X-Git-Url: https://gitweb.ps.run/toc/blobdiff_plain/9f94b672a5dc32da5ad01742bd4e976315a30d9c..c6ad2948bb98d42f8e0883ef82cd14cd2d5eda60:/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/ATNConfig.h

diff --git a/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/ATNConfig.h b/antlr4-cpp-runtime-4.9.2-source/runtime/src/atn/ATNConfig.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
+
+namespace antlr4 {
+namespace atn {
+
+  /// <summary>
+  /// A tuple: (ATN state, predicted alt, syntactic, semantic context).
+  ///  The syntactic context is a graph-structured stack node whose
+  ///  path(s) to the root is the rule invocation(s)
+  ///  chain used to arrive at the state.  The semantic context is
+  ///  the tree of semantic predicates encountered before reaching
+  ///  an ATN state.
+  /// </summary>
+  class ANTLR4CPP_PUBLIC ATNConfig {
+  public:
+    struct Hasher
+    {
+      size_t operator()(ATNConfig const& k) const {
+        return k.hashCode();
+      }
+    };
+
+    struct Comparer {
+      bool operator()(ATNConfig const& lhs, ATNConfig const& rhs) const {
+        return (&lhs == &rhs) || (lhs == rhs);
+      }
+    };
+
+
+    using Set = std::unordered_set<Ref<ATNConfig>, Hasher, Comparer>;
+
+    /// The ATN state associated with this configuration.
+    ATNState * state;
+
+    /// What alt (or lexer rule) is predicted by this configuration.
+    const size_t alt;
+
+    /// The stack of invoking states leading to the rule/states associated
+    /// with this config.  We track only those contexts pushed during
+    /// execution of the ATN simulator.
+    ///
+    /// Can be shared between multiple ANTConfig instances.
+    Ref<PredictionContext> context;
+
+    /**
+     * We cannot execute predicates dependent upon local context unless
+     * we know for sure we are in the correct context. Because there is
+     * no way to do this efficiently, we simply cannot evaluate
+     * dependent predicates unless we are in the rule that initially
+     * invokes the ATN simulator.
+     *
+     * <p>
+     * closure() tracks the depth of how far we dip into the outer context:
+     * depth > 0.  Note that it may not be totally accurate depth since I
+     * don't ever decrement. TODO: make it a boolean then</p>
+     *
+     * <p>
+     * For memory efficiency, the {@link #isPrecedenceFilterSuppressed} method
+     * is also backed by this field. Since the field is publicly accessible, the
+     * highest bit which would not cause the value to become negative is used to
+     * store this field. This choice minimizes the risk that code which only
+     * compares this value to 0 would be affected by the new purpose of the
+     * flag. It also ensures the performance of the existing {@link ATNConfig}
+     * constructors as well as certain operations like
+     * {@link ATNConfigSet#add(ATNConfig, DoubleKeyMap)} method are
+     * <em>completely</em> unaffected by the change.</p>
+     */
+    size_t reachesIntoOuterContext;
+
+    /// Can be shared between multiple ATNConfig instances.
+    Ref<SemanticContext> semanticContext;
+
+    ATNConfig(ATNState *state, size_t alt, Ref<PredictionContext> const& context);
+    ATNConfig(ATNState *state, size_t alt, Ref<PredictionContext> const& context, Ref<SemanticContext> const& semanticContext);
+
+    ATNConfig(Ref<ATNConfig> const& c); // dup
+    ATNConfig(Ref<ATNConfig> const& c, ATNState *state);
+    ATNConfig(Ref<ATNConfig> const& c, ATNState *state, Ref<SemanticContext> const& semanticContext);
+    ATNConfig(Ref<ATNConfig> const& c, Ref<SemanticContext> const& semanticContext);
+    ATNConfig(Ref<ATNConfig> const& c, ATNState *state, Ref<PredictionContext> const& context);
+    ATNConfig(Ref<ATNConfig> const& c, ATNState *state, Ref<PredictionContext> const& context, Ref<SemanticContext> const& semanticContext);
+
+    ATNConfig(ATNConfig const&) = default;
+    virtual ~ATNConfig();
+
+    virtual size_t hashCode() const;
+
+    /**
+     * This method gets the value of the {@link #reachesIntoOuterContext} field
+     * as it existed prior to the introduction of the
+     * {@link #isPrecedenceFilterSuppressed} method.
+     */
+    size_t getOuterContextDepth() const ;
+    bool isPrecedenceFilterSuppressed() const;
+    void setPrecedenceFilterSuppressed(bool value);
+
+    /// An ATN configuration is equal to another if both have
+    /// the same state, they predict the same alternative, and
+    /// syntactic/semantic contexts are the same.
+    bool operator == (const ATNConfig &other) const;
+    bool operator != (const ATNConfig &other) const;
+
+    virtual std::string toString();
+    std::string toString(bool showAlt);
+
+  private:
+    /**
+     * This field stores the bit mask for implementing the
+     * {@link #isPrecedenceFilterSuppressed} property as a bit within the
+     * existing {@link #reachesIntoOuterContext} field.
+     */
+#if __cplusplus >= 201703L
+    static constexpr size_t SUPPRESS_PRECEDENCE_FILTER = 0x40000000;
+#else
+    enum : size_t {
+      SUPPRESS_PRECEDENCE_FILTER = 0x40000000,
+    };
+#endif
+  };
+
+} // namespace atn
+} // namespace antlr4
+
+
+// Hash function for ATNConfig.
+
+namespace std {
+  using antlr4::atn::ATNConfig;
+
+  template <> struct hash<ATNConfig>
+  {
+    size_t operator() (const ATNConfig &x) const
+    {
+      return x.hashCode();
+    }
+  };
+
+  template <> struct hash<std::vector<Ref<ATNConfig>>>
+  {
+    size_t operator() (const std::vector<Ref<ATNConfig>> &vector) const
+    {
+      std::size_t seed = 0;
+      for (const auto &config : vector) {
+        seed ^= config->hashCode() + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+      }
+      return seed;
+    }
+  };
+}