Add Text::Balanced 1.83.

p4raw-id: //depot/perl@9117

2 files changed, 2203 insertions, 0 deletions

diff --git a/lib/Text/Balanced.pm b/lib/Text/Balanced.pm
new file mode 100644
index 0000000000..88218e8c84
--- /dev/null
+++ b/lib/Text/Balanced.pm
@@ -0,0 +1,997 @@
+# EXTRACT VARIOUSLY DELIMITED TEXT SEQUENCES FROM STRINGS.
+# FOR FULL DOCUMENTATION SEE Balanced.pod
+
+use 5.005;
+use strict;
+
+package Text::Balanced;
+
+use Exporter;
+use SelfLoader;
+use vars qw { $VERSION @ISA %EXPORT_TAGS };
+
+$VERSION = '1.83';
+@ISA		= qw ( Exporter );
+		     
+%EXPORT_TAGS	= ( ALL => [ qw(
+				&extract_delimited
+				&extract_bracketed
+				&extract_quotelike
+				&extract_codeblock
+				&extract_variable
+				&extract_tagged
+				&extract_multiple
+
+				&gen_delimited_pat
+				&gen_extract_tagged
+
+				&delimited_pat
+			       ) ] );
+
+Exporter::export_ok_tags('ALL');
+
+# PROTOTYPES
+
+sub _match_bracketed($$$$$$);
+sub _match_variable($$);
+sub _match_codeblock($$$$$$$);
+sub _match_quotelike($$$$);
+
+# HANDLE RETURN VALUES IN VARIOUS CONTEXTS
+
+sub _failmsg {
+	my ($message, $pos) = @_;
+	$@ = bless { error=>$message, pos=>$pos }, "Text::Balanced::ErrorMsg";
+}
+
+sub _fail
+{
+	my ($wantarray, $textref, $message, $pos) = @_;
+	_failmsg $message, $pos if $message;
+	return ("",$$textref,"") if $wantarray;
+	return undef;
+}
+
+sub _succeed
+{
+	$@ = undef;
+	my ($wantarray,$textref) = splice @_, 0, 2;
+	my ($extrapos, $extralen) = @_>18 ? splice(@_, -2, 2) : (0,0);
+	my ($startlen) = $_[5];
+	my $remainderpos = $_[2];
+	if ($wantarray)
+	{
+		my @res;
+		while (my ($from, $len) = splice @_, 0, 2)
+		{
+			push @res, substr($$textref,$from,$len);
+		}
+		if ($extralen) {	# CORRECT FILLET
+			my $extra = substr($res[0], $extrapos-$startlen, $extralen, "\n");
+			$res[1] = "$extra$res[1]";
+			eval { substr($$textref,$remainderpos,0) = $extra;
+			       substr($$textref,$extrapos,$extralen,"\n")} ;
+				#REARRANGE HERE DOC AND FILLET IF POSSIBLE
+			pos($$textref) = $remainderpos-$extralen+1; # RESET \G
+		}
+		else {
+			pos($$textref) = $remainderpos;		    # RESET \G
+		}
+		return @res;
+	}
+	else
+	{
+		my $match = substr($$textref,$_[0],$_[1]);
+		substr($match,$extrapos-$_[0]-$startlen,$extralen,"") if $extralen;
+		my $extra = $extralen
+			? substr($$textref, $extrapos, $extralen)."\n" : "";
+		eval {substr($$textref,$_[4],$_[1]+$_[5])=$extra} ;	#CHOP OUT PREFIX & MATCH, IF POSSIBLE
+		pos($$textref) = $_[4];				# RESET \G
+		return $match;
+	}
+}
+
+# BUILD A PATTERN MATCHING A SIMPLE DELIMITED STRING
+
+sub gen_delimited_pat($;$)  # ($delimiters;$escapes)
+{
+	my ($dels, $escs) = @_;
+	return "" unless $dels =~ /\S/;
+	$escs = '\\' unless $escs;
+	$escs .= substr($escs,-1) x (length($dels)-length($escs));
+	my @pat = ();
+	my $i;
+	for ($i=0; $i<length $dels; $i++)
+	{
+		my $del = quotemeta substr($dels,$i,1);
+		my $esc = quotemeta substr($escs,$i,1);
+		if ($del eq $esc)
+		{
+			push @pat, "$del(?:[^$del]*(?:(?:$del$del)[^$del]*)*)$del";
+		}
+		else
+		{
+			push @pat, "$del(?:[^$esc$del]*(?:$esc.[^$esc$del]*)*)$del";
+		}
+	}
+	my $pat = join '|', @pat;
+	return "(?:$pat)";
+}
+
+*delimited_pat = \&gen_delimited_pat;
+
+
+# THE EXTRACTION FUNCTIONS
+
+sub extract_delimited (;$$$$)
+{
+	my $textref = defined $_[0] ? \$_[0] : \$_;
+	my $wantarray = wantarray;
+	my $del  = defined $_[1] ? $_[1] : qq{\'\"\`};
+	my $pre  = defined $_[2] ? $_[2] : '\s*';
+	my $esc  = defined $_[3] ? $_[3] : qq{\\};
+	my $pat = gen_delimited_pat($del, $esc);
+	my $startpos = pos $$textref || 0;
+	return _fail($wantarray, $textref, "Not a delimited pattern", 0)
+		unless $$textref =~ m/\G($pre)($pat)/gc;
+	my $prelen = length($1);
+	my $matchpos = $startpos+$prelen;
+	my $endpos = pos $$textref;
+	return _succeed $wantarray, $textref,
+			$matchpos, $endpos-$matchpos,		# MATCH
+			$endpos,   length($$textref)-$endpos,	# REMAINDER
+			$startpos, $prelen;			# PREFIX
+}
+
+sub extract_bracketed (;$$$)
+{
+	my $textref = defined $_[0] ? \$_[0] : \$_;
+	my $ldel = defined $_[1] ? $_[1] : '{([<';
+	my $pre  = defined $_[2] ? $_[2] : '\s*';
+	my $wantarray = wantarray;
+	my $qdel = "";
+	my $quotelike;
+	$ldel =~ s/'//g and $qdel .= q{'};
+	$ldel =~ s/"//g and $qdel .= q{"};
+	$ldel =~ s/`//g and $qdel .= q{`};
+	$ldel =~ s/q//g and $quotelike = 1;
+	$ldel =~ tr/[](){}<>\0-\377/[[(({{<</ds;
+	my $rdel = $ldel;
+	unless ($rdel =~ tr/[({</])}>/)
+        {
+		return _fail $wantarray, $textref,
+			     "Did not find a suitable bracket in delimiter: \"$_[1]\"",
+			     0;
+	}
+	my $posbug = pos;
+	$ldel = join('|', map { quotemeta $_ } split('', $ldel));
+	$rdel = join('|', map { quotemeta $_ } split('', $rdel));
+	pos = $posbug;
+
+	my $startpos = pos $$textref || 0;
+	my @match = _match_bracketed($textref,$pre, $ldel, $qdel, $quotelike, $rdel);
+
+	return _fail ($wantarray, $textref) unless @match;
+
+	return _succeed ( $wantarray, $textref,
+			  $match[2], $match[5]+2,	# MATCH
+			  @match[8,9],			# REMAINDER
+			  @match[0,1],			# PREFIX
+			);
+}
+
+sub _match_bracketed($$$$$$)	# $textref, $pre, $ldel, $qdel, $quotelike, $rdel
+{
+	my ($textref, $pre, $ldel, $qdel, $quotelike, $rdel) = @_;
+	my ($startpos, $ldelpos, $endpos) = (pos $$textref = pos $$textref||0);
+	unless ($$textref =~ m/\G$pre/gc)
+	{
+		_failmsg "Did not find prefix: /$pre/", $startpos;
+		return;
+	}
+
+	$ldelpos = pos $$textref;
+
+	unless ($$textref =~ m/\G($ldel)/gc)
+	{
+		_failmsg "Did not find opening bracket after prefix: \"$pre\"",
+		         pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+
+	my @nesting = ( $1 );
+	my $textlen = length $$textref;
+	while (pos $$textref < $textlen)
+	{
+		next if $$textref =~ m/\G\\./gcs;
+
+		if ($$textref =~ m/\G($ldel)/gc)
+		{
+			push @nesting, $1;
+		}
+		elsif ($$textref =~ m/\G($rdel)/gc)
+		{
+			my ($found, $brackettype) = ($1, $1);
+			if ($#nesting < 0)
+			{
+				_failmsg "Unmatched closing bracket: \"$found\"",
+					 pos $$textref;
+				pos $$textref = $startpos;
+			        return;
+			}
+			my $expected = pop(@nesting);
+			$expected =~ tr/({[</)}]>/;
+			if ($expected ne $brackettype)
+			{
+				_failmsg qq{Mismatched closing bracket: expected "$expected" but found "$found"},
+					 pos $$textref;
+				pos $$textref = $startpos;
+			        return;
+			}
+			last if $#nesting < 0;
+		}
+		elsif ($qdel && $$textref =~ m/\G([$qdel])/gc)
+		{
+			$$textref =~ m/\G[^\\$1]*(?:\\.[^\\$1]*)*(\Q$1\E)/gc and next;
+			_failmsg "Unmatched embedded quote ($1)",
+				 pos $$textref;
+			pos $$textref = $startpos;
+			return;
+		}
+		elsif ($quotelike && _match_quotelike($textref,"",1,0))
+		{
+			next;
+		}
+
+		else { $$textref =~ m/\G(?:[a-zA-Z0-9]+|.)/gcs }
+	}
+	if ($#nesting>=0)
+	{
+		_failmsg "Unmatched opening bracket(s): "
+				. join("..",@nesting)."..",
+		         pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+
+	$endpos = pos $$textref;
+	
+	return (
+		$startpos,  $ldelpos-$startpos,		# PREFIX
+		$ldelpos,   1,				# OPENING BRACKET
+		$ldelpos+1, $endpos-$ldelpos-2,		# CONTENTS
+		$endpos-1,  1,				# CLOSING BRACKET
+		$endpos,    length($$textref)-$endpos,	# REMAINDER
+	       );
+}
+
+sub revbracket($)
+{
+	my $brack = reverse $_[0];
+	$brack =~ tr/[({</])}>/;
+	return $brack;
+}
+
+my $XMLNAME = q{[a-zA-Z_:][a-zA-Z0-9_:.-]*};
+
+sub extract_tagged (;$$$$$) # ($text, $opentag, $closetag, $pre, \%options)
+{
+	my $textref = defined $_[0] ? \$_[0] : \$_;
+	my $ldel    = $_[1];
+	my $rdel    = $_[2];
+	my $pre     = defined $_[3] ? $_[3] : '\s*';
+	my %options = defined $_[4] ? %{$_[4]} : ();
+	my $omode   = defined $options{fail} ? $options{fail} : '';
+	my $bad     = ref($options{reject}) eq 'ARRAY' ? join('|', @{$options{reject}})
+		    : defined($options{reject})	       ? $options{reject}
+		    :					 ''
+		    ;
+	my $ignore  = ref($options{ignore}) eq 'ARRAY' ? join('|', @{$options{ignore}})
+		    : defined($options{ignore})	       ? $options{ignore}
+		    :					 ''
+		    ;
+
+	if (!defined $ldel) { $ldel = '<\w+(?:' . gen_delimited_pat(q{'"}) . '|[^>])*>'; }
+	$@ = undef;
+
+	my @match = _match_tagged($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore);
+
+	return _fail(wantarray, $textref) unless @match;
+	return _succeed wantarray, $textref,
+			$match[2], $match[3]+$match[5]+$match[7],	# MATCH
+			@match[8..9,0..1,2..7];				# REM, PRE, BITS
+}
+
+sub _match_tagged	# ($$$$$$$)
+{
+	my ($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore) = @_;
+	my $rdelspec;
+
+	my ($startpos, $opentagpos, $textpos, $parapos, $closetagpos, $endpos) = ( pos($$textref) = pos($$textref)||0 );
+
+	unless ($$textref =~ m/\G($pre)/gc)
+	{
+		_failmsg "Did not find prefix: /$pre/", pos $$textref;
+		goto failed;
+	}
+
+	$opentagpos = pos($$textref);
+
+	unless ($$textref =~ m/\G$ldel/gc)
+	{
+		_failmsg "Did not find opening tag: /$ldel/", pos $$textref;
+		goto failed;
+	}
+
+	$textpos = pos($$textref);
+
+	if (!defined $rdel)
+	{
+		$rdelspec = $&;
+		unless ($rdelspec =~ s/\A([[(<{]+)($XMLNAME).*/ quotemeta "$1\/$2". revbracket($1) /oes)
+		{
+			_failmsg "Unable to construct closing tag to match: $rdel",
+				 pos $$textref;
+			goto failed;
+		}
+	}
+	else
+	{
+		$rdelspec = eval "qq{$rdel}";
+	}
+
+	while (pos($$textref) < length($$textref))
+	{
+		next if $$textref =~ m/\G\\./gc;
+
+		if ($$textref =~ m/\G(\n[ \t]*\n)/gc )
+		{
+			$parapos = pos($$textref) - length($1)
+				unless defined $parapos;
+		}
+		elsif ($$textref =~ m/\G($rdelspec)/gc )
+		{
+			$closetagpos = pos($$textref)-length($1);
+			goto matched;
+		}
+		elsif ($ignore && $$textref =~ m/\G(?:$ignore)/gc)
+		{
+			next;
+		}
+		elsif ($bad && $$textref =~ m/\G($bad)/gcs)
+		{
+			pos($$textref) -= length($1);	# CUT OFF WHATEVER CAUSED THE SHORTNESS
+			goto short if ($omode eq 'PARA' || $omode eq 'MAX');
+			_failmsg "Found invalid nested tag: $1", pos $$textref;
+			goto failed;
+		}
+		elsif ($$textref =~ m/\G($ldel)/gc)
+		{
+			my $tag = $1;
+			pos($$textref) -= length($tag);	# REWIND TO NESTED TAG
+			unless (_match_tagged(@_))	# MATCH NESTED TAG
+			{
+				goto short if $omode eq 'PARA' || $omode eq 'MAX';
+				_failmsg "Found unbalanced nested tag: $tag",
+					 pos $$textref;
+				goto failed;
+			}
+		}
+		else { $$textref =~ m/./gcs }
+	}
+
+short:
+	$closetagpos = pos($$textref);
+	goto matched if $omode eq 'MAX';
+	goto failed unless $omode eq 'PARA';
+
+	if (defined $parapos) { pos($$textref) = $parapos }
+	else		      { $parapos = pos($$textref) }
+
+	return (
+		$startpos,    $opentagpos-$startpos,		# PREFIX
+		$opentagpos,  $textpos-$opentagpos,		# OPENING TAG
+		$textpos,     $parapos-$textpos,		# TEXT
+		$parapos,     0,				# NO CLOSING TAG
+		$parapos,     length($$textref)-$parapos,	# REMAINDER
+	       );
+	
+matched:
+	$endpos = pos($$textref);
+	return (
+		$startpos,    $opentagpos-$startpos,		# PREFIX
+		$opentagpos,  $textpos-$opentagpos,		# OPENING TAG
+		$textpos,     $closetagpos-$textpos,		# TEXT
+		$closetagpos, $endpos-$closetagpos,		# CLOSING TAG
+		$endpos,      length($$textref)-$endpos,	# REMAINDER
+	       );
+
+failed:
+	_failmsg "Did not find closing tag", pos $$textref unless $@;
+	pos($$textref) = $startpos;
+	return;
+}
+
+sub extract_variable (;$$)
+{
+	my $textref = defined $_[0] ? \$_[0] : \$_;
+	return ("","","") unless defined $$textref;
+	my $pre  = defined $_[1] ? $_[1] : '\s*';
+
+	my @match = _match_variable($textref,$pre);
+
+	return _fail wantarray, $textref unless @match;
+
+	return _succeed wantarray, $textref,
+			@match[2..3,4..5,0..1];		# MATCH, REMAINDER, PREFIX
+}
+
+sub _match_variable($$)
+{
+	my ($textref, $pre) = @_;
+	my $startpos = pos($$textref) = pos($$textref)||0;
+	unless ($$textref =~ m/\G($pre)/gc)
+	{
+		_failmsg "Did not find prefix: /$pre/", pos $$textref;
+		return;
+	}
+	my $varpos = pos($$textref);
+	unless ($$textref =~ m/\G(\$#?|[*\@\%]|\\&)+/gc)
+	{
+		_failmsg "Did not find leading dereferencer", pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+
+	unless ($$textref =~ m/\G\s*(?:::|')?(?:[_a-z]\w*(?:::|'))*[_a-z]\w*/gci
+		or _match_codeblock($textref, "", '\{', '\}', '\{', '\}', 0))
+	{
+		_failmsg "Bad identifier after dereferencer", pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+
+	while (1)
+	{
+		next if _match_codeblock($textref,
+					 qr/\s*->\s*(?:[a-zA-Z]\w+\s*)?/,
+					 qr/[({[]/, qr/[)}\]]/,
+					 qr/[({[]/, qr/[)}\]]/, 0);
+		next if _match_codeblock($textref,
+					 qr/\s*/, qr/[{[]/, qr/[}\]]/,
+					 qr/[{[]/, qr/[}\]]/, 0);
+		next if _match_variable($textref,'\s*->\s*');
+		next if $$textref =~ m/\G\s*->\s*\w+(?![{([])/gc;
+		last;
+	}
+	
+	my $endpos = pos($$textref);
+	return ($startpos, $varpos-$startpos,
+		$varpos,   $endpos-$varpos,
+		$endpos,   length($$textref)-$endpos
+		);
+}
+
+sub extract_codeblock (;$$$$$)
+{
+	my $textref = defined $_[0] ? \$_[0] : \$_;
+	my $wantarray = wantarray;
+	my $ldel_inner = defined $_[1] ? $_[1] : '{';
+	my $pre        = defined $_[2] ? $_[2] : '\s*';
+	my $ldel_outer = defined $_[3] ? $_[3] : $ldel_inner;
+	my $rd         = $_[4];
+	my $rdel_inner = $ldel_inner;
+	my $rdel_outer = $ldel_outer;
+	my $posbug = pos;
+	for ($ldel_inner, $ldel_outer) { tr/[]()<>{}\0-\377/[[((<<{{/ds }
+	for ($rdel_inner, $rdel_outer) { tr/[]()<>{}\0-\377/]]))>>}}/ds }
+	for ($ldel_inner, $ldel_outer, $rdel_inner, $rdel_outer)
+	{
+		$_ = '('.join('|',map { quotemeta $_ } split('',$_)).')'
+	}
+	pos = $posbug;
+
+	my @match = _match_codeblock($textref, $pre,
+				     $ldel_outer, $rdel_outer,
+				     $ldel_inner, $rdel_inner,
+				     $rd);
+	return _fail($wantarray, $textref) unless @match;
+	return _succeed($wantarray, $textref,
+			@match[2..3,4..5,0..1]	# MATCH, REMAINDER, PREFIX
+		       );
+
+}
+
+sub _match_codeblock($$$$$$$)
+{
+	my ($textref, $pre, $ldel_outer, $rdel_outer, $ldel_inner, $rdel_inner, $rd) = @_;
+	my $startpos = pos($$textref) = pos($$textref) || 0;
+	unless ($$textref =~ m/\G($pre)/gc)
+	{
+		_failmsg qq{Did not match prefix /$pre/ at"} .
+			    substr($$textref,pos($$textref),20) .
+			    q{..."},
+		         pos $$textref;
+		return; 
+	}
+	my $codepos = pos($$textref);
+	unless ($$textref =~ m/\G($ldel_outer)/gc)	# OUTERMOST DELIMITER
+	{
+		_failmsg qq{Did not find expected opening bracket at "} .
+			     substr($$textref,pos($$textref),20) .
+			     q{..."},
+		         pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+	my $closing = $1;
+	   $closing =~ tr/([<{/)]>}/;
+	my $matched;
+	my $patvalid = 1;
+	while (pos($$textref) < length($$textref))
+	{
+		$matched = '';
+		if ($rd && $$textref =~ m#\G(\Q(?)\E|\Q(s?)\E|\Q(s)\E)#gc)
+		{
+			$patvalid = 0;
+			next;
+		}
+
+		if ($$textref =~ m/\G\s*#.*/gc)
+		{
+			next;
+		}
+
+		if ($$textref =~ m/\G\s*($rdel_outer)/gc)
+		{
+			unless ($matched = ($closing && $1 eq $closing) )
+			{
+				next if $1 eq '>';	# MIGHT BE A "LESS THAN"
+				_failmsg q{Mismatched closing bracket at "} .
+					     substr($$textref,pos($$textref),20) .
+					     qq{...". Expected '$closing'},
+					 pos $$textref;
+			}
+			last;
+		}
+
+		if (_match_variable($textref,'\s*') ||
+		    _match_quotelike($textref,'\s*',$patvalid,$patvalid) )
+		{
+			$patvalid = 0;
+			next;
+		}
+
+
+		# NEED TO COVER MANY MORE CASES HERE!!!
+		if ($$textref =~ m#\G\s*( [-+*x/%^&|.]=?
+					| =(?!>)
+					| (\*\*|&&|\|\||<<|>>)=?
+					| [!=][~=]
+					| split|grep|map|return
+					)#gcx)
+		{
+			$patvalid = 1;
+			next;
+		}
+
+		if ( _match_codeblock($textref, '\s*', $ldel_inner, $rdel_inner, $ldel_inner, $rdel_inner, $rd) )
+		{
+			$patvalid = 1;
+			next;
+		}
+
+		if ($$textref =~ m/\G\s*$ldel_outer/gc)
+		{
+			_failmsg q{Improperly nested codeblock at "} .
+				     substr($$textref,pos($$textref),20) .
+				     q{..."},
+				 pos $$textref;
+			last;
+		}
+
+		$patvalid = 0;
+		$$textref =~ m/\G\s*(\w+|[-=>]>|.|\Z)/gc;
+	}
+	continue { $@ = undef }
+
+	unless ($matched)
+	{
+		_failmsg 'No match found for opening bracket', pos $$textref
+			unless $@;
+		return;
+	}
+
+	my $endpos = pos($$textref);
+	return ( $startpos, $codepos-$startpos,
+		 $codepos, $endpos-$codepos,
+		 $endpos,  length($$textref)-$endpos,
+	       );
+}
+
+
+my %mods   = (
+		'none'	=> '[cgimsox]*',
+		'm'	=> '[cgimsox]*',
+		's'	=> '[cegimsox]*',
+		'tr'	=> '[cds]*',
+		'y'	=> '[cds]*',
+		'qq'	=> '',
+		'qx'	=> '',
+		'qw'	=> '',
+		'qr'	=> '[imsx]*',
+		'q'	=> '',
+	     );
+
+sub extract_quotelike (;$$)
+{
+	my $textref = $_[0] ? \$_[0] : \$_;
+	my $wantarray = wantarray;
+	my $pre  = defined $_[1] ? $_[1] : '\s*';
+
+	my @match = _match_quotelike($textref,$pre,1,0);
+	return _fail($wantarray, $textref) unless @match;
+	return _succeed($wantarray, $textref,
+			$match[2], $match[18]-$match[2],	# MATCH
+			@match[18,19],				# REMAINDER
+			@match[0,1],				# PREFIX
+			@match[2..17],				# THE BITS
+			@match[20,21],				# ANY FILLET?
+		       );
+};
+
+sub _match_quotelike($$$$)	# ($textref, $prepat, $allow_raw_match)
+{
+	my ($textref, $pre, $rawmatch, $qmark) = @_;
+
+	my ($textlen,$startpos,
+	    $oppos,
+	    $preld1pos,$ld1pos,$str1pos,$rd1pos,
+	    $preld2pos,$ld2pos,$str2pos,$rd2pos,
+	    $modpos) = ( length($$textref), pos($$textref) = pos($$textref) || 0 );
+
+	unless ($$textref =~ m/\G($pre)/gc)
+	{
+		_failmsg qq{Did not find prefix /$pre/ at "} .
+			     substr($$textref, pos($$textref), 20) .
+			     q{..."},
+		         pos $$textref;
+		return; 
+	}
+	$oppos = pos($$textref);
+
+	my $initial = substr($$textref,$oppos,1);
+
+	if ($initial && $initial =~ m|^[\"\'\`]|
+		     || $rawmatch && $initial =~ m|^/|
+		     || $qmark && $initial =~ m|^\?|)
+	{
+		unless ($$textref =~ m/ \Q$initial\E [^\\$initial]* (\\.[^\\$initial]*)* \Q$initial\E /gcx)
+		{
+			_failmsg qq{Did not find closing delimiter to match '$initial' at "} .
+				     substr($$textref, $oppos, 20) .
+				     q{..."},
+				 pos $$textref;
+			pos $$textref = $startpos;
+			return;
+		}
+		$modpos= pos($$textref);
+		$rd1pos = $modpos-1;
+
+		if ($initial eq '/' || $initial eq '?') 
+		{
+			$$textref =~ m/\G$mods{none}/gc
+		}
+
+		my $endpos = pos($$textref);
+		return (
+			$startpos,	$oppos-$startpos,	# PREFIX
+			$oppos,		0,			# NO OPERATOR
+			$oppos,		1,			# LEFT DEL
+			$oppos+1,	$rd1pos-$oppos-1,	# STR/PAT
+			$rd1pos,	1,			# RIGHT DEL
+			$modpos,	0,			# NO 2ND LDEL
+			$modpos,	0,			# NO 2ND STR
+			$modpos,	0,			# NO 2ND RDEL
+			$modpos,	$endpos-$modpos,	# MODIFIERS
+			$endpos, 	$textlen-$endpos,	# REMAINDER
+		       );
+	}
+
+	unless ($$textref =~ m{\G((?:m|s|qq|qx|qw|q|qr|tr|y)\b(?=\s*\S)|<<)}gc)
+	{
+		_failmsg q{No quotelike operator found after prefix at "} .
+			     substr($$textref, pos($$textref), 20) .
+			     q{..."},
+		         pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+
+	my $op = $1;
+	$preld1pos = pos($$textref);
+	if ($op eq '<<') {
+		$ld1pos = pos($$textref);
+		my $label;
+		if ($$textref =~ m{\G([A-Za-z_]\w*)}gc) {
+			$label = $1;
+		}
+		elsif ($$textref =~ m{ \G ' ([^'\\]* (?:\\.[^'\\]*)*) '
+				     | \G " ([^"\\]* (?:\\.[^"\\]*)*) "
+				     | \G ` ([^`\\]* (?:\\.[^`\\]*)*) `
+				     }gcx) {
+			$label = $+;
+		}
+		else {
+			$label = "";
+		}
+		my $extrapos = pos($$textref);
+		$$textref =~ m{.*\n}gc;
+		$str1pos = pos($$textref);
+		unless ($$textref =~ m{.*?\n(?=$label\n)}gc) {
+			_failmsg qq{Missing here doc terminator ('$label') after "} .
+				     substr($$textref, $startpos, 20) .
+				     q{..."},
+				 pos $$textref;
+			pos $$textref = $startpos;
+			return;
+		}
+		$rd1pos = pos($$textref);
+		$$textref =~ m{$label\n}gc;
+		$ld2pos = pos($$textref);
+		return (
+			$startpos,	$oppos-$startpos,	# PREFIX
+			$oppos,		length($op),		# OPERATOR
+			$ld1pos,	$extrapos-$ld1pos,	# LEFT DEL
+			$str1pos,	$rd1pos-$str1pos,	# STR/PAT
+			$rd1pos,	$ld2pos-$rd1pos,	# RIGHT DEL
+			$ld2pos,	0,			# NO 2ND LDEL
+			$ld2pos,	0,                	# NO 2ND STR
+			$ld2pos,	0,	                # NO 2ND RDEL
+			$ld2pos,	0,                      # NO MODIFIERS
+			$ld2pos,	$textlen-$ld2pos,	# REMAINDER
+			$extrapos,      $str1pos-$extrapos,	# FILLETED BIT
+		       );
+	}
+
+	$$textref =~ m/\G\s*/gc;
+	$ld1pos = pos($$textref);
+	$str1pos = $ld1pos+1;
+
+	unless ($$textref =~ m/\G(\S)/gc)	# SHOULD USE LOOKAHEAD
+	{
+		_failmsg "No block delimiter found after quotelike $op",
+		         pos $$textref;
+		pos $$textref = $startpos;
+		return;
+	}
+	pos($$textref) = $ld1pos;	# HAVE TO DO THIS BECAUSE LOOKAHEAD BROKEN
+	my ($ldel1, $rdel1) = ("\Q$1","\Q$1");
+	if ($ldel1 =~ /[[(<{]/)
+	{
+		$rdel1 =~ tr/[({</])}>/;
+		_match_bracketed($textref,"",$ldel1,"","",$rdel1)
+		|| do { pos $$textref = $startpos; return };
+	}
+	else
+	{
+		$$textref =~ /$ldel1[^\\$ldel1]*(\\.[^\\$ldel1]*)*$ldel1/gc
+		|| do { pos $$textref = $startpos; return };
+	}
+	$ld2pos = $rd1pos = pos($$textref)-1;
+
+	my $second_arg = $op =~ /s|tr|y/ ? 1 : 0;
+	if ($second_arg)
+	{
+		my ($ldel2, $rdel2);
+		if ($ldel1 =~ /[[(<{]/)
+		{
+			unless ($$textref =~ /\G\s*(\S)/gc)	# SHOULD USE LOOKAHEAD
+			{
+				_failmsg "Missing second block for quotelike $op",
+					 pos $$textref;
+				pos $$textref = $startpos;
+				return;
+			}
+			$ldel2 = $rdel2 = "\Q$1";
+			$rdel2 =~ tr/[({</])}>/;
+		}
+		else
+		{
+			$ldel2 = $rdel2 = $ldel1;
+		}
+		$str2pos = $ld2pos+1;
+
+		if ($ldel2 =~ /[[(<{]/)
+		{
+			pos($$textref)--;	# OVERCOME BROKEN LOOKAHEAD 
+			_match_bracketed($textref,"",$ldel2,"","",$rdel2)
+			|| do { pos $$textref = $startpos; return };
+		}
+		else
+		{
+			$$textref =~ /[^\\$ldel2]*(\\.[^\\$ldel2]*)*$ldel2/gc
+			|| do { pos $$textref = $startpos; return };
+		}
+		$rd2pos = pos($$textref)-1;
+	}
+	else
+	{
+		$ld2pos = $str2pos = $rd2pos = $rd1pos;
+	}
+
+	$modpos = pos $$textref;
+
+	$$textref =~ m/\G($mods{$op})/gc;
+	my $endpos = pos $$textref;
+
+	return (
+		$startpos,	$oppos-$startpos,	# PREFIX
+		$oppos,		length($op),		# OPERATOR
+		$ld1pos,	1,			# LEFT DEL
+		$str1pos,	$rd1pos-$str1pos,	# STR/PAT
+		$rd1pos,	1,			# RIGHT DEL
+		$ld2pos,	$second_arg,		# 2ND LDEL (MAYBE)
+		$str2pos,	$rd2pos-$str2pos,	# 2ND STR (MAYBE)
+		$rd2pos,	$second_arg,		# 2ND RDEL (MAYBE)
+		$modpos,	$endpos-$modpos,	# MODIFIERS
+		$endpos,	$textlen-$endpos,	# REMAINDER
+	       );
+}
+
+my $def_func = 
+[
+	sub { extract_variable($_[0], '') },
+	sub { extract_quotelike($_[0],'') },
+	sub { extract_codeblock($_[0],'{}','') },
+];
+
+sub extract_multiple (;$$$$)	# ($text, $functions_ref, $max_fields, $ignoreunknown)
+{
+	my $textref = defined($_[0]) ? \$_[0] : \$_;
+	my $posbug = pos;
+	my ($lastpos, $firstpos);
+	my @fields = ();
+
+	for ($$textref)
+	{
+		my @func = defined $_[1] ? @{$_[1]} : @{$def_func};
+		my $max  = defined $_[2] && $_[2]>0 ? $_[2] : 1_000_000_000;
+		my $igunk = $_[3];
+
+		pos ||= 0;
+
+		unless (wantarray)
+		{
+			use Carp;
+			carp "extract_multiple reset maximal count to 1 in scalar context"
+				if $^W && defined($_[2]) && $max > 1;
+			$max = 1
+		}
+
+		my $unkpos;
+		my $func;
+		my $class;
+
+		my @class;
+		foreach $func ( @func )
+		{
+			if (ref($func) eq 'HASH')
+			{
+				push @class, (keys %$func)[0];
+				$func = (values %$func)[0];
+			}
+			else
+			{
+				push @class, undef;
+			}
+		}
+
+		FIELD: while (pos() < length())
+		{
+			my $field;
+			foreach my $i ( 0..$#func )
+			{
+				$func = $func[$i];
+				$class = $class[$i];
+				$lastpos = pos;
+				if (ref($func) eq 'CODE')
+					{ ($field) = $func->($_) }
+				elsif (ref($func) eq 'Text::Balanced::Extractor')
+					{ $field = $func->extract($_) }
+				elsif( m/\G$func/gc )
+					{ $field = defined($1) ? $1 : $& }
+
+				if (defined($field) && length($field))
+				{
+					if (defined($unkpos) && !$igunk)
+					{
+						push @fields, substr($_, $unkpos, $lastpos-$unkpos);
+						$firstpos = $unkpos unless defined $firstpos;
+						undef $unkpos;
+						last FIELD if @fields == $max;
+					}
+					push @fields, $class 
+						? bless(\$field, $class)
+						: $field;
+					$firstpos = $lastpos unless defined $firstpos;
+					$lastpos = pos;
+					last FIELD if @fields == $max;
+					next FIELD;
+				}
+			}
+			if (/\G(.)/gcs)
+			{
+				$unkpos = pos()-1
+					unless $igunk || defined $unkpos;
+			}
+		}
+		
+		if (defined $unkpos)
+		{
+			push @fields, substr($_, $unkpos);
+			$firstpos = $unkpos unless defined $firstpos;
+			$lastpos = length;
+		}
+		last;
+	}
+
+	pos $$textref = $lastpos;
+	return @fields if wantarray;
+
+	$firstpos ||= 0;
+	eval { substr($$textref,$firstpos,$lastpos-$firstpos)="";
+	       pos $$textref = $firstpos };
+	return $fields[0];
+}
+
+
+sub gen_extract_tagged # ($opentag, $closetag, $pre, \%options)
+{
+	my $ldel    = $_[0];
+	my $rdel    = $_[1];
+	my $pre     = defined $_[2] ? $_[2] : '\s*';
+	my %options = defined $_[3] ? %{$_[3]} : ();
+	my $omode   = defined $options{fail} ? $options{fail} : '';
+	my $bad     = ref($options{reject}) eq 'ARRAY' ? join('|', @{$options{reject}})
+		    : defined($options{reject})	       ? $options{reject}
+		    :					 ''
+		    ;
+	my $ignore  = ref($options{ignore}) eq 'ARRAY' ? join('|', @{$options{ignore}})
+		    : defined($options{ignore})	       ? $options{ignore}
+		    :					 ''
+		    ;
+
+	if (!defined $ldel) { $ldel = '<\w+(?:' . gen_delimited_pat(q{'"}) . '|[^>])*>'; }
+
+	my $posbug = pos;
+	for ($ldel, $pre, $bad, $ignore) { $_ = qr/$_/ if $_ }
+	pos = $posbug;
+
+	my $closure = sub
+	{
+		my $textref = defined $_[0] ? \$_[0] : \$_;
+		my @match = Text::Balanced::_match_tagged($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore);
+
+		return _fail(wantarray, $textref) unless @match;
+		return _succeed wantarray, $textref,
+				$match[2], $match[3]+$match[5]+$match[7],	# MATCH
+				@match[8..9,0..1,2..7];				# REM, PRE, BITS
+	};
+
+	bless $closure, 'Text::Balanced::Extractor';
+}
+
+package Text::Balanced::Extractor;
+
+sub extract($$)	# ($self, $text)
+{
+	&{$_[0]}($_[1]);
+}
+
+package Text::Balanced::ErrorMsg;
+
+use overload '""' => sub { "$_[0]->{error}, detected at offset $_[0]->{pos}" };
+
+1;
diff --git a/lib/Text/Balanced.pod b/lib/Text/Balanced.pod
new file mode 100644
index 0000000000..7113af33f6
--- /dev/null
+++ b/lib/Text/Balanced.pod
@@ -0,0 +1,1206 @@
+=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. 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)