82 lines
3.3 KiB
C#
82 lines
3.3 KiB
C#
/*
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* [The "BSD licence"]
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* Copyright (c) 2005-2008 Terence Parr
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* All rights reserved.
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*
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* Conversion to C#:
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* Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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namespace Antlr.Runtime.Tree
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{
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/** <summary>Do a depth first walk of a tree, applying pre() and post() actions as we go.</summary> */
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public class TreeVisitor
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{
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protected ITreeAdaptor adaptor;
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public TreeVisitor(ITreeAdaptor adaptor)
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{
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this.adaptor = adaptor;
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}
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public TreeVisitor()
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: this(new CommonTreeAdaptor())
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{
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}
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/** <summary>
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* Visit every node in tree t and trigger an action for each node
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* before/after having visited all of its children. Bottom up walk.
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* Execute both actions even if t has no children. Ignore return
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* results from transforming children since they will have altered
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* the child list of this node (their parent). Return result of
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* applying post action to this node.
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* </summary>
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*/
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public object Visit(object t, ITreeVisitorAction action)
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{
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// System.out.println("visit "+((Tree)t).toStringTree());
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bool isNil = adaptor.IsNil(t);
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if (action != null && !isNil)
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{
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t = action.Pre(t); // if rewritten, walk children of new t
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}
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for (int i = 0; i < adaptor.GetChildCount(t); i++)
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{
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object child = adaptor.GetChild(t, i);
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Visit(child, action);
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}
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if (action != null && !isNil)
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t = action.Post(t);
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return t;
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}
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public object Visit(object t, Func<object, object> preAction, Func<object, object> postAction)
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{
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return Visit(t, new TreeVisitorAction(preAction, postAction));
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}
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}
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}
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