00001 // 00002 // Copyright (c) 2005-2008 Kenichi Watanabe. 00003 // Copyright (c) 2005-2008 Yasuhiro Watari. 00004 // Copyright (c) 2005-2008 Hironori Ichibayashi. 00005 // Copyright (c) 2008-2009 Kazuo Horio. 00006 // Copyright (c) 2009-2013 Naruki Kurata. 00007 // Copyright (c) 2005-2013 Ryota Shioya. 00008 // Copyright (c) 2005-2013 Masahiro Goshima. 00009 // 00010 // This software is provided 'as-is', without any express or implied 00011 // warranty. In no event will the authors be held liable for any damages 00012 // arising from the use of this software. 00013 // 00014 // Permission is granted to anyone to use this software for any purpose, 00015 // including commercial applications, and to alter it and redistribute it 00016 // freely, subject to the following restrictions: 00017 // 00018 // 1. The origin of this software must not be misrepresented; you must not 00019 // claim that you wrote the original software. If you use this software 00020 // in a product, an acknowledgment in the product documentation would be 00021 // appreciated but is not required. 00022 // 00023 // 2. Altered source versions must be plainly marked as such, and must not be 00024 // misrepresented as being the original software. 00025 // 00026 // 3. This notice may not be removed or altered from any source 00027 // distribution. 00028 // 00029 // 00030 00031 00032 #ifndef SHTTL_SIMPLE_HASHER_H 00033 #define SHTTL_SIMPLE_HASHER_H 00034 00035 #include <limits> 00036 #include <stdexcept> 00037 00038 #include "hasher.h" 00039 #include "bit.h" 00040 00041 namespace shttl 00042 { 00043 00044 template<class T = int> 00045 class simple_hasher : public hasher<T> 00046 { 00047 public: 00048 00049 // Types 00050 typedef simple_hasher<T> this_type; 00051 typedef hasher<T> base_type; 00052 00053 typedef typename base_type::size_type size_type; 00054 typedef T value_type; 00055 00056 static std::numeric_limits<value_type> value_info; 00057 00058 // Accessors 00059 size_type size() const { return m_idx_mask + 1; } 00060 00061 // Constructors 00062 explicit simple_hasher(const size_type s) : 00063 m_idx_bit ( s ), 00064 m_idx_mask( (size_type)mask(0, s) ) 00065 { 00066 if( s <= 0 || (u64)value_info.max() < (u64)s ){ 00067 throw std::invalid_argument("simple_hasher::simple_hasher"); 00068 } 00069 } 00070 00071 // Member Functions 00072 size_type index(const T& t) const 00073 { 00074 return static_cast<size_type>(t) & m_idx_mask; 00075 } 00076 00077 // tag (bit) 00078 T tag(const T& key) const 00079 { 00080 return key >> m_idx_bit; 00081 } 00082 00083 // indextagkey 00084 T rebuild(const T& tag, size_type index) const 00085 { 00086 return (T)((tag << m_idx_bit) | index); 00087 } 00088 00089 bool match( const T& lhs, const T& rhs ) const 00090 { 00091 #ifdef SHTTL_DEBUG 00092 if( size() < (size_type)lhs || size() < (size_type)rhs ){ 00093 throw std::range_error("simple_hasher::match"); 00094 } 00095 #endif 00096 return lhs == rhs; 00097 } 00098 00099 protected: 00100 00101 size_type m_idx_bit; 00102 size_type m_idx_mask; 00103 00104 }; 00105 00106 } // namespace shttl 00107 00108 #endif // SHTTL_SIMPLE_HASHER_H