PCRE(3) Introduction to Library Functions PCRE(3)

NAME

PCRE - Perl-compatible regular expressions

#include <pcre.h>

PCRE 32-BIT API BASIC FUNCTIONS
pcre32 *pcre32_compile(PCRE_SPTR32 pattern, int options,
const char **errptr, int *erroffset,
const unsigned char *tableptr);

pcre32 *pcre32_compile2(PCRE_SPTR32 pattern, int options,
int *errorcodeptr,
const unsigned char *tableptr);

pcre32_extra *pcre32_study(const pcre32 *code, int options,
const char **errptr);

void pcre32_free_study(pcre32_extra *extra);

int pcre32_exec(const pcre32 *code, const pcre32_extra *extra,
PCRE_SPTR32 subject, int length, int startoffset,
int options, int *ovector, int ovecsize);

int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
PCRE_SPTR32 subject, int length, int startoffset,
int options, int *ovector, int ovecsize,
int *workspace, int wscount);

PCRE 32-BIT API STRING EXTRACTION FUNCTIONS
int pcre32_copy_named_substring(const pcre32 *code,
PCRE_SPTR32 subject, int *ovector,
int stringcount, PCRE_SPTR32 stringname,
PCRE_UCHAR32 *buffer, int buffersize);

int pcre32_copy_substring(PCRE_SPTR32 subject, int *ovector,
int stringcount, int stringnumber, PCRE_UCHAR32 *buffer,
int buffersize);

int pcre32_get_named_substring(const pcre32 *code,
PCRE_SPTR32 subject, int *ovector,
int stringcount, PCRE_SPTR32 stringname,
PCRE_SPTR32 *stringptr);

int pcre32_get_stringnumber(const pcre32 *code,
PCRE_SPTR32 name);

int pcre32_get_stringtable_entries(const pcre32 *code,
PCRE_SPTR32 name, PCRE_UCHAR32 **first, PCRE_UCHAR32 **last);

int pcre32_get_substring(PCRE_SPTR32 subject, int *ovector,
int stringcount, int stringnumber,
PCRE_SPTR32 *stringptr);

int pcre32_get_substring_list(PCRE_SPTR32 subject,
int *ovector, int stringcount, PCRE_SPTR32 **listptr);

void pcre32_free_substring(PCRE_SPTR32 stringptr);

void pcre32_free_substring_list(PCRE_SPTR32 *stringptr);

PCRE 32-BIT API AUXILIARY FUNCTIONS
pcre32_jit_stack *pcre32_jit_stack_alloc(int startsize, int maxsize);

void pcre32_jit_stack_free(pcre32_jit_stack *stack);

void pcre32_assign_jit_stack(pcre32_extra *extra,
pcre32_jit_callback callback, void *data);

const unsigned char *pcre32_maketables(void);

int pcre32_fullinfo(const pcre32 *code, const pcre32_extra *extra,
int what, void *where);

int pcre32_refcount(pcre32 *code, int adjust);

int pcre32_config(int what, void *where);

const char *pcre32_version(void);

int pcre32_pattern_to_host_byte_order(pcre32 *code,
pcre32_extra *extra, const unsigned char *tables);

PCRE 32-BIT API INDIRECTED FUNCTIONS
void *(*pcre32_malloc)(size_t);

void (*pcre32_free)(void *);

void *(*pcre32_stack_malloc)(size_t);

void (*pcre32_stack_free)(void *);

int (*pcre32_callout)(pcre32_callout_block *);

PCRE 32-BIT API 32-BIT-ONLY FUNCTION
int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *output,
PCRE_SPTR32 input, int length, int *byte_order,
int keep_boms);

THE PCRE 32-BIT LIBRARY
Starting with release 8.32, it is possible to compile a PCRE library
that supports 32-bit character strings, including UTF-32 strings, as
well as or instead of the original 8-bit library. This work was done
by Christian Persch, based on the work done by Zoltan Herczeg for the
16-bit library. All three 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 and 32-bit
libraries. This page describes what is different when you use the
32-bit library.

WARNING: A single application can be linked with all or any of the
three 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
pcre32_compile(), you must do so with pcre32_study(), not
pcre_study(), and you must free the study data with
pcre32_free_study().

THE HEADER FILE

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.

THE LIBRARY NAME

In Unix-like systems, the 32-bit library is called libpcre32, and can
normally be accesss by adding -lpcre32 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 32-bit library,
strings are passed as vectors of unsigned 32-bit quantities. The
macro PCRE_UCHAR32 specifies an appropriate data type, and
PCRE_SPTR32 is defined as "const PCRE_UCHAR32 *". In very many
environments, "unsigned int" is a 32-bit data type. When PCRE is
built, it defines PCRE_UCHAR32 as "unsigned int", but checks that it
really is a 32-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 compiled 32-bit
patterns and JIT stacks are pcre32 and pcre32_jit_stack respectively.
The type of the user-accessible structure that is returned by
pcre32_study() is pcre32_extra, and the type of the structure that is
used for passing data to a callout function is pcre32_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 32-bit instead of 8-bit types.

32-BIT FUNCTIONS
For every function in the 8-bit library there is a corresponding
function in the 32-bit library with a name that starts with pcre32_
instead of pcre_. The prototypes are listed above. In addition, there
is one extra function, pcre32_utf32_to_host_byte_order(). This is a
utility function that converts a UTF-32 character string to host byte
order if necessary. The other 32-bit functions expect the strings
they are passed to be in host byte order.

The input and output arguments of pcre32_utf32_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 32-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 32-bit units placed into
the output 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 32-bit data units, and the offsets within subject strings that are
returned by the matching functions are in also 32-bit units rather
than bytes.

NAMED SUBPATTERNS

The name-to-number translation table that is maintained for named
subpatterns uses 32-bit characters. The
pcre32_get_stringtable_entries() function returns the length of each
entry in the table as the number of 32-bit data units.

OPTION NAMES

There are two new general option names, PCRE_UTF32 and
PCRE_NO_UTF32_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-32 strings in the pcreunicode page.

For the pcre32_config() function there is an option PCRE_CONFIG_UTF32
that returns 1 if UTF-32 support is configured, otherwise 0. If this
option is given to pcre_config() or pcre16_config(), or if the
PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 option is given to
pcre32_config(), the result is the PCRE_ERROR_BADOPTION error.

CHARACTER CODES

In 32-bit mode, when PCRE_UTF32 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 0x7fffffff 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-32 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 ill-formed in UTF-32.

A UTF-32 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
pcre32_utf32_to_host_byte_order() is provided to help with this (see
above).

ERROR NAMES

The error PCRE_ERROR_BADUTF32 corresponds to its 8-bit counterpart.
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
pcre32_exec().

There are new error codes whose names begin with PCRE_UTF32_ERR for
invalid UTF-32 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-32
errors are:

PCRE_UTF32_ERR1 Surrogate character (range from 0xd800 to 0xdfff)
PCRE_UTF32_ERR2 Non-character
PCRE_UTF32_ERR3 Character > 0x10ffff

ERROR TEXTS

If there is an error while compiling a pattern, the error text that
is passed back by pcre32_compile() or pcre32_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 32-bit vectors.

TESTING

The pcretest program continues to operate with 8-bit input and output
files, but it can be used for testing the 32-bit library. If it is
run with the command line option -32, patterns and subject strings
are converted from 8-bit to 32-bit before being passed to PCRE, and
the 32-bit library functions are used instead of the 8-bit ones.
Returned 32-bit strings are converted to 8-bit for output. If both
the 8-bit and the 16-bit libraries were not compiled, pcretest
defaults to 32-bit and the -32 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 32-BIT MODE
Not all the features of the 8-bit library are available with the
32-bit library. The C++ and POSIX wrapper functions support 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 12 May 2013 PCRE(3)