xref: /PHP-7.4/ext/standard/strnatcmp.c (revision f6382985)
1 /*
2 
3   Modified for PHP by Andrei Zmievski <andrei@ispi.net>
4 
5   strnatcmp.c -- Perform 'natural order' comparisons of strings in C.
6   Copyright (C) 2000 by Martin Pool <mbp@humbug.org.au>
7 
8   This software is provided 'as-is', without any express or implied
9   warranty.  In no event will the authors be held liable for any damages
10   arising from the use of this software.
11 
12   Permission is granted to anyone to use this software for any purpose,
13   including commercial applications, and to alter it and redistribute it
14   freely, subject to the following restrictions:
15 
16   1. The origin of this software must not be misrepresented; you must not
17      claim that you wrote the original software. If you use this software
18      in a product, an acknowledgment in the product documentation would be
19      appreciated but is not required.
20   2. Altered source versions must be plainly marked as such, and must not be
21      misrepresented as being the original software.
22   3. This notice may not be removed or altered from any source distribution.
23 */
24 
25 #include <ctype.h>
26 #include <string.h>
27 #include <stdio.h>
28 
29 #include "php.h"
30 #include "php_string.h"
31 
32 /* {{{ compare_right
33  */
34 static int
compare_right(char const ** a,char const * aend,char const ** b,char const * bend)35 compare_right(char const **a, char const *aend, char const **b, char const *bend)
36 {
37 	int bias = 0;
38 
39 	/* The longest run of digits wins.  That aside, the greatest
40 	   value wins, but we can't know that it will until we've scanned
41 	   both numbers to know that they have the same magnitude, so we
42 	   remember it in BIAS. */
43 	for(;; (*a)++, (*b)++) {
44 		if ((*a == aend || !isdigit((int)(unsigned char)**a)) &&
45 			(*b == bend || !isdigit((int)(unsigned char)**b)))
46 			return bias;
47 		else if (*a == aend || !isdigit((int)(unsigned char)**a))
48 			return -1;
49 		else if (*b == bend || !isdigit((int)(unsigned char)**b))
50 			return +1;
51 		else if (**a < **b) {
52 			if (!bias)
53 				bias = -1;
54 		} else if (**a > **b) {
55 			if (!bias)
56 				bias = +1;
57 		}
58      }
59 
60      return 0;
61 }
62 /* }}} */
63 
64 /* {{{ compare_left
65  */
66 static int
compare_left(char const ** a,char const * aend,char const ** b,char const * bend)67 compare_left(char const **a, char const *aend, char const **b, char const *bend)
68 {
69      /* Compare two left-aligned numbers: the first to have a
70         different value wins. */
71 	for(;; (*a)++, (*b)++) {
72 		if ((*a == aend || !isdigit((int)(unsigned char)**a)) &&
73 			(*b == bend || !isdigit((int)(unsigned char)**b)))
74 			return 0;
75 		else if (*a == aend || !isdigit((int)(unsigned char)**a))
76 			return -1;
77 		else if (*b == bend || !isdigit((int)(unsigned char)**b))
78 			return +1;
79 		 else if (**a < **b)
80 			 return -1;
81 		 else if (**a > **b)
82 			 return +1;
83      }
84 
85      return 0;
86 }
87 /* }}} */
88 
89 /* {{{ strnatcmp_ex
90  */
strnatcmp_ex(char const * a,size_t a_len,char const * b,size_t b_len,int fold_case)91 PHPAPI int strnatcmp_ex(char const *a, size_t a_len, char const *b, size_t b_len, int fold_case)
92 {
93 	unsigned char ca, cb;
94 	char const *ap, *bp;
95 	char const *aend = a + a_len,
96 			   *bend = b + b_len;
97 	int fractional, result;
98 	short leading = 1;
99 
100 	if (a_len == 0 || b_len == 0) {
101 		return (a_len == b_len ? 0 : (a_len > b_len ? 1 : -1));
102 	}
103 
104 	ap = a;
105 	bp = b;
106 	while (1) {
107 		ca = *ap; cb = *bp;
108 
109 		/* skip over leading zeros */
110 		while (leading && ca == '0' && (ap+1 < aend) && isdigit((int)(unsigned char)*(ap+1))) {
111 			ca = *++ap;
112 		}
113 
114 		while (leading && cb == '0' && (bp+1 < bend) && isdigit((int)(unsigned char)*(bp+1))) {
115 			cb = *++bp;
116 		}
117 
118 		leading = 0;
119 
120 		/* Skip consecutive whitespace */
121 		while (isspace((int)(unsigned char)ca)) {
122 			ca = *++ap;
123 		}
124 
125 		while (isspace((int)(unsigned char)cb)) {
126 			cb = *++bp;
127 		}
128 
129 		/* process run of digits */
130 		if (isdigit((int)(unsigned char)ca)  &&  isdigit((int)(unsigned char)cb)) {
131 			fractional = (ca == '0' || cb == '0');
132 
133 			if (fractional)
134 				result = compare_left(&ap, aend, &bp, bend);
135 			else
136 				result = compare_right(&ap, aend, &bp, bend);
137 
138 			if (result != 0)
139 				return result;
140 			else if (ap == aend && bp == bend)
141 				/* End of the strings. Let caller sort them out. */
142 				return 0;
143 			else if (ap == aend)
144 				return -1;
145 			else if (bp == bend)
146 				return 1;
147 			else {
148 				/* Keep on comparing from the current point. */
149 				ca = *ap; cb = *bp;
150 			}
151 		}
152 
153 		if (fold_case) {
154 			ca = toupper((int)(unsigned char)ca);
155 			cb = toupper((int)(unsigned char)cb);
156 		}
157 
158 		if (ca < cb)
159 			return -1;
160 		else if (ca > cb)
161 			return +1;
162 
163 		++ap; ++bp;
164 		if (ap >= aend && bp >= bend)
165 			/* The strings compare the same.  Perhaps the caller
166 			   will want to call strcmp to break the tie. */
167 			return 0;
168 		else if (ap >= aend)
169 			return -1;
170 		else if (bp >= bend)
171 			return 1;
172 	}
173 }
174 /* }}} */
175