pattern;
ngx_pool_t *pool;
ngx_int_t options;
ngx_regex_t *regex;
int captures;
int named_captures;
int name_size;
u_char *names;
ngx_str_t err;
} ngx_regex_compile_t;ngx_regex_compile_t表示一个编译的正则表达式模式(pattern)。其各字段含义如下：
-
pattern: 对应的正则表达式模式
-
pool: 所关联的内存池
-
options: 执行pcre_compile()时所传递的参数
-
regex: 编译完成后的pcre实例
-
captures: 用于保存
pattern中所有子模式的个数，包括命名子模式(named subpattern)和非命名子模式。 -
named_captures: 用于保存
pattern中命名子模式的个数 -
name_size:
name table中每一项的大小 -
names:
name table的入口地址 -
err: 用于存放相应的错误
3. ngx_regex_elt_t数据结构
typedef struct {
ngx_regex_t *regex;
u_char *name;
} ngx_regex_elt_t;存放到ngx_pcre_studies链表中的元素， 其中各字段含义如下：
-
regex: pattern编译完成后的pcre实例
-
name: 保存对应的Pattern
4. 相关函数声明
//初始化nginx pcre
void ngx_regex_init(void);
//pcre pattern，封装了pcre_compile()
ngx_int_t ngx_regex_compile(ngx_regex_compile_t *rc);
//pcre_exec()的包装
#define ngx_regex_exec(re, s, captures, size) \
pcre_exec(re->code, re->extra, (const char *) (s)->data, (s)->len, 0, 0, \
captures, size)
#define ngx_regex_exec_n "pcre_exec()"
//将字符串s匹配模式数组中的所有模式
ngx_int_t ngx_regex_exec_array(ngx_array_t *a, ngx_str_t *s, ngx_log_t *log);5. 附录： PCRE库中pcre_fullinfo混合子模式调用结果
#include <stdio.h>
#include <stdlib.h>
#include <pcre.h>
#define NGX_REGEX_CASELESS PCRE_CASELESS
typedef struct {
pcre *code;
pcre_extra *extra;
} ngx_regex_t;
int main(int argc, char *argv[])
{
pcre *re;
const char *errstr;
int erroff;
char *data = "(eeeee)(?<abb> exception)(?<adfa>xydz)(ddddd)\\k<abb>\\1\\2";
int captures = 0;
int named_captures = 0;
int name_entrysize = 0;
char *name_entry;
char *p;
int i,j,n;
printf("pattern: %s\n\n", data);
re = pcre_compile(data, PCRE_CASELESS, &errstr, &erroff, NULL);
if(NULL == re)
{
printf("compile pcre failed\n");
return 0;
}
//1) get all subpatterns count
n = pcre_fullinfo(re, NULL, PCRE_INFO_CAPTURECOUNT, &captures);
if(n < 0)
{
printf("pcre_fullinfo PCRE_INFO_CAPTURECOUNT failed %d \n", n);
return 0;
}
printf("captures %d \n", captures);
//2) get named subpatterns count
n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMECOUNT, &named_captures);
if(n < 0)
{
printf("pcre_fullinfo PCRE_INFO_NAMECOUNT failed %d \n", n);
return 0;
}
printf("named_captures %d \n", named_captures);
//3) get name table entry
n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMETABLE, &name_entry);
if(n < 0)
{
printf("pcre_fullinfo PCRE_INFO_NAMETABLE failed %d \n", n);
return 0;
}
p = name_entry;
//4) get every entry size
n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMEENTRYSIZE, &name_entrysize);
if(n < 0)
{
printf("pcre_fullinfo PCRE_INFO_NAMEENTRYSIZE failed %d \n", n);
return 0;
}
printf("name_entrysize %d \n", name_entrysize);
//5) print all named entry
for(i = 0; i < named_captures; i++)
{
for(j = 0; j < 2; j++)
{
printf("%x ", p[i]);
}
printf("entry: %s\n", &p[2]);
p += name_entrysize;
}
return 1;
}编译运行：
# gcc -c -o test.o test.c
# gcc -o test test.o -lpcre
# ./test
pattern: (eeeee)(?<abb> exception)(?<adfa>xydz)(ddddd)\k<abb>\1\2
captures 4
named_captures 2
name_entrysize 7
0 0 entry: abb
3 3 entry: adfa
[参看]
