pcre16(3)
PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
NAME
PCRE - Perl-compatible regular expressions
#include <pcre.h>
PCRE 16-BIT API BASIC FUNCTIONS
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);
PCRE 16-BIT API STRING EXTRACTION FUNCTIONS
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);
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PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
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);
PCRE 16-BIT API AUXILIARY FUNCTIONS
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);
PCRE 16-BIT API INDIRECTED FUNCTIONS
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 *);
PCRE 16-BIT API 16-BIT-ONLY FUNCTION
int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *output,
PCRE_SPTR16 input, int length, int *byte_order,
int keep_boms);
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PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
THE PCRE 16-BIT LIBRARY
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 occa-
sional 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().
THE HEADER FILE
There is only one header file, pcre.h. It contains proto-
types for all the functions in all libraries, as well as
definitions of flags, structures, error codes, etc.
THE LIBRARY NAME
In Unix-like systems, the 16-bit library is called libp-
cre16, and can normally be accesss by adding -lpcre16 to the
command for linking an application that uses PCRE.
STRING TYPES
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.
STRUCTURE TYPES
The types of the opaque structures that are used for com-
piled 16-bit patterns and JIT stacks are pcre16 and
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PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
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.
16-BIT FUNCTIONS
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 func-
tion 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 speci-
fies 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, other-
wise 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 out-
put buffer, including the zero terminator if the string was
zero-terminated.
SUBJECT STRING OFFSETS
The lengths and starting offsets of subject strings must be
specified in 16-bit data units, and the offsets within sub-
ject strings that are returned by the matching functions are
in also 16-bit units rather than bytes.
NAMED SUBPATTERNS
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
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PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
units.
OPTION NAMES
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.
CHARACTER CODES
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 pro-
vided to help with this (see above).
ERROR NAMES
The errors PCRE_ERROR_BADUTF16_OFFSET and
PCRE_ERROR_SHORTUTF16 correspond to their 8-bit counter-
parts. 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 surro-
gate
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PCRE(3) C LIBRARY FUNCTIONS PCRE(3)
PCRE_UTF16_ERR3 Isolated low surrogate
PCRE_UTF16_ERR4 Non-character
ERROR TEXTS
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.
CALLOUTS
The subject and mark fields in the callout block that is
passed to a callout function point to 16-bit vectors.
TESTING
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, pat-
terns and subject strings are converted from 8-bit to 16-bit
before being passed to PCRE, and the 16-bit library func-
tions 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 SUPPORTED IN 16-BIT MODE
Not all the features of the 8-bit library are available with
the 16-bit library. The C++ and POSIX wrapper functions sup-
port only the 8-bit library, and the pcregrep program is at
present 8-bit only.
AUTHOR
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
REVISION
Last updated: 12 May 2013
Copyright (c) 1997-2013 University of Cambridge.
PCRE 8.33 Last change: 12 May 2013 6
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