Synopsis

#include <pcre2.h>

int pcre2_pattern_info(const pcre2_code *code, uint32_t what,
                       void *where);

Description

This function returns information about a compiled pattern. Its arguments are:

code

Pointer to a compiled regular expression pattern

what

What information is required

where

Where to put the information

The recognized values for the what argument, and the information they request are as follows:

PCRE2_INFO_ALLOPTIONS

Final options after compiling

PCRE2_INFO_ARGOPTIONS

Options passed to pcre2_compile()

PCRE2_INFO_BACKREFMAX

Number of highest backreference

PCRE2_INFO_BSR

What \R matches:

PCRE2_BSR_UNICODE

Unicode line endings

PCRE2_BSR_ANYCRLF

CR, LF, or CRLF only

PCRE2_INFO_CAPTURECOUNT

Number of capturing subpatterns

PCRE2_INFO_DEPTHLIMIT

Backtracking depth limit if set, otherwise PCRE2_ERROR_UNSET

PCRE2_INFO_EXTRAOPTIONS

Extra options that were passed in the compile context

PCRE2_INFO_FIRSTBITMAP

Bitmap of first code units, or NULL

PCRE2_INFO_FIRSTCODETYPE

Type of start-of-match information 0 nothing set 1 first code unit is set 2 start of string or after newline

PCRE2_INFO_FIRSTCODEUNIT

First code unit when type is 1

PCRE2_INFO_FRAMESIZE

Size of backtracking frame

PCRE2_INFO_HASBACKSLASHC

Return 1 if pattern contains \C

PCRE2_INFO_HASCRORLF

Return 1 if explicit CR or LF matches exist in the pattern

PCRE2_INFO_HEAPLIMIT

Heap memory limit if set, otherwise PCRE2_ERROR_UNSET

PCRE2_INFO_JCHANGED

Return 1 if (?J) or (?-J) was used

PCRE2_INFO_JITSIZE

Size of JIT compiled code, or 0

PCRE2_INFO_LASTCODETYPE

Type of must-be-present information 0 nothing set 1 code unit is set

PCRE2_INFO_LASTCODEUNIT

Last code unit when type is 1

PCRE2_INFO_MATCHEMPTY

1 if the pattern can match an empty string, 0 otherwise

PCRE2_INFO_MATCHLIMIT

Match limit if set, otherwise PCRE2_ERROR_UNSET

PCRE2_INFO_MAXLOOKBEHIND

Length (in characters) of the longest lookbehind assertion

PCRE2_INFO_MINLENGTH

Lower bound length of matching strings

PCRE2_INFO_NAMECOUNT

Number of named subpatterns

PCRE2_INFO_NAMEENTRYSIZE

Size of name table entries

PCRE2_INFO_NAMETABLE

Pointer to name table

PCRE2_CONFIG_NEWLINE

Code for the newline sequence:

PCRE2_NEWLINE_CR
PCRE2_NEWLINE_LF
PCRE2_NEWLINE_CRLF
PCRE2_NEWLINE_ANY
PCRE2_NEWLINE_ANYCRLF
PCRE2_NEWLINE_NUL
PCRE2_INFO_RECURSIONLIMIT

Obsolete synonym for PCRE2_INFO_DEPTHLIMIT

PCRE2_INFO_SIZE

Size of compiled pattern

If where is NULL, the function returns the amount of memory needed for the requested information, in bytes. Otherwise, the where argument must point to an unsigned 32-bit integer (uint32_t variable), except for the following what values, when it must point to a variable of the type shown:

PCRE2_INFO_FIRSTBITMAP

const uint8_t *

PCRE2_INFO_JITSIZE

size_t

PCRE2_INFO_NAMETABLE

PCRE2_SPTR

PCRE2_INFO_SIZE

size_t

The yield of the function is zero on success or:

PCRE2_ERROR_NULL

the argument code is NULL

PCRE2_ERROR_BADMAGIC

the "magic number" was not found

PCRE2_ERROR_BADOPTION

the value of what is invalid

PCRE2_ERROR_BADMODE

the pattern was compiled in the wrong mode

PCRE2_ERROR_UNSET

the requested information is not set

There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.