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14d7100d | 1 | .\" -*-nroff-*- |
2 | .TH macros 3 "13 December 2003" "Straylight/Edgeware" "mLib utilities library" | |
3 | .SH NAME | |
4 | macros \- useful macros | |
5 | .\" @N | |
3832000d MW |
6 | .\" @STR |
7 | .\" @GLUE | |
f50c1365 | 8 | .\" @STATIC_ASSERT |
36188114 MW |
9 | .\" @ISALNUM |
10 | .\" @ISALPHA | |
11 | .\" @ISASCII | |
12 | .\" @ISBLANK | |
13 | .\" @ISCNTRL | |
14 | .\" @ISDIGIT | |
15 | .\" @ISGRAPH | |
16 | .\" @ISLOWER | |
17 | .\" @ISPRINT | |
18 | .\" @ISPUNCT | |
19 | .\" @ISSPACE | |
20 | .\" @ISUPPER | |
21 | .\" @ISXDIGIT | |
22 | .\" @TOASCII | |
23 | .\" @TOLOWER | |
24 | .\" @TOUPPER | |
25 | .\" @MEMCMP | |
26 | .\" @STRCMP | |
27 | .\" @STRNCMP | |
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28 | .\" @DISCARD |
29 | .\" @IGNORE | |
30 | .\" @DEPRECATED | |
31 | .\" @EXECL_LIKE | |
32 | .\" @IGNORABLE | |
33 | .\" @NORETURN | |
34 | .\" @PRINTF_LIKE | |
35 | .\" @SCANF_LIKE | |
36 | .\" @MUFFLE_WARNINGS_DECL | |
37 | .\" @MUFFLE_WARNINGS_EXPR | |
38 | .\" @MUFFLE_WARNINGS_STMT | |
3832000d | 39 | .\" @GCC_WARNING |
2f2cb664 | 40 | .\" @CLANG_WARNING |
14d7100d | 41 | .SH SYNOPSIS |
42 | .nf | |
43 | .B "#include <mLib/macros.h>" | |
44 | ||
45 | .BI "size_t N(" array ");" | |
3832000d MW |
46 | .BI "STR(" tokens\fR... ")" |
47 | .BI "GLUE(" tokens\fR... ", " tokens\fR... ")" | |
f50c1365 | 48 | .BI "STATIC_ASSERT(" cond ", " msg ");" |
3832000d | 49 | |
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50 | .BI "ISALNUM(int " ch ");" |
51 | .BI "ISALPHA(int " ch ");" | |
52 | .BI "ISASCII(int " ch ");" | |
53 | .BI "ISBLANK(int " ch ");" | |
54 | .BI "ISCNTRL(int " ch ");" | |
55 | .BI "ISDIGIT(int " ch ");" | |
56 | .BI "ISGRAPH(int " ch ");" | |
57 | .BI "ISLOWER(int " ch ");" | |
58 | .BI "ISPRINT(int " ch ");" | |
59 | .BI "ISPUNCT(int " ch ");" | |
60 | .BI "ISSPACE(int " ch ");" | |
61 | .BI "ISUPPER(int " ch ");" | |
62 | .BI "ISXDIGIT(int " ch ");" | |
63 | .BI "TOASCII(int " ch ");" | |
64 | .BI "TOLOWER(int " ch ");" | |
65 | .BI "TOUPPER(int " ch ");" | |
66 | ||
67 | .BI "MEMCMP(const void *" x ", " op ", const void *" y ", size_t " n ");" | |
68 | .BI "STRCMP(const char *" x ", " op ", const char *" y ");" | |
69 | .BI "STRNCMP(const char *" x ", " op ", const char *" y ", size_t " n ");" | |
70 | ||
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71 | .BI "void DISCARD(" scalar ");" |
72 | .BI "void IGNORE(" variable ");" | |
73 | ||
74 | .BI "DEPRECATED(" msg ")" | |
75 | .BI "EXECL_LIKE(" ntrail ")" | |
76 | .BI "IGNORABLE" | |
77 | .BI "NORETURN" | |
78 | .BI "PRINTF_LIKE(" fmt-index ", " arg-index ")" | |
79 | .BI "SCANF_LIKE(" fmt-index ", " arg-index ")" | |
80 | ||
81 | .BI "MUFFLE_WARNINGS_DECL(" warns ", " decls ")" | |
82 | .BI "MUFFLE_WARNINGS_EXPR(" warns ", " expr ")" | |
83 | .BI "MUFFLE_WARNINGS_STMT(" warns ", " stmt ")" | |
84 | ||
3832000d | 85 | .BI "GCC_WARNING(" option ")" |
c418910f | 86 | .BI "CLANG_WARNING(" option ")" |
14d7100d | 87 | .fi |
88 | .SH DESCRIPTION | |
3832000d | 89 | .SS Utilities |
14d7100d | 90 | The |
91 | .B N | |
92 | macro returns the number of elements in the named | |
93 | .IR array . | |
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94 | .PP |
95 | The | |
96 | .B STR | |
97 | macro expands to a string literal containing the result of expanding its | |
98 | argument | |
99 | .IR tokens . | |
100 | .PP | |
101 | The | |
102 | .B GLUE | |
103 | macro expands to a single token, which is the result of gluing together | |
104 | the tokens resulting from expanding its argument token lists. Each of | |
105 | the argument token lists must expand to a single preprocessing token, | |
106 | and the result of gluing these tokens together must be valid | |
107 | preprocessing token. | |
108 | .PP | |
109 | The | |
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110 | .B STATIC_ASSERT |
111 | causes compilation to fail if the integer constant expression | |
112 | .I cond | |
113 | evaluates to zero. This macro uses the C11 | |
114 | .B static_assert | |
115 | declaration if available, and the | |
116 | .I msg | |
117 | will be reported in the compiler's diagnostic messsage; otherwise, the macro | |
118 | falls back to a somewhat ugly hack which currently ignores the | |
119 | .IR msg . | |
120 | .PP | |
121 | The | |
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122 | .BR IS ...\& |
123 | and | |
124 | .BR TO ...\& | |
125 | macros are wrappers around the corresponding standard | |
126 | .B <ctype.h> | |
127 | macros with the corresponding lowercase names. They take care of | |
128 | forcing the character argument | |
129 | .I ch | |
130 | to | |
131 | .BR "unsigned char" : | |
132 | this conversion is necessary on platforms with signed | |
133 | .B char | |
134 | to avoid passing negative values into the standard macros. | |
135 | .PP | |
136 | The | |
137 | .BR MEMCMP , | |
138 | .BR STRCMP , | |
139 | and | |
140 | .B STRNCMP | |
141 | macros are wrappers around the standard | |
142 | .B <string.h> | |
143 | functions with the corresponding lowercase names. They take an | |
144 | additional argument | |
145 | .I op | |
146 | which is a equality or ordering operator (e.g., | |
147 | .B == | |
148 | or | |
149 | .BR > ) | |
150 | inserted between the two operands. The standard functions return a | |
151 | false value if and only if the operands are equal, which is | |
152 | counterintuitive and leads to mistakes; requiring an explicit relational | |
153 | operator should reduce the number of such mistakes. | |
154 | .PP | |
155 | The | |
3832000d MW |
156 | .B DISCARD |
157 | macro discards its argument, which must be of some scalar type. This | |
158 | can be useful in muffling warnings about ignoring return codes in cases | |
159 | where you really don't care. | |
160 | .PP | |
161 | The | |
162 | .B IGNORE | |
163 | macro ignores its argument, which may be an expression of any type. | |
164 | This can be useful in muffling warnings about unused variables. | |
165 | .SS Annotations | |
166 | The following annotations can be attached to function declarations and | |
167 | definitions, as part of the declaration specifiers. (Other positions | |
168 | may also work, depending on your compiler, but don't bet on it.) They | |
169 | might not have any effect, depending on your specific compiler. | |
170 | Currently only GCC is well supported, but exactly which features are | |
171 | available depend on the compiler version. | |
172 | .PP | |
173 | Using a function or variable marked as | |
174 | .B DEPRECATED | |
175 | may provoke a compiler warning; this warning may (depending on your | |
176 | compiler version) include the given | |
177 | .IR msg . | |
178 | .PP | |
179 | A variadic function marked as | |
180 | .B EXECL_LIKE | |
181 | must be called with a null pointer (i.e., an integer constant | |
182 | expression with value 0, cast to | |
183 | .BR "void *") | |
184 | in the variadic part of its argument list, followed by | |
185 | .I ntrail | |
186 | further arguments. Typically, | |
187 | .I ntrail | |
188 | is zero. Compilers may warn about misuse of such functions. | |
189 | .PP | |
190 | A function or variable marked as | |
191 | .B IGNORABLE | |
192 | need not be used. This may muffle warnings about leaving the marked | |
193 | definition unused. | |
194 | .PP | |
195 | A function marked as | |
196 | .B NORETURN | |
197 | must not return. It must have return type | |
198 | .BR void . | |
199 | This may be useful in muffling warnings about uninitialized variables, | |
200 | for example. | |
201 | .PP | |
202 | A variadic function marked as | |
203 | .B PRINTF_LIKE | |
204 | takes a | |
205 | .BR printf (3)-style | |
206 | format argument (in position | |
207 | .IR fmt-index , | |
208 | counting from 1) and a variable-length list of arguments to be formatted | |
209 | (starting from position | |
210 | .IR arg-index ). | |
211 | Compilers may warn about misuse of such functions. | |
212 | .PP | |
213 | A variadic function marked as | |
214 | .B SCANF_LIKE | |
215 | takes a | |
216 | .BR scanf (3)-style | |
217 | format argument (in position | |
218 | .IR fmt-index , | |
219 | counting from 1) and a variable-length list of arguments to be formatted | |
220 | (starting from position | |
221 | .IR arg-index ). | |
222 | Compilers may warn about misuse of such functions. | |
223 | .SS Muffling warnings | |
224 | Some compilers allow you to muffle warnings in particular pieces of | |
225 | code. These macros provide a compiler-neutral interface to such | |
226 | facilities. Each macro takes an argument | |
227 | .IR warns , | |
228 | which is a sequence of calls to | |
229 | .IB compiler _WARNING | |
230 | macros listing the warnings to be muffled. The list may contain | |
231 | warnings for several different compilers. The other argument is a | |
232 | .I body | |
233 | consisting of declarations (in the case of | |
234 | .BR MUFFLE_WARNINGS_DECL ), | |
235 | an expression (for | |
236 | .BR MUFFLE_WARNINGS_EXPR ), | |
237 | or a statement (for | |
238 | .BR MUFFLE_WARNINGS_STMT ). | |
239 | .SS GCC-specific features | |
240 | The | |
241 | .B GCC_VERSION_P | |
242 | macro returns a nonzero value if the compiler is at least version | |
243 | .IB maj . min | |
244 | of GCC, and zero otherwise. It's useful in preprocessor conditions. | |
245 | .PP | |
246 | The | |
247 | .B GCC_WARNING | |
248 | macro is intended to be used in | |
249 | .I warns | |
250 | lists (see above). It takes a string-literal argument | |
251 | .I option | |
252 | naming a GCC warning option, e.g., | |
253 | .BR """\-Wdiv-by-zero""" . | |
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254 | .PP |
255 | The | |
256 | .B CLANG_WARNING | |
257 | is similar, except that it works with the Clang compiler. | |
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258 | .PP |
259 | Note that including | |
260 | .B <mLib/macros.h> | |
261 | also defines the compiler-test macros in | |
262 | .BR <mLib/compiler.h>; | |
263 | see | |
264 | .BR compiler (3). | |
14d7100d | 265 | .SH "SEE ALSO" |
33e3ac90 MW |
266 | .BR mLib (3), |
267 | .BR compiler (3). | |
14d7100d | 268 | .SH "AUTHOR" |
9b5ac6ff | 269 | Mark Wooding, <mdw@distorted.org.uk> |