Initial Commit
This commit is contained in:
Riley Schneider
814
database/perl/lib/re.pm
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814
database/perl/lib/re.pm
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@@ -0,0 +1,814 @@
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package re;
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# pragma for controlling the regexp engine
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use strict;
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use warnings;
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our $VERSION = "0.40";
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our @ISA = qw(Exporter);
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our @EXPORT_OK = ('regmust',
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qw(is_regexp regexp_pattern
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regname regnames regnames_count));
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our %EXPORT_OK = map { $_ => 1 } @EXPORT_OK;
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my %bitmask = (
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taint => 0x00100000, # HINT_RE_TAINT
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eval => 0x00200000, # HINT_RE_EVAL
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);
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my $flags_hint = 0x02000000; # HINT_RE_FLAGS
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my $PMMOD_SHIFT = 0;
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my %reflags = (
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m => 1 << ($PMMOD_SHIFT + 0),
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s => 1 << ($PMMOD_SHIFT + 1),
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i => 1 << ($PMMOD_SHIFT + 2),
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x => 1 << ($PMMOD_SHIFT + 3),
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xx => 1 << ($PMMOD_SHIFT + 4),
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n => 1 << ($PMMOD_SHIFT + 5),
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p => 1 << ($PMMOD_SHIFT + 6),
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strict => 1 << ($PMMOD_SHIFT + 10),
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# special cases:
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d => 0,
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l => 1,
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u => 2,
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a => 3,
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aa => 4,
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);
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sub setcolor {
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eval { # Ignore errors
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require Term::Cap;
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my $terminal = Tgetent Term::Cap ({OSPEED => 9600}); # Avoid warning.
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my $props = $ENV{PERL_RE_TC} || 'md,me,so,se,us,ue';
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my @props = split /,/, $props;
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my $colors = join "\t", map {$terminal->Tputs($_,1)} @props;
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$colors =~ s/\0//g;
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$ENV{PERL_RE_COLORS} = $colors;
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};
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if ($@) {
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$ENV{PERL_RE_COLORS} ||= qq'\t\t> <\t> <\t\t';
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}
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}
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my %flags = (
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COMPILE => 0x0000FF,
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PARSE => 0x000001,
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OPTIMISE => 0x000002,
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TRIEC => 0x000004,
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DUMP => 0x000008,
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FLAGS => 0x000010,
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TEST => 0x000020,
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EXECUTE => 0x00FF00,
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INTUIT => 0x000100,
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MATCH => 0x000200,
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TRIEE => 0x000400,
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EXTRA => 0x3FF0000,
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TRIEM => 0x0010000,
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OFFSETS => 0x0020000,
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OFFSETSDBG => 0x0040000,
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STATE => 0x0080000,
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OPTIMISEM => 0x0100000,
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STACK => 0x0280000,
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BUFFERS => 0x0400000,
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GPOS => 0x0800000,
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DUMP_PRE_OPTIMIZE => 0x1000000,
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WILDCARD => 0x2000000,
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);
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$flags{ALL} = -1 & ~($flags{OFFSETS}
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|$flags{OFFSETSDBG}
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|$flags{BUFFERS}
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|$flags{DUMP_PRE_OPTIMIZE}
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|$flags{WILDCARD}
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);
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$flags{All} = $flags{all} = $flags{DUMP} | $flags{EXECUTE};
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$flags{Extra} = $flags{EXECUTE} | $flags{COMPILE} | $flags{GPOS};
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$flags{More} = $flags{MORE} =
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$flags{All} | $flags{TRIEC} | $flags{TRIEM} | $flags{STATE};
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$flags{State} = $flags{DUMP} | $flags{EXECUTE} | $flags{STATE};
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$flags{TRIE} = $flags{DUMP} | $flags{EXECUTE} | $flags{TRIEC};
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if (defined &DynaLoader::boot_DynaLoader) {
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require XSLoader;
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XSLoader::load();
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}
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# else we're miniperl
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# We need to work for miniperl, because the XS toolchain uses Text::Wrap, which
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# uses re 'taint'.
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sub _load_unload {
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my ($on)= @_;
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if ($on) {
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# We call install() every time, as if we didn't, we wouldn't
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# "see" any changes to the color environment var since
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# the last time it was called.
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# install() returns an integer, which if casted properly
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# in C resolves to a structure containing the regexp
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# hooks. Setting it to a random integer will guarantee
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# segfaults.
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$^H{regcomp} = install();
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} else {
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delete $^H{regcomp};
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}
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}
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sub bits {
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my $on = shift;
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my $bits = 0;
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my $turning_all_off = ! @_ && ! $on;
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my $seen_Debug = 0;
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my $seen_debug = 0;
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if ($turning_all_off) {
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# Pretend were called with certain parameters, which are best dealt
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# with that way.
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push @_, keys %bitmask; # taint and eval
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push @_, 'strict';
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}
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# Process each subpragma parameter
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ARG:
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foreach my $idx (0..$#_){
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my $s=$_[$idx];
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if ($s eq 'Debug' or $s eq 'Debugcolor') {
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if (! $seen_Debug) {
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$seen_Debug = 1;
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# Reset to nothing, and then add what follows. $seen_Debug
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# allows, though unlikely someone would do it, more than one
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# Debug and flags in the arguments
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${^RE_DEBUG_FLAGS} = 0;
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}
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setcolor() if $s =~/color/i;
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for my $idx ($idx+1..$#_) {
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if ($flags{$_[$idx]}) {
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if ($on) {
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${^RE_DEBUG_FLAGS} |= $flags{$_[$idx]};
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} else {
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${^RE_DEBUG_FLAGS} &= ~ $flags{$_[$idx]};
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}
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} else {
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require Carp;
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Carp::carp("Unknown \"re\" Debug flag '$_[$idx]', possible flags: ",
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join(", ",sort keys %flags ) );
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}
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}
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_load_unload($on ? 1 : ${^RE_DEBUG_FLAGS});
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last;
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} elsif ($s eq 'debug' or $s eq 'debugcolor') {
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# These default flags should be kept in sync with the same values
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# in regcomp.h
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${^RE_DEBUG_FLAGS} = $flags{'EXECUTE'} | $flags{'DUMP'};
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setcolor() if $s =~/color/i;
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_load_unload($on);
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$seen_debug = 1;
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} elsif (exists $bitmask{$s}) {
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$bits |= $bitmask{$s};
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} elsif ($EXPORT_OK{$s}) {
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require Exporter;
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re->export_to_level(2, 're', $s);
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} elsif ($s eq 'strict') {
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if ($on) {
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$^H{reflags} |= $reflags{$s};
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warnings::warnif('experimental::re_strict',
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"\"use re 'strict'\" is experimental");
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# Turn on warnings if not already done.
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if (! warnings::enabled('regexp')) {
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require warnings;
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warnings->import('regexp');
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$^H{re_strict} = 1;
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}
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}
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else {
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$^H{reflags} &= ~$reflags{$s} if $^H{reflags};
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# Turn off warnings if we turned them on.
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warnings->unimport('regexp') if $^H{re_strict};
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}
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if ($^H{reflags}) {
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$^H |= $flags_hint;
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}
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else {
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$^H &= ~$flags_hint;
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}
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} elsif ($s =~ s/^\///) {
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my $reflags = $^H{reflags} || 0;
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my $seen_charset;
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my $x_count = 0;
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while ($s =~ m/( . )/gx) {
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local $_ = $1;
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if (/[adul]/) {
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# The 'a' may be repeated; hide this from the rest of the
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# code by counting and getting rid of all of them, then
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# changing to 'aa' if there is a repeat.
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if ($_ eq 'a') {
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my $sav_pos = pos $s;
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my $a_count = $s =~ s/a//g;
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pos $s = $sav_pos - 1; # -1 because got rid of the 'a'
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if ($a_count > 2) {
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require Carp;
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Carp::carp(
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qq 'The "a" flag may only appear a maximum of twice'
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);
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}
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elsif ($a_count == 2) {
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$_ = 'aa';
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}
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}
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if ($on) {
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if ($seen_charset) {
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require Carp;
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if ($seen_charset ne $_) {
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Carp::carp(
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qq 'The "$seen_charset" and "$_" flags '
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.qq 'are exclusive'
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);
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}
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else {
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Carp::carp(
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qq 'The "$seen_charset" flag may not appear '
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.qq 'twice'
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);
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}
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}
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$^H{reflags_charset} = $reflags{$_};
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$seen_charset = $_;
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}
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else {
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delete $^H{reflags_charset}
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if defined $^H{reflags_charset}
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&& $^H{reflags_charset} == $reflags{$_};
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}
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} elsif (exists $reflags{$_}) {
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if ($_ eq 'x') {
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$x_count++;
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if ($x_count > 2) {
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require Carp;
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Carp::carp(
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qq 'The "x" flag may only appear a maximum of twice'
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);
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}
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elsif ($x_count == 2) {
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$_ = 'xx'; # First time through got the /x
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}
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}
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$on
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? $reflags |= $reflags{$_}
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: ($reflags &= ~$reflags{$_});
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} else {
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require Carp;
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Carp::carp(
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qq'Unknown regular expression flag "$_"'
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);
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next ARG;
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}
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}
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($^H{reflags} = $reflags or defined $^H{reflags_charset})
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? $^H |= $flags_hint
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: ($^H &= ~$flags_hint);
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} else {
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require Carp;
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if ($seen_debug && defined $flags{$s}) {
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Carp::carp("Use \"Debug\" not \"debug\", to list debug types"
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. " in \"re\". \"$s\" ignored");
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}
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else {
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Carp::carp("Unknown \"re\" subpragma '$s' (known ones are: ",
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join(', ', map {qq('$_')} 'debug', 'debugcolor', sort keys %bitmask),
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")");
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}
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}
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}
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if ($turning_all_off) {
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_load_unload(0);
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$^H{reflags} = 0;
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$^H{reflags_charset} = 0;
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$^H &= ~$flags_hint;
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}
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$bits;
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}
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sub import {
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shift;
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$^H |= bits(1, @_);
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}
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sub unimport {
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shift;
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$^H &= ~ bits(0, @_);
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}
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1;
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__END__
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=head1 NAME
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re - Perl pragma to alter regular expression behaviour
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=head1 SYNOPSIS
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use re 'taint';
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($x) = ($^X =~ /^(.*)$/s); # $x is tainted here
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$pat = '(?{ $foo = 1 })';
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use re 'eval';
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/foo${pat}bar/; # won't fail (when not under -T
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# switch)
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{
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no re 'taint'; # the default
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($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here
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no re 'eval'; # the default
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/foo${pat}bar/; # disallowed (with or without -T
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# switch)
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}
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use re 'strict'; # Raise warnings for more conditions
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use re '/ix';
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"FOO" =~ / foo /; # /ix implied
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no re '/x';
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"FOO" =~ /foo/; # just /i implied
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use re 'debug'; # output debugging info during
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/^(.*)$/s; # compile and run time
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use re 'debugcolor'; # same as 'debug', but with colored
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# output
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...
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use re qw(Debug All); # Same as "use re 'debug'", but you
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# can use "Debug" with things other
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# than 'All'
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use re qw(Debug More); # 'All' plus output more details
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no re qw(Debug ALL); # Turn on (almost) all re debugging
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# in this scope
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use re qw(is_regexp regexp_pattern); # import utility functions
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my ($pat,$mods)=regexp_pattern(qr/foo/i);
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if (is_regexp($obj)) {
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print "Got regexp: ",
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scalar regexp_pattern($obj); # just as perl would stringify
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} # it but no hassle with blessed
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# re's.
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(We use $^X in these examples because it's tainted by default.)
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=head1 DESCRIPTION
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=head2 'taint' mode
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When C<use re 'taint'> is in effect, and a tainted string is the target
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of a regexp, the regexp memories (or values returned by the m// operator
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in list context) are tainted. This feature is useful when regexp operations
|
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on tainted data aren't meant to extract safe substrings, but to perform
|
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other transformations.
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=head2 'eval' mode
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When C<use re 'eval'> is in effect, a regexp is allowed to contain
|
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C<(?{ ... })> zero-width assertions and C<(??{ ... })> postponed
|
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subexpressions that are derived from variable interpolation, rather than
|
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appearing literally within the regexp. That is normally disallowed, since
|
||||
it is a
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potential security risk. Note that this pragma is ignored when the regular
|
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expression is obtained from tainted data, i.e. evaluation is always
|
||||
disallowed with tainted regular expressions. See L<perlre/(?{ code })>
|
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and L<perlre/(??{ code })>.
|
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|
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For the purpose of this pragma, interpolation of precompiled regular
|
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expressions (i.e., the result of C<qr//>) is I<not> considered variable
|
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interpolation. Thus:
|
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|
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/foo${pat}bar/
|
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|
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I<is> allowed if $pat is a precompiled regular expression, even
|
||||
if $pat contains C<(?{ ... })> assertions or C<(??{ ... })> subexpressions.
|
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|
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=head2 'strict' mode
|
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|
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Note that this is an experimental feature which may be changed or removed in a
|
||||
future Perl release.
|
||||
|
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When C<use re 'strict'> is in effect, stricter checks are applied than
|
||||
otherwise when compiling regular expressions patterns. These may cause more
|
||||
warnings to be raised than otherwise, and more things to be fatal instead of
|
||||
just warnings. The purpose of this is to find and report at compile time some
|
||||
things, which may be legal, but have a reasonable possibility of not being the
|
||||
programmer's actual intent. This automatically turns on the C<"regexp">
|
||||
warnings category (if not already on) within its scope.
|
||||
|
||||
As an example of something that is caught under C<"strict'>, but not
|
||||
otherwise, is the pattern
|
||||
|
||||
qr/\xABC/
|
||||
|
||||
The C<"\x"> construct without curly braces should be followed by exactly two
|
||||
hex digits; this one is followed by three. This currently evaluates as
|
||||
equivalent to
|
||||
|
||||
qr/\x{AB}C/
|
||||
|
||||
that is, the character whose code point value is C<0xAB>, followed by the
|
||||
letter C<C>. But since C<C> is a hex digit, there is a reasonable chance
|
||||
that the intent was
|
||||
|
||||
qr/\x{ABC}/
|
||||
|
||||
that is the single character at C<0xABC>. Under C<'strict'> it is an error to
|
||||
not follow C<\x> with exactly two hex digits. When not under C<'strict'> a
|
||||
warning is generated if there is only one hex digit, and no warning is raised
|
||||
if there are more than two.
|
||||
|
||||
It is expected that what exactly C<'strict'> does will evolve over time as we
|
||||
gain experience with it. This means that programs that compile under it in
|
||||
today's Perl may not compile, or may have more or fewer warnings, in future
|
||||
Perls. There is no backwards compatibility promises with regards to it. Also
|
||||
there are already proposals for an alternate syntax for enabling it. For
|
||||
these reasons, using it will raise a C<experimental::re_strict> class warning,
|
||||
unless that category is turned off.
|
||||
|
||||
Note that if a pattern compiled within C<'strict'> is recompiled, say by
|
||||
interpolating into another pattern, outside of C<'strict'>, it is not checked
|
||||
again for strictness. This is because if it works under strict it must work
|
||||
under non-strict.
|
||||
|
||||
=head2 '/flags' mode
|
||||
|
||||
When C<use re '/I<flags>'> is specified, the given I<flags> are automatically
|
||||
added to every regular expression till the end of the lexical scope.
|
||||
I<flags> can be any combination of
|
||||
C<'a'>,
|
||||
C<'aa'>,
|
||||
C<'d'>,
|
||||
C<'i'>,
|
||||
C<'l'>,
|
||||
C<'m'>,
|
||||
C<'n'>,
|
||||
C<'p'>,
|
||||
C<'s'>,
|
||||
C<'u'>,
|
||||
C<'x'>,
|
||||
and/or
|
||||
C<'xx'>.
|
||||
|
||||
C<no re '/I<flags>'> will turn off the effect of C<use re '/I<flags>'> for the
|
||||
given flags.
|
||||
|
||||
For example, if you want all your regular expressions to have /msxx on by
|
||||
default, simply put
|
||||
|
||||
use re '/msxx';
|
||||
|
||||
at the top of your code.
|
||||
|
||||
The character set C</adul> flags cancel each other out. So, in this example,
|
||||
|
||||
use re "/u";
|
||||
"ss" =~ /\xdf/;
|
||||
use re "/d";
|
||||
"ss" =~ /\xdf/;
|
||||
|
||||
the second C<use re> does an implicit C<no re '/u'>.
|
||||
|
||||
Similarly,
|
||||
|
||||
use re "/xx"; # Doubled-x
|
||||
...
|
||||
use re "/x"; # Single x from here on
|
||||
...
|
||||
|
||||
Turning on one of the character set flags with C<use re> takes precedence over the
|
||||
C<locale> pragma and the 'unicode_strings' C<feature>, for regular
|
||||
expressions. Turning off one of these flags when it is active reverts to
|
||||
the behaviour specified by whatever other pragmata are in scope. For
|
||||
example:
|
||||
|
||||
use feature "unicode_strings";
|
||||
no re "/u"; # does nothing
|
||||
use re "/l";
|
||||
no re "/l"; # reverts to unicode_strings behaviour
|
||||
|
||||
=head2 'debug' mode
|
||||
|
||||
When C<use re 'debug'> is in effect, perl emits debugging messages when
|
||||
compiling and using regular expressions. The output is the same as that
|
||||
obtained by running a C<-DDEBUGGING>-enabled perl interpreter with the
|
||||
B<-Dr> switch. It may be quite voluminous depending on the complexity
|
||||
of the match. Using C<debugcolor> instead of C<debug> enables a
|
||||
form of output that can be used to get a colorful display on terminals
|
||||
that understand termcap color sequences. Set C<$ENV{PERL_RE_TC}> to a
|
||||
comma-separated list of C<termcap> properties to use for highlighting
|
||||
strings on/off, pre-point part on/off.
|
||||
See L<perldebug/"Debugging Regular Expressions"> for additional info.
|
||||
|
||||
As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
|
||||
lexically scoped, as the other directives are. However they have both
|
||||
compile-time and run-time effects.
|
||||
|
||||
See L<perlmodlib/Pragmatic Modules>.
|
||||
|
||||
=head2 'Debug' mode
|
||||
|
||||
Similarly C<use re 'Debug'> produces debugging output, the difference
|
||||
being that it allows the fine tuning of what debugging output will be
|
||||
emitted. Options are divided into three groups, those related to
|
||||
compilation, those related to execution and those related to special
|
||||
purposes. The options are as follows:
|
||||
|
||||
=over 4
|
||||
|
||||
=item Compile related options
|
||||
|
||||
=over 4
|
||||
|
||||
=item COMPILE
|
||||
|
||||
Turns on all non-extra compile related debug options.
|
||||
|
||||
=item PARSE
|
||||
|
||||
Turns on debug output related to the process of parsing the pattern.
|
||||
|
||||
=item OPTIMISE
|
||||
|
||||
Enables output related to the optimisation phase of compilation.
|
||||
|
||||
=item TRIEC
|
||||
|
||||
Detailed info about trie compilation.
|
||||
|
||||
=item DUMP
|
||||
|
||||
Dump the final program out after it is compiled and optimised.
|
||||
|
||||
=item FLAGS
|
||||
|
||||
Dump the flags associated with the program
|
||||
|
||||
=item TEST
|
||||
|
||||
Print output intended for testing the internals of the compile process
|
||||
|
||||
=back
|
||||
|
||||
=item Execute related options
|
||||
|
||||
=over 4
|
||||
|
||||
=item EXECUTE
|
||||
|
||||
Turns on all non-extra execute related debug options.
|
||||
|
||||
=item MATCH
|
||||
|
||||
Turns on debugging of the main matching loop.
|
||||
|
||||
=item TRIEE
|
||||
|
||||
Extra debugging of how tries execute.
|
||||
|
||||
=item INTUIT
|
||||
|
||||
Enable debugging of start-point optimisations.
|
||||
|
||||
=back
|
||||
|
||||
=item Extra debugging options
|
||||
|
||||
=over 4
|
||||
|
||||
=item EXTRA
|
||||
|
||||
Turns on all "extra" debugging options.
|
||||
|
||||
=item BUFFERS
|
||||
|
||||
Enable debugging the capture group storage during match. Warning,
|
||||
this can potentially produce extremely large output.
|
||||
|
||||
=item TRIEM
|
||||
|
||||
Enable enhanced TRIE debugging. Enhances both TRIEE
|
||||
and TRIEC.
|
||||
|
||||
=item STATE
|
||||
|
||||
Enable debugging of states in the engine.
|
||||
|
||||
=item STACK
|
||||
|
||||
Enable debugging of the recursion stack in the engine. Enabling
|
||||
or disabling this option automatically does the same for debugging
|
||||
states as well. This output from this can be quite large.
|
||||
|
||||
=item GPOS
|
||||
|
||||
Enable debugging of the \G modifier.
|
||||
|
||||
=item OPTIMISEM
|
||||
|
||||
Enable enhanced optimisation debugging and start-point optimisations.
|
||||
Probably not useful except when debugging the regexp engine itself.
|
||||
|
||||
=item OFFSETS
|
||||
|
||||
Dump offset information. This can be used to see how regops correlate
|
||||
to the pattern. Output format is
|
||||
|
||||
NODENUM:POSITION[LENGTH]
|
||||
|
||||
Where 1 is the position of the first char in the string. Note that position
|
||||
can be 0, or larger than the actual length of the pattern, likewise length
|
||||
can be zero.
|
||||
|
||||
=item OFFSETSDBG
|
||||
|
||||
Enable debugging of offsets information. This emits copious
|
||||
amounts of trace information and doesn't mesh well with other
|
||||
debug options.
|
||||
|
||||
Almost definitely only useful to people hacking
|
||||
on the offsets part of the debug engine.
|
||||
|
||||
=item DUMP_PRE_OPTIMIZE
|
||||
|
||||
Enable the dumping of the compiled pattern before the optimization phase.
|
||||
|
||||
=item WILDCARD
|
||||
|
||||
When Perl encounters a wildcard subpattern, (see L<perlunicode/Wildcards in
|
||||
Property Values>), it suspends compilation of the main pattern, compiles the
|
||||
subpattern, and then matches that against all legal possibilities to determine
|
||||
the actual code points the subpattern matches. After that it adds these to
|
||||
the main pattern, and continues its compilation.
|
||||
|
||||
You may very well want to see how your subpattern gets compiled, but it is
|
||||
likely of less use to you to see how Perl matches that against all the legal
|
||||
possibilities, as that is under control of Perl, not you. Therefore, the
|
||||
debugging information of the compilation portion is as specified by the other
|
||||
options, but the debugging output of the matching portion is normally
|
||||
suppressed.
|
||||
|
||||
You can use the WILDCARD option to enable the debugging output of this
|
||||
subpattern matching. Careful! This can lead to voluminous outputs, and it
|
||||
may not make much sense to you what and why Perl is doing what it is.
|
||||
But it may be helpful to you to see why things aren't going the way you
|
||||
expect.
|
||||
|
||||
Note that this option alone doesn't cause any debugging information to be
|
||||
output. What it does is stop the normal suppression of execution-related
|
||||
debugging information during the matching portion of the compilation of
|
||||
wildcards. You also have to specify which execution debugging information you
|
||||
want, such as by also including the EXECUTE option.
|
||||
|
||||
=back
|
||||
|
||||
=item Other useful flags
|
||||
|
||||
These are useful shortcuts to save on the typing.
|
||||
|
||||
=over 4
|
||||
|
||||
=item ALL
|
||||
|
||||
Enable all options at once except OFFSETS, OFFSETSDBG, BUFFERS, WILDCARD, and
|
||||
DUMP_PRE_OPTIMIZE.
|
||||
(To get every single option without exception, use both ALL and EXTRA, or
|
||||
starting in 5.30 on a C<-DDEBUGGING>-enabled perl interpreter, use
|
||||
the B<-Drv> command-line switches.)
|
||||
|
||||
=item All
|
||||
|
||||
Enable DUMP and all non-extra execute options. Equivalent to:
|
||||
|
||||
use re 'debug';
|
||||
|
||||
=item MORE
|
||||
|
||||
=item More
|
||||
|
||||
Enable the options enabled by "All", plus STATE, TRIEC, and TRIEM.
|
||||
|
||||
=back
|
||||
|
||||
=back
|
||||
|
||||
As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
|
||||
lexically scoped, as are the other directives. However they have both
|
||||
compile-time and run-time effects.
|
||||
|
||||
=head2 Exportable Functions
|
||||
|
||||
As of perl 5.9.5 're' debug contains a number of utility functions that
|
||||
may be optionally exported into the caller's namespace. They are listed
|
||||
below.
|
||||
|
||||
=over 4
|
||||
|
||||
=item is_regexp($ref)
|
||||
|
||||
Returns true if the argument is a compiled regular expression as returned
|
||||
by C<qr//>, false if it is not.
|
||||
|
||||
This function will not be confused by overloading or blessing. In
|
||||
internals terms, this extracts the regexp pointer out of the
|
||||
PERL_MAGIC_qr structure so it cannot be fooled.
|
||||
|
||||
=item regexp_pattern($ref)
|
||||
|
||||
If the argument is a compiled regular expression as returned by C<qr//>,
|
||||
then this function returns the pattern.
|
||||
|
||||
In list context it returns a two element list, the first element
|
||||
containing the pattern and the second containing the modifiers used when
|
||||
the pattern was compiled.
|
||||
|
||||
my ($pat, $mods) = regexp_pattern($ref);
|
||||
|
||||
In scalar context it returns the same as perl would when stringifying a raw
|
||||
C<qr//> with the same pattern inside. If the argument is not a compiled
|
||||
reference then this routine returns false but defined in scalar context,
|
||||
and the empty list in list context. Thus the following
|
||||
|
||||
if (regexp_pattern($ref) eq '(?^i:foo)')
|
||||
|
||||
will be warning free regardless of what $ref actually is.
|
||||
|
||||
Like C<is_regexp> this function will not be confused by overloading
|
||||
or blessing of the object.
|
||||
|
||||
=item regmust($ref)
|
||||
|
||||
If the argument is a compiled regular expression as returned by C<qr//>,
|
||||
then this function returns what the optimiser considers to be the longest
|
||||
anchored fixed string and longest floating fixed string in the pattern.
|
||||
|
||||
A I<fixed string> is defined as being a substring that must appear for the
|
||||
pattern to match. An I<anchored fixed string> is a fixed string that must
|
||||
appear at a particular offset from the beginning of the match. A I<floating
|
||||
fixed string> is defined as a fixed string that can appear at any point in
|
||||
a range of positions relative to the start of the match. For example,
|
||||
|
||||
my $qr = qr/here .* there/x;
|
||||
my ($anchored, $floating) = regmust($qr);
|
||||
print "anchored:'$anchored'\nfloating:'$floating'\n";
|
||||
|
||||
results in
|
||||
|
||||
anchored:'here'
|
||||
floating:'there'
|
||||
|
||||
Because the C<here> is before the C<.*> in the pattern, its position
|
||||
can be determined exactly. That's not true, however, for the C<there>;
|
||||
it could appear at any point after where the anchored string appeared.
|
||||
Perl uses both for its optimisations, preferring the longer, or, if they are
|
||||
equal, the floating.
|
||||
|
||||
B<NOTE:> This may not necessarily be the definitive longest anchored and
|
||||
floating string. This will be what the optimiser of the Perl that you
|
||||
are using thinks is the longest. If you believe that the result is wrong
|
||||
please report it via the L<perlbug> utility.
|
||||
|
||||
=item regname($name,$all)
|
||||
|
||||
Returns the contents of a named buffer of the last successful match. If
|
||||
$all is true, then returns an array ref containing one entry per buffer,
|
||||
otherwise returns the first defined buffer.
|
||||
|
||||
=item regnames($all)
|
||||
|
||||
Returns a list of all of the named buffers defined in the last successful
|
||||
match. If $all is true, then it returns all names defined, if not it returns
|
||||
only names which were involved in the match.
|
||||
|
||||
=item regnames_count()
|
||||
|
||||
Returns the number of distinct names defined in the pattern used
|
||||
for the last successful match.
|
||||
|
||||
B<Note:> this result is always the actual number of distinct
|
||||
named buffers defined, it may not actually match that which is
|
||||
returned by C<regnames()> and related routines when those routines
|
||||
have not been called with the $all parameter set.
|
||||
|
||||
=back
|
||||
|
||||
=head1 SEE ALSO
|
||||
|
||||
L<perlmodlib/Pragmatic Modules>.
|
||||
|
||||
=cut
|
||||
Reference in New Issue
Block a user