/* 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 { /// /// An ATN transition between any two ATN states. Subclasses define /// atom, set, epsilon, action, predicate, rule transitions. ///

/// This is a one way link. It emanates from a state (usually via a list of /// transitions) and has a target state. ///

/// 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. ///

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. * *

The default implementation returns {@code false}.

* * @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; } // namespace atn } // namespace antlr4