add antlr

lib/antlr4/include/misc/MurmurHash.h

@@ -0,0 +1,76 @@
+/* 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 "antlr4-common.h"
+
+namespace antlr4 {
+namespace misc {
+
+  class ANTLR4CPP_PUBLIC MurmurHash {
+
+  private:
+    static const size_t DEFAULT_SEED = 0;
+
+    /// Initialize the hash using the default seed value.
+    /// Returns the intermediate hash value.
+  public:
+    static size_t initialize();
+
+    /// Initialize the hash using the specified seed.
+    static size_t initialize(size_t seed);
+
+    /// Update the intermediate hash value for the next input {@code value}.
+    /// <param name="hash"> the intermediate hash value </param>
+    /// <param name="value"> the value to add to the current hash </param>
+    /// Returns the updated intermediate hash value.
+    static size_t update(size_t hash, size_t value);
+
+    /**
+     * Update the intermediate hash value for the next input {@code value}.
+     *
+     * @param hash the intermediate hash value
+     * @param value the value to add to the current hash
+     * @return the updated intermediate hash value
+     */
+    template <class T>
+    static size_t update(size_t hash, Ref<T> const& value) {
+      return update(hash, value != nullptr ? value->hashCode() : 0);
+    }
+
+    template <class T>
+    static size_t update(size_t hash, T *value) {
+      return update(hash, value != nullptr ? value->hashCode() : 0);
+    }
+
+    /// <summary>
+    /// Apply the final computation steps to the intermediate value {@code hash}
+    /// to form the final result of the MurmurHash 3 hash function.
+    /// </summary>
+    /// <param name="hash"> the intermediate hash value </param>
+    /// <param name="entryCount"> the number of calls to update() before calling finish() </param>
+    /// <returns> the final hash result </returns>
+    static size_t finish(size_t hash, size_t entryCount);
+
+    /// Utility function to compute the hash code of an array using the MurmurHash3 algorithm.
+    ///
+    /// @param <T> the array element type </param>
+    /// <param name="data"> the array data </param>
+    /// <param name="seed"> the seed for the MurmurHash algorithm </param>
+    /// <returns> the hash code of the data </returns>
+    template<typename T> // where T is C array type
+    static size_t hashCode(const std::vector<Ref<T>> &data, size_t seed) {
+      size_t hash = initialize(seed);
+      for (auto entry : data) {
+        hash = update(hash, entry->hashCode());
+      }
+
+      return finish(hash, data.size());
+    }
+  };
+
+} // namespace atn
+} // namespace antlr4