# $Id$

package XML::SAX::PurePerl;

use strict;
use vars qw/$VERSION/;

$VERSION = '0.99';

use XML::SAX::PurePerl::Productions qw($NameChar $SingleChar);
use XML::SAX::PurePerl::Reader;
use XML::SAX::PurePerl::EncodingDetect ();
use XML::SAX::Exception;
use XML::SAX::PurePerl::DocType ();
use XML::SAX::PurePerl::DTDDecls ();
use XML::SAX::PurePerl::XMLDecl ();
use XML::SAX::DocumentLocator ();
use XML::SAX::Base ();
use XML::SAX qw(Namespaces);
use XML::NamespaceSupport ();
use IO::File;

if ($] < 5.006) {
    require XML::SAX::PurePerl::NoUnicodeExt;
}
else {
    require XML::SAX::PurePerl::UnicodeExt;
}

use vars qw(@ISA);
@ISA = ('XML::SAX::Base');

my %int_ents = (
        amp => '&',
        lt => '<',
        gt => '>',
        quot => '"',
        apos => "'",
        );

my $xmlns_ns = "http://www.w3.org/2000/xmlns/";
my $xml_ns = "http://www.w3.org/XML/1998/namespace";

use Carp;
sub _parse_characterstream {
    my $self = shift;
    my ($fh) = @_;
    confess("CharacterStream is not yet correctly implemented");
    my $reader = XML::SAX::PurePerl::Reader::Stream->new($fh);
    return $self->_parse($reader);
}

sub _parse_bytestream {
    my $self = shift;
    my ($fh) = @_;
    my $reader = XML::SAX::PurePerl::Reader::Stream->new($fh);
    return $self->_parse($reader);
}

sub _parse_string {
    my $self = shift;
    my ($str) = @_;
    my $reader = XML::SAX::PurePerl::Reader::String->new($str);
    return $self->_parse($reader);
}

sub _parse_systemid {
    my $self = shift;
    my ($uri) = @_;
    my $reader = XML::SAX::PurePerl::Reader::URI->new($uri);
    return $self->_parse($reader);
}

sub _parse {
    my ($self, $reader) = @_;
    
    $reader->public_id($self->{ParseOptions}{Source}{PublicId});
    $reader->system_id($self->{ParseOptions}{Source}{SystemId});

    $self->{NSHelper} = XML::NamespaceSupport->new({xmlns => 1});

    $self->set_document_locator(
        XML::SAX::DocumentLocator->new(
            sub { $reader->public_id },
            sub { $reader->system_id },
            sub { $reader->line },
            sub { $reader->column },
            sub { $reader->get_encoding },
            sub { $reader->get_xml_version },
        ),
    );
    
    $self->start_document({});

    if (defined $self->{ParseOptions}{Source}{Encoding}) {
        $reader->set_encoding($self->{ParseOptions}{Source}{Encoding});
    }
    else {
        $self->encoding_detect($reader);
    }
    
    # parse a document
    $self->document($reader);
    
    return $self->end_document({});
}

sub parser_error {
    my $self = shift;
    my ($error, $reader) = @_;
    
# warn("parser error: $error from ", $reader->line, " : ", $reader->column, "\n");
    my $exception = XML::SAX::Exception::Parse->new(
                Message => $error,
                ColumnNumber => $reader->column,
                LineNumber => $reader->line,
                PublicId => $reader->public_id,
                SystemId => $reader->system_id,
            );

    $self->fatal_error($exception);
    $exception->throw;
}

sub document {
    my ($self, $reader) = @_;
    
    # document ::= prolog element Misc*
    
    $self->prolog($reader);
    $self->element($reader) ||
        $self->parser_error("Document requires an element", $reader);
    
    while(length($reader->data)) {
        $self->Misc($reader) || 
                $self->parser_error("Only Comments, PIs and whitespace allowed at end of document", $reader);
    }
}

sub prolog {
    my ($self, $reader) = @_;
    
    $self->XMLDecl($reader);
    
    # consume all misc bits
    1 while($self->Misc($reader));
    
    if ($self->doctypedecl($reader)) {
        while (length($reader->data)) {
            $self->Misc($reader) || last;
        }
    }
}

sub element {
    my ($self, $reader) = @_;
    
    return 0 unless $reader->match('<');
    
    my $name = $self->Name($reader) || $self->parser_error("Invalid element name", $reader);
    
    my %attribs;
    
    while( my ($k, $v) = $self->Attribute($reader) ) {
        $attribs{$k} = $v;
    }
    
    my $have_namespaces = $self->get_feature(Namespaces);
    
    # Namespace processing
    $self->{NSHelper}->push_context;
    my @new_ns;
#        my %attrs = @attribs;
#        while (my ($k,$v) = each %attrs) {
    if ($have_namespaces) {
        while ( my ($k, $v) = each %attribs ) {
            if ($k =~ m/^xmlns(:(.*))?$/) {
                my $prefix = $2 || '';
                $self->{NSHelper}->declare_prefix($prefix, $v);
                my $ns = 
                    {
                        Prefix       => $prefix,
                        NamespaceURI => $v,
                    };
                push @new_ns, $ns;
                $self->SUPER::start_prefix_mapping($ns);
            }
        }
    }

    # Create element object and fire event
    my %attrib_hash;
    while (my ($name, $value) = each %attribs ) {
        # TODO normalise value here
        my ($ns, $prefix, $lname);
        if ($have_namespaces) {
            ($ns, $prefix, $lname) = $self->{NSHelper}->process_attribute_name($name);
        }
        $ns ||= ''; $prefix ||= ''; $lname ||= '';
        $attrib_hash{"{$ns}$lname"} = {
            Name => $name,
            LocalName => $lname,
            Prefix => $prefix,
            NamespaceURI => $ns,
            Value => $value,
        };
    }
    
    %attribs = (); # lose the memory since we recurse deep
    
    my ($ns, $prefix, $lname);
    if ($self->get_feature(Namespaces)) {
        ($ns, $prefix, $lname) = $self->{NSHelper}->process_element_name($name);
    }
    else {
        $lname = $name;
    }
    $ns ||= ''; $prefix ||= ''; $lname ||= '';

    # Process remainder of start_element
    $self->skip_whitespace($reader);
    my $have_content;
    my $data = $reader->data(2);
    if ($data =~ /^\/>/) {
        $reader->move_along(2);
    }
    else {
        $data =~ /^>/ or $self->parser_error("No close element tag", $reader);
        $reader->move_along(1);
        $have_content++;
    }
    
    my $el = 
    {
        Name => $name,
        LocalName => $lname,
        Prefix => $prefix,
        NamespaceURI => $ns,
        Attributes => \%attrib_hash,
    };
    $self->start_element($el);
    
    # warn("($name\n");
    
    if ($have_content) {
        $self->content($reader);
        
        my $data = $reader->data(2);
        $data =~ /^<\// or $self->parser_error("No close tag marker", $reader);
        $reader->move_along(2);
        my $end_name = $self->Name($reader);
        $end_name eq $name || $self->parser_error("End tag mismatch ($end_name != $name)", $reader);
        $self->skip_whitespace($reader);
        $reader->match('>') or $self->parser_error("No close '>' on end tag", $reader);
    }
        
    my %end_el = %$el;
    delete $end_el{Attributes};
    $self->end_element(\%end_el);

    for my $ns (@new_ns) {
        $self->end_prefix_mapping($ns);
    }
    $self->{NSHelper}->pop_context;
    
    return 1;
}

sub content {
    my ($self, $reader) = @_;
    
    while (1) {
        $self->CharData($reader);
        
        my $data = $reader->data(2);
        
        if ($data =~ /^<\//) {
            return 1;
        }
        elsif ($data =~ /^&/) {
            $self->Reference($reader) or $self->parser_error("bare & not allowed in content", $reader);
            next;
        }
        elsif ($data =~ /^<!/) {
            ($self->CDSect($reader)
             or
             $self->Comment($reader))
             and next;
        }
        elsif ($data =~ /^<\?/) {
            $self->PI($reader) and next;
        }
        elsif ($data =~ /^</) {
            $self->element($reader) and next;
        }
        last;
    }
    
    return 1;
}

sub CDSect {
    my ($self, $reader) = @_;
    
    my $data = $reader->data(9);
    return 0 unless $data =~ /^<!\[CDATA\[/;
    $reader->move_along(9);
    
    $self->start_cdata({});
    
    $data = $reader->data;
    while (1) {
        $self->parser_error("EOF looking for CDATA section end", $reader)
            unless length($data);
        
        if ($data =~ /^(.*?)\]\]>/s) {
            my $chars = $1;
            $reader->move_along(length($chars) + 3);
            $self->characters({Data => $chars});
            last;
        }
        else {
            $self->characters({Data => $data});
            $reader->move_along(length($data));
            $data = $reader->data;
        }
    }
    $self->end_cdata({});
    return 1;
}

sub CharData {
    my ($self, $reader) = @_;
    
    my $data = $reader->data;
    
    while (1) {
        return unless length($data);
        
        if ($data =~ /^([^<&]*)[<&]/s) {
            my $chars = $1;
            $self->parser_error("String ']]>' not allowed in character data", $reader)
                if $chars =~ /\]\]>/;
            $reader->move_along(length($chars));
            $self->characters({Data => $chars}) if length($chars);
            last;
        }
        else {
            $self->characters({Data => $data});
            $reader->move_along(length($data));
            $data = $reader->data;
        }
    }
}

sub Misc {
    my ($self, $reader) = @_;
    if ($self->Comment($reader)) {
        return 1;
    }
    elsif ($self->PI($reader)) {
        return 1;
    }
    elsif ($self->skip_whitespace($reader)) {
        return 1;
    }
    
    return 0;
}

sub Reference {
    my ($self, $reader) = @_;
    
    return 0 unless $reader->match('&');
    
    my $data = $reader->data;

    # Fetch more data if we have an incomplete numeric reference
    if ($data =~ /^(#\d*|#x[0-9a-fA-F]*)$/) {
        $data = $reader->data(length($data) + 6);
    }
    
    if ($data =~ /^#x([0-9a-fA-F]+);/) {
        my $ref = $1;
        $reader->move_along(length($ref) + 3);
        my $char = chr_ref(hex($ref));
        $self->parser_error("Character reference &#$ref; refers to an illegal XML character ($char)", $reader)
            unless $char =~ /$SingleChar/o;
        $self->characters({ Data => $char });
        return 1;
    }
    elsif ($data =~ /^#([0-9]+);/) {
        my $ref = $1;
        $reader->move_along(length($ref) + 2);
        my $char = chr_ref($ref);
        $self->parser_error("Character reference &#$ref; refers to an illegal XML character ($char)", $reader)
            unless $char =~ /$SingleChar/o;
        $self->characters({ Data => $char });
        return 1;
    }
    else {
        # EntityRef
        my $name = $self->Name($reader)
            || $self->parser_error("Invalid name in entity", $reader);
        $reader->match(';') or $self->parser_error("No semi-colon found after entity name", $reader);
        
        # warn("got entity: \&$name;\n");
        
        # expand it
        if ($self->_is_entity($name)) {
            
            if ($self->_is_external($name)) {
                my $value = $self->_get_entity($name);
                my $ent_reader = XML::SAX::PurePerl::Reader::URI->new($value);
                $self->encoding_detect($ent_reader);
                $self->extParsedEnt($ent_reader);
            }
            else {
                my $value = $self->_stringify_entity($name);
                my $ent_reader = XML::SAX::PurePerl::Reader::String->new($value);
                $self->content($ent_reader);
            }
            return 1;
        }
        elsif ($name =~ /^(?:amp|gt|lt|quot|apos)$/) {
            $self->characters({ Data => $int_ents{$name} });
            return 1;
        }
        else {
            $self->parser_error("Undeclared entity", $reader);
        }
    }
}

sub AttReference {
    my ($self, $name, $reader) = @_;
    if ($name =~ /^#x([0-9a-fA-F]+)$/) {
        my $chr = chr_ref(hex($1));
        $chr =~ /$SingleChar/o or $self->parser_error("Character reference '&$name;' refers to an illegal XML character", $reader);
        return $chr;
    }
    elsif ($name =~ /^#([0-9]+)$/) {
        my $chr = chr_ref($1);
        $chr =~ /$SingleChar/o or $self->parser_error("Character reference '&$name;' refers to an illegal XML character", $reader);
        return $chr;
    }
    else {
        if ($self->_is_entity($name)) {
            if ($self->_is_external($name)) {
                $self->parser_error("No external entity references allowed in attribute values", $reader);
            }
            else {
                my $value = $self->_stringify_entity($name);
                return $value;
            }
        }
        elsif ($name =~ /^(?:amp|lt|gt|quot|apos)$/) {
            return $int_ents{$name};
        }
        else {
            $self->parser_error("Undeclared entity '$name'", $reader);
        }
    }
}

sub extParsedEnt {
    my ($self, $reader) = @_;
    
    $self->TextDecl($reader);
    $self->content($reader);
}

sub _is_external {
    my ($self, $name) = @_;
# TODO: Fix this to use $reader to store the entities perhaps.
    if ($self->{ParseOptions}{external_entities}{$name}) {
        return 1;
    }
    return ;
}

sub _is_entity {
    my ($self, $name) = @_;
# TODO: ditto above
    if (exists $self->{ParseOptions}{entities}{$name}) {
        return 1;
    }
    return 0;
}

sub _stringify_entity {
    my ($self, $name) = @_;
# TODO: ditto above
    if (exists $self->{ParseOptions}{expanded_entity}{$name}) {
        return $self->{ParseOptions}{expanded_entity}{$name};
    }
    # expand
    my $reader = XML::SAX::PurePerl::Reader::URI->new($self->{ParseOptions}{entities}{$name});
    my $ent = '';
    while(1) {
        my $data = $reader->data;
        $ent .= $data;
        $reader->move_along(length($data)) or last;
    }
    return $self->{ParseOptions}{expanded_entity}{$name} = $ent;
}

sub _get_entity {
    my ($self, $name) = @_;
# TODO: ditto above
    return $self->{ParseOptions}{entities}{$name};
}

sub skip_whitespace {
    my ($self, $reader) = @_;
    
    my $data = $reader->data;
    
    my $found = 0;
    while ($data =~ s/^([\x20\x0A\x0D\x09]*)//) {
        last unless length($1);
        $found++;
        $reader->move_along(length($1));
        $data = $reader->data;
    }
    
    return $found;
}

sub Attribute {
    my ($self, $reader) = @_;
    
    $self->skip_whitespace($reader) || return;
    
    my $data = $reader->data(2);
    return if $data =~ /^\/?>/;
    
    if (my $name = $self->Name($reader)) {
        $self->skip_whitespace($reader);
        $reader->match('=') or $self->parser_error("No '=' in Attribute", $reader);
        $self->skip_whitespace($reader);
        my $value = $self->AttValue($reader);

        if (!$self->cdata_attrib($name)) {
            $value =~ s/^\x20*//; # discard leading spaces
            $value =~ s/\x20*$//; # discard trailing spaces
            $value =~ s/ {1,}/ /g; # all >1 space to single space
        }
        
        return $name, $value;
    }
    
    return;
}

sub cdata_attrib {
    # TODO implement this!
    return 1;
}

sub AttValue {
    my ($self, $reader) = @_;
    
    my $quote = $self->quote($reader);
    
    my $value = '';
    
    while (1) {
        my $data = $reader->data;
        $self->parser_error("EOF found while looking for the end of attribute value", $reader)
            unless length($data);
        if ($data =~ /^([^$quote]*)$quote/) {
            $reader->move_along(length($1) + 1);
            $value .= $1;
            last;
        }
        else {
            $value .= $data;
            $reader->move_along(length($data));
        }
    }
    
    if ($value =~ /</) {
        $self->parser_error("< character not allowed in attribute values", $reader);
    }
    
    $value =~ s/[\x09\x0A\x0D]/\x20/g;
    $value =~ s/&(#(x[0-9a-fA-F]+)|#([0-9]+)|\w+);/$self->AttReference($1, $reader)/geo;
    
    return $value;
}

sub Comment {
    my ($self, $reader) = @_;
    
    my $data = $reader->data(4);
    if ($data =~ /^<!--/) {
        $reader->move_along(4);
        my $comment_str = '';
        while (1) {
            my $data = $reader->data;
            $self->parser_error("End of data seen while looking for close comment marker", $reader)
                unless length($data);
            if ($data =~ /^(.*?)-->/s) {
                $comment_str .= $1;
                $self->parser_error("Invalid comment (dash)", $reader) if $comment_str =~ /-$/;
                $reader->move_along(length($1) + 3);
                last;
            }
            else {
                $comment_str .= $data;
                $reader->move_along(length($data));
            }
        }
        
        $self->comment({ Data => $comment_str });
        
        return 1;
    }
    return 0;
}

sub PI {
    my ($self, $reader) = @_;
    
    my $data = $reader->data(2);
    
    if ($data =~ /^<\?/) {
        $reader->move_along(2);
        my ($target);
        $target = $self->Name($reader) ||
            $self->parser_error("PI has no target", $reader);
	    
        my $pi_data = '';
        if ($self->skip_whitespace($reader)) {
            while (1) {
                my $data = $reader->data;
                $self->parser_error("End of data seen while looking for close PI marker", $reader)
                    unless length($data);
                if ($data =~ /^(.*?)\?>/s) {
                    $pi_data .= $1;
                    $reader->move_along(length($1) + 2);
                    last;
                }
                else {
                    $pi_data .= $data;
                    $reader->move_along(length($data));
                }
            }
        }
        else {
            my $data = $reader->data(2);
            $data =~ /^\?>/ or $self->parser_error("PI closing sequence not found", $reader);
            $reader->move_along(2);
        }
	
        $self->processing_instruction({ Target => $target, Data => $pi_data });
        
        return 1;
    }
    return 0;
}

sub Name {
    my ($self, $reader) = @_;
    
    my $name = '';
    while(1) {
        my $data = $reader->data;
        return unless length($data);
        $data =~ /^([^\s>\/&\?;=<\)\(\[\],\%\#\!\*\|]*)/ or return;
        $name .= $1;
        my $len = length($1);
        $reader->move_along($len);
        last if ($len != length($data));
    }
    
    return unless length($name);
    
    $name =~ /$NameChar/o or $self->parser_error("Name <$name> does not match NameChar production", $reader);

    return $name;
}

sub quote {
    my ($self, $reader) = @_;
    
    my $data = $reader->data;
    
    $data =~ /^(['"])/ or $self->parser_error("Invalid quote token", $reader);
    $reader->move_along(1);
    return $1;
}

1;
__END__

=head1 NAME

XML::SAX::PurePerl - Pure Perl XML Parser with SAX2 interface

=head1 SYNOPSIS

  use XML::Handler::Foo;
  use XML::SAX::PurePerl;
  my $handler = XML::Handler::Foo->new();
  my $parser = XML::SAX::PurePerl->new(Handler => $handler);
  $parser->parse_uri("myfile.xml");

=head1 DESCRIPTION

This module implements an XML parser in pure perl. It is written around the
upcoming perl 5.8's unicode support and support for multiple document 
encodings (using the PerlIO layer), however it has been ported to work with
ASCII/UTF8 documents under lower perl versions.

The SAX2 API is described in detail at http://sourceforge.net/projects/perl-xml/, in
the CVS archive, under libxml-perl/docs. Hopefully those documents will be in a
better location soon.

Please refer to the SAX2 documentation for how to use this module - it is merely a
front end to SAX2, and implements nothing that is not in that spec (or at least tries
not to - please email me if you find errors in this implementation).

=head1 BUGS

XML::SAX::PurePerl is B<slow>. Very slow. I suggest you use something else
in fact. However it is great as a fallback parser for XML::SAX, where the
user might not be able to install an XS based parser or C library.

Currently lots, probably. At the moment the weakest area is parsing DOCTYPE declarations,
though the code is in place to start doing this. Also parsing parameter entity
references is causing me much confusion, since it's not exactly what I would call
trivial, or well documented in the XML grammar. XML documents with internal subsets
are likely to fail.

I am however trying to work towards full conformance using the Oasis test suite.

=head1 AUTHOR

Matt Sergeant, matt@sergeant.org. Copyright 2001.

Please report all bugs to the Perl-XML mailing list at perl-xml@listserv.activestate.com.

=head1 LICENSE

This is free software. You may use it or redistribute it under the same terms as
Perl 5.7.2 itself.

=cut

