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/*
* [The "BSD licence"]
* Copyright (c) 2005-2008 Terence Parr
* All rights reserved.
*
* Conversion to C#:
* Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
* 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
namespace Antlr.Runtime.Tree
{
using System.Collections.Generic;
/** Return a node stream from a doubly-linked tree whose nodes
* know what child index they are. No remove() is supported.
*
* Emit navigation nodes (DOWN, UP, and EOF) to let show tree structure.
*/
public class TreeIterator : IEnumerator<object>
{
protected ITreeAdaptor adaptor;
protected object root;
protected object tree;
protected bool firstTime = true;
private bool reachedEof;
// navigation nodes to return during walk and at end
public object up;
public object down;
public object eof;
/** If we emit UP/DOWN nodes, we need to spit out multiple nodes per
* next() call.
*/
protected Queue<object> nodes;
public TreeIterator( CommonTree tree )
: this( new CommonTreeAdaptor(), tree )
{
}
public TreeIterator( ITreeAdaptor adaptor, object tree )
{
this.adaptor = adaptor;
this.tree = tree;
this.root = tree;
nodes = new Queue<object>();
down = adaptor.Create( TokenTypes.Down, "DOWN" );
up = adaptor.Create( TokenTypes.Up, "UP" );
eof = adaptor.Create( TokenTypes.EndOfFile, "EOF" );
}
#region IEnumerator<object> Members
public object Current
{
get;
private set;
}
#endregion
#region IDisposable Members
public void Dispose()
{
}
#endregion
#region IEnumerator Members
public bool MoveNext()
{
if ( firstTime )
{
// initial condition
firstTime = false;
if ( adaptor.GetChildCount( tree ) == 0 )
{
// single node tree (special)
nodes.Enqueue( eof );
}
Current = tree;
}
else
{
// if any queued up, use those first
if ( nodes != null && nodes.Count > 0 )
{
Current = nodes.Dequeue();
}
else
{
// no nodes left?
if ( tree == null )
{
Current = eof;
}
else
{
// next node will be child 0 if any children
if ( adaptor.GetChildCount( tree ) > 0 )
{
tree = adaptor.GetChild( tree, 0 );
nodes.Enqueue( tree ); // real node is next after DOWN
Current = down;
}
else
{
// if no children, look for next sibling of tree or ancestor
object parent = adaptor.GetParent( tree );
// while we're out of siblings, keep popping back up towards root
while ( parent != null &&
adaptor.GetChildIndex( tree ) + 1 >= adaptor.GetChildCount( parent ) )
{
nodes.Enqueue( up ); // we're moving back up
tree = parent;
parent = adaptor.GetParent( tree );
}
// no nodes left?
if ( parent == null )
{
tree = null; // back at root? nothing left then
nodes.Enqueue( eof ); // add to queue, might have UP nodes in there
Current = nodes.Dequeue();
}
else
{
// must have found a node with an unvisited sibling
// move to it and return it
int nextSiblingIndex = adaptor.GetChildIndex( tree ) + 1;
tree = adaptor.GetChild( parent, nextSiblingIndex );
nodes.Enqueue( tree ); // add to queue, might have UP nodes in there
Current = nodes.Dequeue();
}
}
}
}
}
bool result = Current != eof || !reachedEof;
reachedEof = Current == eof;
return result;
}
public void Reset()
{
firstTime = true;
tree = root;
nodes.Clear();
}
#endregion
}
}
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