Teuchos - Trilinos Tools Package Version of the Day
Teuchos_HashUtils.hpp
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00041 
00042 #ifndef TEUCHOS_HASHUTILS_H
00043 #define TEUCHOS_HASHUTILS_H
00044 
00049 #include "Teuchos_ConfigDefs.hpp"
00050 
00051 namespace Teuchos
00052 {
00053   using std::string;
00054 
00060   class TEUCHOSCORE_LIB_DLL_EXPORT HashUtils
00061     {
00062     public:
00063       /* Get the next prime in a sequence of hashtable sizes */
00064       static int nextPrime(int newCapacity);
00065 
00066     private:
00067 
00068       // sequence of primes generated via mathematica:
00069       // Table[Prime[Round[1.5^x]], {x, 8, 36}]
00070       static const int primeCount_;
00071       static const int primes_[];
00072       /*={101, 163, 271, 443, 733, 1187, 1907, 3061,
00073         4919, 7759, 12379, 19543, 30841, 48487, 75989,
00074         119089, 185971, 290347, 452027, 703657, 1093237,
00075         1695781, 2627993, 4067599, 6290467, 9718019,
00076         15000607, 23133937, 35650091};*/
00077     };
00078 
00082   template <class T> int hashCode(const T& x);
00083 
00087   template <> inline int hashCode(const int& x) 
00088     {
00089       return x;
00090     }
00091 
00095   template <> inline int hashCode(const double& x)
00096     {
00097       return (int) x;
00098     }
00099 
00103   template <> inline int hashCode(const bool& x)
00104     {
00105       return (int) x;
00106     }
00107 
00111   template <> inline int hashCode(const long long& x)
00112     {
00113       return (int) x;
00114     }
00115 
00119   template <> inline int hashCode(const std::string& x)
00120     {
00121       const char* str = x.c_str();
00122       int len = x.length();
00123       int step = len/4 + 1;
00124       int base = 1;
00125       int rtn = 0;
00126 
00127       for (int i=0; i<len/2; i+=step)
00128         {
00129           rtn += base*(int) str[i];
00130           base *= 128;
00131           rtn += base*(int) str[len-i-1];
00132           base *= 128;
00133         }
00134 
00135       return rtn;
00136     }
00137 
00138 
00139 
00140 }
00141 #endif // TEUCHOS_HASHUTILS_H
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