add antlr

lib/antlr4/include/atn/ATNConfigSet.h

@@ -0,0 +1,110 @@
+/* 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 "support/BitSet.h"
+#include "atn/PredictionContext.h"
+
+namespace antlr4 {
+namespace atn {
+
+  /// Specialized set that can track info about the set, with support for combining similar configurations using a
+  /// graph-structured stack.
+  class ANTLR4CPP_PUBLIC ATNConfigSet {
+  public:
+    /// Track the elements as they are added to the set; supports get(i)
+    std::vector<Ref<ATNConfig>> configs;
+
+    // TODO: these fields make me pretty uncomfortable but nice to pack up info together, saves recomputation
+    // TODO: can we track conflicts as they are added to save scanning configs later?
+    size_t uniqueAlt;
+
+    /** Currently this is only used when we detect SLL conflict; this does
+     *  not necessarily represent the ambiguous alternatives. In fact,
+     *  I should also point out that this seems to include predicated alternatives
+     *  that have predicates that evaluate to false. Computed in computeTargetState().
+     */
+    antlrcpp::BitSet conflictingAlts;
+
+    // Used in parser and lexer. In lexer, it indicates we hit a pred
+    // while computing a closure operation.  Don't make a DFA state from this.
+    bool hasSemanticContext;
+    bool dipsIntoOuterContext;
+
+    /// Indicates that this configuration set is part of a full context
+    /// LL prediction. It will be used to determine how to merge $. With SLL
+    /// it's a wildcard whereas it is not for LL context merge.
+    const bool fullCtx;
+
+    ATNConfigSet(bool fullCtx = true);
+    ATNConfigSet(const Ref<ATNConfigSet> &old);
+
+    virtual ~ATNConfigSet();
+
+    virtual bool add(const Ref<ATNConfig> &config);
+
+    /// <summary>
+    /// Adding a new config means merging contexts with existing configs for
+    /// {@code (s, i, pi, _)}, where {@code s} is the
+    /// <seealso cref="ATNConfig#state"/>, {@code i} is the <seealso cref="ATNConfig#alt"/>, and
+    /// {@code pi} is the <seealso cref="ATNConfig#semanticContext"/>. We use
+    /// {@code (s,i,pi)} as key.
+    /// <p/>
+    /// This method updates <seealso cref="#dipsIntoOuterContext"/> and
+    /// <seealso cref="#hasSemanticContext"/> when necessary.
+    /// </summary>
+    virtual bool add(const Ref<ATNConfig> &config, PredictionContextMergeCache *mergeCache);
+
+    virtual std::vector<ATNState *> getStates();
+
+    /**
+     * Gets the complete set of represented alternatives for the configuration
+     * set.
+     *
+     * @return the set of represented alternatives in this configuration set
+     *
+     * @since 4.3
+     */
+    antlrcpp::BitSet getAlts();
+    virtual std::vector<Ref<SemanticContext>> getPredicates();
+
+    virtual Ref<ATNConfig> get(size_t i) const;
+
+    virtual void optimizeConfigs(ATNSimulator *interpreter);
+
+    bool addAll(const Ref<ATNConfigSet> &other);
+
+    bool operator == (const ATNConfigSet &other);
+    virtual size_t hashCode();
+    virtual size_t size();
+    virtual bool isEmpty();
+    virtual void clear();
+    virtual bool isReadonly();
+    virtual void setReadonly(bool readonly);
+    virtual std::string toString();
+
+  protected:
+    /// Indicates that the set of configurations is read-only. Do not
+    /// allow any code to manipulate the set; DFA states will point at
+    /// the sets and they must not change. This does not protect the other
+    /// fields; in particular, conflictingAlts is set after
+    /// we've made this readonly.
+    bool _readonly;
+
+    virtual size_t getHash(ATNConfig *c); // Hash differs depending on set type.
+
+  private:
+    size_t _cachedHashCode;
+
+    /// All configs but hashed by (s, i, _, pi) not including context. Wiped out
+    /// when we go readonly as this set becomes a DFA state.
+    std::unordered_map<size_t, ATNConfig *> _configLookup;
+
+    void InitializeInstanceFields();
+  };
+
+} // namespace atn
+} // namespace antlr4