Module org.htmlunit.cyberneko
Package org.htmlunit.cyberneko.xerces.dom

Class EntityReferenceImpl

java.lang.Object
org.htmlunit.cyberneko.xerces.dom.NodeImpl
org.htmlunit.cyberneko.xerces.dom.ChildNode
org.htmlunit.cyberneko.xerces.dom.ParentNode
org.htmlunit.cyberneko.xerces.dom.EntityReferenceImpl
All Implemented Interfaces:
Cloneable, EntityReference, EventTarget, Node, NodeList
public class EntityReferenceImpl extends ParentNode implements EntityReference
EntityReference models the XML &entityname; syntax, when used for entities defined by the DOM. Entities hardcoded into XML, such as character entities, should instead have been translated into text by the code which generated the DOM tree.

An XML processor has the alternative of fully expanding Entities into the normal document tree. If it does so, no EntityReference nodes will appear.

Similarly, non-validating XML processors are not required to read or process entity declarations made in the external subset or declared in external parameter entities. Hence, some applications may not make the replacement value available for Parsed Entities of these types.

EntityReference behaves as a read-only node, and the children of the EntityReference (which reflect those of the Entity, and should also be read-only) give its replacement value, if any. They are supposed to automagically stay in synch if the DocumentType is updated with new values for the Entity.

The defined behavior makes efficient storage difficult for the DOM implementor. We can't just look aside to the Entity's definition in the DocumentType since those nodes have the wrong parent (unless we can come up with a clever "imaginary parent" mechanism). We must at least appear to clone those children... which raises the issue of keeping the reference synchronized with its parent. This leads me back to the "cached image of centrally defined data" solution, much as I dislike it.

For now, I have decided, since REC-DOM-Level-1-19980818 doesn't cover this in much detail, that synchronization doesn't have to be considered while the user is deep in the tree. That is, if you're looking within one of the EntityReferennce's children and the Entity changes, you won't be informed; instead, you will continue to access the same object -- which may or may not still be part of the tree. This is the same behavior that obtains elsewhere in the DOM if the subtree you're looking at is deleted from its parent, so it's acceptable here. (If it really bothers folks, we could set things up so deleted subtrees are walked and marked invalid, but that's not part of the DOM's defined behavior.)

As a result, only the EntityReference itself has to be aware of changes in the Entity. And it can take advantage of the same structure-change-monitoring code I implemented to support DeepNodeList.

Author:
Arnaud Le Hors, IBM, Joe Kesselman, IBM, Andy Clark, IBM, Ralf Pfeiffer, IBM

  • Field Details

    • name

      protected final String name
      Name of Entity referenced.

  • Constructor Details

  • Method Details

    • 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. 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 String getNodeName()
      Returns the name of this node. Returns the name of the entity referenced
      Specified by:
      getNodeName in interface Node
      Specified by:
      getNodeName in class NodeImpl

    • cloneNode

      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.

      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. 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.

      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.

      Clone node.
      Specified by:
      cloneNode in interface Node
      Overrides:
      cloneNode in class ParentNode
      Parameters:
      deep - whether to recursively clone all children in the subtree
      Returns:
      the cloned node
      See Also:

    • getBaseURI

      public String getBaseURI()
      Returns the absolute base URI of this node or null if the implementation wasn't able to obtain an absolute URI. Note: If the URI is malformed, a null is returned.
      Specified by:
      getBaseURI in interface Node
      Overrides:
      getBaseURI in class NodeImpl
      Returns:
      The absolute base URI of this node or null.

    • getEntityRefValue

      protected String getEntityRefValue()
      NON-DOM: compute string representation of the entity reference. This method is used to retrieve a string value for an attribute node that has child nodes.
      Returns:
      String representing a value of this entity ref. or null if any node other than EntityReference, Text is encountered during computation

    • synchronizeChildren

      protected void synchronizeChildren()
      Override this method in subclass to hook in efficient internal data structure. EntityReference's children are a reflection of those defined in the named Entity. This method creates them if they haven't been created yet. This doesn't support editing the Entity though, since this only called once for all.
      Overrides:
      synchronizeChildren in class ParentNode