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[toc] / antlr4-cpp-runtime-4.9.2-source / runtime / src / atn / Transition.h

diff --git a/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/Transition.h b/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/Transition.h
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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"
+
+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:
+    // constants for serialization
+    enum SerializationType {
+      EPSILON = 1,
+      RANGE = 2,
+      RULE = 3,
+      PREDICATE = 4, // e.g., {isType(input.LT(1))}?
+      ATOM = 5,
+      ACTION = 6,
+      SET = 7, // ~(A|B) or ~atom, wildcard, which convert to next 2
+      NOT_SET = 8,
+      WILDCARD = 9,
+      PRECEDENCE = 10,
+    };
+
+    static const std::vector<std::string> serializationNames;
+
+    /// The target of this transition.
+    // ml: this is a reference into the ATN.
+    ATNState *target;
+
+    virtual ~Transition();
+
+  protected:
+    Transition(ATNState *target);
+
+  public:
+    virtual SerializationType getSerializationType() const = 0;
+
+    /**
+     * 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;
+  };
+
+} // namespace atn
+} // namespace antlr4