PCRE(3) Library Functions Manual PCRE(3)
PCRE - Perl-compatible regular expressions
#include <pcre.h>
pcre16 *pcre16_compile(PCRE_SPTR16 pattern, int options,
const char **errptr, int *erroffset,
const unsigned char *tableptr);
pcre16 *pcre16_compile2(PCRE_SPTR16 pattern, int options,
int *errorcodeptr,
const char **errptr, int *erroffset,
const unsigned char *tableptr);
pcre16_extra *pcre16_study(const pcre16 *code, int options,
const char **errptr);
void pcre16_free_study(pcre16_extra *extra);
int pcre16_exec(const pcre16 *code, const pcre16_extra *extra,
PCRE_SPTR16 subject, int length, int startoffset,
int options, int *ovector, int ovecsize);
int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
PCRE_SPTR16 subject, int length, int startoffset,
int options, int *ovector, int ovecsize,
int *workspace, int wscount);
int pcre16_copy_named_substring(const pcre16 *code,
PCRE_SPTR16 subject, int *ovector,
int stringcount, PCRE_SPTR16 stringname,
PCRE_UCHAR16 *buffer, int buffersize);
int pcre16_copy_substring(PCRE_SPTR16 subject, int *ovector,
int stringcount, int stringnumber, PCRE_UCHAR16 *buffer,
int buffersize);
int pcre16_get_named_substring(const pcre16 *code,
PCRE_SPTR16 subject, int *ovector,
int stringcount, PCRE_SPTR16 stringname,
PCRE_SPTR16 *stringptr);
int pcre16_get_stringnumber(const pcre16 *code,
PCRE_SPTR16 name);
int pcre16_get_stringtable_entries(const pcre16 *code,
PCRE_SPTR16 name, PCRE_UCHAR16 **first, PCRE_UCHAR16 **last);
int pcre16_get_substring(PCRE_SPTR16 subject, int *ovector,
int stringcount, int stringnumber,
PCRE_SPTR16 *stringptr);
int pcre16_get_substring_list(PCRE_SPTR16 subject,
int *ovector, int stringcount, PCRE_SPTR16 **listptr);
void pcre16_free_substring(PCRE_SPTR16 stringptr);
void pcre16_free_substring_list(PCRE_SPTR16 *stringptr);
pcre16_jit_stack *pcre16_jit_stack_alloc(int startsize, int maxsize);
void pcre16_jit_stack_free(pcre16_jit_stack *stack);
void pcre16_assign_jit_stack(pcre16_extra *extra,
pcre16_jit_callback callback, void *data);
const unsigned char *pcre16_maketables(void);
int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
int what, void *where);
int pcre16_refcount(pcre16 *code, int adjust);
int pcre16_config(int what, void *where);
const char *pcre16_version(void);
int pcre16_pattern_to_host_byte_order(pcre16 *code,
pcre16_extra *extra, const unsigned char *tables);
void *(*pcre16_malloc)(size_t);
void (*pcre16_free)(void *);
void *(*pcre16_stack_malloc)(size_t);
void (*pcre16_stack_free)(void *);
int (*pcre16_callout)(pcre16_callout_block *);
int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
PCRE_SPTR16 input, int length, int *byte_order,
int keep_boms);
Starting with release 8.30, it is possible to compile a PCRE
library that supports 16-bit character strings, including UTF-16
strings, as well as or instead of the original 8-bit library. The
majority of the work to make this possible was done by Zoltan
Herczeg. The two libraries contain identical sets of functions,
used in exactly the same way. Only the names of the functions and
the data types of their arguments and results are different. To
avoid over-complication and reduce the documentation maintenance
load, most of the PCRE documentation describes the 8-bit library,
with only occasional references to the 16-bit library. This page
describes what is different when you use the 16-bit library.
WARNING: A single application can be linked with both libraries,
but you must take care when processing any particular pattern to
use functions from just one library. For example, if you want to
study a pattern that was compiled with pcre16_compile(), you must
do so with pcre16_study(), not pcre_study(), and you must free
the study data with pcre16_free_study().
There is only one header file, pcre.h. It contains prototypes for
all the functions in all libraries, as well as definitions of
flags, structures, error codes, etc.
In Unix-like systems, the 16-bit library is called libpcre16, and
can normally be accesss by adding -lpcre16 to the command for
linking an application that uses PCRE.
In the 8-bit library, strings are passed to PCRE library
functions as vectors of bytes with the C type "char *". In the
16-bit library, strings are passed as vectors of unsigned 16-bit
quantities. The macro PCRE_UCHAR16 specifies an appropriate data
type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In
very many environments, "short int" is a 16-bit data type. When
PCRE is built, it defines PCRE_UCHAR16 as "unsigned short int",
but checks that it really is a 16-bit data type. If it is not,
the build fails with an error message telling the maintainer to
modify the definition appropriately.
The types of the opaque structures that are used for compiled
16-bit patterns and JIT stacks are pcre16 and pcre16_jit_stack
respectively. The type of the user-accessible structure that is
returned by pcre16_study() is pcre16_extra, and the type of the
structure that is used for passing data to a callout function is
pcre16_callout_block. These structures contain the same fields,
with the same names, as their 8-bit counterparts. The only
difference is that pointers to character strings are 16-bit
instead of 8-bit types.
For every function in the 8-bit library there is a corresponding
function in the 16-bit library with a name that starts with
pcre16_ instead of pcre_. The prototypes are listed above. In
addition, there is one extra function,
pcre16_utf16_to_host_byte_order(). This is a utility function
that converts a UTF-16 character string to host byte order if
necessary. The other 16-bit functions expect the strings they are
passed to be in host byte order.
The input and output arguments of
pcre16_utf16_to_host_byte_order() may point to the same address,
that is, conversion in place is supported. The output buffer must
be at least as long as the input.
The length argument specifies the number of 16-bit data units in
the input string; a negative value specifies a zero-terminated
string.
If byte_order is NULL, it is assumed that the string starts off
in host byte order. This may be changed by byte-order marks
(BOMs) anywhere in the string (commonly as the first character).
If byte_order is not NULL, a non-zero value of the integer to
which it points means that the input starts off in host byte
order, otherwise the opposite order is assumed. Again, BOMs in
the string can change this. The final byte order is passed back
at the end of processing.
If keep_boms is not zero, byte-order mark characters (0xfeff) are
copied into the output string. Otherwise they are discarded.
The result of the function is the number of 16-bit units placed
into the output buffer, including the zero terminator if the
string was zero-terminated.
The lengths and starting offsets of subject strings must be
specified in 16-bit data units, and the offsets within subject
strings that are returned by the matching functions are in also
16-bit units rather than bytes.
The name-to-number translation table that is maintained for named
subpatterns uses 16-bit characters. The
pcre16_get_stringtable_entries() function returns the length of
each entry in the table as the number of 16-bit data units.
There are two new general option names, PCRE_UTF16 and
PCRE_NO_UTF16_CHECK, which correspond to PCRE_UTF8 and
PCRE_NO_UTF8_CHECK in the 8-bit library. In fact, these new
options define the same bits in the options word. There is a
discussion about the validity of UTF-16 strings in the
pcreunicode page.
For the pcre16_config() function there is an option
PCRE_CONFIG_UTF16 that returns 1 if UTF-16 support is configured,
otherwise 0. If this option is given to pcre_config() or
pcre32_config(), or if the PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32
option is given to pcre16_config(), the result is the
PCRE_ERROR_BADOPTION error.
In 16-bit mode, when PCRE_UTF16 is not set, character values are
treated in the same way as in 8-bit, non UTF-8 mode, except, of
course, that they can range from 0 to 0xffff instead of 0 to
0xff. Character types for characters less than 0xff can therefore
be influenced by the locale in the same way as before.
Characters greater than 0xff have only one case, and no "type"
(such as letter or digit).
In UTF-16 mode, the character code is Unicode, in the range 0 to
0x10ffff, with the exception of values in the range 0xd800 to
0xdfff because those are "surrogate" values that are used in
pairs to encode values greater than 0xffff.
A UTF-16 string can indicate its endianness by special code knows
as a byte-order mark (BOM). The PCRE functions do not handle
this, expecting strings to be in host byte order. A utility
function called pcre16_utf16_to_host_byte_order() is provided to
help with this (see above).
The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16
correspond to their 8-bit counterparts. The error
PCRE_ERROR_BADMODE is given when a compiled pattern is passed to
a function that processes patterns in the other mode, for
example, if a pattern compiled with pcre_compile() is passed to
pcre16_exec().
There are new error codes whose names begin with PCRE_UTF16_ERR
for invalid UTF-16 strings, corresponding to the PCRE_UTF8_ERR
codes for UTF-8 strings that are described in the section
entitled "Reason codes for invalid UTF-8 strings" in the main
pcreapi page. The UTF-16 errors are:
PCRE_UTF16_ERR1 Missing low surrogate at end of string
PCRE_UTF16_ERR2 Invalid low surrogate follows high surrogate
PCRE_UTF16_ERR3 Isolated low surrogate
PCRE_UTF16_ERR4 Non-character
If there is an error while compiling a pattern, the error text
that is passed back by pcre16_compile() or pcre16_compile2() is
still an 8-bit character string, zero-terminated.
The subject and mark fields in the callout block that is passed
to a callout function point to 16-bit vectors.
The pcretest program continues to operate with 8-bit input and
output files, but it can be used for testing the 16-bit library.
If it is run with the command line option -16, patterns and
subject strings are converted from 8-bit to 16-bit before being
passed to PCRE, and the 16-bit library functions are used instead
of the 8-bit ones. Returned 16-bit strings are converted to 8-bit
for output. If both the 8-bit and the 32-bit libraries were not
compiled, pcretest defaults to 16-bit and the -16 option is
ignored.
When PCRE is being built, the RunTest script that is called by
"make check" uses the pcretest -C option to discover which of the
8-bit, 16-bit and 32-bit libraries has been built, and runs the
tests appropriately.
Not all the features of the 8-bit library are available with the
16-bit library. The C++ and POSIX wrapper functions support only
the 8-bit library, and the pcregrep program is at present 8-bit
only.
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
Last updated: 12 May 2013
Copyright (c) 1997-2013 University of Cambridge.
This page is part of the PCRE (Perl Compatible Regular
Expressions) project. Information about the project can be found
at ⟨http://www.pcre.org/⟩. If you have a bug report for this
manual page, see
⟨http://bugs.exim.org/enter_bug.cgi?product=PCRE⟩. This page was
obtained from the tarball pcre-8.45.tar.gz fetched from
⟨ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/⟩ on
2021-08-27. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
PCRE 8.33 12 May 2013 PCRE(3)
Pages that refer to this page: pcretest(1), pcreapi(3), pcrepattern(3)
|
HTML rendering created 2021-08-27 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|