1 files changed, 144 insertions, 0 deletions
diff --git a/runtime/CSharp3/Sources/Antlr3.Runtime/Tree/TreeRewriter.cs b/runtime/CSharp3/Sources/Antlr3.Runtime/Tree/TreeRewriter.cs
new file mode 100644
index 0000000..b610c2c
--- /dev/null
+++ b/runtime/CSharp3/Sources/Antlr3.Runtime/Tree/TreeRewriter.cs
@@ -0,0 +1,144 @@
+/*
+ * [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
+                state = new RecognizerSharedState();
+                input = 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.
+        public virtual IAstRuleReturnScope Topdown()
+        {
+            return null;
+        }
+
+        public 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);
+        }
+    }
+}