org.apache.xerces.dom
public class AttrImpl extends NodeImpl implements Attr, TypeInfo
If the attribute has not been explicitly assigned a value, but has been declared in the DTD, it will exist and have that default. Only if neither the document nor the DTD specifies a value will the Attribute really be considered absent and have no value; in that case, querying the attribute will return null.
Attributes may have multiple children that contain their data. (XML allows attributes to contain entity references, and tokenized attribute types such as NMTOKENS may have a child for each token.) For convenience, the Attribute object's getValue() method returns the string version of the attribute's value.
Attributes are not children of the Elements they belong to, in the usual sense, and have no valid Parent reference. However, the spec says they _do_ belong to a specific Element, and an INUSE exception is to be thrown if the user attempts to explicitly share them between elements.
Note that Elements do not permit attributes to appear to be shared (see the INUSE exception), so this object's mutability is officially not an issue.
Note: The ownerNode attribute is used to store the Element the Attr node is associated with. Attr nodes do not have parent nodes. Besides, the getOwnerElement() method can be used to get the element node this attribute is associated with.
AttrImpl does not support Namespaces. AttrNSImpl, which inherits from it, does.
AttrImpl used to inherit from ParentNode. It now directly inherits from NodeImpl and provide its own implementation of the ParentNode's behavior. The reason is that we now try and avoid to always create a Text node to hold the value of an attribute. The DOM spec requires it, so we still have to do it in case getFirstChild() is called for instance. The reason attribute values are stored as a list of nodes is so that they can carry more than a simple string. They can also contain EntityReference nodes. However, most of the times people only have a single string that they only set and get through Element.set/getAttribute or Attr.set/getValue. In this new version, the Attr node has a value pointer which can either be the String directly or a pointer to the first ChildNode. A flag tells which one it currently is. Note that while we try to stick with the direct String as much as possible once we've switched to a node there is no going back. This is because we have no way to know whether the application keeps referring to the node we once returned.
The gain in memory varies on the density of attributes in the document. But in the tests I've run I've seen up to 12% of memory gain. And the good thing is that it also leads to a slight gain in speed because we allocate fewer objects! I mean, that's until we have to actually create the node...
To avoid too much duplicated code, I got rid of ParentNode and renamed ChildAndParentNode, which I never really liked, to ParentNode for simplicity, this doesn't make much of a difference in memory usage because there are only very few objects that are only a Parent. This is only true now because AttrImpl now inherits directly from NodeImpl and has its own implementation of the ParentNode's node behavior. So there is still some duplicated code there.
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 ParentNode, be careful to keep these two classes in sync!
Since: PR-DOM-Level-1-19980818.
Version: $Id: AttrImpl.java,v 1.64 2005/05/02 22:02:22 mrglavas Exp $
Field Summary | |
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protected String | name Attribute name. |
protected static TextImpl | textNode |
protected Object | value This can either be a String or the first child node. |
Constructor Summary | |
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protected | AttrImpl(CoreDocumentImpl ownerDocument, String name)
Attribute has no public constructor. |
protected | AttrImpl() False for default attributes. |
Method Summary | |
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Node | cloneNode(boolean deep) |
NodeList | getChildNodes()
Obtain a NodeList enumerating all children of this node. |
Element | getElement()
Returns the element node that this attribute is associated with,
or null if the attribute has not been added to an element.
|
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 |
String | getName()
In Attributes, NodeName is considered a synonym for the
attribute's Name |
String | getNodeName()
Returns the attribute name |
short | getNodeType()
A short integer indicating what type of node this is. |
String | getNodeValue()
In Attribute objects, NodeValue is considered a synonym for
Value.
|
Element | getOwnerElement()
Returns the element node that this attribute is associated with,
or null if the attribute has not been added to an element.
|
TypeInfo | getSchemaTypeInfo()
Method getSchemaTypeInfo. |
boolean | getSpecified()
The "specified" flag is true if and only if this attribute's
value was explicitly specified in the original document. |
String | getTypeName() |
String | getTypeNamespace() |
String | getValue()
The "string value" of an Attribute is its text representation,
which in turn is a concatenation of the string values of its children. |
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 | isDerivedFrom(String typeNamespaceArg, String typeNameArg, int derivationMethod)
Introduced in DOM Level 3. |
boolean | isEqualNode(Node arg)
DOM Level 3 WD- Experimental.
|
boolean | isId() DOM Level 3: isId |
Node | item(int index)
NodeList method: Return the Nth immediate child of this node, or
null if the index is out of bounds. |
protected void | makeChildNode() |
void | normalize() |
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 | setIdAttribute(boolean id)
NON-DOM: set the type of this attribute to be ID type.
|
void | setNodeValue(String value)
Implicit in the rerouting of getNodeValue to getValue is the
need to redefine setNodeValue, for symmetry's sake. |
void | setReadOnly(boolean readOnly, boolean deep)
Override default behavior so that if deep is true, children are also
toggled. |
void | setSpecified(boolean arg) NON-DOM, for use by parser |
void | setType(Object type)
NON-DOM: used by the parser |
void | setValue(String newvalue)
The DOM doesn't clearly define what setValue(null) means. |
protected void | synchronizeChildren()
Override this method in subclass to hook in efficient
internal data structure. |
String | toString() NON-DOM method for debugging convenience |
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.
Deprecated: Previous working draft of DOM Level 2. New method is getOwnerElement().
Returns the element node that this attribute is associated with, or null if the attribute has not been added to an element.See Also: AttrImpl
Returns: int
See Also: getValue
Since: WD-DOM-Level-2-19990719
Returns: TypeInfo
See Also: org.w3c.dom.TypeInfo#getTypeName()
See Also: org.w3c.dom.TypeInfo#getTypeNamespace()
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.)
Throws: DOMException(HIERARCHY_REQUEST_ERR) if newChild is of a type that shouldn't be a child of this node, or if newChild is an ancestor of this node. DOMException(WRONG_DOCUMENT_ERR) if newChild has a different owner document than we do. DOMException(NOT_FOUND_ERR) if refChild is not a child of this node. DOMException(NO_MODIFICATION_ALLOWED_ERR) if this node is read-only.
Checks if a type is derived from another by restriction. See: http://www.w3.org/TR/DOM-Level-3-Core/core.html#TypeInfo-isDerivedFrom
Parameters: ancestorNS The namspace of the ancestor type declaration ancestorName The name of the ancestor type declaration type The reference type definition
Returns: boolean True if the type is derived by restriciton for the reference type
Parameters: Index int
Returns: org.w3c.dom.Node
Returns: oldChild, in its new state (removed).
Throws: DOMException(NOT_FOUND_ERR) if oldChild is not a child of this node. DOMException(NO_MODIFICATION_ALLOWED_ERR) if this node is read-only.
Returns: oldChild, in its new state (removed).
Throws: DOMException(HIERARCHY_REQUEST_ERR) if newChild is of a type that shouldn't be a child of this node, or if newChild is one of our ancestors. DOMException(WRONG_DOCUMENT_ERR) if newChild has a different owner document than we do. DOMException(NOT_FOUND_ERR) if oldChild is not a child of this node. DOMException(NO_MODIFICATION_ALLOWED_ERR) if this node is read-only.
Parameters: id
See Also:
Note: this will not change the state of an EntityReference or its
children, which are always read-only.Node
Parameters: type