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114 lines
4.6 KiB
114 lines
4.6 KiB
/*
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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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using Console = System.Console;
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public class TreeRewriter<TTree> : TreeParser {
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protected ITokenStream originalTokenStream;
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protected ITreeAdaptor originalAdaptor;
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System.Func<IAstRuleReturnScope<TTree>> topdown_func;
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System.Func<IAstRuleReturnScope<TTree>> bottomup_func;
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public TreeRewriter(ITreeNodeStream input)
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: this(input, new RecognizerSharedState()) {
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}
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public TreeRewriter(ITreeNodeStream input, RecognizerSharedState state)
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: base(input, state) {
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originalAdaptor = input.TreeAdaptor;
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originalTokenStream = input.TokenStream;
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topdown_func = () => Topdown();
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bottomup_func = () => Bottomup();
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}
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public virtual object ApplyOnce(object t, System.Func<IAstRuleReturnScope<TTree>> whichRule) {
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if (t == null)
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return null;
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try {
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// share TreeParser object but not parsing-related state
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state = new RecognizerSharedState();
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input = new CommonTreeNodeStream(originalAdaptor, t);
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((CommonTreeNodeStream)input).TokenStream = originalTokenStream;
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BacktrackingLevel = 1;
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IAstRuleReturnScope<TTree> r = whichRule();
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BacktrackingLevel = 0;
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if (Failed)
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return t;
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if (typeof(CommonTree).IsAssignableFrom(typeof(TTree))) {
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if (r != null && !t.Equals(r.Tree) && r.Tree != null) {
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// show any transformations
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Console.Out.WriteLine(((CommonTree)t).ToStringTree() + " -> " +
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((CommonTree)(object)r.Tree).ToStringTree());
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}
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}
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if (r != null && r.Tree != null)
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return r.Tree;
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else
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return t;
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} catch (RecognitionException) {
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}
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return t;
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}
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public virtual object ApplyRepeatedly(object t, System.Func<IAstRuleReturnScope<TTree>> whichRule) {
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bool treeChanged = true;
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while (treeChanged) {
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object u = ApplyOnce(t, whichRule);
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treeChanged = !t.Equals(u);
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t = u;
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}
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return t;
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}
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public virtual object Downup(object t) {
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TreeVisitor v = new TreeVisitor(new CommonTreeAdaptor());
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t = v.Visit(t, (o) => ApplyOnce(o, topdown_func), (o) => ApplyRepeatedly(o, bottomup_func));
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return t;
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}
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// methods the downup strategy uses to do the up and down rules.
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// to override, just define tree grammar rule topdown and turn on
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// filter=true.
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public virtual IAstRuleReturnScope<TTree> Topdown() {
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return null;
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}
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public virtual IAstRuleReturnScope<TTree> Bottomup() {
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return null;
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}
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}
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}
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