| /* |
| * [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 Console = System.Console; |
| |
| public class TreeRewriter<TTree> : TreeParser { |
| protected ITokenStream originalTokenStream; |
| protected ITreeAdaptor originalAdaptor; |
| |
| System.Func<IAstRuleReturnScope<TTree>> topdown_func; |
| System.Func<IAstRuleReturnScope<TTree>> 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, System.Func<IAstRuleReturnScope<TTree>> whichRule) { |
| if (t == null) |
| return null; |
| |
| try { |
| // share TreeParser object but not parsing-related state |
| state = new RecognizerSharedState(); |
| input = new CommonTreeNodeStream(originalAdaptor, t); |
| ((CommonTreeNodeStream)input).TokenStream = originalTokenStream; |
| BacktrackingLevel = 1; |
| IAstRuleReturnScope<TTree> r = whichRule(); |
| BacktrackingLevel = 0; |
| if (Failed) |
| return t; |
| |
| if (typeof(CommonTree).IsAssignableFrom(typeof(TTree))) { |
| if (r != null && !t.Equals(r.Tree) && r.Tree != null) { |
| // show any transformations |
| Console.Out.WriteLine(((CommonTree)t).ToStringTree() + " -> " + |
| ((CommonTree)(object)r.Tree).ToStringTree()); |
| } |
| } |
| |
| if (r != null && r.Tree != null) |
| return r.Tree; |
| else |
| return t; |
| } catch (RecognitionException) { |
| } |
| return t; |
| } |
| |
| public virtual object ApplyRepeatedly(object t, System.Func<IAstRuleReturnScope<TTree>> 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) { |
| 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. |
| public virtual IAstRuleReturnScope<TTree> Topdown() { |
| return null; |
| } |
| |
| public virtual IAstRuleReturnScope<TTree> Bottomup() { |
| return null; |
| } |
| } |
| } |