public class

AttrImpl

extends NodeImpl
implements Attr TypeInfo
java.lang.Object
   ↳ org.apache.xerces.dom.NodeImpl
     ↳ org.apache.xerces.dom.AttrImpl
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

Attribute represents an XML-style attribute of an Element. Typically, the allowable values are controlled by its declaration in the Document Type Definition (DTD) governing this kind of document.

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!@xerces.internal

See Also

Summary

[Expand]
Inherited Constants
From class org.apache.xerces.dom.NodeImpl
From interface org.w3c.dom.Node
From interface org.w3c.dom.TypeInfo
Fields
protected String name Attribute name.
protected static TextImpl textNode
protected Object value This can either be a String or the first child node.
[Expand]
Inherited Fields
From class org.apache.xerces.dom.NodeImpl
Protected Constructors
AttrImpl(CoreDocumentImpl ownerDocument, String name)
Attribute has no public constructor.
AttrImpl()
Public Methods
Node cloneNode(boolean deep)
Returns a duplicate of a given node.
NodeList getChildNodes()
Obtain a NodeList enumerating all children of this node.
Element getElement()
This method is deprecated. Previous working draft of DOM Level 2. New method is getOwnerElement().
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.
void normalize()
Puts all Text nodes in the full depth of the sub-tree underneath this Node, including attribute nodes, into a "normal" form where only markup (e.g., tags, comments, processing instructions, CDATA sections, and entity references) separates Text nodes, i.e., there are no adjacent Text nodes.
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.
String toString()
NON-DOM method for debugging convenience
Protected Methods
void makeChildNode()
void setOwnerDocument(CoreDocumentImpl doc)
NON-DOM set the ownerDocument of this node and its children
void synchronizeChildren()
Override this method in subclass to hook in efficient internal data structure.
[Expand]
Inherited Methods
From class org.apache.xerces.dom.NodeImpl
From class java.lang.Object
From interface org.w3c.dom.Attr
From interface org.w3c.dom.Node
From interface org.w3c.dom.NodeList
From interface org.w3c.dom.TypeInfo
From interface org.w3c.dom.events.EventTarget

Fields

protected String name

Attribute name.

protected static TextImpl textNode

protected Object value

This can either be a String or the first child node.

Protected Constructors

protected AttrImpl (CoreDocumentImpl ownerDocument, String name)

Attribute has no public constructor. Please use the factory method in the Document class.

protected AttrImpl ()

Public Methods

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.

Note: since we never have any children deep is meaningless here, ParentNode overrides this behavior.

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.

public Element getElement ()

This method is 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

public Node getFirstChild ()

The first child of this Node, or null if none.

public Node getLastChild ()

The last child of this Node, or null if none.

public int getLength ()

NodeList method: Count the immediate children of this node

Returns
  • int

public String getName ()

In Attributes, NodeName is considered a synonym for the attribute's Name

public String getNodeName ()

Returns the attribute name

public short getNodeType ()

A short integer indicating what type of node this is. The named constants for this value are defined in the org.w3c.dom.Node interface.

public String getNodeValue ()

In Attribute objects, NodeValue is considered a synonym for Value.

See Also

public Element getOwnerElement ()

Returns the element node that this attribute is associated with, or null if the attribute has not been added to an element.

public TypeInfo getSchemaTypeInfo ()

Method getSchemaTypeInfo.

Returns
  • TypeInfo

public boolean getSpecified ()

The "specified" flag is true if and only if this attribute's value was explicitly specified in the original document. Note that the implementation, not the user, is in charge of this property. If the user asserts an Attribute value (even if it ends up having the same value as the default), it is considered a specified attribute. If you really want to revert to the default, delete the attribute from the Element, and the Implementation will re-assert the default (if any) in its place, with the appropriate specified=false setting.

public String getTypeName ()

See Also

public String getTypeNamespace ()

See Also

public 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.

public boolean hasChildNodes ()

Test whether this node has any children. Convenience shorthand for (Node.getFirstChild()!=null)

public Node insertBefore (Node newChild, Node refChild)

Move one or more node(s) to our list of children. Note that this implicitly removes them from their previous parent.

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
if newChild is of a type that shouldn't be a child of this node, or if newChild is an ancestor of this node.
if newChild has a different owner document than we do.
if refChild is not a child of this node.
if this node is read-only.
DOMException

public boolean isDerivedFrom (String typeNamespaceArg, String typeNameArg, int derivationMethod)

Introduced in DOM Level 3.

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
typeNamespaceArg The namspace of the ancestor type declaration
typeNameArg The name of the ancestor type declaration
derivationMethod The derivation method
Returns
  • boolean True if the type is derived by restriciton for the reference type

public boolean isEqualNode (Node arg)

DOM Level 3 WD- Experimental. Override inherited behavior from ParentNode to support deep equal. isEqualNode is always deep on Attr nodes.

Parameters
arg The node to compare equality with.
Returns
  • If the nodes, and possibly subtrees are equal, true otherwise false.

public boolean isId ()

DOM Level 3: isId

public Node item (int index)

NodeList method: Return the Nth immediate child of this node, or null if the index is out of bounds.

Parameters
index int
Returns
  • org.w3c.dom.Node

public void normalize ()

Puts all Text nodes in the full depth of the sub-tree underneath this Node, including attribute nodes, into a "normal" form where only markup (e.g., tags, comments, processing instructions, CDATA sections, and entity references) separates Text nodes, i.e., there are no adjacent Text nodes. This can be used to ensure that the DOM view of a document is the same as if it were saved and re-loaded, and is useful when operations (such as XPointer lookups) that depend on a particular document tree structure are to be used.In cases where the document contains CDATASections, the normalize operation alone may not be sufficient, since XPointers do not differentiate between Text nodes and CDATASection nodes.

Note that this implementation simply calls normalize() on this Node's children. It is up to implementors or Node to override normalize() to take action.

public Node removeChild (Node oldChild)

Remove a child from this Node. The removed child's subtree remains intact so it may be re-inserted elsewhere.

Returns
  • oldChild, in its new state (removed).
Throws
if oldChild is not a child of this node.
if this node is read-only.
DOMException

public Node replaceChild (Node newChild, Node oldChild)

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.

Returns
  • oldChild, in its new state (removed).
Throws
if newChild is of a type that shouldn't be a child of this node, or if newChild is one of our ancestors.
if newChild has a different owner document than we do.
if oldChild is not a child of this node.
if this node is read-only.
DOMException

public void setIdAttribute (boolean id)

NON-DOM: set the type of this attribute to be ID type.

public void setNodeValue (String value)

Implicit in the rerouting of getNodeValue to getValue is the need to redefine setNodeValue, for symmetry's sake. Note that since we're explicitly providing a value, Specified should be set true.... even if that value equals the default.

Throws
DOMException

public void setReadOnly (boolean readOnly, boolean deep)

Override default behavior so that if deep is true, children are also toggled.

Parameters
readOnly True or false as desired.
deep If true, children are also toggled. Note that this will not change the state of an EntityReference or its children, which are always read-only.
See Also
  • Node

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

public void setSpecified (boolean arg)

NON-DOM, for use by parser

public void setType (Object type)

NON-DOM: used by the parser

public void setValue (String newvalue)

The DOM doesn't clearly define what setValue(null) means. I've taken it as "remove all children", which from outside should appear similar to setting it to the empty string.

public String toString ()

NON-DOM method for debugging convenience

Protected Methods

protected void makeChildNode ()

protected void setOwnerDocument (CoreDocumentImpl doc)

NON-DOM set the ownerDocument of this node and its children

protected void synchronizeChildren ()

Override this method in subclass to hook in efficient internal data structure.