115 lines
3.8 KiB
C++
115 lines
3.8 KiB
C++
// Protocol Buffers - Google's data interchange format
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// Copyright 2008 Google Inc. All rights reserved.
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// https://developers.google.com/protocol-buffers/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Author: kenton@google.com (Kenton Varda)
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#ifndef GOOGLE_PROTOBUF_STUBS_HASH_H__
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#define GOOGLE_PROTOBUF_STUBS_HASH_H__
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#include <cstring>
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#include <string>
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#include <unordered_map>
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#include <unordered_set>
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# define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START \
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namespace google { \
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namespace protobuf {
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# define GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END }}
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namespace google {
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namespace protobuf {
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template <typename Key>
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struct hash : public std::hash<Key> {};
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template <typename Key>
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struct hash<const Key*> {
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inline size_t operator()(const Key* key) const {
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return reinterpret_cast<size_t>(key);
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}
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};
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// Unlike the old SGI version, the TR1 "hash" does not special-case char*. So,
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// we go ahead and provide our own implementation.
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template <>
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struct hash<const char*> {
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inline size_t operator()(const char* str) const {
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size_t result = 0;
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for (; *str != '\0'; str++) {
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result = 5 * result + static_cast<size_t>(*str);
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}
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return result;
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}
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};
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template<>
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struct hash<bool> {
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size_t operator()(bool x) const {
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return static_cast<size_t>(x);
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}
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};
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template <>
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struct hash<std::string> {
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inline size_t operator()(const std::string& key) const {
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return hash<const char*>()(key.c_str());
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}
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static const size_t bucket_size = 4;
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static const size_t min_buckets = 8;
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inline bool operator()(const std::string& a, const std::string& b) const {
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return a < b;
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}
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};
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template <typename First, typename Second>
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struct hash<std::pair<First, Second> > {
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inline size_t operator()(const std::pair<First, Second>& key) const {
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size_t first_hash = hash<First>()(key.first);
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size_t second_hash = hash<Second>()(key.second);
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// FIXME(kenton): What is the best way to compute this hash? I have
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// no idea! This seems a bit better than an XOR.
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return first_hash * ((1 << 16) - 1) + second_hash;
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}
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static const size_t bucket_size = 4;
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static const size_t min_buckets = 8;
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inline bool operator()(const std::pair<First, Second>& a,
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const std::pair<First, Second>& b) const {
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return a < b;
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}
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};
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} // namespace protobuf
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} // namespace google
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#endif // GOOGLE_PROTOBUF_STUBS_HASH_H__
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