parser.pm

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package HTML::Parser;

# Copyright 1996-2007, Gisle Aas.
# Copyright 1999-2000, Michael A. Chase.
#
# This library is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.

use strict;
use vars qw($VERSION @ISA);

$VERSION = '3.56';  # $Date: 2007/01/12 09:18:31 $

require HTML::Entities;

require XSLoader;
XSLoader::load('HTML::Parser', $VERSION);

sub new
{
    my $class = shift;
    my $self = bless {}, $class;
    return $self->init(@_);
}


sub init
{
    my $self = shift;
    $self->_alloc_pstate;

    my %arg = @_;
    my $api_version = delete $arg{api_version} || (@_ ? 3 : 2);
    if ($api_version >= 4) {
	require Carp;
	Carp::croak("API version $api_version not supported " .
		    "by HTML::Parser $VERSION");
    }

    if ($api_version < 3) {
	# Set up method callbacks compatible with HTML-Parser-2.xx
	$self->handler(text    => "text",    "self,text,is_cdata");
	$self->handler(end     => "end",     "self,tagname,text");
	$self->handler(process => "process", "self,token0,text");
	$self->handler(start   => "start",
		                  "self,tagname,attr,attrseq,text");

	$self->handler(comment =>
		       sub {
			   my($self, $tokens) = @_;
			   for (@$tokens) {
			       $self->comment($_);
			   }
		       }, "self,tokens");

	$self->handler(declaration =>
		       sub {
			   my $self = shift;
			   $self->declaration(substr($_[0], 2, -1));
		       }, "self,text");
    }

    if (my $h = delete $arg{handlers}) {
	$h = {@$h} if ref($h) eq "ARRAY";
	while (my($event, $cb) = each %$h) {
	    $self->handler($event => @$cb);
	}
    }

    # In the end we try to assume plain attribute or handler
    while (my($option, $val) = each %arg) {
	if ($option =~ /^(\w+)_h$/) {
	    $self->handler($1 => @$val);
	}
        elsif ($option =~ /^(text|start|end|process|declaration|comment)$/) {
	    require Carp;
	    Carp::croak("Bad constructor option '$option'");
        }
	else {
	    $self->$option($val);
	}
    }

    return $self;
}


sub parse_file
{
    my($self, $file) = @_;
    my $opened;
    if (!ref($file) && ref(\$file) ne "GLOB") {
        # Assume $file is a filename
        local(*F);
        open(F, $file) || return undef;
	binmode(F);  # should we? good for byte counts
        $opened++;
        $file = *F;
    }
    my $chunk = '';
    while (read($file, $chunk, 512)) {
	$self->parse($chunk) || last;
    }
    close($file) if $opened;
    $self->eof;
}


sub netscape_buggy_comment  # legacy
{
    my $self = shift;
    require Carp;
    Carp::carp("netscape_buggy_comment() is deprecated.  " .
	       "Please use the strict_comment() method instead");
    my $old = !$self->strict_comment;
    $self->strict_comment(!shift) if @_;
    return $old;
}

# set up method stubs
sub text { }
*start       = \&text;
*end         = \&text;
*comment     = \&text;
*declaration = \&text;
*process     = \&text;

1;

__END__


=head1 NAME

HTML::Parser - HTML parser class

=head1 SYNOPSIS

 use HTML::Parser ();

 # Create parser object
 $p = HTML::Parser->new( api_version => 3,
                         start_h => [\&start, "tagname, attr"],
                         end_h   => [\&end,   "tagname"],
                         marked_sections => 1,
                       );

 # Parse document text chunk by chunk
 $p->parse($chunk1);
 $p->parse($chunk2);
 #...
 $p->eof;                 # signal end of document

 # Parse directly from file
 $p->parse_file("foo.html");
 # or
 open(my $fh, "<:utf8", "foo.html") || die;
 $p->parse_file($fh);

=head1 DESCRIPTION

Objects of the C<HTML::Parser> class will recognize markup and
separate it from plain text (alias data content) in HTML
documents.  As different kinds of markup and text are recognized, the
corresponding event handlers are invoked.

C<HTML::Parser> is not a generic SGML parser.  We have tried to
make it able to deal with the HTML that is actually "out there", and
it normally parses as closely as possible to the way the popular web
browsers do it instead of strictly following one of the many HTML
specifications from W3C.  Where there is disagreement, there is often
an option that you can enable to get the official behaviour.

The document to be parsed may be supplied in arbitrary chunks.  This
makes on-the-fly parsing as documents are received from the network
possible.

If event driven parsing does not feel right for your application, you
might want to use C<HTML::PullParser>.  This is an C<HTML::Parser>
subclass that allows a more conventional program structure.


=head1 METHODS

The following method is used to construct a new C<HTML::Parser> object:

=over

=item $p = HTML::Parser->new( %options_and_handlers )

This class method creates a new C<HTML::Parser> object and
returns it.  Key/value argument pairs may be provided to assign event
handlers or initialize parser options.  The handlers and parser
options can also be set or modified later by the method calls described below.

If a top level key is in the form "<event>_h" (e.g., "text_h") then it
assigns a handler to that event, otherwise it initializes a parser
option. The event handler specification value must be an array
reference.  Multiple handlers may also be assigned with the 'handlers
=> [%handlers]' option.  See examples below.

If new() is called without any arguments, it will create a parser that
uses callback methods compatible with version 2 of C<HTML::Parser>.
See the section on "version 2 compatibility" below for details.

The special constructor option 'api_version => 2' can be used to
initialize version 2 callbacks while still setting other options and
handlers.  The 'api_version => 3' option can be used if you don't want
to set any options and don't want to fall back to v2 compatible
mode.

Examples:

 $p = HTML::Parser->new(api_version => 3,
                        text_h => [ sub {...}, "dtext" ]);

This creates a new parser object with a text event handler subroutine
that receives the original text with general entities decoded.

 $p = HTML::Parser->new(api_version => 3,
			start_h => [ 'my_start', "self,tokens" ]);

This creates a new parser object with a start event handler method
that receives the $p and the tokens array.

 $p = HTML::Parser->new(api_version => 3,
		        handlers => { text => [\@array, "event,text"],
                                      comment => [\@array, "event,text"],
                                    });

This creates a new parser object that stores the event type and the
original text in @array for text and comment events.

=back

The following methods feed the HTML document
to the C<HTML::Parser> object:

=over

=item $p->parse( $string )

Parse $string as the next chunk of the HTML document.  The return
value is normally a reference to the parser object (i.e. $p).
Handlers invoked should not attempt to modify the $string in-place until
$p->parse returns.

If an invoked event handler aborts parsing by calling $p->eof, then
$p->parse() will return a FALSE value.

=item $p->parse( $code_ref )

If a code reference is passed as the argument to be parsed, then the
chunks to be parsed are obtained by invoking this function repeatedly.
Parsing continues until the function returns an empty (or undefined)
result.  When this happens $p->eof is automatically signaled.

Parsing will also abort if one of the event handlers calls $p->eof.

The effect of this is the same as:

 while (1) {
    my $chunk = &$code_ref();
    if (!defined($chunk) || !length($chunk)) {
        $p->eof;
        return $p;
    }
    $p->parse($chunk) || return undef;
 }

But it is more efficient as this loop runs internally in XS code.

=item $p->parse_file( $file )

Parse text directly from a file.  The $file argument can be a
filename, an open file handle, or a reference to an open file
handle.

If $file contains a filename and the file can't be opened, then the
method returns an undefined value and $! tells why it failed.
Otherwise the return value is a reference to the parser object.

If a file handle is passed as the $file argument, then the file will
normally be read until EOF, but not closed.

If an invoked event handler aborts parsing by calling $p->eof,
then $p->parse_file() may not have read the entire file.

On systems with multi-byte line terminators, the values passed for the
offset and length argspecs may be too low if parse_file() is called on
a file handle that is not in binary mode.

If a filename is passed in, then parse_file() will open the file in
binary mode.

=item $p->eof

Signals the end of the HTML document.  Calling the $p->eof method
outside a handler callback will flush any remaining buffered text
(which triggers the C<text> event if there is any remaining text).

Calling $p->eof inside a handler will terminate parsing at that point
and cause $p->parse to return a FALSE value.  This also terminates
parsing by $p->parse_file().

After $p->eof has been called, the parse() and parse_file() methods
can be invoked to feed new documents with the parser object.

The return value from eof() is a reference to the parser object.

=back


Most parser options are controlled by boolean attributes.
Each boolean attribute is enabled by calling the corresponding method
with a TRUE argument and disabled with a FALSE argument.  The
attribute value is left unchanged if no argument is given.  The return
value from each method is the old attribute value.

Methods that can be used to get and/or set parser options are:

=over

=item $p->attr_encoded

=item $p->attr_encoded( $bool )

By default, the C<attr> and C<@attr> argspecs will have general
entities for attribute values decoded.  Enabling this attribute leaves
entities alone.

=item $p->boolean_attribute_value( $val )

This method sets the value reported for boolean attributes inside HTML
start tags.  By default, the name of the attribute is also used as its
value.  This affects the values reported for C<tokens> and C<attr>
argspecs.

=item $p->case_sensitive

=item $p->case_sensitive( $bool )

By default, tagnames and attribute names are down-cased.  Enabling this
attribute leaves them as found in the HTML source document.

=item $p->closing_plaintext

=item $p->closing_plaintext( $bool )

By default, "plaintext" element can never be closed. Everything up to
the end of the document is parsed in CDATA mode.  This historical
behaviour is what at least MSIE does.  Enabling this attribute makes
closing "</plaintext>" tag effective and the parsing process will resume
after seeing this tag.  This emulates gecko-based browsers.

=item $p->empty_element_tags

=item $p->empty_element_tags( $bool )

By default, empty element tags are not recognized as such and the "/"
before ">" is just treated like a normal name character (unless
C<strict_names> is enabled).  Enabling this attribute make
C<HTML::Parser> recognize these tags.

Empty element tags look like start tags, but end with the character
sequence "/>" instead of ">".  When recognized by C<HTML::Parser> they
cause an artificial end event in addition to the start event.  The
C<text> for the artificial end event will be empty and the C<tokenpos>
array will be undefined even though the the token array will have one
element containing the tag name.

=item $p->marked_sections

=item $p->marked_sections( $bool )

By default, section markings like <![CDATA[...]]> are treated like
ordinary text.  When this attribute is enabled section markings are
honoured.

There are currently no events associated with the marked section
markup, but the text can be returned as C<skipped_text>.

=item $p->strict_comment

=item $p->strict_comment( $bool )

By default, comments are terminated by the first occurrence of "-->".
This is the behaviour of most popular browsers (like Mozilla, Opera and
MSIE), but it is not correct according to the official HTML
standard.  Officially, you need an even number of "--" tokens before
the closing ">" is recognized and there may not be anything but
whitespace between an even and an odd "--".

The official behaviour is enabled by enabling this attribute.

Enabling of 'strict_comment' also disables recognizing these forms as
comments:

  </ comment>
  <! comment>


=item $p->strict_end

=item $p->strict_end( $bool )

By default, attributes and other junk are allowed to be present on end tags in a
manner that emulates MSIE's behaviour.

The official behaviour is enabled with this attribute.  If enabled,
only whitespace is allowed between the tagname and the final ">".