110 lines
5.3 KiB
C++
110 lines
5.3 KiB
C++
/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
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* Use of this file is governed by the BSD 3-clause license that
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* can be found in the LICENSE.txt file in the project root.
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*/
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#pragma once
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#include "Token.h"
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#include "support/BitSet.h"
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#include "atn/PredictionContext.h"
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#include "atn/ATNConfig.h"
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namespace antlr4 {
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namespace atn {
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class ANTLR4CPP_PUBLIC LL1Analyzer {
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public:
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/// Special value added to the lookahead sets to indicate that we hit
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/// a predicate during analysis if {@code seeThruPreds==false}.
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static const size_t HIT_PRED = Token::INVALID_TYPE;
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const atn::ATN &_atn;
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LL1Analyzer(const atn::ATN &atn);
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virtual ~LL1Analyzer();
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/// <summary>
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/// Calculates the SLL(1) expected lookahead set for each outgoing transition
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/// of an <seealso cref="ATNState"/>. The returned array has one element for each
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/// outgoing transition in {@code s}. If the closure from transition
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/// <em>i</em> leads to a semantic predicate before matching a symbol, the
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/// element at index <em>i</em> of the result will be {@code null}.
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/// </summary>
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/// <param name="s"> the ATN state </param>
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/// <returns> the expected symbols for each outgoing transition of {@code s}. </returns>
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virtual std::vector<misc::IntervalSet> getDecisionLookahead(ATNState *s) const;
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/// <summary>
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/// Compute set of tokens that can follow {@code s} in the ATN in the
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/// specified {@code ctx}.
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/// <p/>
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/// If {@code ctx} is {@code null} and the end of the rule containing
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/// {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to the result set.
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/// If {@code ctx} is not {@code null} and the end of the outermost rule is
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/// reached, <seealso cref="Token#EOF"/> is added to the result set.
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/// </summary>
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/// <param name="s"> the ATN state </param>
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/// <param name="ctx"> the complete parser context, or {@code null} if the context
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/// should be ignored
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/// </param>
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/// <returns> The set of tokens that can follow {@code s} in the ATN in the
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/// specified {@code ctx}. </returns>
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virtual misc::IntervalSet LOOK(ATNState *s, RuleContext *ctx) const;
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/// <summary>
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/// Compute set of tokens that can follow {@code s} in the ATN in the
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/// specified {@code ctx}.
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/// <p/>
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/// If {@code ctx} is {@code null} and the end of the rule containing
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/// {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to the result set.
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/// If {@code ctx} is not {@code null} and the end of the outermost rule is
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/// reached, <seealso cref="Token#EOF"/> is added to the result set.
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/// </summary>
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/// <param name="s"> the ATN state </param>
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/// <param name="stopState"> the ATN state to stop at. This can be a
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/// <seealso cref="BlockEndState"/> to detect epsilon paths through a closure. </param>
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/// <param name="ctx"> the complete parser context, or {@code null} if the context
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/// should be ignored
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/// </param>
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/// <returns> The set of tokens that can follow {@code s} in the ATN in the
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/// specified {@code ctx}. </returns>
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virtual misc::IntervalSet LOOK(ATNState *s, ATNState *stopState, RuleContext *ctx) const;
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/// <summary>
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/// Compute set of tokens that can follow {@code s} in the ATN in the
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/// specified {@code ctx}.
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/// <p/>
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/// If {@code ctx} is {@code null} and {@code stopState} or the end of the
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/// rule containing {@code s} is reached, <seealso cref="Token#EPSILON"/> is added to
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/// the result set. If {@code ctx} is not {@code null} and {@code addEOF} is
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/// {@code true} and {@code stopState} or the end of the outermost rule is
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/// reached, <seealso cref="Token#EOF"/> is added to the result set.
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/// </summary>
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/// <param name="s"> the ATN state. </param>
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/// <param name="stopState"> the ATN state to stop at. This can be a
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/// <seealso cref="BlockEndState"/> to detect epsilon paths through a closure. </param>
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/// <param name="ctx"> The outer context, or {@code null} if the outer context should
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/// not be used. </param>
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/// <param name="look"> The result lookahead set. </param>
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/// <param name="lookBusy"> A set used for preventing epsilon closures in the ATN
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/// from causing a stack overflow. Outside code should pass
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/// {@code new HashSet<ATNConfig>} for this argument. </param>
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/// <param name="calledRuleStack"> A set used for preventing left recursion in the
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/// ATN from causing a stack overflow. Outside code should pass
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/// {@code new BitSet()} for this argument. </param>
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/// <param name="seeThruPreds"> {@code true} to true semantic predicates as
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/// implicitly {@code true} and "see through them", otherwise {@code false}
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/// to treat semantic predicates as opaque and add <seealso cref="#HIT_PRED"/> to the
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/// result if one is encountered. </param>
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/// <param name="addEOF"> Add <seealso cref="Token#EOF"/> to the result if the end of the
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/// outermost context is reached. This parameter has no effect if {@code ctx}
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/// is {@code null}. </param>
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protected:
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virtual void _LOOK(ATNState *s, ATNState *stopState, Ref<PredictionContext> const& ctx, misc::IntervalSet &look,
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ATNConfig::Set &lookBusy, antlrcpp::BitSet &calledRuleStack, bool seeThruPreds, bool addEOF) const;
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};
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} // namespace atn
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} // namespace antlr4
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