1/* Internal header for proving correct grouping in strings of numbers.
2 Copyright (C) 1995-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <limits.h>
21#include <stddef.h>
22#include <string.h>
23
24#ifndef MAX
25#define MAX(a,b) ({ typeof(a) _a = (a); typeof(b) _b = (b); \
26 _a > _b ? _a : _b; })
27#endif
28
29#ifdef USE_WIDE_CHAR
30# include <wctype.h>
31# define L_(Ch) L##Ch
32# define UCHAR_TYPE wint_t
33# define STRING_TYPE wchar_t
34#else
35# define L_(Ch) Ch
36# define UCHAR_TYPE unsigned char
37# define STRING_TYPE char
38#endif
39
40#include "grouping.h"
41
42/* Find the maximum prefix of the string between BEGIN and END which
43 satisfies the grouping rules. It is assumed that at least one digit
44 follows BEGIN directly. */
45
46const STRING_TYPE *
47#ifdef USE_WIDE_CHAR
48__correctly_grouped_prefixwc (const STRING_TYPE *begin, const STRING_TYPE *end,
49 wchar_t thousands,
50#else
51__correctly_grouped_prefixmb (const STRING_TYPE *begin, const STRING_TYPE *end,
52 const char *thousands,
53#endif
54 const char *grouping)
55{
56#ifndef USE_WIDE_CHAR
57 size_t thousands_len;
58 int cnt;
59#endif
60
61 if (grouping == NULL)
62 return end;
63
64#ifndef USE_WIDE_CHAR
65 thousands_len = strlen (thousands);
66#endif
67
68 while (end > begin)
69 {
70 const STRING_TYPE *cp = end - 1;
71 const char *gp = grouping;
72
73 /* Check first group. */
74 while (cp >= begin)
75 {
76#ifdef USE_WIDE_CHAR
77 if (*cp == thousands)
78 break;
79#else
80 if (cp[thousands_len - 1] == *thousands)
81 {
82 for (cnt = 1; thousands[cnt] != '\0'; ++cnt)
83 if (thousands[cnt] != cp[thousands_len - 1 - cnt])
84 break;
85 if (thousands[cnt] == '\0')
86 break;
87 }
88#endif
89 --cp;
90 }
91
92 /* We allow the representation to contain no grouping at all even if
93 the locale specifies we can have grouping. */
94 if (cp < begin)
95 return end;
96
97 if (end - cp == (int) *gp + 1)
98 {
99 /* This group matches the specification. */
100
101 const STRING_TYPE *new_end;
102
103 if (cp < begin)
104 /* There is just one complete group. We are done. */
105 return end;
106
107 /* CP points to a thousands separator character. The preceding
108 remainder of the string from BEGIN to NEW_END is the part we
109 will consider if there is a grouping error in this trailing
110 portion from CP to END. */
111 new_end = cp - 1;
112
113 /* Loop while the grouping is correct. */
114 while (1)
115 {
116 /* Get the next grouping rule. */
117 ++gp;
118 if (*gp == 0)
119 /* If end is reached use last rule. */
120 --gp;
121
122 /* Skip the thousands separator. */
123 --cp;
124
125 if (*gp == CHAR_MAX
126#if CHAR_MIN < 0
127 || *gp < 0
128#endif
129 )
130 {
131 /* No more thousands separators are allowed to follow. */
132 while (cp >= begin)
133 {
134#ifdef USE_WIDE_CHAR
135 if (*cp == thousands)
136 break;
137#else
138 for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
139 if (thousands[cnt] != cp[thousands_len - cnt - 1])
140 break;
141 if (thousands[cnt] == '\0')
142 break;
143#endif
144 --cp;
145 }
146
147 if (cp < begin)
148 /* OK, only digits followed. */
149 return end;
150 }
151 else
152 {
153 /* Check the next group. */
154 const STRING_TYPE *group_end = cp;
155
156 while (cp >= begin)
157 {
158#ifdef USE_WIDE_CHAR
159 if (*cp == thousands)
160 break;
161#else
162 for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
163 if (thousands[cnt] != cp[thousands_len - cnt - 1])
164 break;
165 if (thousands[cnt] == '\0')
166 break;
167#endif
168 --cp;
169 }
170
171 if (cp < begin && group_end - cp <= (int) *gp)
172 /* Final group is correct. */
173 return end;
174
175 if (cp < begin || group_end - cp != (int) *gp)
176 /* Incorrect group. Punt. */
177 break;
178 }
179 }
180
181 /* The trailing portion of the string starting at NEW_END
182 contains a grouping error. So we will look for a correctly
183 grouped number in the preceding portion instead. */
184 end = new_end;
185 }
186 else
187 {
188 /* Even the first group was wrong; determine maximum shift. */
189 if (end - cp > (int) *gp + 1)
190 end = cp + (int) *gp + 1;
191 else if (cp < begin)
192 /* This number does not fill the first group, but is correct. */
193 return end;
194 else
195 /* CP points to a thousands separator character. */
196 end = cp;
197 }
198 }
199
200 return MAX (begin, end);
201}
202