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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 "misc/IntervalSet.h"
#include "atn/Transition.h"
#include "atn/ATNStateType.h"
namespace antlr4 {
namespace atn {
/// <summary>
/// The following images show the relation of states and
/// <seealso cref="ATNState#transitions"/> for various grammar constructs.
///
/// <ul>
///
/// <li>Solid edges marked with an ε indicate a required
/// <seealso cref="EpsilonTransition"/>.</li>
///
/// <li>Dashed edges indicate locations where any transition derived from
/// <seealso cref="Transition"/> might appear.</li>
///
/// <li>Dashed nodes are place holders for either a sequence of linked
/// <seealso cref="BasicState"/> states or the inclusion of a block representing a nested
/// construct in one of the forms below.</li>
///
/// <li>Nodes showing multiple outgoing alternatives with a {@code ...} support
/// any number of alternatives (one or more). Nodes without the {@code ...} only
/// support the exact number of alternatives shown in the diagram.</li>
///
/// </ul>
///
/// <h2>Basic Blocks</h2>
///
/// <h3>Rule</h3>
///
/// <embed src="images/Rule.svg" type="image/svg+xml"/>
///
/// <h3>Block of 1 or more alternatives</h3>
///
/// <embed src="images/Block.svg" type="image/svg+xml"/>
///
/// <h2>Greedy Loops</h2>
///
/// <h3>Greedy Closure: {@code (...)*}</h3>
///
/// <embed src="images/ClosureGreedy.svg" type="image/svg+xml"/>
///
/// <h3>Greedy Positive Closure: {@code (...)+}</h3>
///
/// <embed src="images/PositiveClosureGreedy.svg" type="image/svg+xml"/>
///
/// <h3>Greedy Optional: {@code (...)?}</h3>
///
/// <embed src="images/OptionalGreedy.svg" type="image/svg+xml"/>
///
/// <h2>Non-Greedy Loops</h2>
///
/// <h3>Non-Greedy Closure: {@code (...)*?}</h3>
///
/// <embed src="images/ClosureNonGreedy.svg" type="image/svg+xml"/>
///
/// <h3>Non-Greedy Positive Closure: {@code (...)+?}</h3>
///
/// <embed src="images/PositiveClosureNonGreedy.svg" type="image/svg+xml"/>
///
/// <h3>Non-Greedy Optional: {@code (...)??}</h3>
///
/// <embed src="images/OptionalNonGreedy.svg" type="image/svg+xml"/>
/// </summary>
// GCC generates a warning here if ATN has already been declared due to the
// attributes added by ANTLR4CPP_PUBLIC.
// See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39159
// Only forward-declare if it hasn't already been declared.
#ifndef ANTLR4CPP_ATN_DECLARED
class ANTLR4CPP_PUBLIC ATN;
#endif
class ANTLR4CPP_PUBLIC ATNState {
public:
static constexpr size_t INITIAL_NUM_TRANSITIONS = 4;
static constexpr size_t INVALID_STATE_NUMBER = std::numeric_limits<size_t>::max();
size_t stateNumber = INVALID_STATE_NUMBER;
size_t ruleIndex = 0; // at runtime, we don't have Rule objects
bool epsilonOnlyTransitions = false;
/// Track the transitions emanating from this ATN state.
std::vector<ConstTransitionPtr> transitions;
ATNState() = delete;
ATNState(ATNState const&) = delete;
ATNState(ATNState&&) = delete;
virtual ~ATNState() = default;
ATNState& operator=(ATNState const&) = delete;
ATNState& operator=(ATNState&&) = delete;
void addTransition(ConstTransitionPtr e);
void addTransition(size_t index, ConstTransitionPtr e);
ConstTransitionPtr removeTransition(size_t index);
virtual size_t hashCode() const;
virtual bool equals(const ATNState &other) const;
virtual bool isNonGreedyExitState() const;
virtual std::string toString() const;
ATNStateType getStateType() const { return _stateType; }
protected:
explicit ATNState(ATNStateType stateType) : _stateType(stateType) {}
private:
/// Used to cache lookahead during parsing, not used during construction.
misc::IntervalSet _nextTokenWithinRule;
std::atomic<bool> _nextTokenUpdated { false };
const ATNStateType _stateType;
friend class ATN;
};
inline bool operator==(const ATNState &lhs, const ATNState &rhs) { return lhs.equals(rhs); }
inline bool operator!=(const ATNState &lhs, const ATNState &rhs) { return !operator==(lhs, rhs); }
} // namespace atn
} // namespace antlr4