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Revision 959 - (show annotations)
Sat Apr 14 16:16:58 2012 UTC (7 years, 5 months ago) by ph10
File size: 13129 byte(s)
Update documentation to clarify that UTF-8/16 checking is done on complete 
strings before any other processing.
1 .TH PCRE 3 "14 April 2012" "PCRE 8.31"
2 .SH NAME
3 PCRE - Perl-compatible regular expressions
4 .sp
5 .B #include <pcre.h>
6 .
7 .
8 .SH "PCRE 16-BIT API BASIC FUNCTIONS"
9 .rs
10 .sp
11 .SM
12 .B pcre16 *pcre16_compile(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
13 .ti +5n
14 .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
15 .ti +5n
16 .B const unsigned char *\fItableptr\fP);
17 .PP
18 .B pcre16 *pcre16_compile2(PCRE_SPTR16 \fIpattern\fP, int \fIoptions\fP,
19 .ti +5n
20 .B int *\fIerrorcodeptr\fP,
21 .ti +5n
22 .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
23 .ti +5n
24 .B const unsigned char *\fItableptr\fP);
25 .PP
26 .B pcre16_extra *pcre16_study(const pcre16 *\fIcode\fP, int \fIoptions\fP,
27 .ti +5n
28 .B const char **\fIerrptr\fP);
29 .PP
30 .B void pcre16_free_study(pcre16_extra *\fIextra\fP);
31 .PP
32 .B int pcre16_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
33 .ti +5n
34 .B "PCRE_SPTR16 \fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
35 .ti +5n
36 .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
37 .PP
38 .B int pcre16_dfa_exec(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
39 .ti +5n
40 .B "PCRE_SPTR16 \fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
41 .ti +5n
42 .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
43 .ti +5n
44 .B int *\fIworkspace\fP, int \fIwscount\fP);
45 .
46 .
47 .SH "PCRE 16-BIT API STRING EXTRACTION FUNCTIONS"
48 .rs
49 .sp
50 .B int pcre16_copy_named_substring(const pcre16 *\fIcode\fP,
51 .ti +5n
52 .B PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
53 .ti +5n
54 .B int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,
55 .ti +5n
56 .B PCRE_UCHAR16 *\fIbuffer\fP, int \fIbuffersize\fP);
57 .PP
58 .B int pcre16_copy_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
59 .ti +5n
60 .B int \fIstringcount\fP, int \fIstringnumber\fP, PCRE_UCHAR16 *\fIbuffer\fP,
61 .ti +5n
62 .B int \fIbuffersize\fP);
63 .PP
64 .B int pcre16_get_named_substring(const pcre16 *\fIcode\fP,
65 .ti +5n
66 .B PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
67 .ti +5n
68 .B int \fIstringcount\fP, PCRE_SPTR16 \fIstringname\fP,
69 .ti +5n
70 .B PCRE_SPTR16 *\fIstringptr\fP);
71 .PP
72 .B int pcre16_get_stringnumber(const pcre16 *\fIcode\fP,
73 .ti +5n
74 .B PCRE_SPTR16 \fIname\fP);
75 .PP
76 .B int pcre16_get_stringtable_entries(const pcre16 *\fIcode\fP,
77 .ti +5n
78 .B PCRE_SPTR16 \fIname\fP, PCRE_UCHAR16 **\fIfirst\fP, PCRE_UCHAR16 **\fIlast\fP);
79 .PP
80 .B int pcre16_get_substring(PCRE_SPTR16 \fIsubject\fP, int *\fIovector\fP,
81 .ti +5n
82 .B int \fIstringcount\fP, int \fIstringnumber\fP,
83 .ti +5n
84 .B PCRE_SPTR16 *\fIstringptr\fP);
85 .PP
86 .B int pcre16_get_substring_list(PCRE_SPTR16 \fIsubject\fP,
87 .ti +5n
88 .B int *\fIovector\fP, int \fIstringcount\fP, "PCRE_SPTR16 **\fIlistptr\fP);"
89 .PP
90 .B void pcre16_free_substring(PCRE_SPTR16 \fIstringptr\fP);
91 .PP
92 .B void pcre16_free_substring_list(PCRE_SPTR16 *\fIstringptr\fP);
93 .
94 .
95 .SH "PCRE 16-BIT API AUXILIARY FUNCTIONS"
96 .rs
97 .sp
98 .B pcre16_jit_stack *pcre16_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
99 .PP
100 .B void pcre16_jit_stack_free(pcre16_jit_stack *\fIstack\fP);
101 .PP
102 .B void pcre16_assign_jit_stack(pcre16_extra *\fIextra\fP,
103 .ti +5n
104 .B pcre16_jit_callback \fIcallback\fP, void *\fIdata\fP);
105 .PP
106 .B const unsigned char *pcre16_maketables(void);
107 .PP
108 .B int pcre16_fullinfo(const pcre16 *\fIcode\fP, "const pcre16_extra *\fIextra\fP,"
109 .ti +5n
110 .B int \fIwhat\fP, void *\fIwhere\fP);
111 .PP
112 .B int pcre16_refcount(pcre16 *\fIcode\fP, int \fIadjust\fP);
113 .PP
114 .B int pcre16_config(int \fIwhat\fP, void *\fIwhere\fP);
115 .PP
116 .B const char *pcre16_version(void);
117 .PP
118 .B int pcre16_pattern_to_host_byte_order(pcre16 *\fIcode\fP,
119 .ti +5n
120 .B pcre16_extra *\fIextra\fP, const unsigned char *\fItables\fP);
121 .
122 .
123 .SH "PCRE 16-BIT API INDIRECTED FUNCTIONS"
124 .rs
125 .sp
126 .B void *(*pcre16_malloc)(size_t);
127 .PP
128 .B void (*pcre16_free)(void *);
129 .PP
130 .B void *(*pcre16_stack_malloc)(size_t);
131 .PP
132 .B void (*pcre16_stack_free)(void *);
133 .PP
134 .B int (*pcre16_callout)(pcre16_callout_block *);
135 .
136 .
137 .SH "PCRE 16-BIT API 16-BIT-ONLY FUNCTION"
138 .rs
139 .sp
140 .B int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *\fIoutput\fP,
141 .ti +5n
142 .B PCRE_SPTR16 \fIinput\fP, int \fIlength\fP, int *\fIbyte_order\fP,
143 .ti +5n
144 .B int \fIkeep_boms\fP);
145 .
146 .
147 .SH "THE PCRE 16-BIT LIBRARY"
148 .rs
149 .sp
150 Starting with release 8.30, it is possible to compile a PCRE library that
151 supports 16-bit character strings, including UTF-16 strings, as well as or
152 instead of the original 8-bit library. The majority of the work to make this
153 possible was done by Zoltan Herczeg. The two libraries contain identical sets
154 of functions, used in exactly the same way. Only the names of the functions and
155 the data types of their arguments and results are different. To avoid
156 over-complication and reduce the documentation maintenance load, most of the
157 PCRE documentation describes the 8-bit library, with only occasional references
158 to the 16-bit library. This page describes what is different when you use the
159 16-bit library.
160 .P
161 WARNING: A single application can be linked with both libraries, but you must
162 take care when processing any particular pattern to use functions from just one
163 library. For example, if you want to study a pattern that was compiled with
164 \fBpcre16_compile()\fP, you must do so with \fBpcre16_study()\fP, not
165 \fBpcre_study()\fP, and you must free the study data with
166 \fBpcre16_free_study()\fP.
167 .
168 .
169 .SH "THE HEADER FILE"
170 .rs
171 .sp
172 There is only one header file, \fBpcre.h\fP. It contains prototypes for all the
173 functions in both libraries, as well as definitions of flags, structures, error
174 codes, etc.
175 .
176 .
177 .SH "THE LIBRARY NAME"
178 .rs
179 .sp
180 In Unix-like systems, the 16-bit library is called \fBlibpcre16\fP, and can
181 normally be accesss by adding \fB-lpcre16\fP to the command for linking an
182 application that uses PCRE.
183 .
184 .
185 .SH "STRING TYPES"
186 .rs
187 .sp
188 In the 8-bit library, strings are passed to PCRE library functions as vectors
189 of bytes with the C type "char *". In the 16-bit library, strings are passed as
190 vectors of unsigned 16-bit quantities. The macro PCRE_UCHAR16 specifies an
191 appropriate data type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In
192 very many environments, "short int" is a 16-bit data type. When PCRE is built,
193 it defines PCRE_UCHAR16 as "short int", but checks that it really is a 16-bit
194 data type. If it is not, the build fails with an error message telling the
195 maintainer to modify the definition appropriately.
196 .
197 .
198 .SH "STRUCTURE TYPES"
199 .rs
200 .sp
201 The types of the opaque structures that are used for compiled 16-bit patterns
202 and JIT stacks are \fBpcre16\fP and \fBpcre16_jit_stack\fP respectively. The
203 type of the user-accessible structure that is returned by \fBpcre16_study()\fP
204 is \fBpcre16_extra\fP, and the type of the structure that is used for passing
205 data to a callout function is \fBpcre16_callout_block\fP. These structures
206 contain the same fields, with the same names, as their 8-bit counterparts. The
207 only difference is that pointers to character strings are 16-bit instead of
208 8-bit types.
209 .
210 .
211 .SH "16-BIT FUNCTIONS"
212 .rs
213 .sp
214 For every function in the 8-bit library there is a corresponding function in
215 the 16-bit library with a name that starts with \fBpcre16_\fP instead of
216 \fBpcre_\fP. The prototypes are listed above. In addition, there is one extra
217 function, \fBpcre16_utf16_to_host_byte_order()\fP. This is a utility function
218 that converts a UTF-16 character string to host byte order if necessary. The
219 other 16-bit functions expect the strings they are passed to be in host byte
220 order.
221 .P
222 The \fIinput\fP and \fIoutput\fP arguments of
223 \fBpcre16_utf16_to_host_byte_order()\fP may point to the same address, that is,
224 conversion in place is supported. The output buffer must be at least as long as
225 the input.
226 .P
227 The \fIlength\fP argument specifies the number of 16-bit data units in the
228 input string; a negative value specifies a zero-terminated string.
229 .P
230 If \fIbyte_order\fP is NULL, it is assumed that the string starts off in host
231 byte order. This may be changed by byte-order marks (BOMs) anywhere in the
232 string (commonly as the first character).
233 .P
234 If \fIbyte_order\fP is not NULL, a non-zero value of the integer to which it
235 points means that the input starts off in host byte order, otherwise the
236 opposite order is assumed. Again, BOMs in the string can change this. The final
237 byte order is passed back at the end of processing.
238 .P
239 If \fIkeep_boms\fP is not zero, byte-order mark characters (0xfeff) are copied
240 into the output string. Otherwise they are discarded.
241 .P
242 The result of the function is the number of 16-bit units placed into the output
243 buffer, including the zero terminator if the string was zero-terminated.
244 .
245 .
246 .SH "SUBJECT STRING OFFSETS"
247 .rs
248 .sp
249 The offsets within subject strings that are returned by the matching functions
250 are in 16-bit units rather than bytes.
251 .
252 .
253 .SH "NAMED SUBPATTERNS"
254 .rs
255 .sp
256 The name-to-number translation table that is maintained for named subpatterns
257 uses 16-bit characters. The \fBpcre16_get_stringtable_entries()\fP function
258 returns the length of each entry in the table as the number of 16-bit data
259 units.
260 .
261 .
262 .SH "OPTION NAMES"
263 .rs
264 .sp
265 There are two new general option names, PCRE_UTF16 and PCRE_NO_UTF16_CHECK,
266 which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
267 fact, these new options define the same bits in the options word. There is a
268 discussion about the
269 .\" HTML <a href="pcreunicode.html#utf16strings">
270 .\" </a>
271 validity of UTF-16 strings
272 .\"
273 in the
274 .\" HREF
275 \fBpcreunicode\fP
276 .\"
277 page.
278 .P
279 For the \fBpcre16_config()\fP function there is an option PCRE_CONFIG_UTF16
280 that returns 1 if UTF-16 support is configured, otherwise 0. If this option is
281 given to \fBpcre_config()\fP, or if the PCRE_CONFIG_UTF8 option is given to
282 \fBpcre16_config()\fP, the result is the PCRE_ERROR_BADOPTION error.
283 .
284 .
285 .SH "CHARACTER CODES"
286 .rs
287 .sp
288 In 16-bit mode, when PCRE_UTF16 is not set, character values are treated in the
289 same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
290 from 0 to 0xffff instead of 0 to 0xff. Character types for characters less than
291 0xff can therefore be influenced by the locale in the same way as before.
292 Characters greater than 0xff have only one case, and no "type" (such as letter
293 or digit).
294 .P
295 In UTF-16 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
296 the exception of values in the range 0xd800 to 0xdfff because those are
297 "surrogate" values that are used in pairs to encode values greater than 0xffff.
298 .P
299 A UTF-16 string can indicate its endianness by special code knows as a
300 byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
301 to be in host byte order. A utility function called
302 \fBpcre16_utf16_to_host_byte_order()\fP is provided to help with this (see
303 above).
304 .
305 .
306 .SH "ERROR NAMES"
307 .rs
308 .sp
309 The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 correspond to
310 their 8-bit counterparts. The error PCRE_ERROR_BADMODE is given when a compiled
311 pattern is passed to a function that processes patterns in the other
312 mode, for example, if a pattern compiled with \fBpcre_compile()\fP is passed to
313 \fBpcre16_exec()\fP.
314 .P
315 There are new error codes whose names begin with PCRE_UTF16_ERR for invalid
316 UTF-16 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
317 are described in the section entitled
318 .\" HTML <a href="pcreapi.html#badutf8reasons">
319 .\" </a>
320 "Reason codes for invalid UTF-8 strings"
321 .\"
322 in the main
323 .\" HREF
324 \fBpcreapi\fP
325 .\"
326 page. The UTF-16 errors are:
327 .sp
328 PCRE_UTF16_ERR1 Missing low surrogate at end of string
329 PCRE_UTF16_ERR2 Invalid low surrogate follows high surrogate
330 PCRE_UTF16_ERR3 Isolated low surrogate
331 PCRE_UTF16_ERR4 Invalid character 0xfffe
332 .
333 .
334 .SH "ERROR TEXTS"
335 .rs
336 .sp
337 If there is an error while compiling a pattern, the error text that is passed
338 back by \fBpcre16_compile()\fP or \fBpcre16_compile2()\fP is still an 8-bit
339 character string, zero-terminated.
340 .
341 .
342 .SH "CALLOUTS"
343 .rs
344 .sp
345 The \fIsubject\fP and \fImark\fP fields in the callout block that is passed to
346 a callout function point to 16-bit vectors.
347 .
348 .
349 .SH "TESTING"
350 .rs
351 .sp
352 The \fBpcretest\fP program continues to operate with 8-bit input and output
353 files, but it can be used for testing the 16-bit library. If it is run with the
354 command line option \fB-16\fP, patterns and subject strings are converted from
355 8-bit to 16-bit before being passed to PCRE, and the 16-bit library functions
356 are used instead of the 8-bit ones. Returned 16-bit strings are converted to
357 8-bit for output. If the 8-bit library was not compiled, \fBpcretest\fP
358 defaults to 16-bit and the \fB-16\fP option is ignored.
359 .P
360 When PCRE is being built, the \fBRunTest\fP script that is called by "make
361 check" uses the \fBpcretest\fP \fB-C\fP option to discover which of the 8-bit
362 and 16-bit libraries has been built, and runs the tests appropriately.
363 .
364 .
365 .SH "NOT SUPPORTED IN 16-BIT MODE"
366 .rs
367 .sp
368 Not all the features of the 8-bit library are available with the 16-bit
369 library. The C++ and POSIX wrapper functions support only the 8-bit library,
370 and the \fBpcregrep\fP program is at present 8-bit only.
371 .
372 .
373 .SH AUTHOR
374 .rs
375 .sp
376 .nf
377 Philip Hazel
378 University Computing Service
379 Cambridge CB2 3QH, England.
380 .fi
381 .
382 .
383 .SH REVISION
384 .rs
385 .sp
386 .nf
387 Last updated: 14 April 2012
388 Copyright (c) 1997-2012 University of Cambridge.
389 .fi

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