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org.apache.xerces.dom
public class: AttrImpl [javadoc | source]
java.lang.Object
   org.apache.xerces.dom.NodeImpl
      org.apache.xerces.dom.AttrImpl

All Implemented Interfaces:
    TypeInfo, Attr, Cloneable, Node, EventTarget, Serializable, NodeList

Direct Known Subclasses:
    DeferredAttrNSImpl, DeferredAttrImpl, AttrNSImpl, PSVIAttrNSImpl

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!

Field Summary
static final  long serialVersionUID    Serialization version. 
static final  String DTD_URI    DTD namespace. 
protected  Object value    This can either be a String or the first child node. 
protected  String name    Attribute name. 
transient  Object type    Type information 
protected static  TextImpl textNode     
Fields inherited from org.apache.xerces.dom.NodeImpl:
TREE_POSITION_PRECEDING,  TREE_POSITION_FOLLOWING,  TREE_POSITION_ANCESTOR,  TREE_POSITION_DESCENDANT,  TREE_POSITION_EQUIVALENT,  TREE_POSITION_SAME_NODE,  TREE_POSITION_DISCONNECTED,  DOCUMENT_POSITION_DISCONNECTED,  DOCUMENT_POSITION_PRECEDING,  DOCUMENT_POSITION_FOLLOWING,  DOCUMENT_POSITION_CONTAINS,  DOCUMENT_POSITION_IS_CONTAINED,  DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC,  serialVersionUID,  ELEMENT_DEFINITION_NODE,  ownerNode,  flags,  READONLY,  SYNCDATA,  SYNCCHILDREN,  OWNED,  FIRSTCHILD,  SPECIFIED,  IGNORABLEWS,  HASSTRING,  NORMALIZED,  ID
Constructor:
 protected AttrImpl() 
 protected AttrImpl(CoreDocumentImpl ownerDocument,
    String name) 
    Attribute has no public constructor. Please use the factory method in the Document class.
Method from org.apache.xerces.dom.AttrImpl Summary:
checkNormalizationAfterInsert,   checkNormalizationAfterRemove,   cloneNode,   getChildNodes,   getElement,   getFirstChild,   getLastChild,   getLength,   getName,   getNodeName,   getNodeType,   getNodeValue,   getOwnerElement,   getSchemaTypeInfo,   getSpecified,   getTypeName,   getTypeNamespace,   getValue,   hasChildNodes,   insertBefore,   internalInsertBefore,   internalRemoveChild,   isDerivedFrom,   isEqualNode,   isId,   item,   lastChild,   lastChild,   makeChildNode,   normalize,   removeChild,   rename,   replaceChild,   setIdAttribute,   setNodeValue,   setOwnerDocument,   setReadOnly,   setSpecified,   setType,   setValue,   synchronizeChildren,   toString
Methods from org.apache.xerces.dom.NodeImpl:
addEventListener,   appendChild,   changed,   changes,   cloneNode,   compareDocumentPosition,   compareTreePosition,   dispatchEvent,   getAttributes,   getBaseURI,   getChildNodes,   getContainer,   getElementAncestor,   getFeature,   getFirstChild,   getLastChild,   getLength,   getLocalName,   getNamespaceURI,   getNextSibling,   getNodeName,   getNodeNumber,   getNodeType,   getNodeValue,   getOwnerDocument,   getParentNode,   getPrefix,   getPreviousSibling,   getReadOnly,   getTextContent,   getTextContent,   getUserData,   getUserData,   getUserDataRecord,   hasAttributes,   hasChildNodes,   hasStringValue,   hasStringValue,   insertBefore,   internalIsIgnorableWhitespace,   isDefaultNamespace,   isEqualNode,   isFirstChild,   isFirstChild,   isIdAttribute,   isIdAttribute,   isIgnorableWhitespace,   isNormalized,   isNormalized,   isOwned,   isOwned,   isReadOnly,   isReadOnly,   isSameNode,   isSpecified,   isSpecified,   isSupported,   item,   lookupNamespacePrefix,   lookupNamespaceURI,   lookupPrefix,   needsSyncChildren,   needsSyncChildren,   needsSyncData,   needsSyncData,   normalize,   ownerDocument,   parentNode,   previousSibling,   removeChild,   removeEventListener,   replaceChild,   setNodeValue,   setOwnerDocument,   setPrefix,   setReadOnly,   setTextContent,   setUserData,   setUserData,   synchronizeData,   toString
Methods from java.lang.Object:
equals,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from org.apache.xerces.dom.AttrImpl Detail:
  void checkNormalizationAfterInsert(ChildNode insertedChild) 
    Checks the normalized state of this node after inserting a child. If the inserted child causes this node to be unnormalized, then this node is flagged accordingly. The conditions for changing the normalized state are:
    • The inserted child is a text node and one of its adjacent siblings is also a text node.
    • The inserted child is is itself unnormalized.
  void checkNormalizationAfterRemove(ChildNode previousSibling) 
    Checks the normalized of this node after removing a child. If the removed child causes this node to be unnormalized, then this node is flagged accordingly. The conditions for changing the normalized state are:
    • The removed child had two adjacent siblings that were text nodes.
 public Node cloneNode(boolean deep) 
 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() 
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.
 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
 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.
 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.
 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() 
 public String getTypeNamespace() 
 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) throws DOMException 
    Move one or more node(s) to our list of children. Note that this implicitly removes them from their previous parent.
 Node internalInsertBefore(Node newChild,
    Node refChild,
    boolean replace) throws DOMException 
    NON-DOM INTERNAL: Within DOM actions,we sometimes need to be able to control which mutation events are spawned. This version of the insertBefore operation allows us to do so. It is not intended for use by application programs.
 Node internalRemoveChild(Node oldChild,
    boolean replace) throws DOMException 
    NON-DOM INTERNAL: Within DOM actions,we sometimes need to be able to control which mutation events are spawned. This version of the removeChild operation allows us to do so. It is not intended for use by application programs.
 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

 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.
 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.
 final ChildNode lastChild() 
 final  void lastChild(ChildNode node) 
 protected  void makeChildNode() 
 public  void normalize() 
 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.
  void rename(String name) 
 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.
 public  void setIdAttribute(boolean id) 
    NON-DOM: set the type of this attribute to be ID type.
 public  void setNodeValue(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.
 protected  void setOwnerDocument(CoreDocumentImpl doc) 
    NON-DOM set the ownerDocument of this node and its children
 public  void setReadOnly(boolean readOnly,
    boolean deep) 
    Override default behavior so that if deep is true, children are also toggled.
 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.
 protected  void synchronizeChildren() 
    Override this method in subclass to hook in efficient internal data structure.
 public String toString() 
    NON-DOM method for debugging convenience