--- /dev/null
+/* 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 "Recognizer.h"
+#include "atn/ATN.h"
+#include "atn/ATNState.h"
+
+namespace antlr4 {
+namespace atn {
+
+ struct PredictionContextHasher;
+ struct PredictionContextComparer;
+ class PredictionContextMergeCache;
+
+ typedef std::unordered_set<Ref<PredictionContext>, PredictionContextHasher, PredictionContextComparer> PredictionContextCache;
+
+ class ANTLR4CPP_PUBLIC PredictionContext {
+ public:
+ /// Represents $ in local context prediction, which means wildcard.
+ /// *+x = *.
+ static const Ref<PredictionContext> EMPTY;
+
+ /// Represents $ in an array in full context mode, when $
+ /// doesn't mean wildcard: $ + x = [$,x]. Here,
+ /// $ = EMPTY_RETURN_STATE.
+ // ml: originally Integer.MAX_VALUE, which would be -1 for us, but this is already used in places where
+ // -1 is converted to unsigned, so we use a different value here. Any value does the job provided it doesn't
+ // conflict with real return states.
+#if __cplusplus >= 201703L
+ static constexpr size_t EMPTY_RETURN_STATE = std::numeric_limits<size_t>::max() - 9;
+#else
+ enum : size_t {
+ EMPTY_RETURN_STATE = static_cast<size_t>(-10), // std::numeric_limits<size_t>::max() - 9; doesn't work in VS 2013
+ };
+#endif
+
+ private:
+#if __cplusplus >= 201703L
+ static constexpr size_t INITIAL_HASH = 1;
+#else
+ enum : size_t {
+ INITIAL_HASH = 1,
+ };
+#endif
+
+ public:
+ static size_t globalNodeCount;
+ const size_t id;
+
+ /// <summary>
+ /// Stores the computed hash code of this <seealso cref="PredictionContext"/>. The hash
+ /// code is computed in parts to match the following reference algorithm.
+ ///
+ /// <pre>
+ /// private int referenceHashCode() {
+ /// int hash = <seealso cref="MurmurHash#initialize"/>(<seealso cref="#INITIAL_HASH"/>);
+ ///
+ /// for (int i = 0; i < <seealso cref="#size()"/>; i++) {
+ /// hash = <seealso cref="MurmurHash#update"/>(hash, <seealso cref="#getParent"/>(i));
+ /// }
+ ///
+ /// for (int i = 0; i < <seealso cref="#size()"/>; i++) {
+ /// hash = <seealso cref="MurmurHash#update"/>(hash, <seealso cref="#getReturnState"/>(i));
+ /// }
+ ///
+ /// hash = <seealso cref="MurmurHash#finish"/>(hash, 2 * <seealso cref="#size()"/>);
+ /// return hash;
+ /// }
+ /// </pre>
+ /// </summary>
+ const size_t cachedHashCode;
+
+ protected:
+ PredictionContext(size_t cachedHashCode);
+ ~PredictionContext();
+
+ public:
+ /// Convert a RuleContext tree to a PredictionContext graph.
+ /// Return EMPTY if outerContext is empty.
+ static Ref<PredictionContext> fromRuleContext(const ATN &atn, RuleContext *outerContext);
+
+ virtual size_t size() const = 0;
+ virtual Ref<PredictionContext> getParent(size_t index) const = 0;
+ virtual size_t getReturnState(size_t index) const = 0;
+
+ virtual bool operator == (const PredictionContext &o) const = 0;
+
+ /// This means only the EMPTY (wildcard? not sure) context is in set.
+ virtual bool isEmpty() const;
+ virtual bool hasEmptyPath() const;
+ virtual size_t hashCode() const;
+
+ protected:
+ static size_t calculateEmptyHashCode();
+ static size_t calculateHashCode(Ref<PredictionContext> parent, size_t returnState);
+ static size_t calculateHashCode(const std::vector<Ref<PredictionContext>> &parents,
+ const std::vector<size_t> &returnStates);
+
+ public:
+ // dispatch
+ static Ref<PredictionContext> merge(const Ref<PredictionContext> &a, const Ref<PredictionContext> &b,
+ bool rootIsWildcard, PredictionContextMergeCache *mergeCache);
+
+ /// <summary>
+ /// Merge two <seealso cref="SingletonPredictionContext"/> instances.
+ ///
+ /// <p/>
+ ///
+ /// Stack tops equal, parents merge is same; return left graph.<br/>
+ /// <embed src="images/SingletonMerge_SameRootSamePar.svg" type="image/svg+xml"/>
+ ///
+ /// <p/>
+ ///
+ /// Same stack top, parents differ; merge parents giving array node, then
+ /// remainders of those graphs. A new root node is created to point to the
+ /// merged parents.<br/>
+ /// <embed src="images/SingletonMerge_SameRootDiffPar.svg" type="image/svg+xml"/>
+ ///
+ /// <p/>
+ ///
+ /// Different stack tops pointing to same parent. Make array node for the
+ /// root where both element in the root point to the same (original)
+ /// parent.<br/>
+ /// <embed src="images/SingletonMerge_DiffRootSamePar.svg" type="image/svg+xml"/>
+ ///
+ /// <p/>
+ ///
+ /// Different stack tops pointing to different parents. Make array node for
+ /// the root where each element points to the corresponding original
+ /// parent.<br/>
+ /// <embed src="images/SingletonMerge_DiffRootDiffPar.svg" type="image/svg+xml"/>
+ /// </summary>
+ /// <param name="a"> the first <seealso cref="SingletonPredictionContext"/> </param>
+ /// <param name="b"> the second <seealso cref="SingletonPredictionContext"/> </param>
+ /// <param name="rootIsWildcard"> {@code true} if this is a local-context merge,
+ /// otherwise false to indicate a full-context merge </param>
+ /// <param name="mergeCache"> </param>
+ static Ref<PredictionContext> mergeSingletons(const Ref<SingletonPredictionContext> &a,
+ const Ref<SingletonPredictionContext> &b, bool rootIsWildcard, PredictionContextMergeCache *mergeCache);
+
+ /**
+ * Handle case where at least one of {@code a} or {@code b} is
+ * {@link #EMPTY}. In the following diagrams, the symbol {@code $} is used
+ * to represent {@link #EMPTY}.
+ *
+ * <h2>Local-Context Merges</h2>
+ *
+ * <p>These local-context merge operations are used when {@code rootIsWildcard}
+ * is true.</p>
+ *
+ * <p>{@link #EMPTY} is superset of any graph; return {@link #EMPTY}.<br>
+ * <embed src="images/LocalMerge_EmptyRoot.svg" type="image/svg+xml"/></p>
+ *
+ * <p>{@link #EMPTY} and anything is {@code #EMPTY}, so merged parent is
+ * {@code #EMPTY}; return left graph.<br>
+ * <embed src="images/LocalMerge_EmptyParent.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Special case of last merge if local context.<br>
+ * <embed src="images/LocalMerge_DiffRoots.svg" type="image/svg+xml"/></p>
+ *
+ * <h2>Full-Context Merges</h2>
+ *
+ * <p>These full-context merge operations are used when {@code rootIsWildcard}
+ * is false.</p>
+ *
+ * <p><embed src="images/FullMerge_EmptyRoots.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Must keep all contexts; {@link #EMPTY} in array is a special value (and
+ * null parent).<br>
+ * <embed src="images/FullMerge_EmptyRoot.svg" type="image/svg+xml"/></p>
+ *
+ * <p><embed src="images/FullMerge_SameRoot.svg" type="image/svg+xml"/></p>
+ *
+ * @param a the first {@link SingletonPredictionContext}
+ * @param b the second {@link SingletonPredictionContext}
+ * @param rootIsWildcard {@code true} if this is a local-context merge,
+ * otherwise false to indicate a full-context merge
+ */
+ static Ref<PredictionContext> mergeRoot(const Ref<SingletonPredictionContext> &a,
+ const Ref<SingletonPredictionContext> &b, bool rootIsWildcard);
+
+ /**
+ * Merge two {@link ArrayPredictionContext} instances.
+ *
+ * <p>Different tops, different parents.<br>
+ * <embed src="images/ArrayMerge_DiffTopDiffPar.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Shared top, same parents.<br>
+ * <embed src="images/ArrayMerge_ShareTopSamePar.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Shared top, different parents.<br>
+ * <embed src="images/ArrayMerge_ShareTopDiffPar.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Shared top, all shared parents.<br>
+ * <embed src="images/ArrayMerge_ShareTopSharePar.svg" type="image/svg+xml"/></p>
+ *
+ * <p>Equal tops, merge parents and reduce top to
+ * {@link SingletonPredictionContext}.<br>
+ * <embed src="images/ArrayMerge_EqualTop.svg" type="image/svg+xml"/></p>
+ */
+ static Ref<PredictionContext> mergeArrays(const Ref<ArrayPredictionContext> &a,
+ const Ref<ArrayPredictionContext> &b, bool rootIsWildcard, PredictionContextMergeCache *mergeCache);
+
+ protected:
+ /// Make pass over all M parents; merge any equal() ones.
+ /// @returns true if the list has been changed (i.e. duplicates where found).
+ static bool combineCommonParents(std::vector<Ref<PredictionContext>> &parents);
+
+ public:
+ static std::string toDOTString(const Ref<PredictionContext> &context);
+
+ static Ref<PredictionContext> getCachedContext(const Ref<PredictionContext> &context,
+ PredictionContextCache &contextCache,
+ std::map<Ref<PredictionContext>, Ref<PredictionContext>> &visited);
+
+ // ter's recursive version of Sam's getAllNodes()
+ static std::vector<Ref<PredictionContext>> getAllContextNodes(const Ref<PredictionContext> &context);
+ static void getAllContextNodes_(const Ref<PredictionContext> &context,
+ std::vector<Ref<PredictionContext>> &nodes, std::set<PredictionContext *> &visited);
+
+ virtual std::string toString() const;
+ virtual std::string toString(Recognizer *recog) const;
+
+ std::vector<std::string> toStrings(Recognizer *recognizer, int currentState);
+ std::vector<std::string> toStrings(Recognizer *recognizer, const Ref<PredictionContext> &stop, int currentState);
+ };
+
+ struct PredictionContextHasher {
+ size_t operator () (const Ref<PredictionContext> &k) const {
+ return k->hashCode();
+ }
+ };
+
+ struct PredictionContextComparer {
+ bool operator () (const Ref<PredictionContext> &lhs, const Ref<PredictionContext> &rhs) const
+ {
+ if (lhs == rhs) // Object identity.
+ return true;
+ return (lhs->hashCode() == rhs->hashCode()) && (*lhs == *rhs);
+ }
+ };
+
+ class PredictionContextMergeCache {
+ public:
+ Ref<PredictionContext> put(Ref<PredictionContext> const& key1, Ref<PredictionContext> const& key2,
+ Ref<PredictionContext> const& value);
+ Ref<PredictionContext> get(Ref<PredictionContext> const& key1, Ref<PredictionContext> const& key2);
+
+ void clear();
+ std::string toString() const;
+ size_t count() const;
+
+ private:
+ std::unordered_map<Ref<PredictionContext>,
+ std::unordered_map<Ref<PredictionContext>, Ref<PredictionContext>, PredictionContextHasher, PredictionContextComparer>,
+ PredictionContextHasher, PredictionContextComparer> _data;
+
+ };
+
+} // namespace atn
+} // namespace antlr4
+
projects / toc / blobdiff