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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/TransitionType.h"
namespace antlr4 {
namespace atn {
/// <summary>
/// An ATN transition between any two ATN states. Subclasses define
/// atom, set, epsilon, action, predicate, rule transitions.
/// <p/>
/// This is a one way link. It emanates from a state (usually via a list of
/// transitions) and has a target state.
/// <p/>
/// Since we never have to change the ATN transitions once we construct it,
/// we can fix these transitions as specific classes. The DFA transitions
/// on the other hand need to update the labels as it adds transitions to
/// the states. We'll use the term Edge for the DFA to distinguish them from
/// ATN transitions.
/// </summary>
class ANTLR4CPP_PUBLIC Transition {
public:
/// The target of this transition.
// ml: this is a reference into the ATN.
ATNState *target;
virtual ~Transition() = default;
TransitionType getTransitionType() const { return _transitionType; }
/**
* Determines if the transition is an "epsilon" transition.
*
* <p>The default implementation returns {@code false}.</p>
*
* @return {@code true} if traversing this transition in the ATN does not
* consume an input symbol; otherwise, {@code false} if traversing this
* transition consumes (matches) an input symbol.
*/
virtual bool isEpsilon() const;
virtual misc::IntervalSet label() const;
virtual bool matches(size_t symbol, size_t minVocabSymbol, size_t maxVocabSymbol) const = 0;
virtual std::string toString() const;
Transition(Transition const&) = delete;
Transition& operator=(Transition const&) = delete;
protected:
Transition(TransitionType transitionType, ATNState *target);
private:
const TransitionType _transitionType;
};
using ConstTransitionPtr = std::unique_ptr<const Transition>;
} // namespace atn
} // namespace antlr4
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