XML::LibXML::Node

Section: User Contributed Perl Documentation (3)
Updated: 2003-11-07
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NAME

XML::LibXML::Node - Abstract Base Class of XML::LibXML Nodes  

SYNOPSIS

  $name = $node->nodeName;
  $node->setNodeName( $newName );
  $bool = $node->isSameNode( $other_node );
  $bool = $node->isEqual( $other_node );
  $content = $node->nodeValue;
  $content = $node->textContent;
  $lineno = $node->line_number();
  $type = $node->nodeType;
  $lineno = $node->line_number();
  $node->unbindNode()
  $childnode = $node->removeChild( $childnode )
  $oldnode = $node->replaceChild( $newNode, $oldNode )
  $node->replaceNode($newNode);
  $childnode = $node->appendChild( $childnode );
  $childnode = $node->addChild( $chilnode );
  $node = $parent->addNewChild( $nsURI, $name );
  $node->addSibling($newNode);
  $newnode =$node->cloneNode( $deep )
  $parentnode = $node->parentNode;
  $nextnode = $node->nextSibling()
  $prevnode = $node->previousSibling()
  $boolean = $node->hasChildNodes();
  $childnode = $node->firstChild;
  $childnode = $node->lastChild;
  $documentnode = $node->ownerDocument;
  $node = $node->getOwner;
  $node->setOwnerDocument( $doc );
  $node->insertBefore( $newNode, $refNode )
  $node->insertAfter( $newNode, $refNode )
  @nodes = $node->findnodes( $xpath_statement );
  $result = $node->find( $xpath );
  print $node->findvalue( $xpath );
  @childnodes = $node->childNodes;
  $xmlstring = $node->toString($format,$docencoding);
  $c14nstring = $node->toString($with_comments, $xpath_expression);
  $str = $doc->serialze($format); 
  $c14nstr = $doc->serialize_c14n($comment_flag,$xpath); 
  $localname = $node->localname;
  $nameprefix = $node->prefix;
  $uri = $node->namespaceURI()
  $boolean = $node->hasAttributes();
  @attributelist = $node->attributes();
  $URI = $node->lookupNamespaceURI( $prefix );
  $prefix = $node->lookupNamespacePrefix( $URI );
  $iter = $node->iterator;
  $node->normalize;
  @nslist = $node->getNamespaces;
  $node->removeChildNodes();

 

DESCRIPTION

XML::LibXML::Node defines functions that are common to all Node Types. A LibXML::Node should never be created standalone, but as an instance of a high level class such as LibXML::Element or LibXML::Text. The class itself should provide only common functionality. In XML::LibXML each node is part either of a document or a document-fragment. Because of this there is no node without a parent. This may causes confusion with ``unbound'' nodes.
nodeName
  $name = $node->nodeName;

Returns the node's name. This Function is aware of namesaces and returns the full name of the current node (prefix:localname)

setNodeName
  $node->setNodeName( $newName );

In very limited situations, it is useful to change a nodes name. In the DOM specification this should throw an error. This Function is aware of namespaces.

isSameNode
  $bool = $node->isSameNode( $other_node );

returns TRUE (1) if the given nodes refer to the same node structure, otherwise FALSE (0) is returned.

isEqual
  $bool = $node->isEqual( $other_node );

deprecated version of isSameNode().

NOTE isEqual will change behaviour to follow the DOM specification

nodeValue
  $content = $node->nodeValue;

If the node has any content (such as stored in a text node) it can get requested through this function.

NOTE: Element Nodes have no content per definition. To get the text value of an Element use textContent() instead!

textContent
  $content = $node->textContent;

this function returns the content of all text nodes in the descendants of the given node as spacified in DOM.

line_number
  $lineno = $node->line_number();

This function returns the line number where the tag was found during parsing. If a node is added to the document the line number is 0. Problems may occour, if a node from one document is passed to another one.

Note: line_number() is special to XML::LibXML and not part of the DOM specification.

If the line_numbers flag of the parser was not activated before parsing, line_number() will always return 0.

nodeType
  $type = $node->nodeType;

Retrun the node's type. The possible types are described in the libxml2 tree.h documentation. The return value of this function is a numeric value. Therefore it differs from the result of perl ref function.

line_number
  $lineno = $node->line_number();

This function returns the line number where the tag was found during parsing. If a node is added to the document the line number is 0. Problems may occur, if a node from one document is passed to another one.

Note: line_number() is special to XML::LibXML and not part of the DOM specification.

If the line_numbers flag of the parser was not activated before parsing, line_number() will always return 0.

unbindNode
  $node->unbindNode()

Unbinds the Node from its siblings and Parent, but not from the Document it belongs to. If the node is not inserted into the DOM afterwards it will be lost after the programm terminated. From a low level view, the unbound node is stripped from the context it is and inserted into a (hidden) document-fragment.

removeChild
  $childnode = $node->removeChild( $childnode )

This will unbind the Child Node from its parent $node. The function returns the unbound node. If oldNode is not a child of the given Node the function will fail.

replaceChild
  $oldnode = $node->replaceChild( $newNode, $oldNode )

Replaces the $oldNode with the $newNode. The $oldNode will be unbound from the Node. This function differs from the DOM L2 specification, in the case, if the new node is not part of the document, the node will be imported first.

replaceNode
  $node->replaceNode($newNode);

This function is very similar to replaceChild(), but it replaces the node itself rather than a childnode. This is useful if a node found by any XPath function, should be replaced.

appendChild
  $childnode = $node->appendChild( $childnode );

The function will add the $childnode to the end of $node's children. The function should fail, if the new childnode is allready a child of $node. This function differs from the DOM L2 specification, in the case, if the new node is not part of the document, the node will be imported first.

addChild
  $childnode = $node->addChild( $chilnode );

As an alternative to appendChild() one can use the addChild() function. This function is a bit faster, because it avoids all DOM conformity checks. Therefore this function is quite useful if one builds XML documents in memory where the order and ownership (ownerDocument) is assured.

addChild() uses libxml2's own xmlAddChild() function. Thus it has to be used with extra care: If a text node is added to a node and the node itself or its last childnode is as well a text node, the node to add will be merged with the one already available. The current node will be removed from memory after this action. Because perl is not aware of this action, the perl instance is still available. XML::LibXML will catch the loss of a node and refuse to run any function called on that node.

   my $t1 = $doc->createTextNode( "foo" );
   my $t2 = $doc->createTextNode( "bar" );
   $t1->addChild( $t2 );       # is ok
   my $val = $t2->nodeValue(); # will fail, script dies

Also addChild() will not check it the added node belongs to the same document as the node it will be added to. This could lead to inconsistent documents and in more worse cases even to memory violations, if one does not keep track of this issue.

Although this sounds like a lot of trouble, addChild() is useful if a document is built from a stream, such as happens sometimes in SAX handlers or filters.

If you are not sure about the source of your nodes, you better stay with appendChild(), because this function is more user friendly in the sense of being more error tolerant.

addNewChild
  $node = $parent->addNewChild( $nsURI, $name );

Similar to addChild(), this function uses low level libxml2 functionality to provide faster interface for DOM building. addNewChild() uses xmlNewChild() to create a new node on a given parent element.

addNewChild() has two parameters $nsURI and $name, where $nsURI is an (optional) namespace URI. $name is the fully qualified element name; addNewChild() will determine the correct prefix if nessecary.

The function returns the newly created node.

This function is very useful for DOM building, where a created node can be directly associated with its parent. NOTE this function is not part of the DOM specification and its use will limit your code to XML::LibXML.

addSibling
  $node->addSibling($newNode);

addSibling() allows adding an additional node to the end of a nodelist, defined by the given node.

cloneNode
  $newnode =$node->cloneNode( $deep )

cloneNode creates a copy of $node. When $deep is set to 1 (true) the function will copy all childnodes as well. If $deep is 0 only the current node will be copied.

cloneNode will not copy any namespace information if it is not run recursivly.

parentNode
  $parentnode = $node->parentNode;

Returns simply the Parent Node of the current node.

nextSibling
  $nextnode = $node->nextSibling()

Returns the next sibling if any .

previousSibling
  $prevnode = $node->previousSibling()

Analogous to getNextSibling the function returns the previous sibling if any.

hasChildNodes
  $boolean = $node->hasChildNodes();

If the current node has Childnodes this function returns TRUE (1), otherwise it returns FALSE (0, not undef).

firstChild
  $childnode = $node->firstChild;

If a node has childnodes this function will return the first node in the childlist.

lastChild
  $childnode = $node->lastChild;

If the $node has childnodes this function returns the last child node.

ownerDocument
  $documentnode = $node->ownerDocument;

Through this function it is always possible to access the document the current node is bound to.

getOwner
  $node = $node->getOwner;

This function returns the node the current node is associated with. In most cases this will be a document node or a document fragment node.

setOwnerDocument
  $node->setOwnerDocument( $doc );

This function binds a node to another DOM. This method unbinds the node first, if it is allready bound to another document.

This function is the oposite calling of XML::LibXML::Document's adoptNode() function. Because of this it has the same limitations with Entity References as adoptNode().

insertBefore
  $node->insertBefore( $newNode, $refNode )

The method inserts $newNode before $refNode. If $refNode is undefined, the newNode will be set as the new last child of the parent node. This function differs from the DOM L2 specification, in the case, if the new node is not part of the document, the node will be imported first, automatically.

$refNode has to be passed to the function even if it is undefined:

   $node->insertBefore( $newNode, undef ); # the same as $node->appendChild( $newNode );
   $node->insertBefore( $newNode ); # wrong

Note, that the reference node has to be a direct child of the node the function is called on. Also, $newChild is not allowed to be an ancestor of the new parent node.

insertAfter
  $node->insertAfter( $newNode, $refNode )

The method inserts $newNode after $refNode. If $refNode is undefined, the newNode will be set as the new last child of the parent node.

Note, that $refNode has to be passed explicitly even if it is undef.

findnodes
  @nodes = $node->findnodes( $xpath_statement );

findnodes performs the xpath statement on the current node and returns the result as an array. In scalar context returns a XML::LibXML::NodeList object.

find
  $result = $node->find( $xpath );

find performs the xpath expression using the current node as the context of the expression, and returns the result depending on what type of result the XPath expression had. For example, the XPath ``1 * 3 + 52'' results in a XML::LibXML::Number object being returned. Other expressions might return a XML::LibXML::Boolean object, or a XML::LibXML::Literal object (a string). Each of those objects uses Perl's overload feature to ``do the right thing'' in different contexts.

findvalue
  print $node->findvalue( $xpath );

findvalue is exactly equivalent to:

   $node->find( $xpath )->to_literal;

That is, it returns the literal value of the results. This enables you to ensure that you get a string back from your search, allowing certain shortcuts. This could be used as the equivalent of XSLT's <xsl:value-of select=``some_xpath''/>.

childNodes
  @childnodes = $node->childNodes;

getChildnodes implements a more intuitive interface to the childnodes of the current node. It enables you to pass all children directly to a map or grep. If this function is called in scalar context, a XML::LibXML::NodeList object will be returned.

toString
  $xmlstring = $node->toString($format,$docencoding);

This is the equivalent to XML::LibXML::Document::toString for a single node. This means a node and all its childnodes will be dumped into the result string.

Additionally to the $format flag of XML::LibXML::Document, this version accepts the optional $docencoding flag. If this flag is set this function returns the string in its original encoding (the encoding of the document) rather than UTF8.

toStringC14N
  $c14nstring = $node->toString($with_comments, $xpath_expression);

The function is similar to toString(). Instead of simply serializing the document tree, it transforms it as it is specified in the XML-C14N Specification. Such transformation is known as canonization.

If $with_comments is 0 or not defined, the result-document will not contain any comments that exist in the original document. To include comments into the canonized document, $with_comments has to be set to 1.

The parameter $xpath_expression defines the nodeset of nodes that should be visible in the resulting document. This can be used to filter out some nodes. One has to note, that only the nodes that are part of the nodeset, will be included into the result-document. Their child-nodes will not exist in the resulting document, unless they are part of the nodeset defined by the xpath expression.

If $xpath_expression is ommitted or empty, toStringC14N() will include all nodes in the given sub-tree.

No serializing flags will be recognized by this function!

serialize
  $str = $doc->serialze($format);

Alternative form of toString(). This function name added to be more conform with libxml2's examples.

serialize_c14n
  $c14nstr = $doc->serialize_c14n($comment_flag,$xpath);

Alternative form of toStringC14N().

localname
  $localname = $node->localname;

Returns the local name of a tag. This is the part behind the colon.

prefix
  $nameprefix = $node->prefix;

Returns the prefix of a tag. This is the part before the colon.

namespaceURI
  $uri = $node->namespaceURI()

returns the URI of the current namespace.

hasAttributes
  $boolean = $node->hasAttributes();

returns 1 (TRUE) if the current node has any attributes set, otherwise 0 (FALSE) is returned.

attributes
  @attributelist = $node->attributes();

This function returns all attributes and namespace declarations assigned to the given node.

Because XML::LibXML does not implement namespace declarations and attributes the same way, it is required to test what kind of node is handled while accessing the functions result.

If this function is called in array context the attribute nodes are returned as an array. In scalar context the function will return a XML::LibXML::NamedNodeMap object.

lookupNamespaceURI
  $URI = $node->lookupNamespaceURI( $prefix );

Find a namespace URI by its prefix starting at the current node.

lookupNamespacePrefix
  $prefix = $node->lookupNamespacePrefix( $URI );

Find a namespace prefix by its URI starting at the current node.

NOTE Only the namespace URIs are meant to be unique. The prefix is only document related. Also the document might have more than a single prefix defined for a namespace.

iterator
  $iter = $node->iterator;

This function is deprecated since XML::LibXML 1.54. It is only a dummy function that will get removed entirely in one of the next versions.

To make use of iterator functions use XML::LibXML::Iterator Module available on CPAN.

normalize
  $node->normalize;

This function normalizes adjacent textnodes. This function is not as strict as libxml2's xmlTextMerge() function, since it will not free a node that is still referenced by the perl layer.

getNamespaces
  @nslist = $node->getNamespaces;

If a node has any namespaces defined, this function will return these namespaces. Note, that this will not return all namespaces that are in scope, but only the ones declared explicitly for that node.

Although getNamespaces is available for all nodes, it only makes sense if used with element nodes.

removeChildNodes
  $node->removeChildNodes();

This function is not specified for any DOM level: It removes all childnodes from a node in a single step. Other than the libxml2 function itself (xmlFreeNodeList), this function will not immediately remove the nodes from the memory. This saves one from getting memory violations, if there are nodes still referred to from the Perl level.

 

AUTHORS

Matt Sergeant, Christian Glahn, =head1 VERSION

1.58  

COPYRIGHT

2001-2004, AxKit.com Ltd; 2002-2004 Christian Glahn, All rights reserved.


 

Index

NAME
SYNOPSIS
DESCRIPTION
AUTHORS
COPYRIGHT

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