00001 // @HEADER 00002 // *********************************************************************** 00003 // 00004 // Teuchos: Common Tools Package 00005 // Copyright (2004) Sandia Corporation 00006 // 00007 // Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive 00008 // license for use of this work by or on behalf of the U.S. Government. 00009 // 00010 // This library is free software; you can redistribute it and/or modify 00011 // it under the terms of the GNU Lesser General Public License as 00012 // published by the Free Software Foundation; either version 2.1 of the 00013 // License, or (at your option) any later version. 00014 // 00015 // This library is distributed in the hope that it will be useful, but 00016 // WITHOUT ANY WARRANTY; without even the implied warranty of 00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00018 // Lesser General Public License for more details. 00019 // 00020 // You should have received a copy of the GNU Lesser General Public 00021 // License along with this library; if not, write to the Free Software 00022 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 00023 // USA 00024 // Questions? Contact Michael A. Heroux (maherou@sandia.gov) 00025 // 00026 // *********************************************************************** 00027 // @HEADER 00028 00029 #ifndef TEUCHOS_HASHUTILS_H 00030 #define TEUCHOS_HASHUTILS_H 00031 00036 #include "Teuchos_ConfigDefs.hpp" 00037 00038 namespace Teuchos 00039 { 00040 using std::string; 00041 00047 class HashUtils 00048 { 00049 public: 00050 /* Get the next prime in a sequence of hashtable sizes */ 00051 static int nextPrime(int newCapacity); 00052 00053 private: 00054 00055 // sequence of primes generated via mathematica: 00056 // Table[Prime[Round[1.5^x]], {x, 8, 36}] 00057 static const int primeCount_; 00058 static const int primes_[]; 00059 /*={101, 163, 271, 443, 733, 1187, 1907, 3061, 00060 4919, 7759, 12379, 19543, 30841, 48487, 75989, 00061 119089, 185971, 290347, 452027, 703657, 1093237, 00062 1695781, 2627993, 4067599, 6290467, 9718019, 00063 15000607, 23133937, 35650091};*/ 00064 }; 00065 00069 template <class T> int hashCode(const T& x); 00070 00074 template <> inline int hashCode(const int& x) 00075 { 00076 return x; 00077 } 00078 00082 template <> inline int hashCode(const double& x) 00083 { 00084 return (int) x; 00085 } 00086 00090 template <> inline int hashCode(const bool& x) 00091 { 00092 return (int) x; 00093 } 00094 00095 00099 template <> inline int hashCode(const std::string& x) 00100 { 00101 const char* str = x.c_str(); 00102 int len = x.length(); 00103 int step = len/4 + 1; 00104 int base = 1; 00105 int rtn = 0; 00106 00107 for (int i=0; i<len/2; i+=step) 00108 { 00109 rtn += base*(int) str[i]; 00110 base *= 128; 00111 rtn += base*(int) str[len-i-1]; 00112 base *= 128; 00113 } 00114 00115 return rtn; 00116 } 00117 00118 00119 00120 } 00121 #endif // TEUCHOS_HASHUTILS_H