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diff --git a/src/hash-util.h b/src/hash-util.h
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+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef WABT_HASH_UTIL_H_
+#define WABT_HASH_UTIL_H_
+
+#include <cstdlib>
+#include <functional>
+
+namespace wabt {
+
+typedef std::size_t hash_code;
+
+inline hash_code hash_combine() { return 0; }
+inline hash_code hash_combine(hash_code seed) { return seed; }
+hash_code hash_combine(hash_code x, hash_code y);
+
+template <typename T, typename... U>
+inline hash_code hash_combine(const T& first, const U&... rest) {
+  return hash_combine(hash_combine(rest...), std::hash<T>()(first));
+}
+
+template <typename It>
+inline hash_code hash_range(It first, It last) {
+  hash_code result = 0;
+  for (auto iter = first; iter != last; ++iter) {
+    result = hash_combine(result, *iter);
+  }
+  return result;
+}
+
+}  // namespace wabt
+
+#endif  // WABT_HASH_UTIL_H_