NAME

XML::TokeParser - Simplified interface to XML::Parser

SYNOPSIS

use XML::TokeParser;

#parse from file
my $p=XML::TokeParser->new('file.xml')

#parse from open handle
open IN,'file.xml' or die $!;
my $p=XML::TokeParser->new(\*IN,Noempty=>1);

#parse literal text
my $text='<tag xmlns="http://www.omsdev.com">text</tag>';
my $p=XML::TokeParser->new(\$text,Namespaces=>1);

#read next token
my $token=$p->get_token();

#skip to <title> and read text
$p->get_tag('title');
$p->get_text();

#read text of next <para>, ignoring any internal markup
$p->get_tag('para');
$p->get_trimmed_text('/para');

#process <para> if interesting text
$t=$p->get_tag('para');
$p->begin_saving($t);
if ($p->get_trimmed_text('/para') =~ /interesting stuff/) {
  $p->restore_saved();
  process_para($p);
}

DESCRIPTION

XML::TokeParser provides a procedural ("pull mode") interface to XML::Parser in much the same way that Gisle Aas' HTML::TokeParser provides a procedural interface to HTML::Parser. XML::TokeParser splits its XML input up into "tokens," each corresponding to an XML::Parser event.

A token is a reference to an array whose first element is an event-type string and whose last element is the literal text of the XML input that generated the event, with intermediate elements varying according to the event type:

Start tag

The token has five elements: 'S', the element's name, a reference to a hash of attribute values keyed by attribute names, a reference to an array of attribute names in the order in which they appeared in the tag, and the literal text.

End tag

The token has three elements: 'E', the element's name, and the literal text.

Character data (text)

The token has three elements: 'T', the parsed text, and the literal text. All contiguous runs of text are gathered into single tokens; there will never be two 'T' tokens in a row.

Comment

The token has three elements: 'C', the parsed text of the comment, and the literal text.

Processing instruction

The token has four elements: 'PI', the target, the data, and the literal text.

The literal text includes any markup delimiters (pointy brackets, <![CDATA[, etc.), entity references, and numeric character references and is in the XML document's original character encoding. All other text is in UTF-8 (unless the Latin option is set, in which case it's in ISO-8859-1) regardless of the original encoding, and all entity and character references are expanded.

If the Namespaces option is set, element and attribute names are prefixed by their (possibly empty) namespace URIs enclosed in curly brackets and xmlns:* attributes do not appear in 'S' tokens.

METHODS

$p = XML::TokeParser->new($input, [options])

Creates a new parser, specifying the input source and any options. If $input is a string, it is the name of the file to parse. If $input is a reference to a string, that string is the actual text to parse. If $input is a reference to a typeglob or an IO::Handle object corresponding to an open file or socket, the text read from the handle will be parsed.

Options are name=>value pairs and can be any of the following:

Namespaces

If set to a true value, namespace processing is enabled.

ParseParamEnt

This option is passed on to the underlying XML::Parser object; see that module's documentation for details.

Noempty

If set to a true value, text tokens consisting of only whitespace (such as those created by indentation and line breaks in between tags) will be ignored.

Latin

If set to a true value, all text other than the literal text elements of tokens will be translated into the ISO 8859-1 (Latin-1) character encoding rather than the normal UTF-8 encoding.

Catalog

The value is the URI of a catalog file used to resolve PUBLIC and SYSTEM identifiers. See XML::Catalog for details.

$token = $p->get_token()

Returns the next token, as an array reference, from the input. Returns undef if there are no remaining tokens.

$p->unget_token($token,...)

Pushes tokens back so they will be re-read. Useful if you've read one or more tokens too far. Correctly handles "partial" tokens returned by get_tag().

$token = $p->get_tag( [$token] )

If no argument given, skips tokens until the next start tag or end tag token. If an argument is given, skips tokens until the start tag or end tag (if the argument begins with '/') for the named element. The returned token does not include an event type code; its first element is the element name, prefixed by a '/' if the token is for an end tag.

$text = $p->get_text( [$token] )

If no argument given, returns the text at the current position, or an empty string if the next token is not a 'T' token. If an argument is given, gathers up all text between the current position and the specified start or end tag, stripping out any intervening tags (much like the way a typical Web browser deals with unknown tags).

$text = $p->get_trimmed_text( [$token] )

Like get_text(), but deletes any leading or trailing whitespaces and collapses multiple whitespace (including newlines) into single spaces.

$p->begin_saving( [$token] )

Causes subsequent calls to get_token(), get_tag(), get_text(), and get_trimmed_text() to save the returned tokens. In conjunction with restore_saved(), allows you to "back up" within a token stream. If an argument is supplied, it is placed at the beginning of the list of saved tokens (useful because you often won't know you want to begin saving until you've already read the first token you want saved).

$p->restore_saved()

Pushes all the tokens saved by begin_saving() back onto the token stream. Stops saving tokens. To cancel saving without backing up, call begin_saving() and restore_saved() in succession.

DIFFERENCES FROM HTML::TokeParser

Uses a true XML parser rather than a modified HTML parser.

Text and comment tokens include extracted text as well as literal text.

PI tokens include target and data as well as literal text.

No tokens for declarations.

No "textify" hash.

unget_token correctly handles partial tokens returned by get_tag().

begin_saving() and restore_saved()

EXAMPLES

Print method signatures from the XML version of this PODpage

#!/usr/bin/perl -w
use strict;
use XML::TokeParser;
my $t;
my $p=XML::TokeParser->new('tokeparser.xml',Noempty=>1) or die $!;
while ($p->get_tag('title') && $p->get_text('/title') ne 'METHODS') {
  ;
}
$p->get_tag('list');
while (($t=$p->get_tag()->[0]) ne '/list') {
  if ($t eq 'item') {
    $p->get_tag('itemtext');
    print $p->get_text('/itemtext'),"\n";
    $p->get_tag('/item');
  }
  else {
    $p->get_tag('/list');  # assumes no nesting here!
  }
}

AUTHOR

Eric Bohlman (ebohlman@omsdev.com)

Copyright (c) 2001 Eric Bohlman. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

XML::Parser
XML::Catalog
HTML::TokeParser