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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 Antlr.Runtime.Misc;
using Console = System.Console;
public class TreeRewriter : TreeParser
{
protected bool showTransformations;
protected ITokenStream originalTokenStream;
protected ITreeAdaptor originalAdaptor;
Func<IAstRuleReturnScope> topdown_func;
Func<IAstRuleReturnScope> bottomup_func;
public TreeRewriter( ITreeNodeStream input )
: this( input, new RecognizerSharedState() )
{
}
public TreeRewriter( ITreeNodeStream input, RecognizerSharedState state )
: base( input, state )
{
originalAdaptor = input.TreeAdaptor;
originalTokenStream = input.TokenStream;
topdown_func = () => Topdown();
bottomup_func = () => Bottomup();
}
public virtual object ApplyOnce( object t, Func<IAstRuleReturnScope> whichRule )
{
if ( t == null )
return null;
try
{
// share TreeParser object but not parsing-related state
SetState(new RecognizerSharedState());
SetTreeNodeStream(new CommonTreeNodeStream(originalAdaptor, t));
( (CommonTreeNodeStream)input ).TokenStream = originalTokenStream;
BacktrackingLevel = 1;
IAstRuleReturnScope r = whichRule();
BacktrackingLevel = 0;
if ( Failed )
return t;
if (showTransformations && r != null && !t.Equals(r.Tree) && r.Tree != null)
ReportTransformation(t, r.Tree);
if ( r != null && r.Tree != null )
return r.Tree;
else
return t;
}
catch ( RecognitionException )
{
}
return t;
}
public virtual object ApplyRepeatedly( object t, Func<IAstRuleReturnScope> whichRule )
{
bool treeChanged = true;
while ( treeChanged )
{
object u = ApplyOnce( t, whichRule );
treeChanged = !t.Equals( u );
t = u;
}
return t;
}
public virtual object Downup( object t )
{
return Downup( t, false );
}
public virtual object Downup( object t, bool showTransformations )
{
this.showTransformations = showTransformations;
TreeVisitor v = new TreeVisitor( new CommonTreeAdaptor() );
t = v.Visit( t, ( o ) => ApplyOnce( o, topdown_func ), ( o ) => ApplyRepeatedly( o, bottomup_func ) );
return t;
}
// methods the downup strategy uses to do the up and down rules.
// to override, just define tree grammar rule topdown and turn on
// filter=true.
protected virtual IAstRuleReturnScope Topdown()
{
return null;
}
protected virtual IAstRuleReturnScope Bottomup()
{
return null;
}
/** Override this if you need transformation tracing to go somewhere
* other than stdout or if you're not using ITree-derived trees.
*/
protected virtual void ReportTransformation(object oldTree, object newTree)
{
ITree old = oldTree as ITree;
ITree @new = newTree as ITree;
string oldMessage = old != null ? old.ToStringTree() : "??";
string newMessage = @new != null ? @new.ToStringTree() : "??";
Console.WriteLine("{0} -> {1}", oldMessage, newMessage);
}
}
}
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