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 
ParseTreeBuilder( string grammarName )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          */
Create( object payload )70         public virtual ParseTree Create( object payload )
71         {
72             return new ParseTree( payload );
73         }
74 
EpsilonNode()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> */
EnterDecision( int d, bool couldBacktrack )81         public override void EnterDecision( int d, bool couldBacktrack )
82         {
83             backtracking++;
84         }
ExitDecision( int i )85         public override void ExitDecision( int i )
86         {
87             backtracking--;
88         }
89 
EnterRule( string filename, string ruleName )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 
ExitRule( string filename, string ruleName )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 
ConsumeToken( IToken token )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 
ConsumeHiddenToken( IToken token )123         public override void ConsumeHiddenToken( IToken token )
124         {
125             if ( backtracking > 0 )
126                 return;
127             hiddenTokens.Add( token );
128         }
129 
RecognitionException( RecognitionException e )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