1 /** @file
2 * @brief Various handy helpers which std::string really should provide.
3 */
4 /* Copyright (C) 2004,2005,2006,2007,2008,2009,2010,2015 Olly Betts
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program 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
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #ifndef XAPIAN_INCLUDED_STRINGUTILS_H
22 #define XAPIAN_INCLUDED_STRINGUTILS_H
23
24 #include <xapian/constinfo.h>
25
26 #include <algorithm>
27 #include <string>
28 #include <cstring>
29
30 /** Helper macro for STRINGIZE - the nested call is required because of how
31 * # works in macros.
32 */
33 #define STRINGIZE_(X) #X
34
35 /// The STRINGIZE macro converts its parameter into a string constant.
36 #define STRINGIZE(X) STRINGIZE_(X)
37
38 /** Returns the length of a string constant.
39 *
40 * We rely on concatenation of string literals to produce an error if this
41 * macro is applied to something other than a string literal.
42 */
43 #define CONST_STRLEN(S) (sizeof(S"") - 1)
44
45 inline bool
startswith(const std::string & s,char pfx)46 startswith(const std::string & s, char pfx)
47 {
48 return !s.empty() && s[0] == pfx;
49 }
50
51 inline bool
startswith(const std::string & s,const char * pfx,size_t len)52 startswith(const std::string & s, const char * pfx, size_t len)
53 {
54 return s.size() >= len && (std::memcmp(s.data(), pfx, len) == 0);
55 }
56
57 inline bool
startswith(const std::string & s,const char * pfx)58 startswith(const std::string & s, const char * pfx)
59 {
60 return startswith(s, pfx, std::strlen(pfx));
61 }
62
63 inline bool
startswith(const std::string & s,const std::string & pfx)64 startswith(const std::string & s, const std::string & pfx)
65 {
66 return startswith(s, pfx.data(), pfx.size());
67 }
68
69 inline bool
endswith(const std::string & s,char sfx)70 endswith(const std::string & s, char sfx)
71 {
72 return !s.empty() && s[s.size() - 1] == sfx;
73 }
74
75 inline bool
endswith(const std::string & s,const char * sfx,size_t len)76 endswith(const std::string & s, const char * sfx, size_t len)
77 {
78 return s.size() >= len && (std::memcmp(s.data() + s.size() - len, sfx, len) == 0);
79 }
80
81 inline bool
endswith(const std::string & s,const char * sfx)82 endswith(const std::string & s, const char * sfx)
83 {
84 return endswith(s, sfx, std::strlen(sfx));
85 }
86
87 inline bool
endswith(const std::string & s,const std::string & sfx)88 endswith(const std::string & s, const std::string & sfx)
89 {
90 return endswith(s, sfx.data(), sfx.size());
91 }
92
93 inline std::string::size_type
common_prefix_length(const std::string & a,const std::string & b)94 common_prefix_length(const std::string &a, const std::string &b)
95 {
96 std::string::size_type minlen = std::min(a.size(), b.size());
97 std::string::size_type common;
98 for (common = 0; common < minlen; ++common) {
99 if (a[common] != b[common]) break;
100 }
101 return common;
102 }
103
104 // Like C's isXXXXX() but:
105 // (a) always work in the C locale
106 // (b) handle signed char as well as unsigned char
107 // (c) have a suitable signature for use as predicates with find_if()
108 // (d) add negated versions isnotXXXXX() which are useful as predicates
109
110 namespace Xapian {
111 namespace Internal {
112 const unsigned char HEX_MASK = 0x0f;
113 const unsigned char IS_UPPER = 0x10;
114 const unsigned char IS_ALPHA = 0x20; // NB Same as ASCII "case bit".
115 const unsigned char IS_DIGIT = 0x40;
116 const unsigned char IS_SPACE = 0x80;
117 }
118 }
119
120 // FIXME: These functions assume ASCII or an ASCII compatible character set
121 // such as ISO-8859-N or UTF-8. EBCDIC would need some work (patches
122 // welcome!)
123 static_assert('\x20' == ' ', "character set isn't a superset of ASCII");
124
125 // Add explicit conversion to bool to prevent compiler warning from "aCC +w":
126 // Warning (suggestion) 818: [...] # Type `int' is larger than type `bool',
127 // truncation in value may result.
128
C_tab_(char ch)129 inline unsigned char C_tab_(char ch) {
130 const unsigned char * C_tab = Xapian::Internal::get_constinfo_()->C_tab;
131 return C_tab[static_cast<unsigned char>(ch)];
132 }
133
C_isdigit(char ch)134 inline bool C_isdigit(char ch) {
135 using namespace Xapian::Internal;
136 return bool(C_tab_(ch) & IS_DIGIT);
137 }
138
C_isxdigit(char ch)139 inline bool C_isxdigit(char ch) {
140 using namespace Xapian::Internal;
141 // Include IS_DIGIT so '0' gives true.
142 return bool(C_tab_(ch) & (HEX_MASK|IS_DIGIT));
143 }
144
C_isupper(char ch)145 inline bool C_isupper(char ch) {
146 using namespace Xapian::Internal;
147 return bool(C_tab_(ch) & IS_UPPER);
148 }
149
C_islower(char ch)150 inline bool C_islower(char ch) {
151 using namespace Xapian::Internal;
152 return (C_tab_(ch) & (IS_ALPHA|IS_UPPER)) == IS_ALPHA;
153 }
154
C_isalpha(char ch)155 inline bool C_isalpha(char ch) {
156 using namespace Xapian::Internal;
157 return bool(C_tab_(ch) & IS_ALPHA);
158 }
159
C_isalnum(char ch)160 inline bool C_isalnum(char ch) {
161 using namespace Xapian::Internal;
162 return bool(C_tab_(ch) & (IS_ALPHA|IS_DIGIT));
163 }
164
C_isspace(char ch)165 inline bool C_isspace(char ch) {
166 using namespace Xapian::Internal;
167 return bool(C_tab_(ch) & IS_SPACE);
168 }
169
C_isnotdigit(char ch)170 inline bool C_isnotdigit(char ch) { return !C_isdigit(ch); }
C_isnotxdigit(char ch)171 inline bool C_isnotxdigit(char ch) { return !C_isxdigit(ch); }
C_isnotupper(char ch)172 inline bool C_isnotupper(char ch) { return !C_isupper(ch); }
C_isnotlower(char ch)173 inline bool C_isnotlower(char ch) { return !C_islower(ch); }
C_isnotalpha(char ch)174 inline bool C_isnotalpha(char ch) { return !C_isalpha(ch); }
C_isnotalnum(char ch)175 inline bool C_isnotalnum(char ch) { return !C_isalnum(ch); }
C_isnotspace(char ch)176 inline bool C_isnotspace(char ch) { return !C_isspace(ch); }
177
C_tolower(char ch)178 inline char C_tolower(char ch) {
179 using namespace Xapian::Internal;
180 return ch | (C_tab_(ch) & IS_ALPHA);
181 }
182
C_toupper(char ch)183 inline char C_toupper(char ch) {
184 using namespace Xapian::Internal;
185 return ch &~ (C_tab_(ch) & IS_ALPHA);
186 }
187
hex_digit(char ch)188 inline int hex_digit(char ch) {
189 using namespace Xapian::Internal;
190 return C_tab_(ch) & HEX_MASK;
191 }
192
193 #endif // XAPIAN_INCLUDED_STRINGUTILS_H
194