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      1 /*
      2  * [The "BSD licence"]
      3  * Copyright (c) 2005-2008 Terence Parr
      4  * All rights reserved.
      5  *
      6  * Conversion to C#:
      7  * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
      8  * All rights reserved.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. The name of the author may not be used to endorse or promote products
     19  *    derived from this software without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 namespace Antlr.Runtime.Debug
     34 {
     35     using System.Collections.Generic;
     36     using ParseTree = Antlr.Runtime.Tree.ParseTree;
     37 
     38     /** <summary>
     39      *  This parser listener tracks rule entry/exit and token matches
     40      *  to build a simple parse tree using ParseTree nodes.
     41      *  </summary>
     42      */
     43     public class ParseTreeBuilder : BlankDebugEventListener
     44     {
     45         public const string EPSILON_PAYLOAD = "<epsilon>";
     46 
     47         Stack<ParseTree> callStack = new Stack<ParseTree>();
     48         List<IToken> hiddenTokens = new List<IToken>();
     49         int backtracking = 0;
     50 
     51         public ParseTreeBuilder( string grammarName )
     52         {
     53             ParseTree root = Create( "<grammar " + grammarName + ">" );
     54             callStack.Push( root );
     55         }
     56 
     57         public virtual ParseTree Tree
     58         {
     59             get
     60             {
     61                 return callStack.Peek();
     62             }
     63         }
     64 
     65         /** <summary>
     66          *  What kind of node to create.  You might want to override
     67          *  so I factored out creation here.
     68          *  </summary>
     69          */
     70         public virtual ParseTree Create( object payload )
     71         {
     72             return new ParseTree( payload );
     73         }
     74 
     75         public virtual ParseTree EpsilonNode()
     76         {
     77             return Create( EPSILON_PAYLOAD );
     78         }
     79 
     80         /** <summary>Backtracking or cyclic DFA, don't want to add nodes to tree</summary> */
     81         public override void EnterDecision( int d, bool couldBacktrack )
     82         {
     83             backtracking++;
     84         }
     85         public override void ExitDecision( int i )
     86         {
     87             backtracking--;
     88         }
     89 
     90         public override void EnterRule( string filename, string ruleName )
     91         {
     92             if ( backtracking > 0 )
     93                 return;
     94             ParseTree parentRuleNode = callStack.Peek();
     95             ParseTree ruleNode = Create( ruleName );
     96             parentRuleNode.AddChild( ruleNode );
     97             callStack.Push( ruleNode );
     98         }
     99 
    100         public override void ExitRule( string filename, string ruleName )
    101         {
    102             if ( backtracking > 0 )
    103                 return;
    104             ParseTree ruleNode = callStack.Peek();
    105             if ( ruleNode.ChildCount == 0 )
    106             {
    107                 ruleNode.AddChild( EpsilonNode() );
    108             }
    109             callStack.Pop();
    110         }
    111 
    112         public override void ConsumeToken( IToken token )
    113         {
    114             if ( backtracking > 0 )
    115                 return;
    116             ParseTree ruleNode = callStack.Peek();
    117             ParseTree elementNode = Create( token );
    118             elementNode.hiddenTokens = this.hiddenTokens;
    119             this.hiddenTokens = new List<IToken>();
    120             ruleNode.AddChild( elementNode );
    121         }
    122 
    123         public override void ConsumeHiddenToken( IToken token )
    124         {
    125             if ( backtracking > 0 )
    126                 return;
    127             hiddenTokens.Add( token );
    128         }
    129 
    130         public override void RecognitionException( RecognitionException e )
    131         {
    132             if ( backtracking > 0 )
    133                 return;
    134             ParseTree ruleNode = callStack.Peek();
    135             ParseTree errorNode = Create( e );
    136             ruleNode.AddChild( errorNode );
    137         }
    138     }
    139 }
    140