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 <[email protected]>
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
36 static int
compare_right(char const * a,char const * b)37 compare_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
66 static int
compare_left(char const * a,char const * b)67 compare_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
strnatcmp0(char const * a,char const * b,int fold_case)88 static 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
apr_strnatcmp(char const * a,char const * b)139 APR_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. */
apr_strnatcasecmp(char const * a,char const * b)146 APR_DECLARE(int) apr_strnatcasecmp(char const *a, char const *b)
147 {
148 return strnatcmp0(a, b, 1);
149 }
150