Damian-o-rama: upgrade to Attribute::Handlers 0.75,

Filter::Simple 0.61, NEXT 0.02, Switch 2.05, and Text::Balanced 1.86. p4raw-id: //depot/perl@11842
author: Jarkko Hietaniemi <jhi@iki.fi> 2001-09-03 12:17:30 +0000
committer: Jarkko Hietaniemi <jhi@iki.fi> 2001-09-03 12:17:30 +0000
commit: 55a1c97c34bea81a888ebe7db8a5607b1b7b9a39 (patch)
tree: aaa5e306ca29346cdaa4bb179b3d05ff90a6cfc4 /lib/Text
parent: efec44ca9b235a3617685a4d7c0d5b1e8d8d2fbd (diff)
download: perl-55a1c97c34bea81a888ebe7db8a5607b1b7b9a39.tar.gz
12 files changed, 1554 insertions, 1250 deletions
diff --git a/lib/Text/Balanced.pm b/lib/Text/Balanced.pm
index 73d633241a..f50e2f58d4 100644
--- a/lib/Text/Balanced.pm
+++ b/lib/Text/Balanced.pm
@@ -10,7 +10,7 @@ use Exporter;
 use SelfLoader;
 use vars qw { $VERSION @ISA %EXPORT_TAGS };
 
-$VERSION = '1.85';
+$VERSION = '1.86';
 @ISA		= qw ( Exporter );
 		     
 %EXPORT_TAGS	= ( ALL => [ qw(
@@ -566,9 +566,9 @@ sub _match_codeblock($$$$$$$)
 
 		# NEED TO COVER MANY MORE CASES HERE!!!
 		if ($$textref =~ m#\G\s*( [-+*x/%^&|.]=?
+					| [!=]~
 					| =(?!>)
 					| (\*\*|&&|\|\||<<|>>)=?
-					| [!=][~=]
 					| split|grep|map|return
 					)#gcx)
 		{
@@ -995,3 +995,1211 @@ package Text::Balanced::ErrorMsg;
 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.
diff --git a/lib/Text/Balanced.pod b/lib/Text/Balanced.pod
deleted file mode 100644
index 75d67aa2a4..0000000000
--- a/lib/Text/Balanced.pod
+++ /dev/null
@@ -1,1205 +0,0 @@
-=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.
diff --git a/lib/Text/Balanced/Changes b/lib/Text/Balanced/Changes
new file mode 100644
index 0000000000..5b34b73abb
--- /dev/null
+++ b/lib/Text/Balanced/Changes
@@ -0,0 +1,248 @@
+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
diff --git a/lib/Text/Balanced/README b/lib/Text/Balanced/README
new file mode 100755
index 0000000000..feba188b38
--- /dev/null
+++ b/lib/Text/Balanced/README
@@ -0,0 +1,88 @@
+==============================================================================
+                  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
+
+==============================================================================
diff --git a/lib/Text/Balanced/t/xbrak.t b/lib/Text/Balanced/t/extbrk.t
index 5a8e5249a8..a36025ddb0 100644
--- a/lib/Text/Balanced/t/xbrak.t
+++ b/lib/Text/Balanced/t/extbrk.t
@@ -1,8 +1,3 @@
-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'
 
diff --git a/lib/Text/Balanced/t/xcode.t b/lib/Text/Balanced/t/extcbk.t
index 00be51e542..10f974187b 100644
--- a/lib/Text/Balanced/t/xcode.t
+++ b/lib/Text/Balanced/t/extcbk.t
@@ -1,8 +1,3 @@
-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'
 
@@ -11,7 +6,7 @@ BEGIN {
 # 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 );
 $loaded = 1;
@@ -57,6 +52,12 @@ while (defined($str = <DATA>))
 
 __DATA__
 
+# USING: extract_codeblock($str);
+{ $data[4] =~ /['"]/; };
+
+# USING: extract_codeblock($str,'(){}',undef,'()');
+(Foo(')'));
+
 # USING: extract_codeblock($str,'<>');
 < %x = ( try => "this") >;
 < %x = () >;
diff --git a/lib/Text/Balanced/t/xdeli.t b/lib/Text/Balanced/t/extdel.t
index 7e5b06beca..c5ca88eebf 100644
--- a/lib/Text/Balanced/t/xdeli.t
+++ b/lib/Text/Balanced/t/extdel.t
@@ -1,8 +1,3 @@
-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'
 
diff --git a/lib/Text/Balanced/t/xmult.t b/lib/Text/Balanced/t/extmul.t
index 31dd7d4051..46addcc8b4 100644
--- a/lib/Text/Balanced/t/xmult.t
+++ b/lib/Text/Balanced/t/extmul.t
@@ -1,8 +1,3 @@
-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'
 
diff --git a/lib/Text/Balanced/t/xquot.t b/lib/Text/Balanced/t/extqlk.t
index 567e0a54b8..217d7d1fd3 100644
--- a/lib/Text/Balanced/t/xquot.t
+++ b/lib/Text/Balanced/t/extqlk.t
@@ -1,10 +1,4 @@
-#!./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'
 
diff --git a/lib/Text/Balanced/t/xtagg.t b/lib/Text/Balanced/t/exttag.t
index c883181c24..764e7906bb 100644
--- a/lib/Text/Balanced/t/xtagg.t
+++ b/lib/Text/Balanced/t/exttag.t
@@ -1,8 +1,3 @@
-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'
 
diff --git a/lib/Text/Balanced/t/xvari.t b/lib/Text/Balanced/t/extvar.t
index dd35b9c032..93bd22b41c 100644
--- a/lib/Text/Balanced/t/xvari.t
+++ b/lib/Text/Balanced/t/extvar.t
@@ -1,8 +1,3 @@
-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'
 
diff --git a/lib/Text/Balanced/t/genxt.t b/lib/Text/Balanced/t/gentag.t
index 6889653841..4e68b4117a 100644
--- a/lib/Text/Balanced/t/genxt.t
+++ b/lib/Text/Balanced/t/gentag.t
@@ -1,8 +1,3 @@
-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'
author	Jarkko Hietaniemi <jhi@iki.fi>	2001-09-03 12:17:30 +0000
committer	Jarkko Hietaniemi <jhi@iki.fi>	2001-09-03 12:17:30 +0000
commit	55a1c97c34bea81a888ebe7db8a5607b1b7b9a39 (patch)
tree	aaa5e306ca29346cdaa4bb179b3d05ff90a6cfc4 /lib/Text
parent	efec44ca9b235a3617685a4d7c0d5b1e8d8d2fbd (diff)
download	perl-55a1c97c34bea81a888ebe7db8a5607b1b7b9a39.tar.gz