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32

strnatcmp: Add local copy


jcs made amendment 32 4 months ago
--- strnatcmp.c Wed Aug 31 22:04:17 2022 +++ strnatcmp.c Wed Aug 31 22:04:17 2022 @@ -0,0 +1,157 @@ +/* -*- mode: c; c-file-style: "k&r" -*- + + strnatcmp.c -- Perform 'natural order' comparisons of strings in C. + Copyright (C) 2000, 2004 by Martin Pool <mbp sourcefrog net> + + This software is provided 'as-is', without any express or implied + warranty. In no event will the authors be held liable for any damages + arising from the use of this software. + + Permission is granted to anyone to use this software for any purpose, + including commercial applications, and to alter it and redistribute it + freely, subject to the following restrictions: + + 1. The origin of this software must not be misrepresented; you must not + claim that you wrote the original software. If you use this software + in a product, an acknowledgment in the product documentation would be + appreciated but is not required. + 2. Altered source versions must be plainly marked as such, and must not be + misrepresented as being the original software. + 3. This notice may not be removed or altered from any source distribution. +*/ + + +/* partial change history: + * + * 2004-10-10 mbp: Lift out character type dependencies into macros. + * + * Eric Sosman pointed out that ctype functions take a parameter whose + * value must be that of an unsigned int, even on platforms that have + * negative chars in their default char type. + * + * 2021-10-13 jcs: Modified to compile in THINK C 5 + */ + +#include <stddef.h> /* size_t */ +#include <ctype.h> + +#include "strnatcmp.h" + +int compare_right(char const *a, char const *b); + +int +compare_right(char const *a, char const *b) +{ + int bias = 0; + + /* The longest run of digits wins. That aside, the greatest + value wins, but we can't know that it will until we've scanned + both numbers to know that they have the same magnitude, so we + remember it in BIAS. */ + for (;; a++, b++) { + if (!isdigit((unsigned char)*a) && !isdigit((unsigned char)*b)) + return bias; + if (!isdigit((unsigned char)*a)) + return -1; + if (!isdigit((unsigned char)*b)) + return +1; + if (*a < *b) { + if (!bias) + bias = -1; + } else if (*a > *b) { + if (!bias) + bias = +1; + } else if (!*a && !*b) + return bias; + } + + return 0; +} + + +static int +compare_left(char const *a, char const *b) +{ + /* Compare two left-aligned numbers: the first to have a + different value wins. */ + for (;; a++, b++) { + if (!isdigit((unsigned char)*a) && !isdigit((unsigned char)*b)) + return 0; + if (!isdigit((unsigned char)*a)) + return -1; + if (!isdigit((unsigned char)*b)) + return +1; + if (*a < *b) + return -1; + if (*a > *b) + return +1; + } + + return 0; +} + + +static int +strnatcmp0(char const *a, char const *b, int fold_case) +{ + int ai, bi; + char ca, cb; + int fractional, result; + + ai = bi = 0; + while (1) { + ca = a[ai]; cb = b[bi]; + + /* skip over leading spaces or zeros */ + while (isspace((unsigned char)ca)) + ca = a[++ai]; + + while (isspace((unsigned char)cb)) + cb = b[++bi]; + + /* process run of digits */ + if (isdigit((unsigned char)ca) && isdigit((unsigned char)cb)) { + fractional = (ca == '0' || cb == '0'); + + if (fractional) { + if ((result = compare_left(a+ai, b+bi)) != 0) + return result; + } else { + if ((result = compare_right(a+ai, b+bi)) != 0) + return result; + } + } + + if (!ca && !cb) { + /* The strings compare the same. Perhaps the caller + will want to call strcmp to break the tie. */ + return 0; + } + + if (fold_case) { + ca = toupper((unsigned char)ca); + cb = toupper((unsigned char)cb); + } + + if (ca < cb) + return -1; + + if (ca > cb) + return +1; + + ++ai; ++bi; + } +} + + +int +strnatcmp(char const *a, char const *b) { + return strnatcmp0(a, b, 0); +} + + +/* Compare, recognizing numeric string and ignoring case. */ +int +strnatcasecmp(char const *a, char const *b) { + return strnatcmp0(a, b, 1); +} --- strnatcmp.h Wed Aug 31 22:04:05 2022 +++ strnatcmp.h Wed Aug 31 22:04:05 2022 @@ -0,0 +1,7 @@ +#ifndef __STRNATCMP_H__ +#define __STRNATCMP_H__ + +int strnatcmp(char const *a, char const *b); +int strnatcasecmp(char const *a, char const *b); + +#endif