XML::LibXML::Node
XML::LibXML::Node(3) User Contributed Perl Documentation XML::LibXML::Node(3)
NAME
XML::LibXML::Node - Abstract Base Class of XML::LibXML Nodes
SYNOPSIS
use XML::LibXML;
$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;
$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_expression );
$result = $node->find( $xpath );
print $node->findvalue( $xpath );
$bool = $node->exists( $xpath_expression );
@childnodes = $node->childNodes;
$xmlstring = $node->toString($format,$docencoding);
$c14nstring = $node->toStringC14N($with_comments, $xpath_expression);
$ec14nstring = $node->toStringEC14N($with_comments, $xpath_expression, $inclusive_prefix_list);
$str = $doc->serialize($format);
$c14nstr = $doc->serialize_c14n($comment_flag,$xpath);
$ec14nstr = $doc->serialize_ec14n($comment_flag,$xpath,$inclusive_prefix_list);
$localname = $node->localname;
$nameprefix = $node->prefix;
$uri = $node->namespaceURI();
$boolean = $node->hasAttributes();
@attributelist = $node->attributes();
$URI = $node->lookupNamespaceURI( $prefix );
$prefix = $node->lookupNamespacePrefix( $URI );
$node->normalize;
@nslist = $node->getNamespaces;
$node->removeChildNodes();
$strURI = $node->baseURI();
$node->setBaseURI($strURI);
$node->nodePath();
$lineno = $node->line_number();
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.
METHODS
Many functions listed here are extensively documented in the DOM Level
3 specification (<http://www.w3.org/TR/DOM-Level-3-Core/>). Please
refer to the specification for extensive documentation.
nodeName
$name = $node->nodeName;
Returns the node’s name. This function is aware of namespaces and
returns the full name of the current node ("prefix:localname").
Since 1.62 this function also returns the correct DOM names for
node types with constant names, namely: #text, #cdata-section,
#comment, #document, #document-fragment.
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 struc-
ture, 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 descen-
dants of the given node as specified in DOM.
nodeType
$type = $node->nodeType;
Return a numeric value representing the node type of this node.
The module XML::LibXML by default exports constants for the node
types (see the EXPORT section in the XML::LibXML manual page).
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 program 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 func-
tion 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 spec-
ification, in the case, if the new node is not part of the docu-
ment, 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 chil-
dren. The function should fail, if the new childnode is already a
child of $node. This function differs from the DOM L2 specifica-
tion, 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 if 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 vio-
lations, 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 neces-
sary.
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 func-
tion 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. Note that in case of element,
attributes are copied even if $deep is 0.
Note that the behavior of this function for $deep=0 has changed in
1.62 in order to be consistent with the DOM spec (in older ver-
sions attributes and namespace information was not copied for ele-
ments).
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 sib-
ling 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 already bound to another document.
This function is the opposite 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 unde-
fined, 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 unde-
fined, 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( $xpath_expression );
findnodes evaluates the xpath expression (XPath 1.0) on the cur-
rent node and returns the resulting node set as an array. In
scalar context returns a XML::LibXML::NodeList object.
The xpath expression can be passed either as a string or or as a
XML::LibXML::XPathExpression object.
NOTE ON NAMESPACES AND XPATH:
A common mistake about XPath is to assume that node tests consist-
ing of an element name with no prefix match elements in the
default namespace. This assumption is wrong - by XPath specifica-
tion, such node tests can only match elements that are in no (i.e.
null) namespace.
So, for example, one cannot match the root element of an XHTML
document with "$node->find(’/html’)" since ’/html’ would only
match if the root element "<html>" had no namespace, but all XHTML
elements belong to the namespace http://www.w3.org/1999/xhtml.
(Note that "xmlns="..."" namespace declarations can also be speci-
fied in a DTD, which makes the situation even worse, since the XML
document looks as if there was no default namespace).
There are several possible ways to deal with namespaces in XPath:
* The recommended way is to use the XML::LibXML::XPathContext
module to define an explicit context for XPath evaluation, in
which a document independent prefix-to-namespace mapping can
be defined. For example:
my $xpc = XML::LibXML::XPathContext->new;
$xpc->registerNs(’x’, ’http://www.w3.org/1999/xhtml’);
$xpc->find(’/x:html’,$node);
* Another possibility is to use prefixes declared in the queried
document (if known). If the document declares a prefix for the
namespace in question (and the context node is in the scope of
the declaration), "XML::LibXML" allows you to use the prefix
in the XPath expression, e.g.:
$node->find(’/x:html’);
See also XML::LibXML::XPathContext->findnodes.
find
$result = $node->find( $xpath );
find evaluates the XPath 1.0 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.
The xpath expression can be passed either as a string or or as a
XML::LibXML::XPathExpression object.
See also XML::LibXML::XPathContext->find.
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, allow-
ing certain shortcuts. This could be used as the equivalent of
XSLT’s <xsl:value-of select="some_xpath"/>.
See also XML::LibXML::XPathContext->findvalue.
The xpath expression can be passed either as a string or or as a
XML::LibXML::XPathExpression object.
exists
$bool = $node->exists( $xpath_expression );
This method behaves like findnodes, except that it only returns a
boolean value (1 if the expression matches a node, 0 otherwise)
and may be faster than findnodes, because the XPath evaluation may
stop early on the first match (this is true for libxml2 >=
2.6.27).
For XPath expressions that do not return node-set, the method
returns true if the returned value is a non-zero number or a non-
empty string.
childNodes
@childnodes = $node->childNodes;
getChildnodes implements a more intuitive interface to the
childnodes of the current node. It enables you to pass all chil-
dren 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 method is similar to the method "toString" of a
XML::LibXML::Document but for a single node. It returns a string
consisting of XML serialization of the given node and all its
descendants. Unlike "XML::LibXML::Document::toString", in this
case the resulting string is by default a character string (UTF-8
encoded with UTF8 flag on). An optional flag $format controls
indentation, as in "XML::LibXML::Document::toString". If the sec-
ond optional $docencoding flag is true, the result will be a byte
string in the document encoding (see "XML::LibXML::Docu-
ment::actualEncoding").
toStringC14N
$c14nstring = $node->toStringC14N($with_comments, $xpath_expression);
The function is similar to toString(). Instead of simply serializ-
ing the document tree, it transforms it as it is specified in the
XML-C14N Specification (see <http://www.w3.org/TR/xml-c14n>). 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-docu-
ment. Their child-nodes will not exist in the resulting document,
unless they are part of the nodeset defined by the xpath expres-
sion.
If $xpath_expression is omitted or empty, toStringC14N() will
include all nodes in the given sub-tree.
toStringEC14N
$ec14nstring = $node->toStringEC14N($with_comments, $xpath_expression, $inclusive_prefix_list);
The function is similar to toStringC14N() but follows the
XML-EXC-C14N Specification (see
<http://www.w3.org/TR/xml-exc-c14n>) for exclusive canonization of
XML.
The first two arguments are as above. If $inclusive_prefix_list is
used, it should be an ARRAY reference listing namespace prefixes
that are to be handled in the manner described by the Canonical
XML Recommendation (i.e. preserved in the output even if the
namespace is not used). C.f. the spec for details.
serialize
$str = $doc->serialize($format);
An alias for toString(). This function was name added to be more
consistent with libxml2.
serialize_c14n
$c14nstr = $doc->serialize_c14n($comment_flag,$xpath);
An alias for toStringC14N().
serialize_exc_c14n
$ec14nstr = $doc->serialize_ec14n($comment_flag,$xpath,$inclusive_prefix_list);
An alias for toStringEC14N().
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, oth-
erwise 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.
normalize
$node->normalize;
This function normalizes adjacent text nodes. 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 immedi-
ately remove the nodes from the memory. This saves one from get-
ting memory violations, if there are nodes still referred to from
the Perl level.
baseURI ()
$strURI = $node->baseURI();
Searches for the base URL of the node. The method should work on
both XML and HTML documents even if base mechanisms for these are
completely different. It returns the base as defined in RFC 2396
sections "5.1.1. Base URI within Document Content" and "5.1.2.
Base URI from the Encapsulating Entity". However it does not
return the document base (5.1.3), use method "URI" of
"XML::LibXML::Document" for this.
setBaseURI ($strURI)
$node->setBaseURI($strURI);
This method only does something useful for an element node in a
XML document. It sets the xml:base attribute on the node to
$strURI, which effectively sets the base URI of the node to the
same value.
Note: For HTML documents this behaves as if the document was XML
which may not be desired, since it does not effectively set the
base URI of the node. See RFC 2396 appendix D for an example of
how base URI can be specified in HTML.
nodePath
$node->nodePath();
This function is not specified for any DOM level: It returns a
canonical structure based XPath for a given node.
line_number
$lineno = $node->line_number();
This function returns the line number where the tag was found dur-
ing 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.
IMPORTANT: Due to limitations in the libxml2 library line numbers
greater than 65535 will be returned as 65535. Please see
<http://bugzilla.gnome.org/show_bug.cgi?id=325533> for more
details.
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.
AUTHORS
Matt Sergeant, Christian Glahn, Petr Pajas
VERSION
1.66
COPYRIGHT
2001-2007, AxKit.com Ltd; 2002-2006 Christian Glahn; 2006-2008 Petr
Pajas, All rights reserved.
perl v5.8.8 2008-11-11 XML::LibXML::Node(3)
