PCRE2 - Perl-compatible regular expressions (revised API)
#include <pcre2.h>
int pcre2_pattern_info(const pcre2_code *code, uint32_t what,
void *where);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.