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.
16  *  3. The name of the author may not be used to endorse or promote products
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
20  *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21  *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22  *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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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 /**
37  * This is the base class for gathering detailed information about prediction
38  * events which occur during parsing.
39  *
40  * Note that we could record the parser call stack at the time this event
41  * occurred but in the presence of left recursive rules, the stack is kind of
42  * meaningless. It's better to look at the individual configurations for their
43  * individual stacks. Of course that is a {@link PredictionContext} object
44  * not a parse tree node and so it does not have information about the extent
45  * (start...stop) of the various subtrees. Examining the stack tops of all
46  * configurations provide the return states for the rule invocations.
47  * From there you can get the enclosing rule.
48  */
49 class DecisionEventInfo
50 {
51 
52     /**
53      * The invoked decision number which this event is related to.
54      *
55      * @see ATN#decisionToState
56      */
57     public int decision;
58 
59     /**
60      * The configuration set containing additional information relevant to the
61      * prediction state when the current event occurred, or {@code null} if no
62      * additional information is relevant or available.
63      */
64     public ATNConfigSet configs;
65 
66     /**
67      * The input token stream which is being parsed.
68      */
69     public TokenStream input;
70 
71     public int startIndex;
72 
73     public int stopIndex;
74 
75     /**
76      * {@code true} if the current event occurred during LL prediction;
77      * otherwise, {@code false} if the input occurred during SLL prediction.
78      */
79     public bool fullCtx;
80 
81     public this(int decision, ATNConfigSet configs, TokenStream input, int startIndex, int stopIndex,
82         bool fullCtx)
83     {
84         this.decision = decision;
85         this.fullCtx = fullCtx;
86         this.stopIndex = stopIndex;
87         this.input = input;
88         this.startIndex = startIndex;
89         this.configs = configs;
90     }
91 
92 }