# $Id: Tree.pm,v 1.2 2003-07-31 07:54:51 matt Exp $ package XML::Parser::Style::Tree; use strict; sub Init { my $expat = shift; $expat->{Lists} = []; $expat->{Curlist} = $expat->{Tree} = []; } sub Start { my $expat = shift; my $tag = shift; my $newlist = [ {@_} ]; push @{ $expat->{Lists} }, $expat->{Curlist}; push @{ $expat->{Curlist} }, $tag => $newlist; $expat->{Curlist} = $newlist; } sub End { my $expat = shift; my $tag = shift; $expat->{Curlist} = pop @{ $expat->{Lists} }; } sub Char { my $expat = shift; my $text = shift; my $clist = $expat->{Curlist}; my $pos = $#$clist; if ( $pos > 0 and $clist->[ $pos - 1 ] eq '0' ) { $clist->[$pos] .= $text; } else { push @$clist, 0 => $text; } } sub Final { my $expat = shift; delete $expat->{Curlist}; delete $expat->{Lists}; $expat->{Tree}; } 1; __END__ =head1 NAME XML::Parser::Style::Tree - Tree style parser =head1 SYNOPSIS use XML::Parser; my $p = XML::Parser->new(Style => 'Tree'); my $tree = $p->parsefile('foo.xml'); =head1 DESCRIPTION This module implements XML::Parser's Tree style parser. When parsing a document, C will return a parse tree for the document. Each node in the tree takes the form of a tag, content pair. Text nodes are represented with a pseudo-tag of "0" and the string that is their content. For elements, the content is an array reference. The first item in the array is a (possibly empty) hash reference containing attributes. The remainder of the array is a sequence of tag-content pairs representing the content of the element. So for example the result of parsing: Hello thereHowdydo would be: Tag Content ================================================================== [foo, [{}, head, [{id => "a"}, 0, "Hello ", em, [{}, 0, "there"]], bar, [ {}, 0, "Howdy", ref, [{}]], 0, "do" ] ] The root document "foo", has 3 children: a "head" element, a "bar" element and the text "do". After the empty attribute hash, these are represented in it's contents by 3 tag-content pairs. =head2 Entity Expansion The underlying Expat parser always expands predefined XML entity references (C<<>, C<>>, C<&>, C<">, C<'>) in both text content and attribute values before they reach the Tree style handlers. This is required by the XML specification and cannot be prevented. For example, C<<> in the source XML will appear as C<< < >> in the resulting tree structure. If you need access to the original unexpanded text, consider using the handler-based API with the C method on the Expat object instead of the Tree style. =cut