DOMTreeWalker objects are used to navigate a document tree or
* subtree using the view of the document defined by their
* whatToShow flags and filter (if any). Any function which
* performs navigation using a DOMTreeWalker will automatically
* support any view defined by a DOMTreeWalker.
* Omitting nodes from the logical view of a subtree can result in a
* structure that is substantially different from the same subtree in the
* complete, unfiltered document. Nodes that are siblings in the
* DOMTreeWalker view may be children of different, widely
* separated nodes in the original view. For instance, consider a
* DOMNodeFilter that skips all nodes except for DOMText nodes and
* the root node of a document. In the logical view that results, all text
* nodes will be siblings and appear as direct children of the root node, no
* matter how deeply nested the structure of the original document.
*
See also the Document Object Model (DOM) Level 2 Traversal and Range Specification.
*
* @since DOM Level 2
*/
class CDOM_EXPORT DOMTreeWalker {
protected :
// -----------------------------------------------------------------------
// Hidden constructors
// -----------------------------------------------------------------------
/** @name Hidden constructors */
//@{
DOMTreeWalker() {};
DOMTreeWalker(const DOMTreeWalker &) {};
DOMTreeWalker & operator = (const DOMTreeWalker &) {return *this;};
//@}
public:
// -----------------------------------------------------------------------
// All constructors are hidden, just the destructor is available
// -----------------------------------------------------------------------
/** @name Destructor */
//@{
/**
* Destructor
*
*/
virtual ~DOMTreeWalker() {};
//@}
// -----------------------------------------------------------------------
// Virtual DOMTreeWalker interface
// -----------------------------------------------------------------------
/** @name Functions introduced in DOM Level 2 */
//@{
// -----------------------------------------------------------------------
// Getter methods
// -----------------------------------------------------------------------
/**
* The root node of the DOMTreeWalker, as specified
* when it was created.
*
* @since DOM Level 2
*/
virtual DOMNode* getRoot() = 0;
/**
* This attribute determines which node types are presented via the
* DOMTreeWalker. The available set of constants is defined in
* the DOMNodeFilter interface. Nodes not accepted by
* whatToShow will be skipped, but their children may still
* be considered. Note that this skip takes precedence over the filter,
* if any.
*
* @since DOM Level 2
*/
virtual unsigned long getWhatToShow()= 0;
/**
* Return The filter used to screen nodes.
*
* @since DOM Level 2
*/
virtual DOMNodeFilter* getFilter()= 0;
/**
* The value of this flag determines whether the children of entity
* reference nodes are visible to the DOMTreeWalker. If false,
* these children and their descendants will be rejected. Note that
* this rejection takes precedence over whatToShow and the
* filter, if any.
*
To produce a view of the document that has entity references
* expanded and does not expose the entity reference node itself, use
* the whatToShow flags to hide the entity reference node
* and set expandEntityReferences to true when creating the
* DOMTreeWalker. To produce a view of the document that has
* entity reference nodes but no entity expansion, use the
* whatToShow flags to show the entity reference node and
* set expandEntityReferences to false.
*
* @since DOM Level 2
*/
virtual bool getExpandEntityReferences()= 0;
/**
* Return the node at which the DOMTreeWalker is currently positioned.
*
* @since DOM Level 2
*/
virtual DOMNode* getCurrentNode()= 0;
// -----------------------------------------------------------------------
// Query methods
// -----------------------------------------------------------------------
/**
* Moves to and returns the closest visible ancestor node of the current
* node. If the search for parentNode attempts to step
* upward from the DOMTreeWalker's root node, or
* if it fails to find a visible ancestor node, this method retains the
* current position and returns null.
* @return The new parent node, or null if the current node
* has no parent in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* parentNode()= 0;
/**
* Moves the DOMTreeWalker to the first visible child of the
* current node, and returns the new node. If the current node has no
* visible children, returns null, and retains the current
* node.
* @return The new node, or null if the current node has no
* visible children in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* firstChild()= 0;
/**
* Moves the DOMTreeWalker to the last visible child of the
* current node, and returns the new node. If the current node has no
* visible children, returns null, and retains the current
* node.
* @return The new node, or null if the current node has no
* children in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* lastChild()= 0;
/**
* Moves the DOMTreeWalker to the previous sibling of the
* current node, and returns the new node. If the current node has no
* visible previous sibling, returns null, and retains the
* current node.
* @return The new node, or null if the current node has no
* previous sibling. in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* previousSibling()= 0;
/**
* Moves the DOMTreeWalker to the next sibling of the current
* node, and returns the new node. If the current node has no visible
* next sibling, returns null, and retains the current node.
* @return The new node, or null if the current node has no
* next sibling. in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* nextSibling()= 0;
/**
* Moves the DOMTreeWalker to the previous visible node in
* document order relative to the current node, and returns the new
* node. If the current node has no previous node, or if the search for
* previousNode attempts to step upward from the
* DOMTreeWalker's root node, returns
* null, and retains the current node.
* @return The new node, or null if the current node has no
* previous node in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* previousNode()= 0;
/**
* Moves the DOMTreeWalker to the next visible node in document
* order relative to the current node, and returns the new node. If the
* current node has no next node, or if the search for nextNode attempts
* to step upward from the DOMTreeWalker's root
* node, returns null, and retains the current node.
* @return The new node, or null if the current node has no
* next node in the DOMTreeWalker's logical view.
*
* @since DOM Level 2
*/
virtual DOMNode* nextNode()= 0;
// -----------------------------------------------------------------------
// Setter methods
// -----------------------------------------------------------------------
/**
* The node at which the DOMTreeWalker is currently positioned.
*
Alterations to the DOM tree may cause the current node to no longer
* be accepted by the DOMTreeWalker's associated filter.
* currentNode may also be explicitly set to any node,
* whether or not it is within the subtree specified by the
* root node or would be accepted by the filter and
* whatToShow flags. Further traversal occurs relative to
* currentNode even if it is not part of the current view,
* by applying the filters in the requested direction; if no traversal
* is possible, currentNode is not changed.
* @exception DOMException
* NOT_SUPPORTED_ERR: Raised if an attempt is made to set
* currentNode to null.
*
* @since DOM Level 2
*/
virtual void setCurrentNode(DOMNode* currentNode)= 0;
//@}
// -----------------------------------------------------------------------
// Non-standard Extension
// -----------------------------------------------------------------------
/** @name Non-standard Extension */
//@{
/**
* Called to indicate that this TreeWalker is no longer in use
* and that the implementation may relinquish any resources associated with it.
*
* Access to a released object will lead to unexpected result.
*/
virtual void release() = 0;
//@}
};
XERCES_CPP_NAMESPACE_END
#endif