61 lines
1.2 KiB
C
61 lines
1.2 KiB
C
/*
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* strspn, strcspn
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*/
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#include <string.h>
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#include <stddef.h>
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#include <inttypes.h>
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#include <limits.h>
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#ifndef LONG_BIT
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#define LONG_BIT (CHAR_BIT*sizeof(long))
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#endif
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static void set_bit(unsigned long *bitmap, unsigned int bit)
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{
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bitmap[bit / LONG_BIT] |= 1UL << (bit % LONG_BIT);
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}
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static int test_bit(unsigned long *bitmap, unsigned int bit)
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{
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return (int)(bitmap[bit / LONG_BIT] >> (bit % LONG_BIT)) & 1;
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}
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static size_t strxspn(const char *s, const char *map, int parity)
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{
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unsigned long matchmap[((1 << CHAR_BIT) + LONG_BIT - 1) / LONG_BIT];
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size_t n = 0;
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/* Create bitmap */
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memset(matchmap, 0, sizeof matchmap);
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while (*map)
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set_bit(matchmap, (unsigned char)*map++);
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/* Make sure the null character never matches */
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if (parity)
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set_bit(matchmap, 0);
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/* Calculate span length */
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while (test_bit(matchmap, (unsigned char)*s++) ^ parity)
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n++;
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return n;
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}
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size_t strspn(const char *s, const char *accept)
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{
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return strxspn(s, accept, 0);
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}
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size_t strcspn(const char *s, const char *reject)
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{
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return strxspn(s, reject, 1);
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}
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char *strpbrk(const char *s, const char *accept)
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{
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const char *ss = s + strxspn(s, accept, 1);
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return *ss ? (char *)ss : NULL;
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}
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