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