Node.pod

=head1 NAME

XML::DOM::Node - Super class of all nodes in XML::DOM

=head1 DESCRIPTION

XML::DOM::Node is the super class of all nodes in an XML::DOM document.
This means that all nodes that subclass XML::DOM::Node also inherit all
the methods that XML::DOM::Node implements.

=head2 GLOBAL VARIABLES

=over 4

=item @NodeNames

The variable @XML::DOM::Node::NodeNames maps the node type constants to strings.
It is used by XML::DOM::Node::getNodeTypeName.

=back

=head2 METHODS

=over 4

=item getNodeType

Return an integer indicating the node type. See XML::DOM constants.

=item getNodeName

Return a property or a hardcoded string, depending on the node type.
Here are the corresponding functions or values:

 Attr			getName
 AttDef			getName
 AttlistDecl		getName
 CDATASection		"#cdata-section"
 Comment		"#comment"
 Document		"#document"
 DocumentType		getNodeName
 DocumentFragment	"#document-fragment"
 Element		getTagName
 ElementDecl		getName
 EntityReference	getEntityName
 Entity			getNotationName
 Notation		getName
 ProcessingInstruction	getTarget
 Text			"#text"
 XMLDecl		"#xml-declaration"

B<Not In DOM Spec>: AttDef, AttlistDecl, ElementDecl and XMLDecl were added for
completeness.

=item getNodeValue and setNodeValue (value)

Returns a string or undef, depending on the node type. This method is provided 
for completeness. In other languages it saves the programmer an upcast.
The value is either available thru some other method defined in the subclass, or
else undef is returned. Here are the corresponding methods: 
Attr::getValue, Text::getData, CDATASection::getData, Comment::getData, 
ProcessingInstruction::getData.

=item getParentNode and setParentNode (parentNode)

The parent of this node. All nodes, except Document,
DocumentFragment, and Attr may have a parent. However, if a
node has just been created and not yet added to the tree, or
if it has been removed from the tree, this is undef.

=item getChildNodes

A NodeList that contains all children of this node. If there
are no children, this is a NodeList containing no nodes. The
content of the returned NodeList is "live" in the sense that,
for instance, changes to the children of the node object that
it was created from are immediately reflected in the nodes
returned by the NodeList accessors; it is not a static
snapshot of the content of the node. This is true for every
NodeList, including the ones returned by the
getElementsByTagName method.

NOTE: this implementation does not return a "live" NodeList for
getElementsByTagName. See L<CAVEATS>.

When this method is called in a list context, it returns a regular perl list
containing the child nodes. Note that this list is not "live". E.g.

 @list = $node->getChildNodes;	      # returns a perl list
 $nodelist = $node->getChildNodes;    # returns a NodeList (object reference)
 for my $kid ($node->getChildNodes)   # iterate over the children of $node

=item getFirstChild

The first child of this node. If there is no such node, this returns undef.

=item getLastChild

The last child of this node. If there is no such node, this returns undef.

=item getPreviousSibling

The node immediately preceding this node. If there is no such 
node, this returns undef.

=item getNextSibling

The node immediately following this node. If there is no such node, this returns 
undef.

=item getAttributes

A NamedNodeMap containing the attributes (Attr nodes) of this node 
(if it is an Element) or undef otherwise.
Note that adding/removing attributes from the returned object, also adds/removes
attributes from the Element node that the NamedNodeMap came from.

=item getOwnerDocument

The Document object associated with this node. This is also
the Document object used to create new nodes. When this node
is a Document this is undef.

=item insertBefore (newChild, refChild)

Inserts the node newChild before the existing child node
refChild. If refChild is undef, insert newChild at the end of
the list of children.

If newChild is a DocumentFragment object, all of its children
are inserted, in the same order, before refChild. If the
newChild is already in the tree, it is first removed.

Return Value: The node being inserted.

DOMExceptions:

=over 4

=item * HIERARCHY_REQUEST_ERR

Raised if this node is of a type that does not allow children of the type of
the newChild node, or if the node to insert is one of this node's ancestors.

=item * WRONG_DOCUMENT_ERR

Raised if newChild was created from a different document than the one that 
created this node.

=item * NO_MODIFICATION_ALLOWED_ERR

Raised if this node is readonly.

=item * NOT_FOUND_ERR

Raised if refChild is not a child of this node.

=back

=item replaceChild (newChild, oldChild)

Replaces the child node oldChild with newChild in the list of
children, and returns the oldChild node. If the newChild is
already in the tree, it is first removed.

Return Value: The node replaced.

DOMExceptions:

=over 4

=item * HIERARCHY_REQUEST_ERR

Raised if this node is of a type that does not allow children of the type of
the newChild node, or it the node to put in is one of this node's ancestors.

=item * WRONG_DOCUMENT_ERR

Raised if newChild was created from a different document than the one that 
created this node.

=item * NO_MODIFICATION_ALLOWED_ERR

Raised if this node is readonly.

=item * NOT_FOUND_ERR

Raised if oldChild is not a child of this node.

=back

=item removeChild (oldChild)

Removes the child node indicated by oldChild from the list of
children, and returns it.

Return Value: The node removed.

DOMExceptions:

=over 4

=item * NO_MODIFICATION_ALLOWED_ERR

Raised if this node is readonly.

=item * NOT_FOUND_ERR

Raised if oldChild is not a child of this node.

=back

=item appendChild (newChild)

Adds the node newChild to the end of the list of children of
this node. If the newChild is already in the tree, it is
first removed. If it is a DocumentFragment object, the entire contents of 
the document fragment are moved into the child list of this node

Return Value: The node added.

DOMExceptions:

=over 4

=item * HIERARCHY_REQUEST_ERR

Raised if this node is of a type that does not allow children of the type of
the newChild node, or if the node to append is one of this node's ancestors.

=item * WRONG_DOCUMENT_ERR

Raised if newChild was created from a different document than the one that 
created this node.

=item * NO_MODIFICATION_ALLOWED_ERR

Raised if this node is readonly.

=back

=item hasChildNodes

This is a convenience method to allow easy determination of
whether a node has any children.

Return Value: 1 if the node has any children, 0 otherwise.

=item cloneNode (deep)

Returns a duplicate of this node, i.e., serves as a generic
copy constructor for nodes. The duplicate node has no parent
(parentNode returns undef.).

Cloning an Element copies all attributes and their values,
including those generated by the XML processor to represent
defaulted attributes, but this method does not copy any text
it contains unless it is a deep clone, since the text is
contained in a child Text node. Cloning any other type of
node simply returns a copy of this node.

Parameters: 
 I<deep>   If true, recursively clone the subtree under the specified node.
If false, clone only the node itself (and its attributes, if it is an Element).

Return Value: The duplicate node.

=item normalize

Puts all Text nodes in the full depth of the sub-tree
underneath this Element into a "normal" form where only
markup (e.g., tags, comments, processing instructions, CDATA
sections, and entity references) separates Text nodes, i.e.,
there are no adjacent Text nodes. This can be used to ensure
that the DOM view of a document is the same as if it were
saved and re-loaded, and is useful when operations (such as
XPointer lookups) that depend on a particular document tree
structure are to be used.

B<Not In DOM Spec>: In the DOM Spec this method is defined in the Element and 
Document class interfaces only, but it doesn't hurt to have it here...

=item getElementsByTagName (name [, recurse])

Returns a NodeList of all descendant elements with a given
tag name, in the order in which they would be encountered in
a preorder traversal of the Element tree.

Parameters:
 I<name>  The name of the tag to match on. The special value "*" matches all tags.
 I<recurse>  Whether it should return only direct child nodes (0) or any descendant that matches the tag name (1). This argument is optional and defaults to 1. It is not part of the DOM spec.

Return Value: A list of matching Element nodes.

NOTE: this implementation does not return a "live" NodeList for
getElementsByTagName. See L<CAVEATS>.

When this method is called in a list context, it returns a regular perl list
containing the result nodes. E.g.

 @list = $node->getElementsByTagName("tag");       # returns a perl list
 $nodelist = $node->getElementsByTagName("tag");   # returns a NodeList (object ref.)
 for my $elem ($node->getElementsByTagName("tag")) # iterate over the result nodes

=back

=head2 Additional methods not in the DOM Spec

=over 4

=item getNodeTypeName

Return the string describing the node type. 
E.g. returns "ELEMENT_NODE" if getNodeType returns ELEMENT_NODE.
It uses @XML::DOM::Node::NodeNames.

=item toString

Returns the entire subtree as a string.

=item printToFile (filename)

Prints the entire subtree to the file with the specified filename.

Croaks: if the file could not be opened for writing.

=item printToFileHandle (handle)

Prints the entire subtree to the file handle.
E.g. to print to STDOUT:

 $node->printToFileHandle (\*STDOUT);

=item print (obj)

Prints the entire subtree using the object's print method. E.g to print to a
FileHandle object:

 $f = new FileHandle ("file.out", "w");
 $node->print ($f);

=item getChildIndex (child)

Returns the index of the child node in the list returned by getChildNodes.

Return Value: the index or -1 if the node is not found.

=item getChildAtIndex (index)

Returns the child node at the specifed index or undef.

=item addText (text)

Appends the specified string to the last child if it is a Text node, or else 
appends a new Text node (with the specified text.)

Return Value: the last child if it was a Text node or else the new Text node.

=item dispose

Removes all circular references in this node and its descendants so the 
objects can be claimed for garbage collection. The objects should not be used
afterwards.

=item setOwnerDocument (doc)

Sets the ownerDocument property of this node and all its children (and 
attributes etc.) to the specified document.
This allows the user to cut and paste document subtrees between different
XML::DOM::Documents. The node should be removed from the original document
first, before calling setOwnerDocument.

This method does nothing when called on a Document node.

=item isAncestor (parent)

Returns 1 if parent is an ancestor of this node or if it is this node itself.

=item expandEntityRefs (str)

Expands all the entity references in the string and returns the result.
The entity references can be character references (e.g. "&#123;" or "&#x1fc2"),
default entity references ("&quot;", "&gt;", "&lt;", "&apos;" and "&amp;") or
entity references defined in Entity objects as part of the DocumentType of
the owning Document. Character references are expanded into UTF-8.
Parameter entity references (e.g. %ent;) are not expanded.

=item to_sax ( %HANDLERS )

E.g.

 $node->to_sax (DocumentHandler => $my_handler, 
		Handler => $handler2 );

%HANDLERS may contain the following handlers:

=over 4

=item * DocumentHandler

=item * DTDHandler

=item * EntityResolver

=item * Handler 

Default handler when one of the above is not specified

=back

Each XML::DOM::Node generates the appropriate SAX callbacks (for the
appropriate SAX handler.) Different SAX handlers can be plugged in to
accomplish different things, e.g. L<XML::Checker> would check the node 
(currently only Document and Element nodes are supported), L<XML::Handler::BuildDOM>
would create a new DOM subtree (thereby, in essence, copying the Node)
and in the near future, XML::Writer could print the node.
All Perl SAX related work is still in flux, so this interface may change a 
little.

See PerlSAX for the description of the SAX interface.

=item check ( [$checker] )

See descriptions for check() in L<XML::DOM::Document> and L<XML::DOM::Element>.

=item xql ( @XQL_OPTIONS )

To use the xql method, you must first I<use> L<XML::XQL> and L<XML::XQL::DOM>.
This method is basically a shortcut for:

 $query = new XML::XQL::Query ( @XQL_OPTIONS );
 return $query->solve ($node);

If the first parameter in @XQL_OPTIONS is the XQL expression, you can leave off
the 'Expr' keyword, so:

 $node->xql ("doc//elem1[@attr]", @other_options);

is identical to:

 $node->xql (Expr => "doc//elem1[@attr]", @other_options);

See L<XML::XQL::Query> for other available XQL_OPTIONS.
See L<XML::XQL> and L<XML::XQL::Tutorial> for more info.

=item isHidden ()

Whether the node is hidden.
See L<Hidden Nodes|XML::DOM/_Hidden_Nodes_> for details.

=back