NAME¶
HTML::TokeParser::Simple - Easy to use "HTML::TokeParser" interface
SYNOPSIS¶
use HTML::TokeParser::Simple;
my $p = HTML::TokeParser::Simple->new( $somefile );
while ( my $token = $p->get_token ) {
# This prints all text in an HTML doc (i.e., it strips the HTML)
next unless $token->is_text;
print $token->as_is;
}
DESCRIPTION¶
"HTML::TokeParser" is an excellent module that's often used for
parsing HTML. However, the tokens returned are not exactly intuitive to parse:
["S", $tag, $attr, $attrseq, $text]
["E", $tag, $text]
["T", $text, $is_data]
["C", $text]
["D", $text]
["PI", $token0, $text]
To simplify this, "HTML::TokeParser::Simple" allows the user ask more
intuitive (read: more self-documenting) questions about the tokens returned.
You can also rebuild some tags on the fly. Frequently, the attributes associated
with start tags need to be altered, added to, or deleted. This functionality
is built in.
Since this is a subclass of "HTML::TokeParser", all
"HTML::TokeParser" methods are available. To truly appreciate the
power of this module, please read the documentation for
"HTML::TokeParser" and "HTML::Parser".
CONTRUCTORS¶
"new($source)"¶
The constructor for "HTML::TokeParser::Simple" can be used just like
"HTML::TokeParser"'s constructor:
my $parser = HTML::TokeParser::Simple->new($filename);
# or
my $parser = HTML::TokeParser::Simple->new($filehandle);
# or
my $parser = HTML::TokeParser::Simple->new(\$html_string);
"new($source_type, $source)"¶
If you wish to be more explicit, there is a new style of constructor available.
my $parser = HTML::TokeParser::Simple->new(file => $filename);
# or
my $parser = HTML::TokeParser::Simple->new(handle => $filehandle);
# or
my $parser = HTML::TokeParser::Simple->new(string => $html_string);
Note that you do not have to provide a reference for the string if using the
string constructor.
As a convenience, you can also attempt to fetch the HTML directly from a URL.
my $parser = HTML::TokeParser::Simple->new(url => 'http://some.url');
This method relies on "LWP::Simple". If this module is not found or
the page cannot be fetched, the constructor will "croak()".
PARSER METHODS¶
get_token¶
This method will return the next token that
"HTML::TokeParser::get_token()" method would return. However, it
will be blessed into a class appropriate which represents the token type.
get_tag¶
This method will return the next token that
"HTML::TokeParser::get_tag()" method would return. However, it will
be blessed into either the HTML::TokeParser::Simple::Token::Tag::Start or
HTML::TokeParser::Simple::Token::Tag::End class.
peek¶
As of version 3.14, you can now "peek()" at the upcomings tokens
without affecting the state of the parser. By default, "peek()" will
return the text of the next token, but specifying an integer $count will
return the text of the next $count tokens.
This is useful when you're trying to debug where you are in a document.
warn $parser->peek(3); # show the next 3 tokens
ACCESSORS¶
The following methods may be called on the token object which is returned, not
on the parser object.
Boolean Accessors¶
These accessors return true or false.
- •
- "is_tag([$tag])"
Use this to determine if you have any tag. An optional "tag type"
may be passed. This will allow you to match if it's a particular
tag. The supplied tag is case-insensitive.
if ( $token->is_tag ) { ... }
Optionally, you may pass a regular expression as an argument.
- •
- "is_start_tag([$tag])"
Use this to determine if you have a start tag. An optional "tag
type" may be passed. This will allow you to match if it's a
particular start tag. The supplied tag is case-insensitive.
if ( $token->is_start_tag ) { ... }
if ( $token->is_start_tag( 'font' ) ) { ... }
Optionally, you may pass a regular expression as an argument. To match all
header (h1, h2, ... h6) tags:
if ( $token->is_start_tag( qr/^h[123456]$/ ) ) { ... }
- •
- "is_end_tag([$tag])"
Use this to determine if you have an end tag. An optional "tag
type" may be passed. This will allow you to match if it's a
particular end tag. The supplied tag is case-insensitive.
When testing for an end tag, the forward slash on the tag is optional.
while ( $token = $p->get_token ) {
if ( $token->is_end_tag( 'form' ) ) { ... }
}
Or:
while ( $token = $p->get_token ) {
if ( $token->is_end_tag( '/form' ) ) { ... }
}
Optionally, you may pass a regular expression as an argument.
- •
- "is_text()"
Use this to determine if you have text. Note that this is not to be
confused with the "return_text" ( deprecated) method
described below! "is_text" will identify text that the user
typically sees display in the Web browser.
- •
- "is_comment()"
Are you still reading this? Nobody reads POD. Don't you know you're supposed
to go to CLPM, ask a question that's answered in the POD and get flamed?
It's a rite of passage.
Really.
"is_comment" is used to identify comments. See the HTML::Parser
documentation for more information about comments. There's more than you
might think.
- •
- "is_declaration()"
This will match the DTD at the top of your HTML. (You do use DTD's,
don't you?)
- •
- "is_process_instruction()"
Process Instructions are from XML. This is very handy if you need to parse
out PHP and similar things with a parser.
Currently, there appear to be some problems with process instructions. You
can override
"HTML::TokeParser::Simple::Token::ProcessInstruction" if you
need to.
- •
- "is_pi()"
This is a shorthand for "is_process_instruction()".
Data Accessors¶
Some of these were originally "return_" methods, but that name was not
only unwieldy, but also went against reasonable conventions. The
"get_" methods listed below still have "return_" methods
available for backwards compatibility reasons, but they merely call their
"get_" counterpart. For example, calling "return_tag()"
actually calls "get_tag()" internally.
- •
- "get_tag()"
Do you have a start tag or end tag? This will return the type (lower case).
Note that this is not the same as the "get_tag()" method
on the actual parser object.
- •
- "get_attr([$attribute])"
If you have a start tag, this will return a hash ref with the attribute
names as keys and the values as the values.
If you pass in an attribute name, it will return the value for just that
attribute.
Returns false if the token is not a start tag.
- •
- "get_attrseq()"
For a start tag, this is an array reference with the sequence of the
attributes, if any.
Returns false if the token is not a start tag.
- •
- "return_text()"
This method has been heavily deprecated (for a couple of years) in favor of
"as_is". Programmers were getting confused over the difference
between "is_text", "return_text", and some parser
methods such as "HTML::TokeParser::get_text" and friends.
Using this method still succeeds, but will now carp and will be
removed in the next major release of this module.
- •
- "as_is()"
This is the exact text of whatever the token is representing.
- •
- "get_token0()"
For processing instructions, this will return the token found immediately
after the opening tag. Example: For <?php, "php" will be the
start of the returned string.
Note that process instruction handling appears to be incomplete in
"HTML::TokeParser".
Returns false if the token is not a process instruction.
MUTATORS¶
The "delete_attr()" and "set_attr()" methods allow the
programmer to rewrite start tag attributes on the fly. It should be noted that
bad HTML will be "corrected" by this. Specifically, the new tag will
have all attributes lower-cased with the values properly quoted.
Self-closing tags (e.g. <hr />) are also handled correctly. Some older
browsers require a space prior to the final slash in a self-closed tag. If
such a space is detected in the original HTML, it will be preserved.
Calling a mutator on an token type that does not support that property is a
no-op. For example:
if ($token->is_comment) {
$token->set_attr(foo => 'bar'); # does nothing
}
- •
- "delete_attr($name)"
This method attempts to delete the attribute specified. It will silently
fail if called on anything other than a start tag. The argument is
case-insensitive, but must otherwise be an exact match of the attribute
you are attempting to delete. If the attribute is not found, the method
will return without changing the tag.
# <body bgcolor="#FFFFFF">
$token->delete_attr('bgcolor');
print $token->as_is;
# <body>
After this method is called, if successful, the "as_is()",
"get_attr()" and "get_attrseq()" methods will all
return updated results.
- •
- "set_attr($name,$value)"
This method will set the value of an attribute. If the attribute is not
found, then "get_attrseq()" will have the new attribute listed
at the end.
# <p>
$token->set_attr(class => 'some_class');
print $token->as_is;
# <p class="some_class">
# <body bgcolor="#FFFFFF">
$token->set_attr('bgcolor','red');
print $token->as_is;
# <body bgcolor="red">
After this method is called, if successful, the "as_is()",
"get_attr()" and "get_attrseq()" methods will all
return updated results.
- •
- "set_attr($hashref)"
Under the premise that "set_" methods should accept what their
corresponding "get_" methods emit, the following works:
$tag->set_attr($tag->get_attr);
Theoretically that's a no-op and for purposes of rendering HTML, it should
be. However, internally this calls "$tag->rewrite_tag", so
see that method to understand how this may affect you.
Of course, this is useless if you want to actually change the attributes, so
you can do this:
my $attrs = {
class => 'headline',
valign => 'top'
};
$token->set_attr($attrs)
if $token->is_start_tag('td') && $token->get_attr('class') eq 'stories';
- •
- "rewrite_tag()"
This method rewrites the tag. The tag name and the name of all attributes
will be lower-cased. Values that are not quoted with double quotes will
be. This may be called on both start or end tags. Note that both
"set_attr()" and "delete_attr()" call this method
prior to returning.
If called on a token that is not a tag, it simply returns. Regardless of how
it is called, it returns the token.
# <body alink=#0000ff BGCOLOR=#ffffff class='none'>
$token->rewrite_tag;
print $token->as_is;
# <body alink="#0000ff" bgcolor="#ffffff" class="none">
A quick cleanup of sloppy HTML is now the following:
my $parser = HTML::TokeParser::Simple->new( string => $ugly_html );
while (my $token = $parser->get_token) {
$token->rewrite_tag;
print $token->as_is;
}
PARSER VERSUS TOKENS¶
The parser returns tokens that are blessed into appropriate classes. Some people
get confused and try to call parser methods on tokens and token methods on the
parser. To prevent this, "HTML::TokeParser::Simple" versions 1.4 and
above now bless all tokens into appropriate token classes. Please keep this in
mind while using this module (and many thanks to PodMaster
<
http://www.perlmonks.org/index.pl?node_id=107642> for pointing out this
issue to me.)
EXAMPLES¶
For some strange reason, your Pointy-Haired Boss (PHB) is convinced that the
graphics department is making fun of him by embedding rude things about him in
HTML comments. You need to get all HTML comments from the HTML.
use strict;
use HTML::TokeParser::Simple;
my @html_docs = glob( "*.html" );
open PHB, "> phbreport.txt" or die "Cannot open phbreport for writing: $!";
foreach my $doc ( @html_docs ) {
print "Processing $doc\n";
my $p = HTML::TokeParser::Simple->new( file => $doc );
while ( my $token = $p->get_token ) {
next unless $token->is_comment;
print PHB $token->as_is, "\n";
}
}
close PHB;
Uh oh. Turns out that your PHB was right for a change. Many of the comments in
the HTML weren't very polite. Since your entire graphics department was just
fired, it falls on you need to strip those comments from the HTML.
use strict;
use HTML::TokeParser::Simple;
my $new_folder = 'no_comment/';
my @html_docs = glob( "*.html" );
foreach my $doc ( @html_docs ) {
print "Processing $doc\n";
my $new_file = "$new_folder$doc";
open PHB, "> $new_file" or die "Cannot open $new_file for writing: $!";
my $p = HTML::TokeParser::Simple->new( $file => doc );
while ( my $token = $p->get_token ) {
next if $token->is_comment;
print PHB $token->as_is;
}
close PHB;
}
Your company was foo.com and now is bar.com. Unfortunately, whoever wrote your
HTML decided to hardcode "
http://www.foo.com/" into the
"action" attribute of the form tags. You need to change it to
"
http://www.bar.com/".
use strict;
use HTML::TokeParser::Simple;
my $new_folder = 'new_html/';
my @html_docs = glob( "*.html" );
foreach my $doc ( @html_docs ) {
print "Processing $doc\n";
my $new_file = "$new_folder$doc";
open FILE, "> $new_file" or die "Cannot open $new_file for writing: $!";
my $p = HTML::TokeParser::Simple->new( file => $doc );
while ( my $token = $p->get_token ) {
if ( $token->is_start_tag('form') ) {
my $action = $token->get_attr(action);
$action =~ s/www\.foo\.com/www.bar.com/;
$token->set_attr('action', $action);
}
print FILE $token->as_is;
}
close FILE;
}
CAVEATS¶
For compatibility reasons with "HTML::TokeParser", methods that return
references are violating encapsulation and altering the references directly
will alter the state of the object. Subsequent calls to
"rewrite_tag()" can thus have unexpected results. Do not alter these
references directly unless you are following behavior described in these docs.
In the future, certain methods such as "get_attr",
"get_attrseq" and others may return a copy of the reference rather
than the original reference. This behavior has not yet been changed in order
to maintain compatibility with previous versions of this module. At the
present time, your author is not aware of anyone taking advantage of this
"feature," but it's better to be safe than sorry.
Use of $HTML::Parser::VERSION which is less than 3.25 may result in incorrect
behavior as older versions do not always handle XHTML correctly. It is the
programmer's responsibility to verify that the behavior of this code matches
the programmer's needs.
Note that "HTML::Parser" processes text in 512 byte chunks. This
sometimes will cause strange behavior and cause text to be broken into more
than one token. You can suppress this behavior with the following command:
$p->unbroken_text( [$bool] );
See the "HTML::Parser" documentation and
http://www.perlmonks.org/index.pl?node_id=230667 for more information.
BUGS¶
There are no known bugs, but that's no guarantee.
Address bug reports and comments to: <eop_divo_sitruc@yahoo.com>. When
sending bug reports, please provide the version of "HTML::Parser",
"HTML::TokeParser", "HTML::TokeParser::Simple", the
version of Perl, and the version of the operating system you are using.
Reverse the name to email the author.
SUBCLASSING¶
You may wish to change the behavior of this module. You probably do not want to
subclass "HTML::TokeParser::Simple". Instead, you'll want to
subclass one of the token classes. "HTML::TokeParser::Simple::Token"
is the base class for all tokens. Global behavioral changes should go there.
Otherwise, see the appropriate token class for the behavior you wish to alter.
SEE ALSO¶
HTML::TokeParser::Simple::Token
HTML::TokeParser::Simple::Token::Tag
HTML::TokeParser::Simple::Token::Text
HTML::TokeParser::Simple::Token::Comment
HTML::TokeParser::Simple::Token::Declaration
HTML::TokeParser::Simple::Token::ProcessInstruction
COPYRIGHT¶
Copyright (c) 2004 by Curtis "Ovid" Poe. All rights reserved. This
program is free software; you may redistribute it and/or modify it under the
same terms as Perl itself
AUTHOR¶
Curtis "Ovid" Poe <eop_divo_sitruc@yahoo.com>
Reverse the name to email the author.