[Libclc-developers] libclc: New function for the string module?

[<bo...@me...>]

Hello.

Below is the source code for a function I needed at work today. Since it 
is pretty general, it might be a candidate for the clc_string module?

The function is a case insensitive version of strstr(), with one 
exception: I didn't have the stomach to let the function return a char* 
like strstr() does. ;-)

Please suggest a new name for the function, I'm only semi happy about 
the current clc_strcasestr(), but couldn't come up with anything better.

Bjørn



/* $Id: $ */
/*
  * Copyright(c) 2003, B. Augestad, bo...@me...
  * COPYING RESTRICTIONS APPLY, see COPYING file.
  */

#include <ctype.h>
#include <string.h>
#include "clc_assert.h"
#include "clc_string.h"

const char* clc_strcasestr(const char *haystack, const char *needle)
{
     size_t cb1, cb2;
     const char *start, *stop, *org_needle = needle;
     int c1, c2;

     clc_assert_not_null(clc_strcasestr, haystack);
     clc_assert_not_null(clc_strcasestr, needle);

     cb1 = strlen(haystack);
     cb2 = strlen(needle);

     /* The standard says that empty needles, "", returns haystack. */
     if(cb2 == 0)
         return haystack;

     /* No point in finding needles bigger than haystack */
     if(cb2 > cb1)
         return NULL;

     /* Compute the last starting point of a possible match */
     start = haystack;
     stop = start + cb1 - cb2;

     /* Now compare strings */
     while(start <= stop) {
         needle = org_needle;
         haystack = start;
         for (;; haystack++, needle++) {
             c1 = tolower((int)*haystack);
             c2 = tolower((int)*needle);

             /* If end of needle */
             if (c2 == '\0')
                 return start;
             else if(c1 != c2)
                 break;
         }

         start++;
     }

     return NULL;
}

#ifdef CLC_STRCASESTR_TEST

int main(void)
{
     const char *s;

     /* Legal variants */
     s = clc_strcasestr("A", "A");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AAA", "A");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AAA", "a");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AAB", "B");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AAB", "b");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AABcdEfGhIj123", "bcdefg");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AAA", "");
     clc_assert(main, s != NULL);

     s = clc_strcasestr("AA1AA2AA3", "AA2");
     clc_assert(main, s != NULL);

     /* Illegal variants */
     s = clc_strcasestr("AAA", "x");
     clc_assert(main, s == NULL);

     s = clc_strcasestr("AAA", "AAAAAA");
     clc_assert(main, s == NULL);

     return 0;
}
#endif