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HTML::TokeParser(3) |
User Contributed Perl Documentation |
HTML::TokeParser(3) |
HTML::TokeParser - Alternative HTML::Parser interface
require HTML::TokeParser;
$p = HTML::TokeParser->new("index.html") ||
die "Can't open: $!";
$p->empty_element_tags(1); # configure its behaviour
while (my $token = $p->get_token) {
#...
}
The "HTML::TokeParser" is an alternative
interface to the "HTML::Parser" class. It is
an "HTML::PullParser" subclass with a
predeclared set of token types. If you wish the tokens to be reported
differently you probably want to use the
"HTML::PullParser" directly.
The following methods are available:
- $p = HTML::TokeParser->new( $filename, %opt );
- $p = HTML::TokeParser->new( $filehandle, %opt );
- $p = HTML::TokeParser->new( \$document, %opt );
- The object constructor argument is either a file name, a file handle
object, or the complete document to be parsed. Extra options can be
provided as key/value pairs and are processed as documented by the base
classes.
If the argument is a plain scalar, then it is taken as the
name of a file to be opened and parsed. If the file can't be opened for
reading, then the constructor will return
"undef" and $! will tell you why it
failed.
If the argument is a reference to a plain scalar, then this
scalar is taken to be the literal document to parse. The value of this
scalar should not be changed before all tokens have been extracted.
Otherwise the argument is taken to be some object that the
"HTML::TokeParser" can read()
from when it needs more data. Typically it will be a filehandle of some
kind. The stream will be read() until EOF, but not closed.
A newly constructed
"HTML::TokeParser" differ from its
base classes by having the
"unbroken_text" attribute enabled by
default. See HTML::Parser for a description of this and other attributes
that influence how the document is parsed. It is often a good idea to
enable "empty_element_tags"
behaviour.
Note that the parsing result will likely not be valid if raw
undecoded UTF-8 is used as a source. When parsing UTF-8 encoded files
turn on UTF-8 decoding:
open(my $fh, "<:utf8", "index.html") || die "Can't open 'index.html': $!";
my $p = HTML::TokeParser->new( $fh );
# ...
If a $filename is passed to the
constructor the file will be opened in raw mode and the parsing result
will only be valid if its content is Latin-1 or pure ASCII.
If parsing from an UTF-8 encoded string buffer decode it
first:
utf8::decode($document);
my $p = HTML::TokeParser->new( \$document );
# ...
- $p->get_token
- This method will return the next token found in the HTML document,
or "undef" at the end of the document.
The token is returned as an array reference. The first element of the
array will be a string denoting the type of this token: "S" for
start tag, "E" for end tag, "T" for text,
"C" for comment, "D" for declaration, and
"PI" for process instructions. The rest of the token array
depend on the type like this:
["S", $tag, $attr, $attrseq, $text]
["E", $tag, $text]
["T", $text, $is_data]
["C", $text]
["D", $text]
["PI", $token0, $text]
where $attr is a hash reference,
$attrseq is an array reference and the rest are
plain scalars. The "Argspec" in HTML::Parser explains the
details.
- $p->unget_token( @tokens )
- If you find you have read too many tokens you can push them back, so that
they are returned the next time $p->get_token
is called.
- $p->get_tag
- $p->get_tag( @tags )
- This method returns the next start or end tag (skipping any other tokens),
or "undef" if there are no more tags in
the document. If one or more arguments are given, then we skip tokens
until one of the specified tag types is found. For example:
$p->get_tag("font", "/font");
will find the next start or end tag for a font-element.
The tag information is returned as an array reference in the
same form as for $p->get_token above, but the
type code (first element) is missing. A start tag will be returned like
this:
[$tag, $attr, $attrseq, $text]
The tagname of end tags are prefixed with "/", i.e.
end tag is returned like this:
["/$tag", $text]
- $p->get_text
- $p->get_text( @endtags )
- This method returns all text found at the current position. It will return
a zero length string if the next token is not text. Any entities will be
converted to their corresponding character.
If one or more arguments are given, then we return all text
occurring before the first of the specified tags found. For example:
$p->get_text("p", "br");
will return the text up to either a paragraph of line break
element.
The text might span tags that should be textified. This
is controlled by the $p->{textify} attribute,
which is a hash that defines how certain tags can be treated as text. If
the name of a start tag matches a key in this hash then this tag is
converted to text. The hash value is used to specify which tag attribute
to obtain the text from. If this tag attribute is missing, then the
upper case name of the tag enclosed in brackets is returned, e.g.
"[IMG]". The hash value can also be a subroutine reference. In
this case the routine is called with the start tag token content as its
argument and the return value is treated as the text.
The default $p->{textify} value
is:
{img => "alt", applet => "alt"}
This means that <IMG> and <APPLET> tags are
treated as text, and that the text to substitute can be found in the ALT
attribute.
- $p->get_trimmed_text
- $p->get_trimmed_text( @endtags )
- Same as $p->get_text above, but will collapse
any sequences of white space to a single space character. Leading and
trailing white space is removed.
- $p->get_phrase
- This will return all text found at the current position ignoring any
phrasal-level tags. Text is extracted until the first non phrasal-level
tag. Textification of tags is the same as for get_text(). This
method will collapse white space in the same way as
get_trimmed_text() does.
The definition of <i>phrasal-level tags</i> is
obtained from the HTML::Tagset module.
This example extracts all links from a document. It will print one line for each
link, containing the URL and the textual description between the
<A>...</A> tags:
use HTML::TokeParser;
$p = HTML::TokeParser->new(shift||"index.html");
while (my $token = $p->get_tag("a")) {
my $url = $token->[1]{href} || "-";
my $text = $p->get_trimmed_text("/a");
print "$url\t$text\n";
}
This example extract the <TITLE> from the document:
use HTML::TokeParser;
$p = HTML::TokeParser->new(shift||"index.html");
if ($p->get_tag("title")) {
my $title = $p->get_trimmed_text;
print "Title: $title\n";
}
HTML::PullParser, HTML::Parser
Copyright 1998-2005 Gisle Aas.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
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