org.apache.xerces.dom

Class ParentNode

Implemented Interfaces:
Cloneable, EventTarget, Node, NodeList, Serializable
Known Direct Subclasses:
CoreDocumentImpl, DocumentFragmentImpl, DocumentTypeImpl, ElementDefinitionImpl, ElementImpl, EntityImpl, EntityReferenceImpl

public abstract class ParentNode
extends ChildNode

ParentNode inherits from ChildNode and adds the capability of having child nodes. Not every node in the DOM can have children, so only nodes that can should inherit from this class and pay the price for it.

ParentNode, just like NodeImpl, also implements NodeList, so it can return itself in response to the getChildNodes() query. This eliminiates the need for a separate ChildNodeList object. Note that this is an IMPLEMENTATION DETAIL; applications should _never_ assume that this identity exists. On the other hand, subclasses may need to override this, in case of conflicting names. This is the case for the classes HTMLSelectElementImpl and HTMLFormElementImpl of the HTML DOM.

While we have a direct reference to the first child, the last child is stored as the previous sibling of the first child. First child nodes are marked as being so, and getNextSibling hides this fact.

Note: Not all parent nodes actually need to also be a child. At some point we used to have ParentNode inheriting from NodeImpl and another class called ChildAndParentNode that inherited from ChildNode. But due to the lack of multiple inheritance a lot of code had to be duplicated which led to a maintenance nightmare. At the same time only a few nodes (Document, DocumentFragment, Entity, and Attribute) cannot be a child so the gain in memory wasn't really worth it. The only type for which this would be the case is Attribute, but we deal with there in another special way, so this is not applicable.

This class doesn't directly support mutation events, however, it notifies the document when mutations are performed so that the document class do so.

WARNING: Some of the code here is partially duplicated in AttrImpl, be careful to keep these two classes in sync!

Version:
$Id: ParentNode.java,v 1.50 2005/05/02 22:02:22 mrglavas Exp $
Authors:
Arnaud Le Hors, IBM
Joe Kesselman, IBM
Andy Clark, IBM

Field Summary

protected org.apache.xerces.dom.NodeListCache
fNodeListCache
NodeList cache
protected ChildNode
firstChild
First child.
protected CoreDocumentImpl
ownerDocument
Owner document.

Fields inherited from class org.apache.xerces.dom.ChildNode

nextSibling, previousSibling

Fields inherited from class org.apache.xerces.dom.NodeImpl

DOCUMENT_POSITION_CONTAINS, DOCUMENT_POSITION_DISCONNECTED, DOCUMENT_POSITION_FOLLOWING, DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC, DOCUMENT_POSITION_IS_CONTAINED, DOCUMENT_POSITION_PRECEDING, ELEMENT_DEFINITION_NODE, FIRSTCHILD, HASSTRING, ID, IGNORABLEWS, NORMALIZED, OWNED, READONLY, SPECIFIED, SYNCCHILDREN, SYNCDATA, TREE_POSITION_ANCESTOR, TREE_POSITION_DESCENDANT, TREE_POSITION_DISCONNECTED, TREE_POSITION_EQUIVALENT, TREE_POSITION_FOLLOWING, TREE_POSITION_PRECEDING, TREE_POSITION_SAME_NODE, flags, ownerNode

Constructor Summary

ParentNode()
Constructor for serialization.
ParentNode(CoreDocumentImpl ownerDocument)
No public constructor; only subclasses of ParentNode should be instantiated, and those normally via a Document's factory methods

Method Summary

Node
cloneNode(boolean deep)
Returns a duplicate of a given node.
NodeList
getChildNodes()
Obtain a NodeList enumerating all children of this node.
protected NodeList
getChildNodesUnoptimized()
Create a NodeList to access children that is use by subclass elements that have methods named getLength() or item(int).
Node
getFirstChild()
The first child of this Node, or null if none.
Node
getLastChild()
The last child of this Node, or null if none.
int
getLength()
NodeList method: Count the immediate children of this node
Document
getOwnerDocument()
Find the Document that this Node belongs to (the document in whose context the Node was created).
String
getTextContent()
This attribute returns the text content of this node and its descendants.
boolean
hasChildNodes()
Test whether this node has any children.
Node
insertBefore(Node newChild, Node refChild)
Move one or more node(s) to our list of children.
boolean
isEqualNode(Node arg)
DOM Level 3 WD- Experimental.
Node
item(int index)
NodeList method: Return the Nth immediate child of this node, or null if the index is out of bounds.
void
normalize()
Override default behavior to call normalize() on this Node's children.
Node
removeChild(Node oldChild)
Remove a child from this Node.
Node
replaceChild(Node newChild, Node oldChild)
Make newChild occupy the location that oldChild used to have.
void
setReadOnly(boolean readOnly, boolean deep)
Override default behavior so that if deep is true, children are also toggled.
void
setTextContent(String textContent)
This attribute returns the text content of this node and its descendants.
protected void
synchronizeChildren()
Override this method in subclass to hook in efficient internal data structure.

Methods inherited from class org.apache.xerces.dom.ChildNode

cloneNode, getNextSibling, getParentNode, getPreviousSibling

Methods inherited from class org.apache.xerces.dom.NodeImpl

addEventListener, appendChild, changed, changes, cloneNode, compareDocumentPosition, compareTreePosition, dispatchEvent, getAttributes, getBaseURI, getChildNodes, getContainer, getFeature, getFirstChild, getLastChild, getLength, getLocalName, getNamespaceURI, getNextSibling, getNodeName, getNodeNumber, getNodeType, getNodeValue, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getReadOnly, getTextContent, getUserData, getUserData, getUserDataRecord, hasAttributes, hasChildNodes, insertBefore, isDefaultNamespace, isEqualNode, isSameNode, isSupported, item, lookupNamespaceURI, lookupPrefix, needsSyncChildren, normalize, removeChild, removeEventListener, replaceChild, setNodeValue, setPrefix, setReadOnly, setTextContent, setUserData, setUserData, synchronizeData, toString

Field Details

fNodeListCache

protected org.apache.xerces.dom.NodeListCache fNodeListCache
NodeList cache

firstChild

protected ChildNode firstChild
First child.

ownerDocument

protected CoreDocumentImpl ownerDocument
Owner document.

Constructor Details

ParentNode

public ParentNode()
Constructor for serialization.

ParentNode

protected ParentNode(CoreDocumentImpl ownerDocument)
No public constructor; only subclasses of ParentNode should be instantiated, and those normally via a Document's factory methods

Method Details

cloneNode

public Node cloneNode(boolean deep)
Returns a duplicate of a given node. You can consider this a generic "copy constructor" for nodes. The newly returned object should be completely independent of the source object's subtree, so changes in one after the clone has been made will not affect the other.

Example: Cloning a Text node will copy both the node and the text it contains.

Example: Cloning something that has children -- Element or Attr, for example -- will _not_ clone those children unless a "deep clone" has been requested. A shallow clone of an Attr node will yield an empty Attr of the same name.

NOTE: Clones will always be read/write, even if the node being cloned is read-only, to permit applications using only the DOM API to obtain editable copies of locked portions of the tree.

Overrides:
cloneNode in interface ChildNode

getChildNodes

public NodeList getChildNodes()
Obtain a NodeList enumerating all children of this node. If there are none, an (initially) empty NodeList is returned.

NodeLists are "live"; as children are added/removed the NodeList will immediately reflect those changes. Also, the NodeList refers to the actual nodes, so changes to those nodes made via the DOM tree will be reflected in the NodeList and vice versa.

In this implementation, Nodes implement the NodeList interface and provide their own getChildNodes() support. Other DOMs may solve this differently.

Overrides:
getChildNodes in interface NodeImpl

getChildNodesUnoptimized

protected final NodeList getChildNodesUnoptimized()
Create a NodeList to access children that is use by subclass elements that have methods named getLength() or item(int). ChildAndParentNode optimizes getChildNodes() by implementing NodeList itself. However if a subclass Element implements methods with the same name as the NodeList methods, they will override the actually methods in this class.

To use this method, the subclass should implement getChildNodes() and have it call this method. The resulting NodeList instance maybe shared and cached in a transient field, but the cached value must be cleared if the node is cloned.


getFirstChild

public Node getFirstChild()
The first child of this Node, or null if none.
Overrides:
getFirstChild in interface NodeImpl

getLastChild

public Node getLastChild()
The last child of this Node, or null if none.
Overrides:
getLastChild in interface NodeImpl

getLength

public int getLength()
NodeList method: Count the immediate children of this node
Overrides:
getLength in interface NodeImpl
Returns:
int

getOwnerDocument

public Document getOwnerDocument()
Find the Document that this Node belongs to (the document in whose context the Node was created). The Node may or may not currently be part of that Document's actual contents.
Overrides:
getOwnerDocument in interface NodeImpl

getTextContent

public String getTextContent()
            throws DOMException
This attribute returns the text content of this node and its descendants. When it is defined to be null, setting it has no effect. When set, any possible children this node may have are removed and replaced by a single Text node containing the string this attribute is set to. On getting, no serialization is performed, the returned string does not contain any markup. No whitespace normalization is performed, the returned string does not contain the element content whitespaces . Similarly, on setting, no parsing is performed either, the input string is taken as pure textual content.
The string returned is made of the text content of this node depending on its type, as defined below: Text
Node typeContent
Node typeContent
ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, DOCUMENT_FRAGMENT_NODEconcatenation of the textContent attribute value of every child node, excluding COMMENT_NODE and PROCESSING_INSTRUCTION_NODE nodes
ATTRIBUTE_NODE, TEXT_NODE, CDATA_SECTION_NODE, COMMENT_NODE, PROCESSING_INSTRUCTION_NODE nodeValue
DOCUMENT_NODE, DOCUMENT_TYPE_NODE, NOTATION_NODE null
Overrides:
getTextContent in interface NodeImpl
Since:
DOM Level 3

hasChildNodes

public boolean hasChildNodes()
Test whether this node has any children. Convenience shorthand for (Node.getFirstChild()!=null)
Overrides:
hasChildNodes in interface NodeImpl

insertBefore

public Node insertBefore(Node newChild,
                         Node refChild)
            throws DOMException
Move one or more node(s) to our list of children. Note that this implicitly removes them from their previous parent.
Overrides:
insertBefore in interface NodeImpl
Parameters:
newChild - The Node to be moved to our subtree. As a convenience feature, inserting a DocumentNode will instead insert all its children.
refChild - Current child which newChild should be placed immediately before. If refChild is null, the insertion occurs after all existing Nodes, like appendChild().
Returns:
newChild, in its new state (relocated, or emptied in the case of DocumentNode.)

isEqualNode

public boolean isEqualNode(Node arg)
DOM Level 3 WD- Experimental. Override inherited behavior from NodeImpl to support deep equal.
Overrides:
isEqualNode in interface NodeImpl

item

public Node item(int index)
NodeList method: Return the Nth immediate child of this node, or null if the index is out of bounds.
Overrides:
item in interface NodeImpl
Parameters:
index - int
Returns:
org.w3c.dom.Node

normalize

public void normalize()
Override default behavior to call normalize() on this Node's children. It is up to implementors or Node to override normalize() to take action.
Overrides:
normalize in interface NodeImpl

removeChild

public Node removeChild(Node oldChild)
            throws DOMException
Remove a child from this Node. The removed child's subtree remains intact so it may be re-inserted elsewhere.
Overrides:
removeChild in interface NodeImpl
Returns:
oldChild, in its new state (removed).

replaceChild

public Node replaceChild(Node newChild,
                         Node oldChild)
            throws DOMException
Make newChild occupy the location that oldChild used to have. Note that newChild will first be removed from its previous parent, if any. Equivalent to inserting newChild before oldChild, then removing oldChild.
Overrides:
replaceChild in interface NodeImpl
Returns:
oldChild, in its new state (removed).

setReadOnly

public void setReadOnly(boolean readOnly,
                        boolean deep)
Override default behavior so that if deep is true, children are also toggled.
Overrides:
setReadOnly in interface NodeImpl
See Also:

Note: this will not change the state of an EntityReference or its children, which are always read-only.


setTextContent

public void setTextContent(String textContent)
            throws DOMException
This attribute returns the text content of this node and its descendants. When it is defined to be null, setting it has no effect. When set, any possible children this node may have are removed and replaced by a single Text node containing the string this attribute is set to. On getting, no serialization is performed, the returned string does not contain any markup. No whitespace normalization is performed, the returned string does not contain the element content whitespaces . Similarly, on setting, no parsing is performed either, the input string is taken as pure textual content.
The string returned is made of the text content of this node depending on its type, as defined below:
Node typeContent
ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, DOCUMENT_FRAGMENT_NODEconcatenation of the textContent attribute value of every child node, excluding COMMENT_NODE and PROCESSING_INSTRUCTION_NODE nodes
ATTRIBUTE_NODE, TEXT_NODE, CDATA_SECTION_NODE, COMMENT_NODE, PROCESSING_INSTRUCTION_NODE nodeValue
DOCUMENT_NODE, DOCUMENT_TYPE_NODE, NOTATION_NODE null
Overrides:
setTextContent in interface NodeImpl
Since:
DOM Level 3

synchronizeChildren

protected void synchronizeChildren()
Override this method in subclass to hook in efficient internal data structure.

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