hash: add hash_all variadic tpl func, use in rose

src/util/hash.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2016, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ * \brief Hashing utility functions.
+ */
+
+#ifndef UTIL_HASH_H
+#define UTIL_HASH_H
+
+#include <boost/functional/hash/hash_fwd.hpp>
+
+namespace ue2 {
+
+namespace hash_detail {
+
+template<typename T>
+void hash_build(size_t &v, const T &obj) {
+    boost::hash_combine(v, obj);
+}
+
+template<typename T, typename... Args>
+void hash_build(size_t &v, const T &obj, Args&&... args) {
+    hash_build(v, obj);
+    hash_build(v, args...); // recursive
+}
+
+} // namespace hash_detail
+
+/**
+ * \brief Computes the combined hash of all its arguments.
+ *
+ * Simply use:
+ *
+ *     size_t hash = hash_all(a, b, c, d);
+ *
+ * Where a, b, c and d are hashable.
+ */
+template<typename... Args>
+size_t hash_all(Args&&... args) {
+    size_t v = 0;
+    hash_detail::hash_build(v, args...);
+    return v;
+}
+
+} // namespace ue2
+
+#endif // UTIL_HASH_H