org.apache.xerces.dom
Class AttrImpl

java.lang.Object
  org.apache.xerces.dom.NodeImpl
      org.apache.xerces.dom.AttrImpl

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, Attr, EventTarget, Node, NodeList, TypeInfo

Direct Known Subclasses:

AttrNSImpl, DeferredAttrImpl

public class AttrImpl
extends NodeImpl
implements Attr, TypeInfo

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!

Since:

PR-DOM-Level-1-19980818.

Version:

$Id: AttrImpl.java 449328 2006-09-23 22:58:23Z mrglavas $

Author:

Arnaud Le Hors, IBM, Joe Kesselman, IBM, Andy Clark, IBM

See Also:

AttrNSImpl, Serialized Form

Field Summary

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, TREE_POSITION_ANCESTOR, TREE_POSITION_DESCENDANT, TREE_POSITION_DISCONNECTED, TREE_POSITION_EQUIVALENT, TREE_POSITION_FOLLOWING, TREE_POSITION_PRECEDING, TREE_POSITION_SAME_NODE

Fields inherited from interface org.w3c.dom.Node

ATTRIBUTE_NODE, CDATA_SECTION_NODE, COMMENT_NODE, DOCUMENT_FRAGMENT_NODE, DOCUMENT_NODE, DOCUMENT_POSITION_CONTAINED_BY, DOCUMENT_POSITION_CONTAINS, DOCUMENT_POSITION_DISCONNECTED, DOCUMENT_POSITION_FOLLOWING, DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC, DOCUMENT_POSITION_PRECEDING, DOCUMENT_TYPE_NODE, ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, NOTATION_NODE, PROCESSING_INSTRUCTION_NODE, TEXT_NODE

Fields inherited from interface org.w3c.dom.TypeInfo

DERIVATION_EXTENSION, DERIVATION_LIST, DERIVATION_RESTRICTION, DERIVATION_UNION

Method Summary

Node	cloneNode(boolean deep) Returns a duplicate of a given node.
NodeList	getChildNodes() Obtain a NodeList enumerating all children of this node.
Element	getElement() 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
java.lang.String	getName() In Attributes, NodeName is considered a synonym for the attribute's Name
java.lang.String	getNodeName() Returns the attribute name
short	getNodeType() A short integer indicating what type of node this is.
java.lang.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.
java.lang.String	getTypeName() The name of a type declared for the associated element or attribute, or null if unknown.
java.lang.String	getTypeNamespace() The namespace of the type declared for the associated element or attribute or null if the element does not have declaration or if no namespace information is available.
java.lang.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(java.lang.String typeNamespaceArg, java.lang.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(java.lang.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(java.lang.Object type) NON-DOM: used by the parser
void	setValue(java.lang.String newvalue) The DOM doesn't clearly define what setValue(null) means.
java.lang.String	toString() NON-DOM method for debugging convenience

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

addEventListener, appendChild, compareDocumentPosition, compareTreePosition, dispatchEvent, getAttributes, getBaseURI, getFeature, getLocalName, getNamespaceURI, getNextSibling, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getReadOnly, getTextContent, getUserData, getUserData, hasAttributes, isDefaultNamespace, isSameNode, isSupported, lookupNamespaceURI, lookupPrefix, needsSyncChildren, removeEventListener, setPrefix, setTextContent, setUserData, setUserData

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.w3c.dom.Node

appendChild, compareDocumentPosition, getAttributes, getBaseURI, getFeature, getLocalName, getNamespaceURI, getNextSibling, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, getTextContent, getUserData, hasAttributes, isDefaultNamespace, isSameNode, isSupported, lookupNamespaceURI, lookupPrefix, setPrefix, setTextContent, setUserData

Method Detail

setIdAttribute

public void setIdAttribute(boolean id)

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

Parameters:

id -

isId

public boolean isId()

DOM Level 3: isId

Specified by:

isId in interface Attr

cloneNode

public Node cloneNode(boolean deep)

Description copied from class: NodeImpl

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.

Specified by:

cloneNode in interface Node

Overrides:

cloneNode in class NodeImpl

Parameters:

deep - If true, recursively clone the subtree under the specified node; if false, clone only the node itself (and its attributes, if it is an Element).

Returns:

The duplicate node.

See Also:

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.

getNodeType

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.

Specified by:

getNodeType in interface Node

Specified by:

getNodeType in class NodeImpl

getNodeName

public java.lang.String getNodeName()

Returns the attribute name

Specified by:

getNodeName in interface Node

Specified by:

getNodeName in class NodeImpl

setNodeValue

public void setNodeValue(java.lang.String value)
                  throws DOMException

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.

Specified by:

setNodeValue in interface Node

Overrides:

setNodeValue in class NodeImpl

Throws:

DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly and if it is not defined to be null.

getTypeName

public java.lang.String getTypeName()

Description copied from interface: TypeInfo

The name of a type declared for the associated element or attribute, or null if unknown.

Specified by:

getTypeName in interface TypeInfo

See Also:

TypeInfo.getTypeName()

getTypeNamespace

public java.lang.String getTypeNamespace()

Description copied from interface: TypeInfo

The namespace of the type declared for the associated element or attribute or null if the element does not have declaration or if no namespace information is available.

Specified by:

getTypeNamespace in interface TypeInfo

See Also:

TypeInfo.getTypeNamespace()

getSchemaTypeInfo

public TypeInfo getSchemaTypeInfo()

Method getSchemaTypeInfo.

Specified by:

getSchemaTypeInfo in interface Attr

Returns:

TypeInfo

getNodeValue

public java.lang.String getNodeValue()

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

Specified by:

getNodeValue in interface Node

Overrides:

getNodeValue in class NodeImpl

See Also:

getValue()

getName

public java.lang.String getName()

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

Specified by:

getName in interface Attr

setValue

public void setValue(java.lang.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.

Specified by:

setValue in interface Attr

getValue

public java.lang.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.

Specified by:

getValue in interface Attr

getSpecified

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.

Specified by:

getSpecified in interface Attr

getElement

public Element getElement()

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:

getOwnerElement()

getOwnerElement

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.

Specified by:

getOwnerElement in interface Attr

Since:

WD-DOM-Level-2-19990719

normalize

public void normalize()

Description copied from class: NodeImpl

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.

Specified by:

normalize in interface Node

Overrides:

normalize in class NodeImpl

setSpecified

public void setSpecified(boolean arg)

NON-DOM, for use by parser

setType

public void setType(java.lang.Object type)

NON-DOM: used by the parser

Parameters:

type -

toString

public java.lang.String toString()

NON-DOM method for debugging convenience

Overrides:

toString in class NodeImpl

hasChildNodes

public boolean hasChildNodes()

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

Specified by:

hasChildNodes in interface Node

Overrides:

hasChildNodes in class NodeImpl

Returns:

Returns true if this node has any children, false otherwise.

See Also:

ParentNode

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.

Specified by:

getChildNodes in interface Node

Overrides:

getChildNodes in class NodeImpl

getFirstChild

public Node getFirstChild()

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

Specified by:

getFirstChild in interface Node

Overrides:

getFirstChild in class NodeImpl

See Also:

ParentNode

getLastChild

public Node getLastChild()

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

Specified by:

getLastChild in interface Node

Overrides:

getLastChild in class NodeImpl

See Also:

ParentNode

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.

Specified by:

insertBefore in interface Node

Overrides:

insertBefore in class 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.)

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.

DOMException - HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to insert is one of this node's ancestors or this node itself, or if this node is of type Document and the DOM application attempts to insert a second DocumentType or Element node.
WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly or if the parent of the node being inserted is readonly.
NOT_FOUND_ERR: Raised if refChild is not a child of this node.
NOT_SUPPORTED_ERR: if this node is of type Document, this exception might be raised if the DOM implementation doesn't support the insertion of a DocumentType or Element node.

See Also:

ParentNode

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.

Specified by:

removeChild in interface Node

Overrides:

removeChild in class NodeImpl

Parameters:

oldChild - The node being removed.

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.

DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
NOT_FOUND_ERR: Raised if oldChild is not a child of this node.
NOT_SUPPORTED_ERR: if this node is of type Document, this exception might be raised if the DOM implementation doesn't support the removal of the DocumentType child or the Element child.

See Also:

ParentNode

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.

Specified by:

replaceChild in interface Node

Overrides:

replaceChild in class NodeImpl

Parameters:

newChild - The new node to put in the child list.

oldChild - The node being replaced in the list.

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.

DOMException - HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to put in is one of this node's ancestors or this node itself, or if this node is of type Document and the result of the replacement operation would add a second DocumentType or Element on the Document node.
WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.
NO_MODIFICATION_ALLOWED_ERR: Raised if this node or the parent of the new node is readonly.
NOT_FOUND_ERR: Raised if oldChild is not a child of this node.
NOT_SUPPORTED_ERR: if this node is of type Document, this exception might be raised if the DOM implementation doesn't support the replacement of the DocumentType child or Element child.

See Also:

ParentNode

getLength

public int getLength()

NodeList method: Count the immediate children of this node

Specified by:

getLength in interface NodeList

Overrides:

getLength in class NodeImpl

Returns:

int

See Also:

ParentNode

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.

Specified by:

item in interface NodeList

Overrides:

item in class NodeImpl

Parameters:

index - int

Returns:

org.w3c.dom.Node

See Also:

ParentNode

isEqualNode

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.

Specified by:

isEqualNode in interface Node

Overrides:

isEqualNode in class NodeImpl

Parameters:

arg - The node to compare equality with.

Returns:

If the nodes, and possibly subtrees are equal, true otherwise false.

isDerivedFrom

public boolean isDerivedFrom(java.lang.String typeNamespaceArg,
                             java.lang.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

Specified by:

isDerivedFrom in interface TypeInfo

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

setReadOnly

public void setReadOnly(boolean readOnly,
                        boolean deep)

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

Overrides:

setReadOnly in class NodeImpl

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:

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