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java.lang.Object
|
+--org.apache.xerces.dom.NodeImpl
|
+--org.apache.xerces.dom.AttrImpl
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!
AttrNSImpl, Serialized Form| Field Summary | |
protected java.lang.String |
name
Attribute name. |
protected static TextImpl |
textNode
|
protected java.lang.Object |
value
This can either be a String or the first child node. |
| Fields inherited from class org.apache.xerces.dom.NodeImpl |
ELEMENT_DEFINITION_NODE,
FIRSTCHILD,
flags,
HASSTRING,
IGNORABLEWS,
OWNED,
ownerNode,
READONLY,
SPECIFIED,
SYNCCHILDREN,
SYNCDATA,
UNNORMALIZED |
| Fields inherited from interface org.w3c.dom.Node |
ATTRIBUTE_NODE,
CDATA_SECTION_NODE,
COMMENT_NODE,
DOCUMENT_FRAGMENT_NODE,
DOCUMENT_NODE,
DOCUMENT_TYPE_NODE,
ELEMENT_NODE,
ENTITY_NODE,
ENTITY_REFERENCE_NODE,
NOTATION_NODE,
PROCESSING_INSTRUCTION_NODE,
TEXT_NODE |
| Constructor Summary | |
protected |
AttrImpl()
|
protected |
AttrImpl(CoreDocumentImpl ownerDocument,
java.lang.String name)
Attribute has no public constructor. |
| Method Summary | |
Node |
cloneNode(boolean deep)
Returns a duplicate of this node, i.e., serves as a generic copy constructor for nodes. |
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. |
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 |
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. |
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()
Puts all Text nodes in the full depth of the sub-tree
underneath this Node, including attribute nodes, into a
"normal" form where only structure (e.g., elements, comments,
processing instructions, CDATA sections, and entity references)
separates Text nodes, i.e., there are neither adjacent
Text nodes nor empty 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 |
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 |
setValue(java.lang.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. |
java.lang.String |
toString()
NON-DOM method for debugging convenience |
| Methods inherited from class org.apache.xerces.dom.NodeImpl |
addEventListener,
appendChild,
changed,
changes,
dispatchEvent,
getAttributes,
getLocalName,
getNamespaceURI,
getNextSibling,
getOwnerDocument,
getParentNode,
getPrefix,
getPreviousSibling,
getReadOnly,
getUserData,
hasAttributes,
isSupported,
removeEventListener,
setPrefix,
setUserData,
synchronizeData |
| Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
wait,
wait,
wait |
| Field Detail |
protected java.lang.Object value
protected java.lang.String name
protected static TextImpl textNode
| Constructor Detail |
protected AttrImpl(CoreDocumentImpl ownerDocument,
java.lang.String name)
protected AttrImpl()
| Method Detail |
protected void makeChildNode()
public Node cloneNode(boolean deep)
parentNode is null.).
Element copies all attributes and their
values, including those generated by the XML processor to represent
defaulted attributes, but this method does not copy any text it
contains unless it is a deep clone, since the text is contained in a
child Text node. Cloning an Attribute
directly, as opposed to be cloned as part of an Element
cloning operation, returns a specified attribute (
specified is true). Cloning any other type
of node simply returns a copy of this node.
EntityReference clone are readonly
. In addition, clones of unspecified Attr nodes are
specified. And, cloning Document,
DocumentType, Entity, and
Notation nodes is implementation dependent.deepIf - true, recursively clone the subtree under
the specified node; if false, clone only the node
itself (and its attributes, if it is an Element).public short getNodeType()
public java.lang.String getNodeName()
public void setNodeValue(java.lang.String value)
throws DOMException
public java.lang.String getNodeValue()
getValue()public java.lang.String getName()
public void setValue(java.lang.String newvalue)
public java.lang.String getValue()
public boolean getSpecified()
public Element getElement()
getOwnerElement()public Element getOwnerElement()
public void normalize()
Text nodes in the full depth of the sub-tree
underneath this Node, including attribute nodes, into a
"normal" form where only structure (e.g., elements, comments,
processing instructions, CDATA sections, and entity references)
separates Text nodes, i.e., there are neither adjacent
Text nodes nor empty 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.public void setSpecified(boolean arg)
public java.lang.String toString()
public boolean hasChildNodes()
true if this node has any children,
false otherwise.public NodeList getChildNodes()
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 Node getFirstChild()
ParentNodepublic Node getLastChild()
ParentNode
public Node insertBefore(Node newChild,
Node refChild)
throws DOMException
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().
public Node removeChild(Node oldChild)
throws DOMException
public Node replaceChild(Node newChild,
Node oldChild)
throws DOMException
public int getLength()
public Node item(int index)
Index - int
public void setReadOnly(boolean readOnly,
boolean deep)
Note: this will not change the state of an EntityReference or its
children, which are always read-only.
protected void synchronizeChildren()
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