├── Makefile
├── README
├── simple_re_match.c
└── simple_re_match.h


/Makefile:
--------------------------------------------------------------------------------
1 | all: simple_re_match
2 | simple_re_match:
3 | 	gcc simple_re_match.c -o simple_re_match
4 | 


--------------------------------------------------------------------------------
/README:
--------------------------------------------------------------------------------
1 | A simple regular expression matcher based on Rob Pike's implementation.
2 | 


--------------------------------------------------------------------------------
/simple_re_match.c:
--------------------------------------------------------------------------------
 1 | #include <stdio.h>
 2 | 
 3 | #include "simple_re_match.h"
 4 | 
 5 | /*
 6 | Regular expresions:
 7 |     c    matches any literal character c
 8 |     .    matches any single character
 9 |     ^    matches the beginning of the input string
10 |     $    matches the end of the input string
11 |     *    matches zero or more occurrences of the previous character
12 |     +    matches one or more occurrences of the previous character
13 | */
14 | 
15 | /*
16 |  @brief search for regexp anywhere in the text and return the index that matches
17 |  @param regular expression string
18 |  @param string to perform the regex on
19 |  */
20 | int
21 | match(char *regexp, char *text) 
22 | {
23 |     if (regexp[0] == '^')
24 |         return matchhere(regexp+1, text);
25 |     do { //should check if the string is empty
26 |         if (matchhere(regexp, text))
27 |             return 1;
28 |     }while(*text++ != '\0');
29 |     return 0;
30 | }
31 | 
32 | int
33 | matchhere(char *regexp, char *text)
34 | {
35 |     if (regexp[0] == '\0')
36 |         return 1;
37 |     if (regexp[1] == '*')
38 |         return matchstar(regexp[0], regexp+2, text);
39 |     if (regexp[1] == '+')
40 |         return matchplus(regexp[0], regexp+2, text);
41 |     if (regexp[0] == '\0' && regexp[1] == '\0')
42 |         return *text == '\0';
43 |     if (*text != '\0' && (regexp[0] == '.' || regexp[0] == *text))
44 |         return matchhere(regexp + 1, text + 1);
45 |     return 0;
46 | }
47 | 
48 | /* matchstar: leftmost longest search for c*regexp */
49 | int 
50 | matchstar(int c, char *regexp, char *text)
51 | {
52 |     char *t;
53 |     for (t = text; *t != '\0' && (*t == c || c == '.'); t++)
54 |         ;
55 |     do {        /* * matches zero or more */
56 |         if (matchhere(regexp, t))
57 |             return 1;
58 |     } while (t-- > text);
59 |     return 0;
60 | }
61 | 
62 | int
63 | matchplus(int c, char *regexp, char *text)
64 | {
65 |     int i = 0;
66 |     do { //a matches one or more instances
67 |         if (matchhere(regexp, text))
68 |             if (i == 0)
69 |                 i++;
70 |             else
71 |                 return 1;
72 |     } while (*text != '\0' && (*text++ == c || c == '.'));
73 |     return 0;
74 | }
75 | 
76 | int main(){
77 |     char *regex = "c+";
78 |     char *text = "caglar";
79 |     if(match(regex, text))
80 |         printf("Ok!\n");
81 |     else 
82 |         printf("No!\n");
83 |     return 0;
84 | }
85 | 


--------------------------------------------------------------------------------
/simple_re_match.h:
--------------------------------------------------------------------------------
 1 | /*
 2 |  * =====================================================================================
 3 |  *
 4 |  *       Filename:  simple_re_match.h
 5 |  *
 6 |  *    Description:  
 7 |  *
 8 |  *        Version:  1.0
 9 |  *        Created:  10/06/2011 01:19:46 PM
10 |  *       Revision:  none
11 |  *       Compiler:  gcc
12 |  *
13 |  *         Author:  YOUR NAME (), 
14 |  *        Company:  
15 |  *
16 |  * =====================================================================================
17 |  */
18 | #ifndef SIMPLE_RE_MATCH
19 | #define SIMPLE_RE_MATCH
20 | 
21 | int
22 | match(char *regexp, char *text);
23 | 
24 | int
25 | matchhere(char *regexp, char *text);
26 | 
27 | int 
28 | matchstar(int c, char *regexp, char *text);
29 | 
30 | int
31 | matchplus(int c, char *regexp, char *text);
32 | 
33 | #endif
34 | 


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