//
// NodeIterator.h
//
// $Id: //poco/Main/XML/include/DOM/NodeIterator.h#5 $
//
// Definition of the DOM NodeIterator class.
//
// Copyright (c) 2004, Guenter Obiltschnig/Applied Informatics.
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 
// 3. Redistributions in any form must be accompanied by information on
//    how to obtain complete source code for this software and any
//    accompanying software that uses this software.  The source code
//    must either be included in the distribution or be available for no
//    more than the cost of distribution plus a nominal fee, and must be
//    freely redistributable under reasonable conditions.  For an
//    executable file, complete source code means the source code for all
//    modules it contains.  It does not include source code for modules or
//    files that typically accompany the major components of the operating
//    system on which the executable file runs.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//


#ifndef DOM_NodeIterator_INCLUDED
#define DOM_NodeIterator_INCLUDED


#ifndef XML_XML_INCLUDED
#include "XML/XML.h"
#endif


XML_BEGIN


class Node;
class NodeFilter;


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.

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


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


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


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


XML_END


#endif // DOM_NodeIterator_INCLUDED