lib/Attribute/Handlers/demo/demo_rawdata.pl Attribute::Handlers demo
lib/Attribute/Handlers/demo/Descriptions.pm Attribute::Handlers demo
lib/Attribute/Handlers/demo/MyClass.pm Attribute::Handlers demo
-lib/Attribute/Handlers/README Attribute::Handlers
-lib/Attribute/Handlers/test.pl See if Attribute::Handlers works
+lib/Attribute/Handlers/README Attribute::Handlers
+lib/Attribute/Handlers/t/multi.t See if Attribute::Handlers works
lib/attributes.pm For "sub foo : attrlist"
lib/AutoLoader.pm Autoloader base class
lib/AutoLoader.t See if AutoLoader works
lib/FileHandle.t See if FileHandle works
lib/filetest.pm For "use filetest"
lib/Filter/Simple.pm Simple frontend to Filter::Util::Call
-lib/Filter/Simple/test.pl See if Filter::Simple works
+lib/Filter/Simple/Changes Filter::Simple
+lib/Filter/Simple/README Filter::Simple
+lib/Filter/Simple/t/filter.t See if Filter::Simple works
lib/find.pl A find emulator--used by find2perl
lib/FindBin.pm Find name of currently executing program
lib/FindBin.t See if FindBin works
lib/Net/t/smtp.t libnet
lib/Net/Time.pm libnet
lib/newgetopt.pl A perl library supporting long option parsing
-lib/NEXT.pm Pseudo-class NEXT for method redispatch
+lib/NEXT.pm Pseudo-class NEXT for method redispatch
+lib/NEXT/Changes NEXT
+lib/NEXT/README NEXT
lib/NEXT/test.pl See if NEXT works
lib/open.pm Pragma to specify default I/O disciplines
lib/open2.pl Open a two-ended pipe (uses IPC::Open2)
lib/subs.pm Declare overriding subs
lib/subs.t See if subroutine pseudo-importation works
lib/Switch.pm Switch for Perl
-lib/Switch/Changes Switch for Perl
-lib/Switch/README Switch for Perl
-lib/Switch/t/given_when.t See if Perl 6 given (switch) works
-lib/Switch/t/switch_case.t See if Perl 5 switch works
+lib/Switch/Changes Switch
+lib/Switch/README Switch
+lib/Switch/t/given.t See if Perl 6 given (switch) works
+lib/Switch/t/nested.t See if nested switch works
+lib/Switch/t/switch.t See if Perl 5 switch works
lib/Symbol.pm Symbol table manipulation routines
lib/Symbol.t See if Symbol works
lib/syslog.pl Perl library supporting syslogging
lib/Text/Abbrev.pm An abbreviation table builder
lib/Text/Abbrev.t Test Text::Abbrev
lib/Text/Balanced.pm Text::Balanced
-lib/Text/Balanced.pod Text::Balanced
-lib/Text/Balanced/t/genxt.t See if Text::Balanced works
-lib/Text/Balanced/t/xbrak.t See if Text::Balanced works
-lib/Text/Balanced/t/xcode.t See if Text::Balanced works
-lib/Text/Balanced/t/xdeli.t See if Text::Balanced works
-lib/Text/Balanced/t/xmult.t See if Text::Balanced works
-lib/Text/Balanced/t/xquot.t See if Text::Balanced works
-lib/Text/Balanced/t/xtagg.t See if Text::Balanced works
-lib/Text/Balanced/t/xvari.t See if Text::Balanced works
+lib/Text/Balanced/Changes Text::Balanced
+lib/Text/Balanced/README Text::Balanced
+lib/Text/Balanced/t/gentag.t See if Text::Balanced works
+lib/Text/Balanced/t/extbrk.t See if Text::Balanced works
+lib/Text/Balanced/t/extcbk.t See if Text::Balanced works
+lib/Text/Balanced/t/extdel.t See if Text::Balanced works
+lib/Text/Balanced/t/extmul.t See if Text::Balanced works
+lib/Text/Balanced/t/extqlk.t See if Text::Balanced works
+lib/Text/Balanced/t/exttag.t See if Text::Balanced works
+lib/Text/Balanced/t/extvar.t See if Text::Balanced works
lib/Text/ParseWords.pm Perl module to split words on arbitrary delimiter
lib/Text/ParseWords.t See if Text::ParseWords works
lib/Text/Soundex.pm Perl module to implement Soundex
use 5.006;
use Carp;
use warnings;
-$VERSION = '0.70';
-$DB::single=1;
+$VERSION = '0.75';
+# $DB::single=1;
my %symcache;
sub findsym {
croak "Usage: use $_[0] autotie => {AttrName => TieClassName,...}";
}
+my $qual_id = qr/^[_a-z]\w*(::[_a-z]\w*)*$/i;
+
sub import {
my $class = shift @_;
return unless $class eq "Attribute::Handlers";
while (@_) {
my $cmd = shift;
- if ($cmd eq 'autotie') {
+ if ($cmd =~ /^autotie((?:ref)?)$/) {
+ my $tiedata = '($was_arrayref ? $data : @$data)';
+ $tiedata = ($1 ? '$ref, ' : '') . $tiedata;
my $mapping = shift;
_usage_AH_ $class unless ref($mapping) eq 'HASH';
while (my($attr, $tieclass) = each %$mapping) {
- $tieclass =~ s/^([_a-z]\w*(::[_a-z]\w*))(.*)/$1/is;
+ $tieclass =~ s/^([_a-z]\w*(::[_a-z]\w*)*)(.*)/$1/is;
my $args = $3||'()';
- usage $class unless $attr =~ m/^[_a-z]\w*(::[_a-z]\w*)*$/i
- && $tieclass =~ m/^[_a-z]\w*(::[_a-z]\w*)/i
+ _usage_AH_ $class unless $attr =~ $qual_id
+ && $tieclass =~ $qual_id
&& eval "use base $tieclass; 1";
if ($tieclass->isa('Exporter')) {
local $Exporter::ExportLevel = 2;
eval qq{
sub $attr : ATTR(VAR) {
my (\$ref, \$data) = \@_[2,4];
- \$data = [ \$data ] unless ref \$data eq 'ARRAY';
- # print \$ref, ": ";
- # use Data::Dumper 'Dumper';
- # print Dumper [ [\$ref, \$data] ];
+ my \$was_arrayref = ref \$data eq 'ARRAY';
+ \$data = [ \$data ] unless \$was_arrayref;
my \$type = ref(\$ref)||"value (".(\$ref||"<undef>").")";
- (\$type eq 'SCALAR')? tie \$\$ref,'$tieclass',\@\$data
- :(\$type eq 'ARRAY') ? tie \@\$ref,'$tieclass',\@\$data
- :(\$type eq 'HASH') ? tie \%\$ref,'$tieclass',\@\$data
+ (\$type eq 'SCALAR')? tie \$\$ref,'$tieclass',$tiedata
+ :(\$type eq 'ARRAY') ? tie \@\$ref,'$tieclass',$tiedata
+ :(\$type eq 'HASH') ? tie \%\$ref,'$tieclass',$tiedata
: die "Can't autotie a \$type\n"
} 1
} or die "Internal error: $@";
}
sub AUTOLOAD {
- my ($class) = @_;
- $AUTOLOAD =~ /_ATTR_(.*?)_(.*)/ or
+ my ($class) = $AUTOLOAD =~ m/(.*)::/g;
+ $AUTOLOAD =~ m/_ATTR_(.*?)_(.*)/ or
croak "Can't locate class method '$AUTOLOAD' via package '$class'";
- croak "Attribute handler '$2' doesn't handle $1 attributes";
+ croak "Attribute handler '$3' doesn't handle $2 attributes";
}
sub DESTROY {}
_resolve_lastattr;
my ($pkg, $ref, @attrs) = @_;
foreach (@attrs) {
- my ($attr, $data) = /^([a-z_]\w*)(?:[(](.*)[)])?$/i or next;
+ my ($attr, $data) = /^([a-z_]\w*)(?:[(](.*)[)])?$/is or next;
if ($attr eq 'ATTR') {
$data ||= "ANY";
$raw{$ref} = $data =~ s/\s*,?\s*RAWDATA\s*,?\s*//;
=head1 VERSION
-This document describes version 0.70 of Attribute::Handlers,
-released June 3, 2001.
+This document describes version 0.75 of Attribute::Handlers,
+released September 3, 2001.
=head1 SYNOPSIS
package Tie::Me::Kangaroo:Down::Sport;
- use Attribute::Handler autotie => { __CALLER__::Roo => __PACKAGE__ };
+ use Attribute::Handlers autotie => { __CALLER__::Roo => __PACKAGE__ };
This causes Attribute::Handlers to define the C<Roo> attribute in the package
that imports the Tie::Me::Kangaroo:Down::Sport module.
+=head3 Passing the tied object to C<tie>
+
+Occasionally it is important to pass a reference to the object being tied
+to the TIESCALAR, TIEHASH, etc. that ties it.
+
+The C<autotie> mechanism supports this too. The following code:
+
+ use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
+ my $var : Selfish(@args);
+
+has the same effect as:
+
+ tie my $var, 'Tie::Selfish', @args;
+
+But when C<"autotieref"> is used instead of C<"autotie">:
+
+ use Attribute::Handlers autotieref => { Selfish => Tie::Selfish };
+ my $var : Selfish(@args);
+
+the effect is to pass the C<tie> call an extra reference to the variable
+being tied:
+
+ tie my $var, 'Tie::Selfish', \$var, @args;
+
+
=head1 EXAMPLES
Copyright (c) 2001, Damian Conway. All Rights Reserved.
This module is free software. It may be used, redistributed
- and/or modified under the terms of the Perl Artistic License
- (see http://www.perl.com/perl/misc/Artistic.html)
+ and/or modified under the same terms as Perl itself.
- Critical doc patch
-0.65 Sun Jun 3 07:40:03 2001
+0.70 Sun Jun 3 07:40:03 2001
- Added __CALLER__ pseudo class for 'autotie'
- Cleaned up interactions with other class hierarchies
(due to being base class of UNIVERSAL)
+
+
+0.75 Mon Sep 3 09:07:08 2001
+
+ - Cleaned up AUTOLOAD
+
+ - Numerous bug fixes (thanks Pete)
+
+ - Fixed handling of attribute data that includes a newline (thanks Pete)
+
+ - Added "autotieref" option (thanks Pete)
+
+ - Switched off $DB::single
+
+ - Changed licence for inclusion in core distribution
+
+ - Fixed 'autotie' for tied classes with multi-level names (thanks Jeff)
==============================================================================
- Release of version 0.70 of Attribute::Handlers
+ Release of version 0.75 of Attribute::Handlers
==============================================================================
COPYRIGHT
Copyright (c) 2001, Damian Conway. All Rights Reserved.
This module is free software. It may be used, redistributed
- and/or modified under the terms of the Perl Artistic License
- (see http://www.perl.com/perl/misc/Artistic.html)
+ and/or modified under the same terms as Perl itself.
==============================================================================
-CHANGES IN VERSION 0.70
+CHANGES IN VERSION 0.75
+
+
+ - Cleaned up AUTOLOAD
+
+ - Numerous bug fixes (thanks Pete)
+
+ - Fixed handling of attribute data that includes a newline (thanks Pete)
+
+ - Added "autotieref" option (thanks Pete)
+
+ - Switched off $DB::single
+
+ - Changed licence for inclusion in core distribution
+
+ - Fixed 'autotie' for tied classes with multi-level names (thanks Jeff)
-(No changes have been documented for this version)
==============================================================================
use base Demo;
my $y : Demo :This($this) = sub : Demo(1,2,3) {};
-sub x : Demo(4,5,6) :Multi {}
+sub x : Demo(4, 5, 6) :Multi {}
my %z : Demo(hash) :Multi(method,maybe);
# my %a : NDemo(hash);
-use Attribute::Handlers autotie => { Cycle => Tie::Cycle };
+package Selfish;
-my $next : Cycle(['A'..'Z']);
+sub TIESCALAR {
+ use Data::Dumper 'Dumper';
+ print Dumper [ \@_ ];
+ bless {}, $_[0];
+}
-print tied $next, "\n";
+package main;
-while (<>) {
- print $next, "\n";
-}
+use Attribute::Handlers autotieref => { Selfish => Selfish };
+
+my $next : Selfish("me");
+
+print "$next\n";
--- /dev/null
+END {print "not ok 1\n" unless $loaded;}
+use v5.6.0;
+use Attribute::Handlers;
+$loaded = 1;
+
+CHECK { $main::phase++ }
+
+######################### End of black magic.
+
+# Insert your test code below (better if it prints "ok 13"
+# (correspondingly "not ok 13") depending on the success of chunk 13
+# of the test code):
+
+sub ok { $::count++; push @::results, [$_[1], $_[0]?"":"not "]; }
+
+END { print "1..$::count\n";
+ print map "$_->[1]ok $_->[0]\n",
+ sort {$a->[0]<=>$b->[0]}
+ grep $_->[0], @::results }
+
+package Test;
+use warnings;
+no warnings 'redefine';
+
+sub UNIVERSAL::Lastly :ATTR(INIT) { ::ok $_[4][0] && $main::phase, $_[4][1] }
+
+sub UNIVERSAL::Okay :ATTR(BEGIN) { ::ok $_[4][0] && !$main::phase, $_[4][1] }
+
+sub Dokay :ATTR(SCALAR) { ::ok @{$_[4]} }
+sub Dokay :ATTR(HASH) { ::ok @{$_[4]} }
+sub Dokay :ATTR(ARRAY) { ::ok @{$_[4]} }
+sub Dokay :ATTR(CODE) { ::ok @{$_[4]} }
+
+sub Vokay :ATTR(VAR) { ::ok @{$_[4]} }
+
+sub Aokay :ATTR(ANY) { ::ok @{$_[4]} }
+
+package main;
+use warnings;
+
+my $x1 :Lastly(1,41);
+my @x1 :Lastly(1=>42);
+my %x1 :Lastly(1,43);
+sub x1 :Lastly(1,44) {}
+
+my Test $x2 :Dokay(1,5);
+
+package Test;
+my $x3 :Dokay(1,6);
+my Test $x4 :Dokay(1,7);
+sub x3 :Dokay(1,8) {}
+
+my $y1 :Okay(1,9);
+my @y1 :Okay(1,10);
+my %y1 :Okay(1,11);
+sub y1 :Okay(1,12) {}
+
+my $y2 :Vokay(1,13);
+my @y2 :Vokay(1,14);
+my %y2 :Vokay(1,15);
+# BEGIN {eval 'sub y2 :Vokay(0,16) {}; 1' or
+::ok(1,16);
+# }
+
+my $z :Aokay(1,17);
+my @z :Aokay(1,18);
+my %z :Aokay(1,19);
+sub z :Aokay(1,20) {};
+
+package DerTest;
+use base 'Test';
+use warnings;
+
+my $x5 :Dokay(1,21);
+my Test $x6 :Dokay(1,22);
+sub x5 :Dokay(1,23);
+
+my $y3 :Okay(1,24);
+my @y3 :Okay(1,25);
+my %y3 :Okay(1,26);
+sub y3 :Okay(1,27) {}
+
+package Unrelated;
+
+my $x11 :Okay(1,1);
+my @x11 :Okay(1=>2);
+my %x11 :Okay(1,3);
+sub x11 :Okay(1,4) {}
+
+BEGIN { eval 'my $x7 :Dokay(0,28)' or ::ok(1,28); }
+my Test $x8 :Dokay(1,29);
+eval 'sub x7 :Dokay(0,30) {}' or ::ok(1,30);
+
+
+package Tie::Loud;
+
+sub TIESCALAR { ::ok(1,31); bless {}, $_[0] }
+sub FETCH { ::ok(1,32); return 1 }
+sub STORE { ::ok(1,33); return 1 }
+
+package Tie::Noisy;
+
+sub TIEARRAY { ::ok(1,$_[1]); bless {}, $_[0] }
+sub FETCH { ::ok(1,35); return 1 }
+sub STORE { ::ok(1,36); return 1 }
+sub FETCHSIZE { 100 }
+
+package Tie::Row::dy;
+
+sub TIEHASH { ::ok(1,$_[1]); bless {}, $_[0] }
+sub FETCH { ::ok(1,38); return 1 }
+sub STORE { ::ok(1,39); return 1 }
+
+package main;
+
+eval 'sub x7 :ATTR(SCALAR) :ATTR(CODE) {}' and ::ok(0,40) or ::ok(1,40);
+
+use Attribute::Handlers autotie => { Other::Loud => Tie::Loud,
+ Noisy => Tie::Noisy,
+ UNIVERSAL::Rowdy => Tie::Row::dy,
+ };
+
+my Other $loud : Loud;
+$loud++;
+
+my @noisy : Noisy(34);
+$noisy[0]++;
+
+my %rowdy : Rowdy(37);
+$rowdy{key}++;
+
use vars qw{ $VERSION };
-$VERSION = '0.60';
+$VERSION = '0.61';
use Filter::Util::Call;
use Carp;
sub FILTER (&;$) {
my $caller = caller;
my ($filter, $terminator) = @_;
- croak "Usage: use Filter::Simple sub {...}, $terminator_opt;"
- unless ref $filter eq CODE;
*{"${caller}::import"} = gen_filter_import($caller,$filter,$terminator);
*{"${caller}::unimport"} = \*filter_unimport;
}
=item 1.
Download, build, and install the Filter::Util::Call module.
-(If you have Perl 5.7.1 or later you already have Filter::Util::Call.)
+(If you have Perl 5.7.1 or later, this is already done for you.)
=item 2.
=item 1.
+Download and install the Filter::Simple module.
+(If you have Perl 5.7.1 or later, this is already done for you.)
+
+=item 2.
+
Set up a module that does a C<use Filter::Simple> and then
calls C<FILTER { ... }>.
-=item 2.
+=item 3.
Within the anonymous subroutine or block that is passed to
C<FILTER>, process the contents of $_ to change the source code in
except that the C<FILTER> subroutine is not exported by Filter::Simple.
+=head2 Using Filter::Simple and Exporter together
+
+You can't directly use Exporter when Filter::Simple.
+
+Filter::Simple generates an C<import> subroutine for your module
+(which hides the one inherited from Exporter).
+
+The C<FILTER> code you specify will, however, receive the C<import>'s argument
+list, so you can use that filter block as your C<import> subroutine.
+
+You'll need to call C<Exporter::export_to_level> from your C<FILTER> code
+to make it work correctly.
+
+For example:
+
+ use Filter::Simple;
+
+ use base Exporter;
+ @EXPORT = qw(foo);
+ @EXPORT_OK = qw(bar);
+
+ sub foo { print "foo\n" }
+ sub bar { print "bar\n" }
+
+ FILTER {
+ # Your filtering code here
+ __PACKAGE__->export_to_level(2,undef,@_);
+ }
+
=head2 How it works
=head1 COPYRIGHT
- Copyright (c) 2000, Damian Conway. All Rights Reserved.
- This module is free software. It may be used, redistributed
-and/or modified under the terms of the Perl Artistic License
- (see http://www.perl.com/perl/misc/Artistic.html)
+ Copyright (c) 2000-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
--- /dev/null
+Revision history for Perl extension Filter::Simple
+
+0.01 Tue Sep 19 20:18:44 2000
+ - original version; created by h2xs 1.18
+
+0.01 Tue Sep 26 09:30:14 2000
+
+ - Changed module name to Filter::Simple
+
+
+0.60 Wed May 2 07:38:18 2001
+
+ - Fixed POD nit (thanks Dean)
+
+ - Added optional second argument to import to allow
+ terminator to be changed (thanks Brad)
+
+ - Fixed bug when empty filtered text was appended to (thanks Brad)
+
+ - Added FILTER as the normal mechanism for specifying filters
+
+
+0.61 Mon Sep 3 08:25:21 2001
+
+ - Added a real test suite (thanks Jarkko)
+
+ - Changed licence to facilitate inclusion in
+ core distribution
+
+ - Added documentation for using F::S and Exporter together
+
+
--- /dev/null
+==============================================================================
+ Release of version 0.61 of Filter::Simple
+==============================================================================
+
+
+NAME
+ Filter::Simple - Simplified source filtering
+
+SYNOPSIS
+ # in MyFilter.pm:
+
+ package MyFilter;
+
+ use Filter::Simple;
+
+ FILTER { ... };
+
+ # or just:
+ #
+ # use Filter::Simple sub { ... };
+
+
+ # in user's code:
+
+ use MyFilter;
+
+ # this is filtered
+
+ no MyFilter;
+
+ # this is not
+
+
+DESCRIPTION
+ The Filter::Simple module provides a simplified interface to
+ Filter::Util::Call; one that is sufficient for most common cases.
+
+AUTHOR
+ Damian Conway (damian@conway.org)
+
+COPYRIGHT
+ Copyright (c) 2000-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
+
+
+==============================================================================
+
+CHANGES IN VERSION 0.61
+
+(No changes have been documented for this version)
+
+==============================================================================
+
+AVAILABILITY
+
+Filter::Simple has been uploaded to the CPAN
+and is also available from:
+
+ http://www.csse.monash.edu.au/~damian/CPAN/Filter-Simple.tar.gz
+
+==============================================================================
-#!./perl
-
-BEGIN {
- chdir('t') if -d 't';
- @INC = 'lib';
-}
-
+use FilterTest qr/not ok/ => "ok", fail => "ok";
print "1..6\n";
-use MyFilter qr/not ok/ => "ok", fail => "ok";
-
sub fail { print "fail ", $_[0], "\n" }
print "not ok 1\n";
print "not " unless "whatnot okapi" eq "whatokapi";
print "ok 5\n";
-no MyFilter;
+no FilterTest;
print "not " unless "not ok" =~ /^not /;
print "ok 6\n";
}
no strict 'refs';
@{$NEXT::NEXT{$self,$wanted_method}} =
- map { *{"${_}::$caller_method"}{CODE}||() } @forebears;
+ map { *{"${_}::$caller_method"}{CODE}||() } @forebears
+ unless $wanted_method eq 'AUTOLOAD';
@{$NEXT::NEXT{$self,$wanted_method}} =
- map { *{"${_}::AUTOLOAD"}{CODE}||() } @forebears
- unless @{$NEXT::NEXT{$self,$wanted_method}};
+ map { (*{"${_}::AUTOLOAD"}{CODE}) ?
+ "${_}::AUTOLOAD" : () } @forebears
+ unless @{$NEXT::NEXT{$self,$wanted_method}||[]};
+ }
+ my $call_method = shift @{$NEXT::NEXT{$self,$wanted_method}};
+ return unless defined $call_method;
+ if (ref $call_method eq 'CODE') {
+ return shift()->$call_method(@_)
+ }
+ else { # AN AUTOLOAD
+ no strict 'refs';
+ ${$call_method} = $caller_method eq 'AUTOLOAD' && ${"${caller_class}::AUTOLOAD"} || $wanted;
+ return $call_method->(@_);
}
- $wanted_method = shift @{$NEXT::NEXT{$self,$wanted_method}};
- return shift()->$wanted_method(@_) if $wanted_method;
- return;
}
1;
C<m> is redispatched as if the calling method had not originally been found.
In other words, a call to C<$self->NEXT::m()> resumes the depth-first,
-left-to-right search of parent classes that resulted in the original
-call to C<m>.
+left-to-right search of C<$self>'s class hierarchy that resulted in the
+original call to C<m>.
+
+Note that this is not the same thing as C<$self->SUPER::m()>, which
+begins a new dispatch that is restricted to searching the ancestors
+of the current class. C<$self->NEXT::m()> can backtrack
+past the current class -- to look for a suitable method in other
+ancestors of C<$self> -- whereas C<$self->SUPER::m()> cannot.
A typical use would be in the destructors of a class hierarchy,
as illustrated in the synopsis above. Each class in the hierarchy
=head1 COPYRIGHT
- Copyright (c) 2000, Damian Conway. All Rights Reserved.
+ Copyright (c) 2000-2001, Damian Conway. All Rights Reserved.
This module is free software. It may be used, redistributed
-and/or modified under the terms of the Perl Artistic License
- (see http://www.perl.com/perl/misc/Artistic.html)
+ and/or modified under the same terms as Perl itself.
--- /dev/null
+Revision history for Perl extension NEXT.pm.
+
+0.01 Tue Apr 10 18:27:00 EST 2001
+
+ - original version
+
+
+0.01 Thu Apr 12 17:06:49 2001
+
+ - Documented the difference between NEXT and SUPER (thanks Ken)
+
+
+
+0.01 Thu Apr 12 17:15:42 2001
+
+
+
+0.02 Mon Sep 3 07:52:27 2001
+
+ - Fixed setting of $AUTOLOAD in NEXT'd AUTOLOADS (thanks Leonid)
+
+ - Changed licence for inclusion in core distribution
--- /dev/null
+==============================================================================
+ Release of version 0.02 of NEXT
+==============================================================================
+
+
+NAME
+
+ NEXT - Pseudo class for method redispatch
+
+
+DESCRIPTION
+
+ NEXT.pm adds a pseudoclass named C<NEXT> to any program that
+ uses it. If a method C<m> calls C<$self->NEXT::m()>, the call to
+ C<m> is redispatched as if the calling method had not originally
+ been found.
+
+ In other words, a call to C<$self->NEXT::m()> resumes the
+ depth-first, left-to-right search of parent classes that
+ resulted in the original call to C<m>.
+
+ Note that this is not the same thing as C<$self->SUPER::m()>, which
+ begins a new dispatch that is restricted to searching the ancestors
+ of the current class. C<$self->NEXT::m()> can backtrack past
+ the current class -- to look for a suitable method in other
+ ancestors of C<$self> -- whereas C<$self->SUPER::m()> cannot.
+
+ An particularly interesting use of redispatch is in
+ C<AUTOLOAD>'ed methods. If such a method determines that it is
+ not able to handle a particular call, it may choose to
+ redispatch that call, in the hope that some other C<AUTOLOAD>
+ (above it, or to its left) might do better.
+
+ Note that it is a fatal error for any method (including C<AUTOLOAD>)
+ to attempt to redispatch any method except itself. For example:
+
+ sub D::oops { $_[0]->NEXT::other_method() } # BANG!
+
+
+AUTHOR
+
+ Damian Conway (damian@conway.org)
+
+
+COPYRIGHT
+
+ Copyright (c) 2000-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
+
+
+==============================================================================
+
+CHANGES IN VERSION 0.02
+
+
+ - Fixed setting of $AUTOLOAD in NEXT'd AUTOLOADS (thanks Leonid)
+
+ - Changed licence for inclusion in core distribution
+
+
+==============================================================================
+
+AVAILABILITY
+
+NEXT has been uploaded to the CPAN
+and is also available from:
+
+ http://www.csse.monash.edu.au/~damian/CPAN/NEXT.tar.gz
+
+==============================================================================
#! /usr/local/bin/perl -w
-
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
-BEGIN { print "1..20\n"; }
+BEGIN { print "1..25\n"; }
use NEXT;
package B;
use base qw( A );
-sub B::AUTOLOAD { return ( 9, $_[0]->NEXT::AUTOLOAD() ) }
+sub B::AUTOLOAD { return ( 9, $_[0]->NEXT::AUTOLOAD() )
+ if $AUTOLOAD =~ /.*(missing_method|secondary)/ }
sub B::DESTROY { $_[0]->NEXT::DESTROY() }
package C;
-sub C::DESTROY { print "ok 18\n"; $_[0]->NEXT::DESTROY() }
+sub C::DESTROY { print "ok 23\n"; $_[0]->NEXT::DESTROY() }
package D;
@D::ISA = qw( B C E );
sub D::method { return ( 2, $_[0]->NEXT::method() ) }
sub D::AUTOLOAD { return ( 8, $_[0]->NEXT::AUTOLOAD() ) }
-sub D::DESTROY { print "ok 17\n"; $_[0]->NEXT::DESTROY() }
+sub D::DESTROY { print "ok 22\n"; $_[0]->NEXT::DESTROY() }
sub D::oops { $_[0]->NEXT::method() }
+sub D::secondary { return ( 17, 18, map { $_+10 } $_[0]->NEXT::secondary() ) }
package E;
@E::ISA = qw( F G );
sub E::method { return ( 4, $_[0]->NEXT::method(), $_[0]->NEXT::method() ) }
-sub E::AUTOLOAD { return ( 10, $_[0]->NEXT::AUTOLOAD() ) }
-sub E::DESTROY { print "ok 19\n"; $_[0]->NEXT::DESTROY() }
+sub E::AUTOLOAD { return ( 10, $_[0]->NEXT::AUTOLOAD() )
+ if $AUTOLOAD =~ /.*(missing_method|secondary)/ }
+sub E::DESTROY { print "ok 24\n"; $_[0]->NEXT::DESTROY() }
package F;
sub F::method { return ( 5 ) }
-sub F::AUTOLOAD { return ( 11 ) }
-sub F::DESTROY { print "ok 20\n" }
+sub F::AUTOLOAD { return ( 11 ) if $AUTOLOAD =~ /.*(missing_method|secondary)/ }
+sub F::DESTROY { print "ok 25\n" }
package G;
sub G::method { return ( 6 ) }
print "ok 12\n";
# AUTOLOAD'ED METHOD CAN'T REDISPATCH TO NAMED METHOD (ok 13)
-eval q{
- package C;
- sub AUTOLOAD { $_[0]->NEXT::method() };
+
+eval {
+ local *C::AUTOLOAD = sub { $_[0]->NEXT::method() };
+ *C::AUTOLOAD = *C::AUTOLOAD;
+ eval { $obj->missing_method(); } && print "not ";
};
-eval { $obj->missing_method(); } && print "not ";
print "ok 13\n";
# NAMED METHOD CAN'T REDISPATCH TO AUTOLOAD'ED METHOD (ok 14)
-eval q{
- package C;
- sub method { $_[0]->NEXT::AUTOLOAD() };
+eval {
+ *C::method = sub{ $_[0]->NEXT::AUTOLOAD() };
+ *C::method = *C::method;
+ eval { $obj->method(); } && print "not ";
};
-eval { $obj->method(); } && print "not ";
print "ok 14\n";
# BASE CLASS METHODS ONLY REDISPATCHED WITHIN HIERARCHY (ok 15..16)
print "not " unless @val==1 && $val[0]==9;
print "ok 16\n";
-# CAN REDISPATCH DESTRUCTORS (ok 17..20)
+# TEST SECONDARY AUTOLOAD REDISPATCH (ok 17..21)
+@vals = $obj->secondary();
+print map "ok $_\n", @vals;
+
+# CAN REDISPATCH DESTRUCTORS (ok 22..25)
use vars qw($VERSION);
use Carp;
-$VERSION = '2.04';
+$VERSION = '2.05';
# LOAD FILTERING MODULE...
=head1 VERSION
-This document describes version 2.04 of Switch,
-released July 30, 2001.
+This document describes version 2.05 of Switch,
+released September 3, 2001.
=head1 SYNOPSIS
=head1 COPYRIGHT
-Copyright (c) 1997-2000, Damian Conway. All Rights Reserved.
-This module is free software; you can redistribute it and/or
-modify it under the same terms as Perl itself.
+ Copyright (c) 1997-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
- Added support for Perl 6 given..when syntax
-2.04 Mon Jul 30 13:17:35 2001
+2.05 Mon Sep 3 08:13:25 2001
- - Suppressed 'undef value' warning under -w (thanks Michael)
+ - Changed licence for inclusion in core distribution
- - Added support for Perl 6 given..when syntax
+ - Added new test file for non-fallthrough and nested switches
==============================================================================
- Release of version 2.04 of Switch
+ Release of version 2.05 of Switch
==============================================================================
Damian Conway (damian@conway.org)
COPYRIGHT
- Copyright (c) 1997-2000, Damian Conway. All Rights Reserved. This module
- is free software. It may be used, redistributed and/or modified under
- the terms of the Perl Artistic License (see
- http://www.perl.com/perl/misc/Artistic.html)
+ Copyright (c) 1997-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
==============================================================================
-CHANGES IN VERSION 2.04
+CHANGES IN VERSION 2.05
- - Suppressed 'undef value' warning under -w (thanks Michael)
+ - Changed licence for inclusion in core distribution
- - Added support for Perl 6 given..when syntax
+ - Added new test file for non-fallthrough and nested switches
==============================================================================
--- /dev/null
+use Switch;
+
+print "1..4\n";
+
+my $count = 1;
+for my $count (1..3, 'four')
+{
+ switch ([$count])
+ {
+ case qr/\d/ {
+ switch ($count) {
+ case 1 { print "ok 1\n" }
+ case [2,3] { print "ok $count\n" }
+ }
+ }
+ case 'four' { print "ok 4\n" }
+ }
+}
use SelfLoader;
use vars qw { $VERSION @ISA %EXPORT_TAGS };
-$VERSION = '1.85';
+$VERSION = '1.86';
@ISA = qw ( Exporter );
%EXPORT_TAGS = ( ALL => [ qw(
# NEED TO COVER MANY MORE CASES HERE!!!
if ($$textref =~ m#\G\s*( [-+*x/%^&|.]=?
+ | [!=]~
| =(?!>)
| (\*\*|&&|\|\||<<|>>)=?
- | [!=][~=]
| split|grep|map|return
)#gcx)
{
use overload '""' => sub { "$_[0]->{error}, detected at offset $_[0]->{pos}" };
1;
+
+__END__
+
+=head1 NAME
+
+Text::Balanced - Extract delimited text sequences from strings.
+
+
+=head1 SYNOPSIS
+
+ use Text::Balanced qw (
+ extract_delimited
+ extract_bracketed
+ extract_quotelike
+ extract_codeblock
+ extract_variable
+ extract_tagged
+ extract_multiple
+
+ gen_delimited_pat
+ gen_extract_tagged
+ );
+
+ # Extract the initial substring of $text that is delimited by
+ # two (unescaped) instances of the first character in $delim.
+
+ ($extracted, $remainder) = extract_delimited($text,$delim);
+
+
+ # Extract the initial substring of $text that is bracketed
+ # with a delimiter(s) specified by $delim (where the string
+ # in $delim contains one or more of '(){}[]<>').
+
+ ($extracted, $remainder) = extract_bracketed($text,$delim);
+
+
+ # Extract the initial substring of $text that is bounded by
+ # an HTML/XML tag.
+
+ ($extracted, $remainder) = extract_tagged($text);
+
+
+ # Extract the initial substring of $text that is bounded by
+ # a C<BEGIN>...C<END> pair. Don't allow nested C<BEGIN> tags
+
+ ($extracted, $remainder) =
+ extract_tagged($text,"BEGIN","END",undef,{bad=>["BEGIN"]});
+
+
+ # Extract the initial substring of $text that represents a
+ # Perl "quote or quote-like operation"
+
+ ($extracted, $remainder) = extract_quotelike($text);
+
+
+ # Extract the initial substring of $text that represents a block
+ # of Perl code, bracketed by any of character(s) specified by $delim
+ # (where the string $delim contains one or more of '(){}[]<>').
+
+ ($extracted, $remainder) = extract_codeblock($text,$delim);
+
+
+ # Extract the initial substrings of $text that would be extracted by
+ # one or more sequential applications of the specified functions
+ # or regular expressions
+
+ @extracted = extract_multiple($text,
+ [ \&extract_bracketed,
+ \&extract_quotelike,
+ \&some_other_extractor_sub,
+ qr/[xyz]*/,
+ 'literal',
+ ]);
+
+# Create a string representing an optimized pattern (a la Friedl)
+# that matches a substring delimited by any of the specified characters
+# (in this case: any type of quote or a slash)
+
+ $patstring = gen_delimited_pat(q{'"`/});
+
+
+# Generate a reference to an anonymous sub that is just like extract_tagged
+# but pre-compiled and optimized for a specific pair of tags, and consequently
+# much faster (i.e. 3 times faster). It uses qr// for better performance on
+# repeated calls, so it only works under Perl 5.005 or later.
+
+ $extract_head = gen_extract_tagged('<HEAD>','</HEAD>');
+
+ ($extracted, $remainder) = $extract_head->($text);
+
+
+=head1 DESCRIPTION
+
+The various C<extract_...> subroutines may be used to extract a
+delimited string (possibly after skipping a specified prefix string).
+The search for the string always begins at the current C<pos>
+location of the string's variable (or at index zero, if no C<pos>
+position is defined).
+
+=head2 General behaviour in list contexts
+
+In a list context, all the subroutines return a list, the first three
+elements of which are always:
+
+=over 4
+
+=item [0]
+
+The extracted string, including the specified delimiters.
+If the extraction fails an empty string is returned.
+
+=item [1]
+
+The remainder of the input string (i.e. the characters after the
+extracted string). On failure, the entire string is returned.
+
+=item [2]
+
+The skipped prefix (i.e. the characters before the extracted string).
+On failure, the empty string is returned.
+
+=back
+
+Note that in a list context, the contents of the original input text (the first
+argument) are not modified in any way.
+
+However, if the input text was passed in a variable, that variable's
+C<pos> value is updated to point at the first character after the
+extracted text. That means that in a list context the various
+subroutines can be used much like regular expressions. For example:
+
+ while ( $next = (extract_quotelike($text))[0] )
+ {
+ # process next quote-like (in $next)
+ }
+
+
+=head2 General behaviour in scalar and void contexts
+
+In a scalar context, the extracted string is returned, having first been
+removed from the input text. Thus, the following code also processes
+each quote-like operation, but actually removes them from $text:
+
+ while ( $next = extract_quotelike($text) )
+ {
+ # process next quote-like (in $next)
+ }
+
+Note that if the input text is a read-only string (i.e. a literal),
+no attempt is made to remove the extracted text.
+
+In a void context the behaviour of the extraction subroutines is
+exactly the same as in a scalar context, except (of course) that the
+extracted substring is not returned.
+
+=head2 A note about prefixes
+
+Prefix patterns are matched without any trailing modifiers (C</gimsox> etc.)
+This can bite you if you're expecting a prefix specification like
+'.*?(?=<H1>)' to skip everything up to the first <H1> tag. Such a prefix
+pattern will only succeed if the <H1> tag is on the current line, since
+. normally doesn't match newlines.
+
+To overcome this limitation, you need to turn on /s matching within
+the prefix pattern, using the C<(?s)> directive: '(?s).*?(?=<H1>)'
+
+
+=head2 C<extract_delimited>
+
+The C<extract_delimited> function formalizes the common idiom
+of extracting a single-character-delimited substring from the start of
+a string. For example, to extract a single-quote delimited string, the
+following code is typically used:
+
+ ($remainder = $text) =~ s/\A('(\\.|[^'])*')//s;
+ $extracted = $1;
+
+but with C<extract_delimited> it can be simplified to:
+
+ ($extracted,$remainder) = extract_delimited($text, "'");
+
+C<extract_delimited> takes up to four scalars (the input text, the
+delimiters, a prefix pattern to be skipped, and any escape characters)
+and extracts the initial substring of the text that
+is appropriately delimited. If the delimiter string has multiple
+characters, the first one encountered in the text is taken to delimit
+the substring.
+The third argument specifies a prefix pattern that is to be skipped
+(but must be present!) before the substring is extracted.
+The final argument specifies the escape character to be used for each
+delimiter.
+
+All arguments are optional. If the escape characters are not specified,
+every delimiter is escaped with a backslash (C<\>).
+If the prefix is not specified, the
+pattern C<'\s*'> - optional whitespace - is used. If the delimiter set
+is also not specified, the set C</["'`]/> is used. If the text to be processed
+is not specified either, C<$_> is used.
+
+In list context, C<extract_delimited> returns a array of three
+elements, the extracted substring (I<including the surrounding
+delimiters>), the remainder of the text, and the skipped prefix (if
+any). If a suitable delimited substring is not found, the first
+element of the array is the empty string, the second is the complete
+original text, and the prefix returned in the third element is an
+empty string.
+
+In a scalar context, just the extracted substring is returned. In
+a void context, the extracted substring (and any prefix) are simply
+removed from the beginning of the first argument.
+
+Examples:
+
+ # Remove a single-quoted substring from the very beginning of $text:
+
+ $substring = extract_delimited($text, "'", '');
+
+ # Remove a single-quoted Pascalish substring (i.e. one in which
+ # doubling the quote character escapes it) from the very
+ # beginning of $text:
+
+ $substring = extract_delimited($text, "'", '', "'");
+
+ # Extract a single- or double- quoted substring from the
+ # beginning of $text, optionally after some whitespace
+ # (note the list context to protect $text from modification):
+
+ ($substring) = extract_delimited $text, q{"'};
+
+
+ # Delete the substring delimited by the first '/' in $text:
+
+ $text = join '', (extract_delimited($text,'/','[^/]*')[2,1];
+
+Note that this last example is I<not> the same as deleting the first
+quote-like pattern. For instance, if C<$text> contained the string:
+
+ "if ('./cmd' =~ m/$UNIXCMD/s) { $cmd = $1; }"
+
+then after the deletion it would contain:
+
+ "if ('.$UNIXCMD/s) { $cmd = $1; }"
+
+not:
+
+ "if ('./cmd' =~ ms) { $cmd = $1; }"
+
+
+See L<"extract_quotelike"> for a (partial) solution to this problem.
+
+
+=head2 C<extract_bracketed>
+
+Like C<"extract_delimited">, the C<extract_bracketed> function takes
+up to three optional scalar arguments: a string to extract from, a delimiter
+specifier, and a prefix pattern. As before, a missing prefix defaults to
+optional whitespace and a missing text defaults to C<$_>. However, a missing
+delimiter specifier defaults to C<'{}()[]E<lt>E<gt>'> (see below).
+
+C<extract_bracketed> extracts a balanced-bracket-delimited
+substring (using any one (or more) of the user-specified delimiter
+brackets: '(..)', '{..}', '[..]', or '<..>'). Optionally it will also
+respect quoted unbalanced brackets (see below).
+
+A "delimiter bracket" is a bracket in list of delimiters passed as
+C<extract_bracketed>'s second argument. Delimiter brackets are
+specified by giving either the left or right (or both!) versions
+of the required bracket(s). Note that the order in which
+two or more delimiter brackets are specified is not significant.
+
+A "balanced-bracket-delimited substring" is a substring bounded by
+matched brackets, such that any other (left or right) delimiter
+bracket I<within> the substring is also matched by an opposite
+(right or left) delimiter bracket I<at the same level of nesting>. Any
+type of bracket not in the delimiter list is treated as an ordinary
+character.
+
+In other words, each type of bracket specified as a delimiter must be
+balanced and correctly nested within the substring, and any other kind of
+("non-delimiter") bracket in the substring is ignored.
+
+For example, given the string:
+
+ $text = "{ an '[irregularly :-(] {} parenthesized >:-)' string }";
+
+then a call to C<extract_bracketed> in a list context:
+
+ @result = extract_bracketed( $text, '{}' );
+
+would return:
+
+ ( "{ an '[irregularly :-(] {} parenthesized >:-)' string }" , "" , "" )
+
+since both sets of C<'{..}'> brackets are properly nested and evenly balanced.
+(In a scalar context just the first element of the array would be returned. In
+a void context, C<$text> would be replaced by an empty string.)
+
+Likewise the call in:
+
+ @result = extract_bracketed( $text, '{[' );
+
+would return the same result, since all sets of both types of specified
+delimiter brackets are correctly nested and balanced.
+
+However, the call in:
+
+ @result = extract_bracketed( $text, '{([<' );
+
+would fail, returning:
+
+ ( undef , "{ an '[irregularly :-(] {} parenthesized >:-)' string }" );
+
+because the embedded pairs of C<'(..)'>s and C<'[..]'>s are "cross-nested" and
+the embedded C<'E<gt>'> is unbalanced. (In a scalar context, this call would
+return an empty string. In a void context, C<$text> would be unchanged.)
+
+Note that the embedded single-quotes in the string don't help in this
+case, since they have not been specified as acceptable delimiters and are
+therefore treated as non-delimiter characters (and ignored).
+
+However, if a particular species of quote character is included in the
+delimiter specification, then that type of quote will be correctly handled.
+for example, if C<$text> is:
+
+ $text = '<A HREF=">>>>">link</A>';
+
+then
+
+ @result = extract_bracketed( $text, '<">' );
+
+returns:
+
+ ( '<A HREF=">>>>">', 'link</A>', "" )
+
+as expected. Without the specification of C<"> as an embedded quoter:
+
+ @result = extract_bracketed( $text, '<>' );
+
+the result would be:
+
+ ( '<A HREF=">', '>>>">link</A>', "" )
+
+In addition to the quote delimiters C<'>, C<">, and C<`>, full Perl quote-like
+quoting (i.e. q{string}, qq{string}, etc) can be specified by including the
+letter 'q' as a delimiter. Hence:
+
+ @result = extract_bracketed( $text, '<q>' );
+
+would correctly match something like this:
+
+ $text = '<leftop: conj /and/ conj>';
+
+See also: C<"extract_quotelike"> and C<"extract_codeblock">.
+
+
+=head2 C<extract_tagged>
+
+C<extract_tagged> extracts and segments text between (balanced)
+specified tags.
+
+The subroutine takes up to five optional arguments:
+
+=over 4
+
+=item 1.
+
+A string to be processed (C<$_> if the string is omitted or C<undef>)
+
+=item 2.
+
+A string specifying a pattern to be matched as the opening tag.
+If the pattern string is omitted (or C<undef>) then a pattern
+that matches any standard HTML/XML tag is used.
+
+=item 3.
+
+A string specifying a pattern to be matched at the closing tag.
+If the pattern string is omitted (or C<undef>) then the closing
+tag is constructed by inserting a C</> after any leading bracket
+characters in the actual opening tag that was matched (I<not> the pattern
+that matched the tag). For example, if the opening tag pattern
+is specified as C<'{{\w+}}'> and actually matched the opening tag
+C<"{{DATA}}">, then the constructed closing tag would be C<"{{/DATA}}">.
+
+=item 4.
+
+A string specifying a pattern to be matched as a prefix (which is to be
+skipped). If omitted, optional whitespace is skipped.
+
+=item 5.
+
+A hash reference containing various parsing options (see below)
+
+=back
+
+The various options that can be specified are:
+
+=over 4
+
+=item C<reject =E<gt> $listref>
+
+The list reference contains one or more strings specifying patterns
+that must I<not> appear within the tagged text.
+
+For example, to extract
+an HTML link (which should not contain nested links) use:
+
+ extract_tagged($text, '<A>', '</A>', undef, {reject => ['<A>']} );
+
+=item C<ignore =E<gt> $listref>
+
+The list reference contains one or more strings specifying patterns
+that are I<not> be be treated as nested tags within the tagged text
+(even if they would match the start tag pattern).
+
+For example, to extract an arbitrary XML tag, but ignore "empty" elements:
+
+ extract_tagged($text, undef, undef, undef, {ignore => ['<[^>]*/>']} );
+
+(also see L<"gen_delimited_pat"> below).
+
+
+=item C<fail =E<gt> $str>
+
+The C<fail> option indicates the action to be taken if a matching end
+tag is not encountered (i.e. before the end of the string or some
+C<reject> pattern matches). By default, a failure to match a closing
+tag causes C<extract_tagged> to immediately fail.
+
+However, if the string value associated with <reject> is "MAX", then
+C<extract_tagged> returns the complete text up to the point of failure.
+If the string is "PARA", C<extract_tagged> returns only the first paragraph
+after the tag (up to the first line that is either empty or contains
+only whitespace characters).
+If the string is "", the the default behaviour (i.e. failure) is reinstated.
+
+For example, suppose the start tag "/para" introduces a paragraph, which then
+continues until the next "/endpara" tag or until another "/para" tag is
+encountered:
+
+ $text = "/para line 1\n\nline 3\n/para line 4";
+
+ extract_tagged($text, '/para', '/endpara', undef,
+ {reject => '/para', fail => MAX );
+
+ # EXTRACTED: "/para line 1\n\nline 3\n"
+
+Suppose instead, that if no matching "/endpara" tag is found, the "/para"
+tag refers only to the immediately following paragraph:
+
+ $text = "/para line 1\n\nline 3\n/para line 4";
+
+ extract_tagged($text, '/para', '/endpara', undef,
+ {reject => '/para', fail => MAX );
+
+ # EXTRACTED: "/para line 1\n"
+
+Note that the specified C<fail> behaviour applies to nested tags as well.
+
+=back
+
+On success in a list context, an array of 6 elements is returned. The elements are:
+
+=over 4
+
+=item [0]
+
+the extracted tagged substring (including the outermost tags),
+
+=item [1]
+
+the remainder of the input text,
+
+=item [2]
+
+the prefix substring (if any),
+
+=item [3]
+
+the opening tag
+
+=item [4]
+
+the text between the opening and closing tags
+
+=item [5]
+
+the closing tag (or "" if no closing tag was found)
+
+=back
+
+On failure, all of these values (except the remaining text) are C<undef>.
+
+In a scalar context, C<extract_tagged> returns just the complete
+substring that matched a tagged text (including the start and end
+tags). C<undef> is returned on failure. In addition, the original input
+text has the returned substring (and any prefix) removed from it.
+
+In a void context, the input text just has the matched substring (and
+any specified prefix) removed.
+
+
+=head2 C<gen_extract_tagged>
+
+(Note: This subroutine is only available under Perl5.005)
+
+C<gen_extract_tagged> generates a new anonymous subroutine which
+extracts text between (balanced) specified tags. In other words,
+it generates a function identical in function to C<extract_tagged>.
+
+The difference between C<extract_tagged> and the anonymous
+subroutines generated by
+C<gen_extract_tagged>, is that those generated subroutines:
+
+=over 4
+
+=item *
+
+do not have to reparse tag specification or parsing options every time
+they are called (whereas C<extract_tagged> has to effectively rebuild
+its tag parser on every call);
+
+=item *
+
+make use of the new qr// construct to pre-compile the regexes they use
+(whereas C<extract_tagged> uses standard string variable interpolation
+to create tag-matching patterns).
+
+=back
+
+The subroutine takes up to four optional arguments (the same set as
+C<extract_tagged> except for the string to be processed). It returns
+a reference to a subroutine which in turn takes a single argument (the text to
+be extracted from).
+
+In other words, the implementation of C<extract_tagged> is exactly
+equivalent to:
+
+ sub extract_tagged
+ {
+ my $text = shift;
+ $extractor = gen_extract_tagged(@_);
+ return $extractor->($text);
+ }
+
+(although C<extract_tagged> is not currently implemented that way, in order
+to preserve pre-5.005 compatibility).
+
+Using C<gen_extract_tagged> to create extraction functions for specific tags
+is a good idea if those functions are going to be called more than once, since
+their performance is typically twice as good as the more general-purpose
+C<extract_tagged>.
+
+
+=head2 C<extract_quotelike>
+
+C<extract_quotelike> attempts to recognize, extract, and segment any
+one of the various Perl quotes and quotelike operators (see
+L<perlop(3)>) Nested backslashed delimiters, embedded balanced bracket
+delimiters (for the quotelike operators), and trailing modifiers are
+all caught. For example, in:
+
+ extract_quotelike 'q # an octothorpe: \# (not the end of the q!) #'
+
+ extract_quotelike ' "You said, \"Use sed\"." '
+
+ extract_quotelike ' s{([A-Z]{1,8}\.[A-Z]{3})} /\L$1\E/; '
+
+ extract_quotelike ' tr/\\\/\\\\/\\\//ds; '
+
+the full Perl quotelike operations are all extracted correctly.
+
+Note too that, when using the /x modifier on a regex, any comment
+containing the current pattern delimiter will cause the regex to be
+immediately terminated. In other words:
+
+ 'm /
+ (?i) # CASE INSENSITIVE
+ [a-z_] # LEADING ALPHABETIC/UNDERSCORE
+ [a-z0-9]* # FOLLOWED BY ANY NUMBER OF ALPHANUMERICS
+ /x'
+
+will be extracted as if it were:
+
+ 'm /
+ (?i) # CASE INSENSITIVE
+ [a-z_] # LEADING ALPHABETIC/'
+
+This behaviour is identical to that of the actual compiler.
+
+C<extract_quotelike> takes two arguments: the text to be processed and
+a prefix to be matched at the very beginning of the text. If no prefix
+is specified, optional whitespace is the default. If no text is given,
+C<$_> is used.
+
+In a list context, an array of 11 elements is returned. The elements are:
+
+=over 4
+
+=item [0]
+
+the extracted quotelike substring (including trailing modifiers),
+
+=item [1]
+
+the remainder of the input text,
+
+=item [2]
+
+the prefix substring (if any),
+
+=item [3]
+
+the name of the quotelike operator (if any),
+
+=item [4]
+
+the left delimiter of the first block of the operation,
+
+=item [5]
+
+the text of the first block of the operation
+(that is, the contents of
+a quote, the regex of a match or substitution or the target list of a
+translation),
+
+=item [6]
+
+the right delimiter of the first block of the operation,
+
+=item [7]
+
+the left delimiter of the second block of the operation
+(that is, if it is a C<s>, C<tr>, or C<y>),
+
+=item [8]
+
+the text of the second block of the operation
+(that is, the replacement of a substitution or the translation list
+of a translation),
+
+=item [9]
+
+the right delimiter of the second block of the operation (if any),
+
+=item [10]
+
+the trailing modifiers on the operation (if any).
+
+=back
+
+For each of the fields marked "(if any)" the default value on success is
+an empty string.
+On failure, all of these values (except the remaining text) are C<undef>.
+
+
+In a scalar context, C<extract_quotelike> returns just the complete substring
+that matched a quotelike operation (or C<undef> on failure). In a scalar or
+void context, the input text has the same substring (and any specified
+prefix) removed.
+
+Examples:
+
+ # Remove the first quotelike literal that appears in text
+
+ $quotelike = extract_quotelike($text,'.*?');
+
+ # Replace one or more leading whitespace-separated quotelike
+ # literals in $_ with "<QLL>"
+
+ do { $_ = join '<QLL>', (extract_quotelike)[2,1] } until $@;
+
+
+ # Isolate the search pattern in a quotelike operation from $text
+
+ ($op,$pat) = (extract_quotelike $text)[3,5];
+ if ($op =~ /[ms]/)
+ {
+ print "search pattern: $pat\n";
+ }
+ else
+ {
+ print "$op is not a pattern matching operation\n";
+ }
+
+
+=head2 C<extract_quotelike> and "here documents"
+
+C<extract_quotelike> can successfully extract "here documents" from an input
+string, but with an important caveat in list contexts.
+
+Unlike other types of quote-like literals, a here document is rarely
+a contiguous substring. For example, a typical piece of code using
+here document might look like this:
+
+ <<'EOMSG' || die;
+ This is the message.
+ EOMSG
+ exit;
+
+Given this as an input string in a scalar context, C<extract_quotelike>
+would correctly return the string "<<'EOMSG'\nThis is the message.\nEOMSG",
+leaving the string " || die;\nexit;" in the original variable. In other words,
+the two separate pieces of the here document are successfully extracted and
+concatenated.
+
+In a list context, C<extract_quotelike> would return the list
+
+=over 4
+
+=item [0]
+
+"<<'EOMSG'\nThis is the message.\nEOMSG\n" (i.e. the full extracted here document,
+including fore and aft delimiters),
+
+=item [1]
+
+" || die;\nexit;" (i.e. the remainder of the input text, concatenated),
+
+=item [2]
+
+"" (i.e. the prefix substring -- trivial in this case),
+
+=item [3]
+
+"<<" (i.e. the "name" of the quotelike operator)
+
+=item [4]
+
+"'EOMSG'" (i.e. the left delimiter of the here document, including any quotes),
+
+=item [5]
+
+"This is the message.\n" (i.e. the text of the here document),
+
+=item [6]
+
+"EOMSG" (i.e. the right delimiter of the here document),
+
+=item [7..10]
+
+"" (a here document has no second left delimiter, second text, second right
+delimiter, or trailing modifiers).
+
+=back
+
+However, the matching position of the input variable would be set to
+"exit;" (i.e. I<after> the closing delimiter of the here document),
+which would cause the earlier " || die;\nexit;" to be skipped in any
+sequence of code fragment extractions.
+
+To avoid this problem, when it encounters a here document whilst
+extracting from a modifiable string, C<extract_quotelike> silently
+rearranges the string to an equivalent piece of Perl:
+
+ <<'EOMSG'
+ This is the message.
+ EOMSG
+ || die;
+ exit;
+
+in which the here document I<is> contiguous. It still leaves the
+matching position after the here document, but now the rest of the line
+on which the here document starts is not skipped.
+
+To prevent <extract_quotelike> from mucking about with the input in this way
+(this is the only case where a list-context C<extract_quotelike> does so),
+you can pass the input variable as an interpolated literal:
+
+ $quotelike = extract_quotelike("$var");
+
+
+=head2 C<extract_codeblock>
+
+C<extract_codeblock> attempts to recognize and extract a balanced
+bracket delimited substring that may contain unbalanced brackets
+inside Perl quotes or quotelike operations. That is, C<extract_codeblock>
+is like a combination of C<"extract_bracketed"> and
+C<"extract_quotelike">.
+
+C<extract_codeblock> takes the same initial three parameters as C<extract_bracketed>:
+a text to process, a set of delimiter brackets to look for, and a prefix to
+match first. It also takes an optional fourth parameter, which allows the
+outermost delimiter brackets to be specified separately (see below).
+
+Omitting the first argument (input text) means process C<$_> instead.
+Omitting the second argument (delimiter brackets) indicates that only C<'{'> is to be used.
+Omitting the third argument (prefix argument) implies optional whitespace at the start.
+Omitting the fourth argument (outermost delimiter brackets) indicates that the
+value of the second argument is to be used for the outermost delimiters.
+
+Once the prefix an dthe outermost opening delimiter bracket have been
+recognized, code blocks are extracted by stepping through the input text and
+trying the following alternatives in sequence:
+
+=over 4
+
+=item 1.
+
+Try and match a closing delimiter bracket. If the bracket was the same
+species as the last opening bracket, return the substring to that
+point. If the bracket was mismatched, return an error.
+
+=item 2.
+
+Try to match a quote or quotelike operator. If found, call
+C<extract_quotelike> to eat it. If C<extract_quotelike> fails, return
+the error it returned. Otherwise go back to step 1.
+
+=item 3.
+
+Try to match an opening delimiter bracket. If found, call
+C<extract_codeblock> recursively to eat the embedded block. If the
+recursive call fails, return an error. Otherwise, go back to step 1.
+
+=item 4.
+
+Unconditionally match a bareword or any other single character, and
+then go back to step 1.
+
+=back
+
+
+Examples:
+
+ # Find a while loop in the text
+
+ if ($text =~ s/.*?while\s*\{/{/)
+ {
+ $loop = "while " . extract_codeblock($text);
+ }
+
+ # Remove the first round-bracketed list (which may include
+ # round- or curly-bracketed code blocks or quotelike operators)
+
+ extract_codeblock $text, "(){}", '[^(]*';
+
+
+The ability to specify a different outermost delimiter bracket is useful
+in some circumstances. For example, in the Parse::RecDescent module,
+parser actions which are to be performed only on a successful parse
+are specified using a C<E<lt>defer:...E<gt>> directive. For example:
+
+ sentence: subject verb object
+ <defer: {$::theVerb = $item{verb}} >
+
+Parse::RecDescent uses C<extract_codeblock($text, '{}E<lt>E<gt>')> to extract the code
+within the C<E<lt>defer:...E<gt>> directive, but there's a problem.
+
+A deferred action like this:
+
+ <defer: {if ($count>10) {$count--}} >
+
+will be incorrectly parsed as:
+
+ <defer: {if ($count>
+
+because the "less than" operator is interpreted as a closing delimiter.
+
+But, by extracting the directive using
+S<C<extract_codeblock($text, '{}', undef, 'E<lt>E<gt>')>>
+the '>' character is only treated as a delimited at the outermost
+level of the code block, so the directive is parsed correctly.
+
+=head2 C<extract_multiple>
+
+The C<extract_multiple> subroutine takes a string to be processed and a
+list of extractors (subroutines or regular expressions) to apply to that string.
+
+In an array context C<extract_multiple> returns an array of substrings
+of the original string, as extracted by the specified extractors.
+In a scalar context, C<extract_multiple> returns the first
+substring successfully extracted from the original string. In both
+scalar and void contexts the original string has the first successfully
+extracted substring removed from it. In all contexts
+C<extract_multiple> starts at the current C<pos> of the string, and
+sets that C<pos> appropriately after it matches.
+
+Hence, the aim of of a call to C<extract_multiple> in a list context
+is to split the processed string into as many non-overlapping fields as
+possible, by repeatedly applying each of the specified extractors
+to the remainder of the string. Thus C<extract_multiple> is
+a generalized form of Perl's C<split> subroutine.
+
+The subroutine takes up to four optional arguments:
+
+=over 4
+
+=item 1.
+
+A string to be processed (C<$_> if the string is omitted or C<undef>)
+
+=item 2.
+
+A reference to a list of subroutine references and/or qr// objects and/or
+literal strings and/or hash references, specifying the extractors
+to be used to split the string. If this argument is omitted (or
+C<undef>) the list:
+
+ [
+ sub { extract_variable($_[0], '') },
+ sub { extract_quotelike($_[0],'') },
+ sub { extract_codeblock($_[0],'{}','') },
+ ]
+
+is used.
+
+
+=item 3.
+
+An number specifying the maximum number of fields to return. If this
+argument is omitted (or C<undef>), split continues as long as possible.
+
+If the third argument is I<N>, then extraction continues until I<N> fields
+have been successfully extracted, or until the string has been completely
+processed.
+
+Note that in scalar and void contexts the value of this argument is
+automatically reset to 1 (under C<-w>, a warning is issued if the argument
+has to be reset).
+
+=item 4.
+
+A value indicating whether unmatched substrings (see below) within the
+text should be skipped or returned as fields. If the value is true,
+such substrings are skipped. Otherwise, they are returned.
+
+=back
+
+The extraction process works by applying each extractor in
+sequence to the text string. If the extractor is a subroutine it
+is called in a list
+context and is expected to return a list of a single element, namely
+the extracted text.
+Note that the value returned by an extractor subroutine need not bear any
+relationship to the corresponding substring of the original text (see
+examples below).
+
+If the extractor is a precompiled regular expression or a string,
+it is matched against the text in a scalar context with a leading
+'\G' and the gc modifiers enabled. The extracted value is either
+$1 if that variable is defined after the match, or else the
+complete match (i.e. $&).
+
+If the extractor is a hash reference, it must contain exactly one element.
+The value of that element is one of the
+above extractor types (subroutine reference, regular expression, or string).
+The key of that element is the name of a class into which the successful
+return value of the extractor will be blessed.
+
+If an extractor returns a defined value, that value is immediately
+treated as the next extracted field and pushed onto the list of fields.
+If the extractor was specified in a hash reference, the field is also
+blessed into the appropriate class,
+
+If the extractor fails to match (in the case of a regex extractor), or returns an empty list or an undefined value (in the case of a subroutine extractor), it is
+assumed to have failed to extract.
+If none of the extractor subroutines succeeds, then one
+character is extracted from the start of the text and the extraction
+subroutines reapplied. Characters which are thus removed are accumulated and
+eventually become the next field (unless the fourth argument is true, in which
+case they are disgarded).
+
+For example, the following extracts substrings that are valid Perl variables:
+
+ @fields = extract_multiple($text,
+ [ sub { extract_variable($_[0]) } ],
+ undef, 1);
+
+This example separates a text into fields which are quote delimited,
+curly bracketed, and anything else. The delimited and bracketed
+parts are also blessed to identify them (the "anything else" is unblessed):
+
+ @fields = extract_multiple($text,
+ [
+ { Delim => sub { extract_delimited($_[0],q{'"}) } },
+ { Brack => sub { extract_bracketed($_[0],'{}') } },
+ ]);
+
+This call extracts the next single substring that is a valid Perl quotelike
+operator (and removes it from $text):
+
+ $quotelike = extract_multiple($text,
+ [
+ sub { extract_quotelike($_[0]) },
+ ], undef, 1);
+
+Finally, here is yet another way to do comma-separated value parsing:
+
+ @fields = extract_multiple($csv_text,
+ [
+ sub { extract_delimited($_[0],q{'"}) },
+ qr/([^,]+)(.*)/,
+ ],
+ undef,1);
+
+The list in the second argument means:
+I<"Try and extract a ' or " delimited string, otherwise extract anything up to a comma...">.
+The undef third argument means:
+I<"...as many times as possible...">,
+and the true value in the fourth argument means
+I<"...discarding anything else that appears (i.e. the commas)">.
+
+If you wanted the commas preserved as separate fields (i.e. like split
+does if your split pattern has capturing parentheses), you would
+just make the last parameter undefined (or remove it).
+
+
+=head2 C<gen_delimited_pat>
+
+The C<gen_delimited_pat> subroutine takes a single (string) argument and
+ > builds a Friedl-style optimized regex that matches a string delimited
+by any one of the characters in the single argument. For example:
+
+ gen_delimited_pat(q{'"})
+
+returns the regex:
+
+ (?:\"(?:\\\"|(?!\").)*\"|\'(?:\\\'|(?!\').)*\')
+
+Note that the specified delimiters are automatically quotemeta'd.
+
+A typical use of C<gen_delimited_pat> would be to build special purpose tags
+for C<extract_tagged>. For example, to properly ignore "empty" XML elements
+(which might contain quoted strings):
+
+ my $empty_tag = '<(' . gen_delimited_pat(q{'"}) . '|.)+/>';
+
+ extract_tagged($text, undef, undef, undef, {ignore => [$empty_tag]} );
+
+
+C<gen_delimited_pat> may also be called with an optional second argument,
+which specifies the "escape" character(s) to be used for each delimiter.
+For example to match a Pascal-style string (where ' is the delimiter
+and '' is a literal ' within the string):
+
+ gen_delimited_pat(q{'},q{'});
+
+Different escape characters can be specified for different delimiters.
+For example, to specify that '/' is the escape for single quotes
+and '%' is the escape for double quotes:
+
+ gen_delimited_pat(q{'"},q{/%});
+
+If more delimiters than escape chars are specified, the last escape char
+is used for the remaining delimiters.
+If no escape char is specified for a given specified delimiter, '\' is used.
+
+Note that
+C<gen_delimited_pat> was previously called
+C<delimited_pat>. That name may still be used, but is now deprecated.
+
+
+=head1 DIAGNOSTICS
+
+In a list context, all the functions return C<(undef,$original_text)>
+on failure. In a scalar context, failure is indicated by returning C<undef>
+(in this case the input text is not modified in any way).
+
+In addition, on failure in I<any> context, the C<$@> variable is set.
+Accessing C<$@-E<gt>{error}> returns one of the error diagnostics listed
+below.
+Accessing C<$@-E<gt>{pos}> returns the offset into the original string at
+which the error was detected (although not necessarily where it occurred!)
+Printing C<$@> directly produces the error message, with the offset appended.
+On success, the C<$@> variable is guaranteed to be C<undef>.
+
+The available diagnostics are:
+
+=over 4
+
+=item C<Did not find a suitable bracket: "%s">
+
+The delimiter provided to C<extract_bracketed> was not one of
+C<'()[]E<lt>E<gt>{}'>.
+
+=item C<Did not find prefix: /%s/>
+
+A non-optional prefix was specified but wasn't found at the start of the text.
+
+=item C<Did not find opening bracket after prefix: "%s">
+
+C<extract_bracketed> or C<extract_codeblock> was expecting a
+particular kind of bracket at the start of the text, and didn't find it.
+
+=item C<No quotelike operator found after prefix: "%s">
+
+C<extract_quotelike> didn't find one of the quotelike operators C<q>,
+C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y> at the start of the substring
+it was extracting.
+
+=item C<Unmatched closing bracket: "%c">
+
+C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> encountered
+a closing bracket where none was expected.
+
+=item C<Unmatched opening bracket(s): "%s">
+
+C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> ran
+out of characters in the text before closing one or more levels of nested
+brackets.
+
+=item C<Unmatched embedded quote (%s)>
+
+C<extract_bracketed> attempted to match an embedded quoted substring, but
+failed to find a closing quote to match it.
+
+=item C<Did not find closing delimiter to match '%s'>
+
+C<extract_quotelike> was unable to find a closing delimiter to match the
+one that opened the quote-like operation.
+
+=item C<Mismatched closing bracket: expected "%c" but found "%s">
+
+C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> found
+a valid bracket delimiter, but it was the wrong species. This usually
+indicates a nesting error, but may indicate incorrect quoting or escaping.
+
+=item C<No block delimiter found after quotelike "%s">
+
+C<extract_quotelike> or C<extract_codeblock> found one of the
+quotelike operators C<q>, C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y>
+without a suitable block after it.
+
+=item C<Did not find leading dereferencer>
+
+C<extract_variable> was expecting one of '$', '@', or '%' at the start of
+a variable, but didn't find any of them.
+
+=item C<Bad identifier after dereferencer>
+
+C<extract_variable> found a '$', '@', or '%' indicating a variable, but that
+character was not followed by a legal Perl identifier.
+
+=item C<Did not find expected opening bracket at %s>
+
+C<extract_codeblock> failed to find any of the outermost opening brackets
+that were specified.
+
+=item C<Improperly nested codeblock at %s>
+
+A nested code block was found that started with a delimiter that was specified
+as being only to be used as an outermost bracket.
+
+=item C<Missing second block for quotelike "%s">
+
+C<extract_codeblock> or C<extract_quotelike> found one of the
+quotelike operators C<s>, C<tr> or C<y> followed by only one block.
+
+=item C<No match found for opening bracket>
+
+C<extract_codeblock> failed to find a closing bracket to match the outermost
+opening bracket.
+
+=item C<Did not find opening tag: /%s/>
+
+C<extract_tagged> did not find a suitable opening tag (after any specified
+prefix was removed).
+
+=item C<Unable to construct closing tag to match: /%s/>
+
+C<extract_tagged> matched the specified opening tag and tried to
+modify the matched text to produce a matching closing tag (because
+none was specified). It failed to generate the closing tag, almost
+certainly because the opening tag did not start with a
+bracket of some kind.
+
+=item C<Found invalid nested tag: %s>
+
+C<extract_tagged> found a nested tag that appeared in the "reject" list
+(and the failure mode was not "MAX" or "PARA").
+
+=item C<Found unbalanced nested tag: %s>
+
+C<extract_tagged> found a nested opening tag that was not matched by a
+corresponding nested closing tag (and the failure mode was not "MAX" or "PARA").
+
+=item C<Did not find closing tag>
+
+C<extract_tagged> reached the end of the text without finding a closing tag
+to match the original opening tag (and the failure mode was not
+"MAX" or "PARA").
+
+
+
+
+=back
+
+
+=head1 AUTHOR
+
+Damian Conway (damian@conway.org)
+
+
+=head1 BUGS AND IRRITATIONS
+
+There are undoubtedly serious bugs lurking somewhere in this code, if
+only because parts of it give the impression of understanding a great deal
+more about Perl than they really do.
+
+Bug reports and other feedback are most welcome.
+
+
+=head1 COPYRIGHT
+
+ Copyright (c) 1997-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
+++ /dev/null
-=head1 NAME
-
-Text::Balanced - Extract delimited text sequences from strings.
-
-
-=head1 SYNOPSIS
-
- use Text::Balanced qw (
- extract_delimited
- extract_bracketed
- extract_quotelike
- extract_codeblock
- extract_variable
- extract_tagged
- extract_multiple
-
- gen_delimited_pat
- gen_extract_tagged
- );
-
- # Extract the initial substring of $text that is delimited by
- # two (unescaped) instances of the first character in $delim.
-
- ($extracted, $remainder) = extract_delimited($text,$delim);
-
-
- # Extract the initial substring of $text that is bracketed
- # with a delimiter(s) specified by $delim (where the string
- # in $delim contains one or more of '(){}[]<>').
-
- ($extracted, $remainder) = extract_bracketed($text,$delim);
-
-
- # Extract the initial substring of $text that is bounded by
- # an HTML/XML tag.
-
- ($extracted, $remainder) = extract_tagged($text);
-
-
- # Extract the initial substring of $text that is bounded by
- # a C<BEGIN>...C<END> pair. Don't allow nested C<BEGIN> tags
-
- ($extracted, $remainder) =
- extract_tagged($text,"BEGIN","END",undef,{bad=>["BEGIN"]});
-
-
- # Extract the initial substring of $text that represents a
- # Perl "quote or quote-like operation"
-
- ($extracted, $remainder) = extract_quotelike($text);
-
-
- # Extract the initial substring of $text that represents a block
- # of Perl code, bracketed by any of character(s) specified by $delim
- # (where the string $delim contains one or more of '(){}[]<>').
-
- ($extracted, $remainder) = extract_codeblock($text,$delim);
-
-
- # Extract the initial substrings of $text that would be extracted by
- # one or more sequential applications of the specified functions
- # or regular expressions
-
- @extracted = extract_multiple($text,
- [ \&extract_bracketed,
- \&extract_quotelike,
- \&some_other_extractor_sub,
- qr/[xyz]*/,
- 'literal',
- ]);
-
-# Create a string representing an optimized pattern (a la Friedl)
-# that matches a substring delimited by any of the specified characters
-# (in this case: any type of quote or a slash)
-
- $patstring = gen_delimited_pat(q{'"`/});
-
-
-# Generate a reference to an anonymous sub that is just like extract_tagged
-# but pre-compiled and optimized for a specific pair of tags, and consequently
-# much faster (i.e. 3 times faster). It uses qr// for better performance on
-# repeated calls, so it only works under Perl 5.005 or later.
-
- $extract_head = gen_extract_tagged('<HEAD>','</HEAD>');
-
- ($extracted, $remainder) = $extract_head->($text);
-
-
-=head1 DESCRIPTION
-
-The various C<extract_...> subroutines may be used to extract a
-delimited string (possibly after skipping a specified prefix string).
-The search for the string always begins at the current C<pos>
-location of the string's variable (or at index zero, if no C<pos>
-position is defined).
-
-=head2 General behaviour in list contexts
-
-In a list context, all the subroutines return a list, the first three
-elements of which are always:
-
-=over 4
-
-=item [0]
-
-The extracted string, including the specified delimiters.
-If the extraction fails an empty string is returned.
-
-=item [1]
-
-The remainder of the input string (i.e. the characters after the
-extracted string). On failure, the entire string is returned.
-
-=item [2]
-
-The skipped prefix (i.e. the characters before the extracted string).
-On failure, the empty string is returned.
-
-=back
-
-Note that in a list context, the contents of the original input text (the first
-argument) are not modified in any way.
-
-However, if the input text was passed in a variable, that variable's
-C<pos> value is updated to point at the first character after the
-extracted text. That means that in a list context the various
-subroutines can be used much like regular expressions. For example:
-
- while ( $next = (extract_quotelike($text))[0] )
- {
- # process next quote-like (in $next)
- }
-
-
-=head2 General behaviour in scalar and void contexts
-
-In a scalar context, the extracted string is returned, having first been
-removed from the input text. Thus, the following code also processes
-each quote-like operation, but actually removes them from $text:
-
- while ( $next = extract_quotelike($text) )
- {
- # process next quote-like (in $next)
- }
-
-Note that if the input text is a read-only string (i.e. a literal),
-no attempt is made to remove the extracted text.
-
-In a void context the behaviour of the extraction subroutines is
-exactly the same as in a scalar context, except (of course) that the
-extracted substring is not returned.
-
-=head2 A note about prefixes
-
-Prefix patterns are matched without any trailing modifiers (C</gimsox> etc.)
-This can bite you if you're expecting a prefix specification like
-'.*?(?=<H1>)' to skip everything up to the first <H1> tag. Such a prefix
-pattern will only succeed if the <H1> tag is on the current line, since
-. normally doesn't match newlines.
-
-To overcome this limitation, you need to turn on /s matching within
-the prefix pattern, using the C<(?s)> directive: '(?s).*?(?=<H1>)'
-
-
-=head2 C<extract_delimited>
-
-The C<extract_delimited> function formalizes the common idiom
-of extracting a single-character-delimited substring from the start of
-a string. For example, to extract a single-quote delimited string, the
-following code is typically used:
-
- ($remainder = $text) =~ s/\A('(\\.|[^'])*')//s;
- $extracted = $1;
-
-but with C<extract_delimited> it can be simplified to:
-
- ($extracted,$remainder) = extract_delimited($text, "'");
-
-C<extract_delimited> takes up to four scalars (the input text, the
-delimiters, a prefix pattern to be skipped, and any escape characters)
-and extracts the initial substring of the text that
-is appropriately delimited. If the delimiter string has multiple
-characters, the first one encountered in the text is taken to delimit
-the substring.
-The third argument specifies a prefix pattern that is to be skipped
-(but must be present!) before the substring is extracted.
-The final argument specifies the escape character to be used for each
-delimiter.
-
-All arguments are optional. If the escape characters are not specified,
-every delimiter is escaped with a backslash (C<\>).
-If the prefix is not specified, the
-pattern C<'\s*'> - optional whitespace - is used. If the delimiter set
-is also not specified, the set C</["'`]/> is used. If the text to be processed
-is not specified either, C<$_> is used.
-
-In list context, C<extract_delimited> returns a array of three
-elements, the extracted substring (I<including the surrounding
-delimiters>), the remainder of the text, and the skipped prefix (if
-any). If a suitable delimited substring is not found, the first
-element of the array is the empty string, the second is the complete
-original text, and the prefix returned in the third element is an
-empty string.
-
-In a scalar context, just the extracted substring is returned. In
-a void context, the extracted substring (and any prefix) are simply
-removed from the beginning of the first argument.
-
-Examples:
-
- # Remove a single-quoted substring from the very beginning of $text:
-
- $substring = extract_delimited($text, "'", '');
-
- # Remove a single-quoted Pascalish substring (i.e. one in which
- # doubling the quote character escapes it) from the very
- # beginning of $text:
-
- $substring = extract_delimited($text, "'", '', "'");
-
- # Extract a single- or double- quoted substring from the
- # beginning of $text, optionally after some whitespace
- # (note the list context to protect $text from modification):
-
- ($substring) = extract_delimited $text, q{"'};
-
-
- # Delete the substring delimited by the first '/' in $text:
-
- $text = join '', (extract_delimited($text,'/','[^/]*')[2,1];
-
-Note that this last example is I<not> the same as deleting the first
-quote-like pattern. For instance, if C<$text> contained the string:
-
- "if ('./cmd' =~ m/$UNIXCMD/s) { $cmd = $1; }"
-
-then after the deletion it would contain:
-
- "if ('.$UNIXCMD/s) { $cmd = $1; }"
-
-not:
-
- "if ('./cmd' =~ ms) { $cmd = $1; }"
-
-
-See L<"extract_quotelike"> for a (partial) solution to this problem.
-
-
-=head2 C<extract_bracketed>
-
-Like C<"extract_delimited">, the C<extract_bracketed> function takes
-up to three optional scalar arguments: a string to extract from, a delimiter
-specifier, and a prefix pattern. As before, a missing prefix defaults to
-optional whitespace and a missing text defaults to C<$_>. However, a missing
-delimiter specifier defaults to C<'{}()[]E<lt>E<gt>'> (see below).
-
-C<extract_bracketed> extracts a balanced-bracket-delimited
-substring (using any one (or more) of the user-specified delimiter
-brackets: '(..)', '{..}', '[..]', or '<..>'). Optionally it will also
-respect quoted unbalanced brackets (see below).
-
-A "delimiter bracket" is a bracket in list of delimiters passed as
-C<extract_bracketed>'s second argument. Delimiter brackets are
-specified by giving either the left or right (or both!) versions
-of the required bracket(s). Note that the order in which
-two or more delimiter brackets are specified is not significant.
-
-A "balanced-bracket-delimited substring" is a substring bounded by
-matched brackets, such that any other (left or right) delimiter
-bracket I<within> the substring is also matched by an opposite
-(right or left) delimiter bracket I<at the same level of nesting>. Any
-type of bracket not in the delimiter list is treated as an ordinary
-character.
-
-In other words, each type of bracket specified as a delimiter must be
-balanced and correctly nested within the substring, and any other kind of
-("non-delimiter") bracket in the substring is ignored.
-
-For example, given the string:
-
- $text = "{ an '[irregularly :-(] {} parenthesized >:-)' string }";
-
-then a call to C<extract_bracketed> in a list context:
-
- @result = extract_bracketed( $text, '{}' );
-
-would return:
-
- ( "{ an '[irregularly :-(] {} parenthesized >:-)' string }" , "" , "" )
-
-since both sets of C<'{..}'> brackets are properly nested and evenly balanced.
-(In a scalar context just the first element of the array would be returned. In
-a void context, C<$text> would be replaced by an empty string.)
-
-Likewise the call in:
-
- @result = extract_bracketed( $text, '{[' );
-
-would return the same result, since all sets of both types of specified
-delimiter brackets are correctly nested and balanced.
-
-However, the call in:
-
- @result = extract_bracketed( $text, '{([<' );
-
-would fail, returning:
-
- ( undef , "{ an '[irregularly :-(] {} parenthesized >:-)' string }" );
-
-because the embedded pairs of C<'(..)'>s and C<'[..]'>s are "cross-nested" and
-the embedded C<'E<gt>'> is unbalanced. (In a scalar context, this call would
-return an empty string. In a void context, C<$text> would be unchanged.)
-
-Note that the embedded single-quotes in the string don't help in this
-case, since they have not been specified as acceptable delimiters and are
-therefore treated as non-delimiter characters (and ignored).
-
-However, if a particular species of quote character is included in the
-delimiter specification, then that type of quote will be correctly handled.
-for example, if C<$text> is:
-
- $text = '<A HREF=">>>>">link</A>';
-
-then
-
- @result = extract_bracketed( $text, '<">' );
-
-returns:
-
- ( '<A HREF=">>>>">', 'link</A>', "" )
-
-as expected. Without the specification of C<"> as an embedded quoter:
-
- @result = extract_bracketed( $text, '<>' );
-
-the result would be:
-
- ( '<A HREF=">', '>>>">link</A>', "" )
-
-In addition to the quote delimiters C<'>, C<">, and C<`>, full Perl quote-like
-quoting (i.e. q{string}, qq{string}, etc) can be specified by including the
-letter 'q' as a delimiter. Hence:
-
- @result = extract_bracketed( $text, '<q>' );
-
-would correctly match something like this:
-
- $text = '<leftop: conj /and/ conj>';
-
-See also: C<"extract_quotelike"> and C<"extract_codeblock">.
-
-
-=head2 C<extract_tagged>
-
-C<extract_tagged> extracts and segments text between (balanced)
-specified tags.
-
-The subroutine takes up to five optional arguments:
-
-=over 4
-
-=item 1.
-
-A string to be processed (C<$_> if the string is omitted or C<undef>)
-
-=item 2.
-
-A string specifying a pattern to be matched as the opening tag.
-If the pattern string is omitted (or C<undef>) then a pattern
-that matches any standard HTML/XML tag is used.
-
-=item 3.
-
-A string specifying a pattern to be matched at the closing tag.
-If the pattern string is omitted (or C<undef>) then the closing
-tag is constructed by inserting a C</> after any leading bracket
-characters in the actual opening tag that was matched (I<not> the pattern
-that matched the tag). For example, if the opening tag pattern
-is specified as C<'{{\w+}}'> and actually matched the opening tag
-C<"{{DATA}}">, then the constructed closing tag would be C<"{{/DATA}}">.
-
-=item 4.
-
-A string specifying a pattern to be matched as a prefix (which is to be
-skipped). If omitted, optional whitespace is skipped.
-
-=item 5.
-
-A hash reference containing various parsing options (see below)
-
-=back
-
-The various options that can be specified are:
-
-=over 4
-
-=item C<reject =E<gt> $listref>
-
-The list reference contains one or more strings specifying patterns
-that must I<not> appear within the tagged text.
-
-For example, to extract
-an HTML link (which should not contain nested links) use:
-
- extract_tagged($text, '<A>', '</A>', undef, {reject => ['<A>']} );
-
-=item C<ignore =E<gt> $listref>
-
-The list reference contains one or more strings specifying patterns
-that are I<not> be be treated as nested tags within the tagged text
-(even if they would match the start tag pattern).
-
-For example, to extract an arbitrary XML tag, but ignore "empty" elements:
-
- extract_tagged($text, undef, undef, undef, {ignore => ['<[^>]*/>']} );
-
-(also see L<"gen_delimited_pat"> below).
-
-
-=item C<fail =E<gt> $str>
-
-The C<fail> option indicates the action to be taken if a matching end
-tag is not encountered (i.e. before the end of the string or some
-C<reject> pattern matches). By default, a failure to match a closing
-tag causes C<extract_tagged> to immediately fail.
-
-However, if the string value associated with <reject> is "MAX", then
-C<extract_tagged> returns the complete text up to the point of failure.
-If the string is "PARA", C<extract_tagged> returns only the first paragraph
-after the tag (up to the first line that is either empty or contains
-only whitespace characters).
-If the string is "", the the default behaviour (i.e. failure) is reinstated.
-
-For example, suppose the start tag "/para" introduces a paragraph, which then
-continues until the next "/endpara" tag or until another "/para" tag is
-encountered:
-
- $text = "/para line 1\n\nline 3\n/para line 4";
-
- extract_tagged($text, '/para', '/endpara', undef,
- {reject => '/para', fail => MAX );
-
- # EXTRACTED: "/para line 1\n\nline 3\n"
-
-Suppose instead, that if no matching "/endpara" tag is found, the "/para"
-tag refers only to the immediately following paragraph:
-
- $text = "/para line 1\n\nline 3\n/para line 4";
-
- extract_tagged($text, '/para', '/endpara', undef,
- {reject => '/para', fail => MAX );
-
- # EXTRACTED: "/para line 1\n"
-
-Note that the specified C<fail> behaviour applies to nested tags as well.
-
-=back
-
-On success in a list context, an array of 6 elements is returned. The elements are:
-
-=over 4
-
-=item [0]
-
-the extracted tagged substring (including the outermost tags),
-
-=item [1]
-
-the remainder of the input text,
-
-=item [2]
-
-the prefix substring (if any),
-
-=item [3]
-
-the opening tag
-
-=item [4]
-
-the text between the opening and closing tags
-
-=item [5]
-
-the closing tag (or "" if no closing tag was found)
-
-=back
-
-On failure, all of these values (except the remaining text) are C<undef>.
-
-In a scalar context, C<extract_tagged> returns just the complete
-substring that matched a tagged text (including the start and end
-tags). C<undef> is returned on failure. In addition, the original input
-text has the returned substring (and any prefix) removed from it.
-
-In a void context, the input text just has the matched substring (and
-any specified prefix) removed.
-
-
-=head2 C<gen_extract_tagged>
-
-(Note: This subroutine is only available under Perl5.005)
-
-C<gen_extract_tagged> generates a new anonymous subroutine which
-extracts text between (balanced) specified tags. In other words,
-it generates a function identical in function to C<extract_tagged>.
-
-The difference between C<extract_tagged> and the anonymous
-subroutines generated by
-C<gen_extract_tagged>, is that those generated subroutines:
-
-=over 4
-
-=item *
-
-do not have to reparse tag specification or parsing options every time
-they are called (whereas C<extract_tagged> has to effectively rebuild
-its tag parser on every call);
-
-=item *
-
-make use of the new qr// construct to pre-compile the regexes they use
-(whereas C<extract_tagged> uses standard string variable interpolation
-to create tag-matching patterns).
-
-=back
-
-The subroutine takes up to four optional arguments (the same set as
-C<extract_tagged> except for the string to be processed). It returns
-a reference to a subroutine which in turn takes a single argument (the text to
-be extracted from).
-
-In other words, the implementation of C<extract_tagged> is exactly
-equivalent to:
-
- sub extract_tagged
- {
- my $text = shift;
- $extractor = gen_extract_tagged(@_);
- return $extractor->($text);
- }
-
-(although C<extract_tagged> is not currently implemented that way, in order
-to preserve pre-5.005 compatibility).
-
-Using C<gen_extract_tagged> to create extraction functions for specific tags
-is a good idea if those functions are going to be called more than once, since
-their performance is typically twice as good as the more general-purpose
-C<extract_tagged>.
-
-
-=head2 C<extract_quotelike>
-
-C<extract_quotelike> attempts to recognize, extract, and segment any
-one of the various Perl quotes and quotelike operators (see
-L<perlop(3)>) Nested backslashed delimiters, embedded balanced bracket
-delimiters (for the quotelike operators), and trailing modifiers are
-all caught. For example, in:
-
- extract_quotelike 'q # an octothorpe: \# (not the end of the q!) #'
-
- extract_quotelike ' "You said, \"Use sed\"." '
-
- extract_quotelike ' s{([A-Z]{1,8}\.[A-Z]{3})} /\L$1\E/; '
-
- extract_quotelike ' tr/\\\/\\\\/\\\//ds; '
-
-the full Perl quotelike operations are all extracted correctly.
-
-Note too that, when using the /x modifier on a regex, any comment
-containing the current pattern delimiter will cause the regex to be
-immediately terminated. In other words:
-
- 'm /
- (?i) # CASE INSENSITIVE
- [a-z_] # LEADING ALPHABETIC/UNDERSCORE
- [a-z0-9]* # FOLLOWED BY ANY NUMBER OF ALPHANUMERICS
- /x'
-
-will be extracted as if it were:
-
- 'm /
- (?i) # CASE INSENSITIVE
- [a-z_] # LEADING ALPHABETIC/'
-
-This behaviour is identical to that of the actual compiler.
-
-C<extract_quotelike> takes two arguments: the text to be processed and
-a prefix to be matched at the very beginning of the text. If no prefix
-is specified, optional whitespace is the default. If no text is given,
-C<$_> is used.
-
-In a list context, an array of 11 elements is returned. The elements are:
-
-=over 4
-
-=item [0]
-
-the extracted quotelike substring (including trailing modifiers),
-
-=item [1]
-
-the remainder of the input text,
-
-=item [2]
-
-the prefix substring (if any),
-
-=item [3]
-
-the name of the quotelike operator (if any),
-
-=item [4]
-
-the left delimiter of the first block of the operation,
-
-=item [5]
-
-the text of the first block of the operation
-(that is, the contents of
-a quote, the regex of a match or substitution or the target list of a
-translation),
-
-=item [6]
-
-the right delimiter of the first block of the operation,
-
-=item [7]
-
-the left delimiter of the second block of the operation
-(that is, if it is a C<s>, C<tr>, or C<y>),
-
-=item [8]
-
-the text of the second block of the operation
-(that is, the replacement of a substitution or the translation list
-of a translation),
-
-=item [9]
-
-the right delimiter of the second block of the operation (if any),
-
-=item [10]
-
-the trailing modifiers on the operation (if any).
-
-=back
-
-For each of the fields marked "(if any)" the default value on success is
-an empty string.
-On failure, all of these values (except the remaining text) are C<undef>.
-
-
-In a scalar context, C<extract_quotelike> returns just the complete substring
-that matched a quotelike operation (or C<undef> on failure). In a scalar or
-void context, the input text has the same substring (and any specified
-prefix) removed.
-
-Examples:
-
- # Remove the first quotelike literal that appears in text
-
- $quotelike = extract_quotelike($text,'.*?');
-
- # Replace one or more leading whitespace-separated quotelike
- # literals in $_ with "<QLL>"
-
- do { $_ = join '<QLL>', (extract_quotelike)[2,1] } until $@;
-
-
- # Isolate the search pattern in a quotelike operation from $text
-
- ($op,$pat) = (extract_quotelike $text)[3,5];
- if ($op =~ /[ms]/)
- {
- print "search pattern: $pat\n";
- }
- else
- {
- print "$op is not a pattern matching operation\n";
- }
-
-
-=head2 C<extract_quotelike> and "here documents"
-
-C<extract_quotelike> can successfully extract "here documents" from an input
-string, but with an important caveat in list contexts.
-
-Unlike other types of quote-like literals, a here document is rarely
-a contiguous substring. For example, a typical piece of code using
-here document might look like this:
-
- <<'EOMSG' || die;
- This is the message.
- EOMSG
- exit;
-
-Given this as an input string in a scalar context, C<extract_quotelike>
-would correctly return the string "<<'EOMSG'\nThis is the message.\nEOMSG",
-leaving the string " || die;\nexit;" in the original variable. In other words,
-the two separate pieces of the here document are successfully extracted and
-concatenated.
-
-In a list context, C<extract_quotelike> would return the list
-
-=over 4
-
-=item [0]
-
-"<<'EOMSG'\nThis is the message.\nEOMSG\n" (i.e. the full extracted here document,
-including fore and aft delimiters),
-
-=item [1]
-
-" || die;\nexit;" (i.e. the remainder of the input text, concatenated),
-
-=item [2]
-
-"" (i.e. the prefix substring -- trivial in this case),
-
-=item [3]
-
-"<<" (i.e. the "name" of the quotelike operator)
-
-=item [4]
-
-"'EOMSG'" (i.e. the left delimiter of the here document, including any quotes),
-
-=item [5]
-
-"This is the message.\n" (i.e. the text of the here document),
-
-=item [6]
-
-"EOMSG" (i.e. the right delimiter of the here document),
-
-=item [7..10]
-
-"" (a here document has no second left delimiter, second text, second right
-delimiter, or trailing modifiers).
-
-=back
-
-However, the matching position of the input variable would be set to
-"exit;" (i.e. I<after> the closing delimiter of the here document),
-which would cause the earlier " || die;\nexit;" to be skipped in any
-sequence of code fragment extractions.
-
-To avoid this problem, when it encounters a here document whilst
-extracting from a modifiable string, C<extract_quotelike> silently
-rearranges the string to an equivalent piece of Perl:
-
- <<'EOMSG'
- This is the message.
- EOMSG
- || die;
- exit;
-
-in which the here document I<is> contiguous. It still leaves the
-matching position after the here document, but now the rest of the line
-on which the here document starts is not skipped.
-
-To prevent <extract_quotelike> from mucking about with the input in this way
-(this is the only case where a list-context C<extract_quotelike> does so),
-you can pass the input variable as an interpolated literal:
-
- $quotelike = extract_quotelike("$var");
-
-
-=head2 C<extract_codeblock>
-
-C<extract_codeblock> attempts to recognize and extract a balanced
-bracket delimited substring that may contain unbalanced brackets
-inside Perl quotes or quotelike operations. That is, C<extract_codeblock>
-is like a combination of C<"extract_bracketed"> and
-C<"extract_quotelike">.
-
-C<extract_codeblock> takes the same initial three parameters as C<extract_bracketed>:
-a text to process, a set of delimiter brackets to look for, and a prefix to
-match first. It also takes an optional fourth parameter, which allows the
-outermost delimiter brackets to be specified separately (see below).
-
-Omitting the first argument (input text) means process C<$_> instead.
-Omitting the second argument (delimiter brackets) indicates that only C<'{'> is to be used.
-Omitting the third argument (prefix argument) implies optional whitespace at the start.
-Omitting the fourth argument (outermost delimiter brackets) indicates that the
-value of the second argument is to be used for the outermost delimiters.
-
-Once the prefix an dthe outermost opening delimiter bracket have been
-recognized, code blocks are extracted by stepping through the input text and
-trying the following alternatives in sequence:
-
-=over 4
-
-=item 1.
-
-Try and match a closing delimiter bracket. If the bracket was the same
-species as the last opening bracket, return the substring to that
-point. If the bracket was mismatched, return an error.
-
-=item 2.
-
-Try to match a quote or quotelike operator. If found, call
-C<extract_quotelike> to eat it. If C<extract_quotelike> fails, return
-the error it returned. Otherwise go back to step 1.
-
-=item 3.
-
-Try to match an opening delimiter bracket. If found, call
-C<extract_codeblock> recursively to eat the embedded block. If the
-recursive call fails, return an error. Otherwise, go back to step 1.
-
-=item 4.
-
-Unconditionally match a bareword or any other single character, and
-then go back to step 1.
-
-=back
-
-
-Examples:
-
- # Find a while loop in the text
-
- if ($text =~ s/.*?while\s*\{/{/)
- {
- $loop = "while " . extract_codeblock($text);
- }
-
- # Remove the first round-bracketed list (which may include
- # round- or curly-bracketed code blocks or quotelike operators)
-
- extract_codeblock $text, "(){}", '[^(]*';
-
-
-The ability to specify a different outermost delimiter bracket is useful
-in some circumstances. For example, in the Parse::RecDescent module,
-parser actions which are to be performed only on a successful parse
-are specified using a C<E<lt>defer:...E<gt>> directive. For example:
-
- sentence: subject verb object
- <defer: {$::theVerb = $item{verb}} >
-
-Parse::RecDescent uses C<extract_codeblock($text, '{}E<lt>E<gt>')> to extract the code
-within the C<E<lt>defer:...E<gt>> directive, but there's a problem.
-
-A deferred action like this:
-
- <defer: {if ($count>10) {$count--}} >
-
-will be incorrectly parsed as:
-
- <defer: {if ($count>
-
-because the "less than" operator is interpreted as a closing delimiter.
-
-But, by extracting the directive using
-S<C<extract_codeblock($text, '{}', undef, 'E<lt>E<gt>')>>
-the '>' character is only treated as a delimited at the outermost
-level of the code block, so the directive is parsed correctly.
-
-=head2 C<extract_multiple>
-
-The C<extract_multiple> subroutine takes a string to be processed and a
-list of extractors (subroutines or regular expressions) to apply to that string.
-
-In an array context C<extract_multiple> returns an array of substrings
-of the original string, as extracted by the specified extractors.
-In a scalar context, C<extract_multiple> returns the first
-substring successfully extracted from the original string. In both
-scalar and void contexts the original string has the first successfully
-extracted substring removed from it. In all contexts
-C<extract_multiple> starts at the current C<pos> of the string, and
-sets that C<pos> appropriately after it matches.
-
-Hence, the aim of of a call to C<extract_multiple> in a list context
-is to split the processed string into as many non-overlapping fields as
-possible, by repeatedly applying each of the specified extractors
-to the remainder of the string. Thus C<extract_multiple> is
-a generalized form of Perl's C<split> subroutine.
-
-The subroutine takes up to four optional arguments:
-
-=over 4
-
-=item 1.
-
-A string to be processed (C<$_> if the string is omitted or C<undef>)
-
-=item 2.
-
-A reference to a list of subroutine references and/or qr// objects and/or
-literal strings and/or hash references, specifying the extractors
-to be used to split the string. If this argument is omitted (or
-C<undef>) the list:
-
- [
- sub { extract_variable($_[0], '') },
- sub { extract_quotelike($_[0],'') },
- sub { extract_codeblock($_[0],'{}','') },
- ]
-
-is used.
-
-
-=item 3.
-
-An number specifying the maximum number of fields to return. If this
-argument is omitted (or C<undef>), split continues as long as possible.
-
-If the third argument is I<N>, then extraction continues until I<N> fields
-have been successfully extracted, or until the string has been completely
-processed.
-
-Note that in scalar and void contexts the value of this argument is
-automatically reset to 1 (under C<-w>, a warning is issued if the argument
-has to be reset).
-
-=item 4.
-
-A value indicating whether unmatched substrings (see below) within the
-text should be skipped or returned as fields. If the value is true,
-such substrings are skipped. Otherwise, they are returned.
-
-=back
-
-The extraction process works by applying each extractor in
-sequence to the text string. If the extractor is a subroutine it
-is called in a list
-context and is expected to return a list of a single element, namely
-the extracted text.
-Note that the value returned by an extractor subroutine need not bear any
-relationship to the corresponding substring of the original text (see
-examples below).
-
-If the extractor is a precompiled regular expression or a string,
-it is matched against the text in a scalar context with a leading
-'\G' and the gc modifiers enabled. The extracted value is either
-$1 if that variable is defined after the match, or else the
-complete match (i.e. $&).
-
-If the extractor is a hash reference, it must contain exactly one element.
-The value of that element is one of the
-above extractor types (subroutine reference, regular expression, or string).
-The key of that element is the name of a class into which the successful
-return value of the extractor will be blessed.
-
-If an extractor returns a defined value, that value is immediately
-treated as the next extracted field and pushed onto the list of fields.
-If the extractor was specified in a hash reference, the field is also
-blessed into the appropriate class,
-
-If the extractor fails to match (in the case of a regex extractor), or returns an empty list or an undefined value (in the case of a subroutine extractor), it is
-assumed to have failed to extract.
-If none of the extractor subroutines succeeds, then one
-character is extracted from the start of the text and the extraction
-subroutines reapplied. Characters which are thus removed are accumulated and
-eventually become the next field (unless the fourth argument is true, in which
-case they are disgarded).
-
-For example, the following extracts substrings that are valid Perl variables:
-
- @fields = extract_multiple($text,
- [ sub { extract_variable($_[0]) } ],
- undef, 1);
-
-This example separates a text into fields which are quote delimited,
-curly bracketed, and anything else. The delimited and bracketed
-parts are also blessed to identify them (the "anything else" is unblessed):
-
- @fields = extract_multiple($text,
- [
- { Delim => sub { extract_delimited($_[0],q{'"}) } },
- { Brack => sub { extract_bracketed($_[0],'{}') } },
- ]);
-
-This call extracts the next single substring that is a valid Perl quotelike
-operator (and removes it from $text):
-
- $quotelike = extract_multiple($text,
- [
- sub { extract_quotelike($_[0]) },
- ], undef, 1);
-
-Finally, here is yet another way to do comma-separated value parsing:
-
- @fields = extract_multiple($csv_text,
- [
- sub { extract_delimited($_[0],q{'"}) },
- qr/([^,]+)(.*)/,
- ],
- undef,1);
-
-The list in the second argument means:
-I<"Try and extract a ' or " delimited string, otherwise extract anything up to a comma...">.
-The undef third argument means:
-I<"...as many times as possible...">,
-and the true value in the fourth argument means
-I<"...discarding anything else that appears (i.e. the commas)">.
-
-If you wanted the commas preserved as separate fields (i.e. like split
-does if your split pattern has capturing parentheses), you would
-just make the last parameter undefined (or remove it).
-
-
-=head2 C<gen_delimited_pat>
-
-The C<gen_delimited_pat> subroutine takes a single (string) argument and
-builds a Friedl-style optimized regex that matches a string delimited
-by any one of the characters in the single argument. For example:
-
- gen_delimited_pat(q{'"})
-
-returns the regex:
-
- (?:\"(?:\\\"|(?!\").)*\"|\'(?:\\\'|(?!\').)*\')
-
-Note that the specified delimiters are automatically quotemeta'd.
-
-A typical use of C<gen_delimited_pat> would be to build special purpose tags
-for C<extract_tagged>. For example, to properly ignore "empty" XML elements
-(which might contain quoted strings):
-
- my $empty_tag = '<(' . gen_delimited_pat(q{'"}) . '|.)+/>';
-
- extract_tagged($text, undef, undef, undef, {ignore => [$empty_tag]} );
-
-
-C<gen_delimited_pat> may also be called with an optional second argument,
-which specifies the "escape" character(s) to be used for each delimiter.
-For example to match a Pascal-style string (where ' is the delimiter
-and '' is a literal ' within the string):
-
- gen_delimited_pat(q{'},q{'});
-
-Different escape characters can be specified for different delimiters.
-For example, to specify that '/' is the escape for single quotes
-and '%' is the escape for double quotes:
-
- gen_delimited_pat(q{'"},q{/%});
-
-If more delimiters than escape chars are specified, the last escape char
-is used for the remaining delimiters.
-If no escape char is specified for a given specified delimiter, '\' is used.
-
-Note that
-C<gen_delimited_pat> was previously called
-C<delimited_pat>. That name may still be used, but is now deprecated.
-
-
-=head1 DIAGNOSTICS
-
-In a list context, all the functions return C<(undef,$original_text)>
-on failure. In a scalar context, failure is indicated by returning C<undef>
-(in this case the input text is not modified in any way).
-
-In addition, on failure in I<any> context, the C<$@> variable is set.
-Accessing C<$@-E<gt>{error}> returns one of the error diagnostics listed
-below.
-Accessing C<$@-E<gt>{pos}> returns the offset into the original string at
-which the error was detected (although not necessarily where it occurred!)
-Printing C<$@> directly produces the error message, with the offset appended.
-On success, the C<$@> variable is guaranteed to be C<undef>.
-
-The available diagnostics are:
-
-=over 4
-
-=item C<Did not find a suitable bracket: "%s">
-
-The delimiter provided to C<extract_bracketed> was not one of
-C<'()[]E<lt>E<gt>{}'>.
-
-=item C<Did not find prefix: /%s/>
-
-A non-optional prefix was specified but wasn't found at the start of the text.
-
-=item C<Did not find opening bracket after prefix: "%s">
-
-C<extract_bracketed> or C<extract_codeblock> was expecting a
-particular kind of bracket at the start of the text, and didn't find it.
-
-=item C<No quotelike operator found after prefix: "%s">
-
-C<extract_quotelike> didn't find one of the quotelike operators C<q>,
-C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y> at the start of the substring
-it was extracting.
-
-=item C<Unmatched closing bracket: "%c">
-
-C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> encountered
-a closing bracket where none was expected.
-
-=item C<Unmatched opening bracket(s): "%s">
-
-C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> ran
-out of characters in the text before closing one or more levels of nested
-brackets.
-
-=item C<Unmatched embedded quote (%s)>
-
-C<extract_bracketed> attempted to match an embedded quoted substring, but
-failed to find a closing quote to match it.
-
-=item C<Did not find closing delimiter to match '%s'>
-
-C<extract_quotelike> was unable to find a closing delimiter to match the
-one that opened the quote-like operation.
-
-=item C<Mismatched closing bracket: expected "%c" but found "%s">
-
-C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> found
-a valid bracket delimiter, but it was the wrong species. This usually
-indicates a nesting error, but may indicate incorrect quoting or escaping.
-
-=item C<No block delimiter found after quotelike "%s">
-
-C<extract_quotelike> or C<extract_codeblock> found one of the
-quotelike operators C<q>, C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y>
-without a suitable block after it.
-
-=item C<Did not find leading dereferencer>
-
-C<extract_variable> was expecting one of '$', '@', or '%' at the start of
-a variable, but didn't find any of them.
-
-=item C<Bad identifier after dereferencer>
-
-C<extract_variable> found a '$', '@', or '%' indicating a variable, but that
-character was not followed by a legal Perl identifier.
-
-=item C<Did not find expected opening bracket at %s>
-
-C<extract_codeblock> failed to find any of the outermost opening brackets
-that were specified.
-
-=item C<Improperly nested codeblock at %s>
-
-A nested code block was found that started with a delimiter that was specified
-as being only to be used as an outermost bracket.
-
-=item C<Missing second block for quotelike "%s">
-
-C<extract_codeblock> or C<extract_quotelike> found one of the
-quotelike operators C<s>, C<tr> or C<y> followed by only one block.
-
-=item C<No match found for opening bracket>
-
-C<extract_codeblock> failed to find a closing bracket to match the outermost
-opening bracket.
-
-=item C<Did not find opening tag: /%s/>
-
-C<extract_tagged> did not find a suitable opening tag (after any specified
-prefix was removed).
-
-=item C<Unable to construct closing tag to match: /%s/>
-
-C<extract_tagged> matched the specified opening tag and tried to
-modify the matched text to produce a matching closing tag (because
-none was specified). It failed to generate the closing tag, almost
-certainly because the opening tag did not start with a
-bracket of some kind.
-
-=item C<Found invalid nested tag: %s>
-
-C<extract_tagged> found a nested tag that appeared in the "reject" list
-(and the failure mode was not "MAX" or "PARA").
-
-=item C<Found unbalanced nested tag: %s>
-
-C<extract_tagged> found a nested opening tag that was not matched by a
-corresponding nested closing tag (and the failure mode was not "MAX" or "PARA").
-
-=item C<Did not find closing tag>
-
-C<extract_tagged> reached the end of the text without finding a closing tag
-to match the original opening tag (and the failure mode was not
-"MAX" or "PARA").
-
-
-
-
-=back
-
-
-=head1 AUTHOR
-
-Damian Conway (damian@conway.org)
-
-
-=head1 BUGS AND IRRITATIONS
-
-There are undoubtedly serious bugs lurking somewhere in this code, if
-only because parts of it give the impression of understanding a great deal
-more about Perl than they really do.
-
-Bug reports and other feedback are most welcome.
-
-
-=head1 COPYRIGHT
-
- Copyright (c) 1997-2000, Damian Conway. All Rights Reserved.
-This module is free software; you can redistribute it and/or
-modify it under the same terms as Perl itself.
--- /dev/null
+Revision history for Perl extension Text::Balanced.
+
+1.00 Mon Aug 11 12:42:56 1997
+
+ - original version
+
+
+1.01 Mon Sep 8 18:09:18 EST 1997
+
+ - changed "quotemeta" to "quotemeta $_" to work
+ around bug in Perl 5.002 and 5.003
+
+
+1.10 Tue Sep 30 17:23:23 EST 1997
+
+ - reworked extract_quotelike to correct handling of some obscure cases
+
+
+1.21 Sat Oct 4 17:21:54 EST 1997
+
+ - synchronised with Parse::RecDescent distribution (version number
+ will now reflect that package)
+
+1.23 Fri Oct 17 10:26:38 EST 1997
+
+ - changed behaviour in scalar and void contexts. Scalar contexts
+ now return only the extracted string. Void contexts now remove
+ the extracted string from the first argument (or $_).
+
+1.24
+
+ - changed behaviour in scalar contexts. Scalar contexts
+ now return the extracted string _and_ remove it from the
+ first argument (or $_).
+
+ - changed return values on failure (all contexts return undef
+ for invalid return fields)
+
+ - fixed some lurking bugs with trailing modifier handling
+
+ - added :ALL tag to simplify wholesale importing of functions
+
+ - fixed serious bug with embedded division operators ("/")
+ This now also allows the ?...? form of pattern matching!
+
+1.35 Wed Jun 24 09:53:31 1998
+
+ - fixed handling of :: quantifiers in extract_variable()
+
+ - numerous trivial lexical changes to make xemacs happy
+
+
+1.36 Tue Jul 14 12:26:04 1998
+
+ - Reinstated POD file missing from previous distribution
+
+ - Added undocumented fourth parameter to extract_codeblock
+ so as to correctly handle (?) and (s?) modifiers in
+ RecDescent grammars.
+
+
+1.40 Tue Aug 4 13:54:52 1998
+
+ - Added (optional) handling of embedded quoted text to
+ extract_delimited (see revised entry in Balanced.pod)
+
+ - Added extract_tagged which extracts text between arbitrary,
+ optionally nested start and end tags (see new entry in
+ Balanced.pod).
+
+ - Added delimited_pat which builds a pattern which matches a
+ string delimited by any of the delimiters specified (see new
+ entry in Balanced.pod).
+
+ - Added test.pl
+
+
+1.41 Mon Aug 10 14:51:50 1998
+
+ - Reinstated change to extract_codeblock from 1.36 which were
+ mysteriously lost in 1.40
+
+
+1.50 Thu Aug 27 09:20:19 1998
+
+ - Improved the structure of the regex generated by
+ delimited_pat (and used in extract_delimited). It's
+ considerably more complex, but also more robust and
+ much faster in the worst case.
+
+ - Altered extract_variable to accept whitespace in variables,
+ e.g. '$ a -> {'b'} -> [2]'
+
+
+
+1.51 Sat Feb 13 10:31:55 1999
+
+ - Fixed bugs in prefix matching in extract_variable:
+ * incorrectly used default if '' specified
+ * now handles $#array correctly
+
+ - Fixed bugs in extract_codeblock:
+ * Now handles !~ properly
+ * Now handles embedded comments better.
+ * Now handles "raw" pattern matches better.
+
+ - Added support for single strings or qr's as
+ 'reject' and 'ignore' args to extract_tagged()
+
+ - Added gen_extract_tagged() to "precompile"
+ a specific tag extractor for repeated use
+ (approximately 3 times faster!)
+
+
+1.52 Thu Mar 4 12:43:38 1999
+
+ - Added CSV parsing example to documentation of extract_multiple.
+
+ - Fixed a bug with extract_codeblock in "RecDescent" mode
+ (it would accept "subrule(s?)" and "subrule(?)", but
+ not "subrule(s)"). Thanks, Jan.
+
+
+1.66 Fri Jul 2 13:29:22 1999
+
+ - Added ability to use quotelike operators in extract_bracketed
+
+ - Fixed bug under 5.003 ('foreach my $func' not understood)
+
+ - Added escape specification as fourth arg to &extract_delimited
+
+ - Fixed handling of &delimited_pat and &extract_delimited
+ when delimiter is same as escape
+
+ - Fixed handling of ->, =>, and >> in &extract_code
+ when delimiters are "<>"
+
+
+1.76 Fri Nov 19 06:51:54 1999
+
+ - IMPORTANT: Now requires 5.005 or better.
+
+ - IMPORTANT: Made extract methods sensitive to the pos()
+ value of the text they are parsing. In other words,
+ all extract subroutines now act like patterns of the form
+ /\G.../gc. See documentation for details.
+
+ - IMPORTANT: Changed semantics of extract_multiple, in line
+ with the above change, and to simplify the semantics to
+ something vaguely predictable. See documentation for details.
+
+ - Added ability to use qr/../'s and raw strings as extractors
+ in extract_multiple. See documentation.
+
+ - Added fourth argument to extract_codeblock to allow
+ outermost brackets to be separately specified. See
+ documentation for details.
+
+ - Reimplemented internals of all extraction subroutines
+ for significant speed-ups (between 100% and 2000%
+ improvement).
+
+ - Fixed nasty bug in extract_variable and extract_codeblock
+ (they were returning prefix as well in scalar context)
+
+ - Allowed read-only strings to be used as arguments in
+ scalar contexts.
+
+ - Renamed delimited_pat to gen-delimited pat (in line with
+ gen_extract_tagged). Old name still works, but is now deprecated.
+
+ - Tweaked all extraction subs so they correctly handle
+ zero-length prefix matches after another zero-length match.
+
+
+1.77 Mon Nov 22 06:08:23 1999
+
+ - Fixed major bug in extract_codeblock (would not
+ terminate if there was trailing whitespace)
+
+ - Improved /.../ pattern parsing within codeblocks
+
+
+1.81 Wed Sep 13 11:58:49 2000
+
+ - Fixed test count in extract_codeblock.t
+
+ - Fixed improbable bug with trailing ->'s in extract_variable
+
+ - Fixed (HT|X)ML tag extraction in extract_tagged (thanks, Tim)
+
+ - Added explanatory note about prefix matching (thanks again, Tim)
+
+ - Added handling of globs and sub refs to extract_variable
+
+ - Pod tweak (thanks Abigail)
+
+ - Allowed right tags to be run-time evaluated, so
+ extract_tagged($text, '/([a-z]+)', '/end$1') works
+ as expected.
+
+ - Added optional blessing of matches via extract_multiple
+
+ - Fixed bug in autogeneration of closing tags in extract_tagged
+ (Thanks, Coke)
+
+ - Fixed bug in interaction between extract_multiple and
+ gen_extract_tagged (Thanks Anthony)
+
+
+1.82 Sun Jan 14 16:56:04 2001
+
+ - Fixed nit in extract_variable.t
+ (tested more cases than it promised to)
+
+ - Fixed bug extracting prefix in extract_quotelike (Thanks Michael)
+
+ - Added handling of Perl 4 package qualifier: $Package'var, etc.
+
+ - Added handling of here docs (see documentation for limitations)
+
+ - Added reporting of failure position via $@->{pos} (see documentation)
+
+
+1.83 Mon Jan 15 12:43:12 2001
+
+ - Fixed numerous bugs in here doc extraction (many thanks Tim)
+
+
+1.84 Thu Apr 26 11:58:13 2001
+
+ - Fixed bug in certain extractions not matching strings
+ with embedded newlines (thanks Robin)
+
+
+1.85 Sun Jun 3 07:47:18 2001
+
+ - Fixed bug in extract_variable recognizing method calls that
+ start with an underscore (thanks Jeff)
+
+
+1.86 Mon Sep 3 06:57:08 2001
+
+ - Revised licence for inclusion in core distribution
+
+ - Consolidated POD in .pm file
+
+ - renamed tests to let DOS cope with them
--- /dev/null
+==============================================================================
+ Release of version 1.86 of Text::Balanced
+==============================================================================
+
+
+NAME
+
+ Text::Balanced - Extract delimited text sequences from strings.
+
+
+SUMMARY (see Balanced.pod for full details)
+
+ Text::Balanced::extract_delimited
+
+ `extract_delimited' extracts the initial substring of a string
+ which is delimited by a user-specified set of single-character
+ delimiters, whilst ignoring any backslash-escaped delimiter
+ characters.
+
+ Text::Balanced::extract_bracketed
+
+ `extract_bracketed' extracts a balanced-bracket-delimited substring
+ (using any one (or more) of the user-specified delimiter brackets:
+ '(..)', '{..}', '[..]', or '<..>').
+
+ Text::Balanced::extract_quotelike
+
+ `extract_quotelike' attempts to recognize and extract any one of the
+ various Perl quote and quotelike operators (see "perlop(3)"). Embedded
+ backslashed delimiters, nested bracket delimiters (for the
+ quotelike operators), and trailing modifiers are all correctly handled.
+
+ Text::Balanced::extract_codeblock
+
+ `extract_codeblock' attempts to recognize and extract a
+ balanced bracket-delimited substring which may also contain
+ unbalanced brackets inside Perl quotes or quotelike
+ operations. That is, `extract_codeblock' is like a combination
+ of `extract_bracketed' and `extract_quotelike'.
+
+ Text::Balanced::extract_tagged
+
+ `extract_tagged' attempts to recognize and extract a
+ substring between two arbitrary "tag" patterns (a start tag
+ and an end tag).
+
+
+INSTALLATION
+
+ It's all pure Perl, so just put the .pm file in its appropriate
+ local Perl subdirectory.
+
+
+AUTHOR
+
+ Damian Conway (damian@cs.monash.edu.au)
+
+
+COPYRIGHT
+
+ Copyright (c) 1997-2001, Damian Conway. All Rights Reserved.
+ This module is free software. It may be used, redistributed
+ and/or modified under the same terms as Perl itself.
+
+
+
+==============================================================================
+
+CHANGES IN VERSION 1.86
+
+
+ - Revised licence for inclusion in core distribution
+
+ - Consolidated POD in .pm file
+
+ - renamed tests to let DOS cope with them
+
+
+==============================================================================
+
+AVAILABILITY
+
+Text::Balanced has been uploaded to the CPAN
+and is also available from:
+
+ http://www.csse.monash.edu.au/~damian/CPAN/Text-Balanced.tar.gz
+
+==============================================================================
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
# Change 1..1 below to 1..last_test_to_print .
# (It may become useful if the test is moved to ./t subdirectory.)
-BEGIN { $| = 1; print "1..37\n"; }
+BEGIN { $| = 1; print "1..41\n"; }
END {print "not ok 1\n" unless $loaded;}
use Text::Balanced qw ( extract_codeblock );
$loaded = 1;
__DATA__
+# USING: extract_codeblock($str);
+{ $data[4] =~ /['"]/; };
+
+# USING: extract_codeblock($str,'(){}',undef,'()');
+(Foo(')'));
+
# USING: extract_codeblock($str,'<>');
< %x = ( try => "this") >;
< %x = () >;
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-#!./perl -ws
-
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
+#! /usr/local/bin/perl -ws
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
-BEGIN {
- chdir 't' if -d 't';
- @INC = '../lib';
-}
-
# Before `make install' is performed this script should be runnable with
# `make test'. After `make install' it should work as `perl test.pl'
https://perl5.git.perl.org / perl5.git / commitdiff