1/* -*- mode: c; c-file-style: "k&r" -*- 2 3 strnatcmp.c -- Perform 'natural order' comparisons of strings in C. 4 Copyright (C) 2000 by Martin Pool <mbp@humbug.org.au> 5 6 This software is provided 'as-is', without any express or implied 7 warranty. In no event will the authors be held liable for any damages 8 arising from the use of this software. 9 10 Permission is granted to anyone to use this software for any purpose, 11 including commercial applications, and to alter it and redistribute it 12 freely, subject to the following restrictions: 13 14 1. The origin of this software must not be misrepresented; you must not 15 claim that you wrote the original software. If you use this software 16 in a product, an acknowledgment in the product documentation would be 17 appreciated but is not required. 18 2. Altered source versions must be plainly marked as such, and must not be 19 misrepresented as being the original software. 20 3. This notice may not be removed or altered from any source distribution. 21*/ 22 23#include <ctype.h> 24#include <string.h> 25#include "apr_strings.h" 26#include "apr_lib.h" /* for apr_is*() */ 27 28#if defined(__GNUC__) 29# define UNUSED __attribute__((__unused__)) 30#else 31# define UNUSED 32#endif 33 34/* based on "strnatcmp.c,v 1.6 2000/04/20 07:30:11 mbp Exp $" */ 35 36static int 37compare_right(char const *a, char const *b) 38{ 39 int bias = 0; 40 41 /* The longest run of digits wins. That aside, the greatest 42 value wins, but we can't know that it will until we've scanned 43 both numbers to know that they have the same magnitude, so we 44 remember it in BIAS. */ 45 for (;; a++, b++) { 46 if (!apr_isdigit(*a) && !apr_isdigit(*b)) 47 break; 48 else if (!apr_isdigit(*a)) 49 return -1; 50 else if (!apr_isdigit(*b)) 51 return +1; 52 else if (*a < *b) { 53 if (!bias) 54 bias = -1; 55 } else if (*a > *b) { 56 if (!bias) 57 bias = +1; 58 } else if (!*a && !*b) 59 break; 60 } 61 62 return bias; 63} 64 65 66static int 67compare_left(char const *a, char const *b) 68{ 69 /* Compare two left-aligned numbers: the first to have a 70 different value wins. */ 71 for (;; a++, b++) { 72 if (!apr_isdigit(*a) && !apr_isdigit(*b)) 73 break; 74 else if (!apr_isdigit(*a)) 75 return -1; 76 else if (!apr_isdigit(*b)) 77 return +1; 78 else if (*a < *b) 79 return -1; 80 else if (*a > *b) 81 return +1; 82 } 83 84 return 0; 85} 86 87 88static int strnatcmp0(char const *a, char const *b, int fold_case) 89{ 90 int ai, bi; 91 char ca, cb; 92 int fractional, result; 93 ai = bi = 0; 94 while (1) { 95 ca = a[ai]; cb = b[bi]; 96 97 /* skip over leading spaces or zeros */ 98 while (apr_isspace(ca)) 99 ca = a[++ai]; 100 101 while (apr_isspace(cb)) 102 cb = b[++bi]; 103 104 /* process run of digits */ 105 if (apr_isdigit(ca) && apr_isdigit(cb)) { 106 fractional = (ca == '0' || cb == '0'); 107 108 if (fractional) { 109 if ((result = compare_left(a+ai, b+bi)) != 0) 110 return result; 111 } else { 112 if ((result = compare_right(a+ai, b+bi)) != 0) 113 return result; 114 } 115 } 116 117 if (!ca && !cb) { 118 /* The strings compare the same. Perhaps the caller 119 will want to call strcmp to break the tie. */ 120 return 0; 121 } 122 123 if (fold_case) { 124 ca = apr_toupper(ca); 125 cb = apr_toupper(cb); 126 } 127 128 if (ca < cb) 129 return -1; 130 else if (ca > cb) 131 return +1; 132 133 ++ai; ++bi; 134 } 135} 136 137 138 139APR_DECLARE(int) apr_strnatcmp(char const *a, char const *b) 140{ 141 return strnatcmp0(a, b, 0); 142} 143 144 145/* Compare, recognizing numeric string and ignoring case. */ 146APR_DECLARE(int) apr_strnatcasecmp(char const *a, char const *b) 147{ 148 return strnatcmp0(a, b, 1); 149} 150