PC Professionell 2004 December/PCpro_2004_12.ISO/files/webserver/tsw/TSW_3.4.0.exe/Apache2/perl/Node.pod

Text File | 2003-08-22 | 17.1 KB | 784 lines

=head1 NAME

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

=head1 SYNOPSIS

  $name = $node->nodeName;
  $node->setNodeName( $newName );
  $bool = $node->isSameNode( $other_node );
  $bool = $node->isEqual( $other_node );
  $content = $node->nodeValue;
  $content = $node->textContent;
  $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();


=head1 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.

=over 4

=item B<nodeName>

  $name = $node->nodeName;

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



=back

=over 4

=item B<setNodeName>

  $node->setNodeName( $newName );

In very limited situation it is usefull to change a nodes name. In the DOM
specification this should throw an error. This Function is aware about
namespaces.



=back

=over 4

=item B<isSameNode>

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

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



=back

=over 4

=item B<isEqual>

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

depraced version of isSameNode().

NOTE isEqual will change behaviour to follow the DOM specification



=back

=over 4

=item B<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!



=back

=over 4

=item B<textContent>

  $content = $node->textContent;

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



=back

=over 4

=item B<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 differst with the result of perl ref function.


=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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 confomity checks. Therefore
this function is quite usefull if one builds XML documents in memory where the
order and ownership (ownerDocument) is ashured.

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 aswell 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 about this action, the perl instance is still
available. XML::LibXML will catch the loss of a node an avoid 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 usefull if a document
is build from a stream, such as happens sometimes in SAX handlers or filters.

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



=back

=over 4

=item B<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 usefull for DOM building, where a created node can be
directly associated to its parent. NOTE this function is not part of the DOM
specification and its use will limit your code to XML::LibXML.



=back

=over 4

=item B<addSibling>

  $node->addSibling($newNode);

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



=back

=over 4

=item B<cloneNode>

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

cloneNode creates a copy of $node. Wether $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.



=back

=over 4

=item B<parentNode>

  $parentnode = $node->parentNode;

Returns simply the Parent Node of the current node.



=back

=over 4

=item B<nextSibling>

  $nextnode = $node->nextSibling()

Returns the next sibling if any .



=back

=over 4

=item B<previousSibling>

  $prevnode = $node->previousSibling()

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



=back

=over 4

=item B<hasChildNodes>

  $boolean = $node->hasChildNodes();

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



=back

=over 4

=item B<firstChild>

  $childnode = $node->firstChild;

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



=back

=over 4

=item B<lastChild>

  $childnode = $node->lastChild;

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



=back

=over 4

=item B<ownerDocument>

  $documentnode = $node->ownerDocument;

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



=back

=over 4

=item B<getOwner>

  $node = $node->getOwner;

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



=back

=over 4

=item B<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().



=back

=over 4

=item B<insertBefore>

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

The method inserts $newNode before $refNode. If $refNode is undefined, the
newNode will be set as the new first 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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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"/>.



=back

=over 4

=item B<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.



=back

=over 4

=item B<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.


=item B<toStringC14N>

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

The function is similar to toString(). Instead of simply searializing 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!


=item B<serialize>

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

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


=item B<serialize_c14n>

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

Alternative form of toStringC14N().



=back

=over 4

=item B<localname>

  $localname = $node->localname;

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



=back

=over 4

=item B<prefix>

  $nameprefix = $node->prefix;

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



=back

=over 4

=item B<namespaceURI>

  $uri = $node->namespaceURI()

returns the URI of the current namespace.



=back

=over 4

=item B<hasAttributes>

  $boolean = $node->hasAttributes();

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



=back

=over 4

=item B<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.



=back

=over 4

=item B<lookupNamespaceURI>

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

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



=back

=over 4

=item B<lookupNamespacePrefix>

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

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

NOTE Only the namespace URIs are ment to be unique. The prefix is only document
related. also document might has more than a single prefix defined for a
namespace.



=back

=over 4

=item B<iterator>

  $iter = $node->iterator;

This function is depraced sind XML::LibXML 1.54. It is only a dummyfunction
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.



=back

=over 4

=item B<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
refered by the perl layer.



=back

=over 4

=item B<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 declares explicitly for that node.

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



=back

=over 4

=item B<removeChildNode>

  $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 imediatly remove the nodes from the
memory. This safes one from getting memory violations, if there are nodes still
refered from the Perl level.



=back

=head1 AUTHORS

Matt Sergeant,
Christian Glahn,
=head1 VERSION

1.56

=head1 COPYRIGHT

2001-2002, AxKit.com Ltd; 2001-2003 Christian Glahn, All rights reserved.

=cut