NAME

HTML::Gumbo - HTML5 parser based on gumbo C library

DESCRIPTION

Gumbo is an implementation of the HTML5 parsing algorithm implemented as a pure C99 library with no outside dependencies.

Goals and features of the C library:

• Fully conformant with the HTML5 spec.

• Robust and resilient to bad input.

• Simple API that can be easily wrapped by other languages. (This is one of such wrappers.)

• Support for source locations and pointers back to the original text. (Not exposed by this implementation at the moment.)

• Relatively lightweight, with no outside dependencies.

• Passes all html5lib-0.95 tests.

• Tested on over 2.5 billion pages from Google's index.

SUPPORTED OUTPUT FORMATS

string

Beta readiness.

HTML is parsed and re-built from the tree, so tags are balanced (except void elements). Since fragments parsing is not supported at the moment the result always gets html, head and body elements.

No additional arguments for this format.

    $html = HTML::Gumbo->new->parse( $html );

callback

Beta readiness.

HTML::Parser like interface. Pass a sub as callback argument to "parse" method and it will be called for every node in the document:

    HTML::Gumbo->new->parse( $html, format => 'callback', callback => sub {
        my ($event) = shift;
        if ( $event eq 'document start' ) {
            my ($doctype) = @_;
        }
        elsif ( $event eq 'document end' ) {
        }
        elsif ( $event eq 'start' ) {
            my ($tag, $attrs) = @_;
        }
        elsif ( $event eq 'end' ) {
            my ($tag) = @_;
        }
        elsif ( $event eq /^(text|space|cdata|comment)$/ ) {
            my ($text) = @_;
        }
        else {
            die "Unknown event";
        }
    } );

Note that 'end' events are not generated for void elements, for example hr, br and img.

No additional arguments except mentioned callback.

tree

Alpha stage.

Produces tree based on HTML::Elements, like HTML::TreeBuilder.

There is major difference from HTML::TreeBuilder, this method produces top level element with tag name 'document' which may have doctype, comments and html tags.

Yes, it's not ready to use as drop in replacement of tree builder. Patches are wellcome. I don't use this formatter at the moment.

CHARACTER ENCODING OF THE INPUT

The C parser works only with UTF-8, so you have several options to make sure input is UTF-8. First of all define input_is:

string

Input is Perl string, for example obtained from "decoded_content" in HTTP::Response. Default value.

octets

Input are octets. Partial implementation of encoding sniffing algorithm is used:

encoding argument

Use it to hardcode a specific encoding.

BOM

UTF-8/UTF-16 BOMs are checked.

encoding_content_type

Encdoning from rransport layer, charset in content-type header.

Prescan

Not implemented, follow issue 58.

HTML5 defines prescan algorithm that extracts encoding from meta tags in the head.

It would be cool to get it in the C library, but I will accept a patch that impements it in pure perl.

encoding_tentative argument

The likely encoding for this page, e.g. based on the encoding of the page when it was last visited.

nested browsing context

Not implemented. Fragment parsing with or without context is not implemented. Parser also has no origin information, so it wouldn't be implemented.

autodetection

Not implemented.

Can be implemented using Encode::Detect::Detector. Patches are welcome.

otherwise

It dies.

utf8

Use utf8 as input_is when you're sure input is UTF-8, but octets. No pre-processing at all. Should only be used on trusted input or when it's preprocessed already.

METHODS

new

    my $parser = HTML::Gumbo->new;

No options at the moment.

parse

    my $res = $parser->parse(
        "<h1>hello world!</h1>",
        format => 'tree',
        input_is => 'string',
    );

Takes html string and pairs of named arguments:

format

Output format, default is string. See "SUPPORTED OUTPUT FORMATS".

input_is

Whether html is perl 'string', 'octets' or 'utf8' (octets known to be utf8). See "CHARACTER ENCODING OF THE INPUT".

encoding, encoding_content_type, encoding_tentative

See "CHARACTER ENCODING OF THE INPUT".

...

Some formatters may have additional arguments.

Return value depends on the picked format.

AUTHOR

Ruslan Zakirov <ruz@bestpractical.com>

LICENSE

Under the same terms as perl itself.

cpanm HTML::Gumbo

perl -MCPAN -e shell
install HTML::Gumbo