1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#pragma once
#include "Token.h"
#include "support/BitSet.h"
#include "atn/PredictionContext.h"
#include "atn/ATNConfig.h"
namespace antlr4 {
namespace atn {
class ANTLR4CPP_PUBLIC LL1Analyzer {
public:
/// Special value added to the lookahead sets to indicate that we hit
/// a predicate during analysis if {@code seeThruPreds==false}.
#if __cplusplus >= 201703L
static constexpr size_t HIT_PRED = Token::INVALID_TYPE;
#else
enum : size_t {
HIT_PRED = Token::INVALID_TYPE,
};
#endif
const atn::ATN &_atn;
LL1Analyzer(const atn::ATN &atn);
virtual ~LL1Analyzer();
/// <summary>
/// Calculates the SLL(1) expected lookahead set for each outgoing transition
/// of an <seealso cref="ATNState"/>. The returned array has one element for each
/// outgoing transition in {@code s}. If the closure from transition
/// <em>i</em> leads to a semantic predicate before matching a symbol, the
/// element at index <em>i</em> of the result will be {@code null}.
/// </summary>
/// <param name="s"> the ATN state </param>
/// <returns> the expected symbols for each outgoing transition of {@code s}. </returns>
virtual std::vector<misc::IntervalSet> getDecisionLookahead(ATNState *s) const;
/// <summary>
/// Compute set of tokens that can follow {@code s} in the ATN in the
/// specified {@code ctx}.
/// <p/>
/// If {@code ctx} is {@code null} and the end of the rule containing
/// {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to the result set.
/// If {@code ctx} is not {@code null} and the end of the outermost rule is
/// reached, <seealso cref="Token#EOF"/> is added to the result set.
/// </summary>
/// <param name="s"> the ATN state </param>
/// <param name="ctx"> the complete parser context, or {@code null} if the context
/// should be ignored
/// </param>
/// <returns> The set of tokens that can follow {@code s} in the ATN in the
/// specified {@code ctx}. </returns>
virtual misc::IntervalSet LOOK(ATNState *s, RuleContext *ctx) const;
/// <summary>
/// Compute set of tokens that can follow {@code s} in the ATN in the
/// specified {@code ctx}.
/// <p/>
/// If {@code ctx} is {@code null} and the end of the rule containing
/// {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to the result set.
/// If {@code ctx} is not {@code null} and the end of the outermost rule is
/// reached, <seealso cref="Token#EOF"/> is added to the result set.
/// </summary>
/// <param name="s"> the ATN state </param>
/// <param name="stopState"> the ATN state to stop at. This can be a
/// <seealso cref="BlockEndState"/> to detect epsilon paths through a closure. </param>
/// <param name="ctx"> the complete parser context, or {@code null} if the context
/// should be ignored
/// </param>
/// <returns> The set of tokens that can follow {@code s} in the ATN in the
/// specified {@code ctx}. </returns>
virtual misc::IntervalSet LOOK(ATNState *s, ATNState *stopState, RuleContext *ctx) const;
/// <summary>
/// Compute set of tokens that can follow {@code s} in the ATN in the
/// specified {@code ctx}.
/// <p/>
/// If {@code ctx} is {@code null} and {@code stopState} or the end of the
/// rule containing {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to
/// the result set. If {@code ctx} is not {@code null} and {@code addEOF} is
/// {@code true} and {@code stopState} or the end of the outermost rule is
/// reached, <seealso cref="Token#EOF"/> is added to the result set.
/// </summary>
/// <param name="s"> the ATN state. </param>
/// <param name="stopState"> the ATN state to stop at. This can be a
/// <seealso cref="BlockEndState"/> to detect epsilon paths through a closure. </param>
/// <param name="ctx"> The outer context, or {@code null} if the outer context should
/// not be used. </param>
/// <param name="look"> The result lookahead set. </param>
/// <param name="lookBusy"> A set used for preventing epsilon closures in the ATN
/// from causing a stack overflow. Outside code should pass
/// {@code new HashSet<ATNConfig>} for this argument. </param>
/// <param name="calledRuleStack"> A set used for preventing left recursion in the
/// ATN from causing a stack overflow. Outside code should pass
/// {@code new BitSet()} for this argument. </param>
/// <param name="seeThruPreds"> {@code true} to true semantic predicates as
/// implicitly {@code true} and "see through them", otherwise {@code false}
/// to treat semantic predicates as opaque and add <seealso cref="#HIT_PRED"/> to the
/// result if one is encountered. </param>
/// <param name="addEOF"> Add <seealso cref="Token#EOF"/> to the result if the end of the
/// outermost context is reached. This parameter has no effect if {@code ctx}
/// is {@code null}. </param>
protected:
virtual void _LOOK(ATNState *s, ATNState *stopState, Ref<PredictionContext> const& ctx, misc::IntervalSet &look,
ATNConfig::Set &lookBusy, antlrcpp::BitSet &calledRuleStack, bool seeThruPreds, bool addEOF) const;
};
} // namespace atn
} // namespace antlr4
|
