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NodeIterator.h

//
// NodeIterator.h
//
// $Id: //poco/1.2/XML/include/Poco/DOM/NodeIterator.h#1 $
//
// Library: XML
// Package: DOM
// Module:  NodeIterator
//
// Definition of the DOM NodeIterator class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef DOM_NodeIterator_INCLUDED
#define DOM_NodeIterator_INCLUDED


#include "Poco/XML/XML.h"


namespace Poco {
namespace XML {


class Node;
class NodeFilter;


00054 class XML_API NodeIterator
      /// Iterators are used to step through a set of nodes, e.g. the set of nodes
      /// in a NodeList, the document subtree governed by a particular Node, the results
      /// of a query, or any other set of nodes. The set of nodes to be iterated is
      /// determined by the implementation of the NodeIterator. DOM Level 2 specifies
      /// a single NodeIterator implementation for document-order traversal of a document
      /// subtree.
      ///
      /// A NodeIterator can be directly instantiated using one of its constructors -
      /// the DocumentTraversal interface is not needed and therefore not implemented.
      /// Unlike most other DOM classes, NodeIterator supports value semantics.
      ///
      /// If the NodeIterator's current node is removed from the document, the
      /// result of calling any of the movement methods is undefined. This behavior does
      /// not conform to the DOM Level 2 Traversal specification.
{
public:
      NodeIterator(Node* root, unsigned long whatToShow, NodeFilter* pFilter = 0);
            /// Creates a NodeIterator over the subtree rooted at the specified node.
            
      NodeIterator(const NodeIterator& iterator);
            /// Creates a NodeIterator by copying another NodeIterator.
            
      NodeIterator& operator = (const NodeIterator& iterator);
            /// Assignment operator.
            
      ~NodeIterator();
            /// Destroys the NodeIterator.

      Node* root() const;
            /// The root node of the NodeIterator, as specified when it was created.

      unsigned long whatToShow() const;
            /// This attribute determines which node types are presented via the iterator. 
            /// The available set of constants is defined in the NodeFilter 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.

      NodeFilter* filter() const;
            /// The NodeFilter used to screen nodes.

      bool expandEntityReferences() const;
            /// The value of this flag determines whether the children of entity reference
            /// nodes are visible to the iterator. If false, they and their descendants
            /// will be rejected. Note that this rejection takes precedence over whatToShow
            /// and the filter. Also note that this is currently the only situation where
            /// NodeIterators may reject a complete subtree rather than skipping individual
            /// nodes.
            /// 
            /// 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 iterator. 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.
            ///
            /// This implementation does not support entity reference expansion and
            /// thus always returns false.

      Node* nextNode();
            /// Returns the next node in the set and advances the position of the iterator
            /// in the set. After a NodeIterator is created, the first call to nextNode()
            /// returns the first node in the set.

      Node* previousNode();
            /// Returns the previous node in the set and moves the position of the NodeIterator
            /// backwards in the set.

      Node* currentNodeNP() const;
            /// Returns the current node in the set.
            ///
            /// Leaves the NodeIterator unchanged.
            ///
            /// Warning: This is a proprietary extension to the DOM Level 2 NodeIterator
            /// interface.

      void detach();
            /// Detaches the NodeIterator from the set which it iterated over, releasing
            /// any computational resources and placing the iterator in the INVALID state.
            /// After detach has been invoked, calls to nextNode or previousNode will raise
            /// the exception INVALID_STATE_ERR.

protected:
      bool accept(Node* pNode) const;
      Node* next() const;
      Node* previous() const;
      Node* last();

private:
      NodeIterator();
      
      Node*         _pRoot;
      unsigned long _whatToShow;
      NodeFilter*   _pFilter;
      Node*         _pCurrent;
};


//
// inlines
//
00156 inline Node* NodeIterator::root() const
{
      return _pRoot;
}


00162 inline Node* NodeIterator::currentNodeNP() const
{
      return _pCurrent;
}


00168 inline unsigned long NodeIterator::whatToShow() const
{
      return _whatToShow;
}


00174 inline NodeFilter* NodeIterator::filter() const
{
      return _pFilter;
}


00180 inline bool NodeIterator::expandEntityReferences() const
{
      return false;
}


} } // namespace Poco::XML


#endif // DOM_NodeIterator_INCLUDED

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