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Gisle Aas


HTML::Element - Class for objects that represent HTML elements


 require HTML::Element;
 $a = new HTML::Element 'a', href => 'http://www.oslonett.no/';
 $a->push_content("Oslonett AS");

 $tag = $a->tag;
 $tag = $a->starttag;
 $tag = $a->endtag;
 $ref = $a->attr('href');

 $links = $a->extract_links();

 print $a->as_HTML;


Objects of the HTML::Element class can be used to represent elements of HTML. These objects have attributes and content. The content is an array of text segments and other HTML::Element objects. Thus a tree of HTML::Element objects as nodes can represent the syntax tree for a HTML document.

The following methods are available:

$h = HTML::Element->new('tag', 'attrname' => 'value',...)

The object constructor. Takes a tag name as argument. Optionally, allows you to specify initial attributes at object creation time.


Returns (optionally sets) the tag name for the element. The tag is always converted to lower case.


Returns the complete start tag for the element. Including leading "<", trailing ">" and attributes.


Returns the complete end tag. Includes leading "</" and the trailing ">".


Returns (optionally sets) the parent for this element.


Returns (optionally sets) the implicit attribute. This attribute is used to indicate that the element was not originally present in the source, but was inserted in order to conform to HTML strucure.


Returns true if this tag is contained inside one of the specified tags.


Returns (and optionally sets) the current position. The position is a reference to a HTML::Element object that is part of the tree that has the current object as root. This restriction is not enforced when setting pos(), but unpredictable things will happen if this is not true.

$h->attr('attr', [$value])

Returns (and optionally sets) the value of some attribute.


Returns the content of this element. The content is represented as a reference to an array of text segments and references to other HTML::Element objects.


Returns true if there is no content.

$h->insert_element($element, $implicit)

Inserts a new element at current position and updates pos() to point to the inserted element. Returns $element.


Adds to the content of the element. The content should be a text segment (scalar) or a reference to a HTML::Element object.


Clears the content.


Frees memory associated with the element and all children. This is needed because perl's reference counting does not work since we use circular references.

$h->traverse(\&callback, [$ignoretext])

Traverse the element and all of its children. For each node visited, the callback routine is called with the node, a startflag and the depth as arguments. If the $ignoretext parameter is true, then the callback will not be called for text content. The flag is 1 when we enter a node and 0 when we leave the node.

If the returned value from the callback is false then we will not traverse the children.


Returns links found by traversing the element and all of its children. The return value is a reference to an array. Each element of the array is an array with 2 values; the link value and a reference to the corresponding element.

You might specify that you just want to extract some types of links. For instance if you only want to extract <a href="..."> and <img src="..."> links you might code it like this:

  for (@{ $e->extract_links(qw(a img)) }) {
      ($link, $linkelem) = @$_;

Prints the element and all its children to STDOUT. Mainly useful for debugging. The structure of the document is shown by indentation (no end tags).


Returns a string (the HTML document) that represents the element and its children.


If you want to free the memory assosiated with a tree built of HTML::Element nodes then you will have to delete it explicitly. The reason for this is that perl currently has no proper garbage collector, but depends on reference counts in the objects. This scheme fails because the parse tree contains circular references (parents have references to their children and children have a reference to their parent).




Copyright 1995-1998 Gisle Aas.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.