PCRE_FULLINFO(3)

💖 PCRE_FULLINFO — bestie, come get the tea on your compiled pattern 💖

okay so this is the pcre_fullinfo page from the PCRE manual (that's Perl-compatible regular expressions, and yes she ate). grab a snack, we're getting all the lore about a pattern you already compiled.

✨ SYNOPSIS ✨

first things first, pull in the header:

#include <pcre.h>

then here's the whole girlboss lineup — three of them, one for each library width, all identical in shape:

int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
     int what, void *where);

int pcre16_fullinfo(const pcre16 *code, const pcre16_extra *extra,
     int what, void *where);

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

🌸 DESCRIPTION 🌸

so this function is literally just gossip about a compiled pattern. it tells you stuff. that's the whole job. here's who's in the group chat:

• code — the compiled regular expression 🫶
• extra — whatever pcre[16|32]_study() handed back, or NULL
• what — which piece of info you're asking for
• where — where the info should go

🎀 the info menu (a.k.a. what you can ask for) 🎀

• PCRE_INFO_BACKREFMAX — number of the highest back reference
• PCRE_INFO_CAPTURECOUNT — number of capturing subpatterns
• PCRE_INFO_DEFAULT_TABLES — pointer to default tables
• PCRE_INFO_FIRSTBYTE — fixed first data unit for a match, or -1 for start of string or after newline, or -2 otherwise
• PCRE_INFO_FIRSTTABLE — table of first data units (after studying)
• PCRE_INFO_HASCRORLF — returns 1 if explicit CR or LF matches exist
• PCRE_INFO_JCHANGED — returns 1 if (?J) or (?-J) was used
• PCRE_INFO_JIT — returns 1 after successful JIT compilation
• PCRE_INFO_JITSIZE — size of JIT compiled code
• PCRE_INFO_LASTLITERAL — literal last data unit required
• PCRE_INFO_MINLENGTH — lower bound length of matching strings
• PCRE_INFO_MATCHEMPTY — returns 1 if the pattern can match an empty string, 0 otherwise
• PCRE_INFO_MATCHLIMIT — match limit if set, otherwise PCRE_RROR_UNSET
• PCRE_INFO_MAXLOOKBEHIND — length (in characters) of the longest lookbehind assertion
• PCRE_INFO_NAMECOUNT — number of named subpatterns
• PCRE_INFO_NAMEENTRYSIZE — size of name table entry
• PCRE_INFO_NAMETABLE — pointer to name table
• PCRE_INFO_OKPARTIAL — returns 1 if partial matching can be tried (always returns 1 after release 8.00)
• PCRE_INFO_OPTIONS — option bits used for compilation
• PCRE_INFO_SIZE — size of compiled pattern
• PCRE_INFO_STUDYSIZE — size of study data
• PCRE_INFO_FIRSTCHARACTER — fixed first data unit for a match
• PCRE_INFO_FIRSTCHARACTERFLAGS — returns 1 if there is a first data character set, which can then be retrieved using PCRE_INFO_FIRSTCHARACTER; 2 if the first character is at the start of the data string or after a newline; and 0 otherwise
• PCRE_INFO_RECURSIONLIMIT — recursion limit if set, otherwise PCRE_ERROR_UNSET
• PCRE_INFO_REQUIREDCHAR — literal last data unit required
• PCRE_INFO_REQUIREDCHARFLAGS — returns 1 if the last data character is set (which can then be retrieved using PCRE_INFO_REQUIREDCHAR); 0 otherwise

🦋 what where has to point at 🦋

bestie listen. normally your where argument has to point at an integer variable. except for these what values, which need their own special lil types:

• PCRE_INFO_DEFAULT_TABLES — const uint8_t *
• PCRE_INFO_FIRSTCHARACTER — uint32_t
• PCRE_INFO_FIRSTTABLE — const uint8_t *
• PCRE_INFO_JITSIZE — size_t
• PCRE_INFO_MATCHLIMIT — uint32_t
• PCRE_INFO_NAMETABLE — PCRE_SPTR16 (16-bit library)
• PCRE_INFO_NAMETABLE — PCRE_SPTR32 (32-bit library)
• PCRE_INFO_NAMETABLE — const unsigned char * (8-bit library)
• PCRE_INFO_OPTIONS — unsigned long int
• PCRE_INFO_SIZE — size_t
• PCRE_INFO_STUDYSIZE — size_t
• PCRE_INFO_RECURSIONLIMIT — uint32_t
• PCRE_INFO_REQUIREDCHAR — uint32_t

💅 the return value 💅

the function yields zero on success. and when it doesn't? she gives you one of these instead:

• PCRE_ERROR_NULL — the argument code was NULL
  • or the argument where was NULL
• PCRE_ERROR_BADMAGIC — the "magic number" was not found 🪄
• PCRE_ERROR_BADOPTION — the value of what was invalid
• PCRE_ERROR_UNSET — the option was not set

💀 heads up: there's a whole complete description of the PCRE native API chilling in the pcreapi page, and a description of the POSIX API in the pcreposix page. go read those too, no cap.

and that's the whole page, bestie, you're officially informed ✨ this was PCRE 8.36, dated 21 April 2014, and it lives under PCRE_FULLINFO(3). mwah, go slay those regexes 💖🎀🦋