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/* 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 "atn/ATNConfig.h"
#include "atn/PredictionContext.h"
#include "support/BitSet.h"
namespace antlr4 {
namespace atn {
class ANTLR4CPP_PUBLIC LL1Analyzer final {
public:
/// Special value added to the lookahead sets to indicate that we hit
/// a predicate during analysis if {@code seeThruPreds==false}.
static constexpr size_t HIT_PRED = Token::INVALID_TYPE;
explicit LL1Analyzer(const atn::ATN &atn) : _atn(atn) {}
/// <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>
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>
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>
misc::IntervalSet LOOK(ATNState *s, ATNState *stopState, RuleContext *ctx) const;
private:
const atn::ATN &_atn;
};
} // namespace atn
} // namespace antlr4
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