Advanced Regular Expression Patterns

Named Captures

Named captures make a match easier to read when several pieces are extracted.

named-captures Named captures keep the extracted fields tied to their meaning instead of only their position in the pattern.

Named Captures

code
named_captures.pl
Replay: real traced execution (multi-file project)
use strict;
use warnings;

my $code = "ticket-42";
my $matched = $code =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;
my $kind = $matched ? $+{kind} : "none";
my $id = $matched ? $+{id} : "none";

print "code=$code\n";
print "matched=$matched\n";
print "kind=$kind\n";
print "id=$id\n";

use strict;
use warnings;

my $code = "bug-7";
my $matched = $code =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;
my $kind = $matched ? $+{kind} : "none";
my $id = $matched ? $+{id} : "none";

print "code=$code\n";
print "matched=$matched\n";
print "kind=$kind\n";
print "id=$id\n";

use strict;
use warnings;

my $code = "bad";
my $matched = $code =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;
my $kind = $matched ? $+{kind} : "none";
my $id = $matched ? $+{id} : "none";

print "code=$code\n";
print "matched=$matched\n";
print "kind=$kind\n";
print "id=$id\n";

  1. $code ← ticket-42, $matched ← 1, $kind ← ticket, $id ← 42

    4my $code→ ticket-42 = "ticket-42"; #@code="bug-7", "bad"5my $matched→ 1 = $codeticket-42 =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;6my $kind→ ticket = $matched1 ? $+{kind} : "none";7my $id→ 42 = $matched1 ? $+{id} : "none";89print "code=$codeticket-42\n";10print "matched=$matched1\n";11print "kind=$kindticket\n";12print "id=$id42\n";
    outputcode=ticket-42
matched=1
kind=ticket
id=42

  1. $code ← bug-7, $matched ← 1, $kind ← bug, $id ← 7

    4my $code→ bug-7 = "bug-7";5my $matched→ 1 = $codebug-7 =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;6my $kind→ bug = $matched1 ? $+{kind} : "none";7my $id→ 7 = $matched1 ? $+{id} : "none";89print "code=$codebug-7\n";10print "matched=$matched1\n";11print "kind=$kindbug\n";12print "id=$id7\n";
    outputcode=bug-7
matched=1
kind=bug
id=7

  1. $code ← bad, $matched ← (empty), $kind ← none, $id ← none

    4my $code→ bad = "bad";5my $matched→ (empty) = $codebad =~ /^(?<kind>[a-z]+)-(?<id>\d+)$/;6my $kind→ none = $matched(empty) ? $+{kind} : "none";7my $id→ none = $matched(empty) ? $+{id} : "none";89print "code=$codebad\n";10print "matched=$matched(empty)\n";11print "kind=$kindnone\n";12print "id=$idnone\n";
    outputcode=bad
matched=
kind=none
id=none