antlr.v4.runtime.atn.DecisionEventInfo source code

1 /*
2  * [The "BSD license"]
3  *  Copyright (c) 2014 Terence Parr
4  *  Copyright (c) 2014 Sam Harwell
5  *  All rights reserved.
6  *
7  *  Redistribution and use in source and binary forms, with or without
8  *  modification, are permitted provided that the following conditions
9  *  are met:
10  *
11  *  1. Redistributions of source code must retain the above copyright
12  *     notice, this list of conditions and the following disclaimer.
13  *  2. Redistributions in binary form must reproduce the above copyright
14  *     notice, this list of conditions and the following disclaimer in the
15  *     documentation and/or other materials provided with the distribution.
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17  *     derived from this software without specific prior written permission.
18  *
19  *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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21  *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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29  */
30 
31 module antlr.v4.runtime.atn.DecisionEventInfo;
32 
33 import antlr.v4.runtime.atn.ATNConfigSet;
34 import antlr.v4.runtime.TokenStream;
35 
36 // Class DecisionEventInfo
37 /**
38  * This is the base class for gathering detailed information about prediction
39  * events which occur during parsing.
40  *
41  * Note that we could record the parser call stack at the time this event
42  * occurred but in the presence of left recursive rules, the stack is kind of
43  * meaningless. It's better to look at the individual configurations for their
44  * individual stacks. Of course that is a {@link PredictionContext} object
45  * not a parse tree node and so it does not have information about the extent
46  * (start...stop) of the various subtrees. Examining the stack tops of all
47  * configurations provide the return states for the rule invocations.
48  * From there you can get the enclosing rule.
49  */
50 class DecisionEventInfo
51 {
52 
53     /**
54      * The invoked decision number which this event is related to.
55      *
56      * @see ATN#decisionToState
57      */
58     public int decision;
59 
60     /**
61      * The configuration set containing additional information relevant to the
62      * prediction state when the current event occurred, or {@code null} if no
63      * additional information is relevant or available.
64      */
65     public ATNConfigSet configs;
66 
67     /**
68      * The input token stream which is being parsed.
69      */
70     public TokenStream input;
71 
72     public int startIndex;
73 
74     public int stopIndex;
75 
76     /**
77      * {@code true} if the current event occurred during LL prediction;
78      * otherwise, {@code false} if the input occurred during SLL prediction.
79      */
80     public bool fullCtx;
81 
82     public this(int decision, ATNConfigSet configs, TokenStream input, int startIndex, int stopIndex,
83         bool fullCtx)
84     {
85         this.decision = decision;
86         this.fullCtx = fullCtx;
87         this.stopIndex = stopIndex;
88         this.input = input;
89         this.startIndex = startIndex;
90         this.configs = configs;
91     }
92 
93 }