60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
/** @license 2023 Neil Edelman, distributed under the terms of the
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[MIT License](https://opensource.org/licenses/MIT).
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A `pair` is `[a, b)` pair of pointers to char.
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@std C99 */
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#include "pair.h"
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#include <stdint.h>
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#include <errno.h>
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#include <assert.h>
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/** @return Constructs `a` and `b` as a pair. */
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struct pair pair(const char *const a, const char *const b) {
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struct pair p;
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p.a = a, p.b = b;
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return p;
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}
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/** Doesn't check anything.
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@return Whether it was able to parse unsigned `p` to `n`. */
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int pair_to_natural(const char *s, const char *const e, uint32_t *const n) {
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uint32_t accum = 0;
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while(s < e) {
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unsigned next = accum * 10 + (unsigned)(*s - '0');
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if(accum >= next) return errno = ERANGE, 0;
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accum = next;
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s++;
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}
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*n = accum;
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return 1;
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}
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int pair_is_equal(struct pair x, struct pair y) {
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assert(x.a <= x.b && y.a <= y.b);
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if(!x.a) return !y.a;
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if(!y.a) return 0;
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if(x.b - x.a != y.b - y.a) return 0;
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while(x.a < x.b) { if(*x.a != *y.a) return 0; x.a++, y.a++; }
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return 1;
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}
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int pair_is_string(struct pair x, const char *y) {
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assert(x.a <= x.b);
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if(!x.a) return !y;
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if(!y) return 0;
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while(x.a < x.b) { if(*x.a != *y || !*y) return 0; x.a++, y++; }
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return !*y;
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}
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/** djb2 <http://www.cse.yorku.ca/~oz/hash.html> */
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uint32_t pair_djb2(struct pair p) {
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uint32_t hash = 5381, c;
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while(p.a < p.b) {
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c = (unsigned char)*p.a++;
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hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
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}
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return hash;
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}
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