关于float /double、string类型的hash函数/hash表实现

#include <ext/hash_map>#include <math.h>using namespace std;using namespace __gnu_cxx;#define FLT_EPSILON 1.192093e-007#define DBL_EPSILON 2.2204460492503131e-016#define FLOAT_EPSILON(a,b) ( a > b ? fabs(a) * FLT_EPSILON : fabs(b) * FLT_EPSILON)#define DOUBLE_EPSILON(a,b) ( a > b ? fabs(a) * FLT_EPSILON : fabs(b) * DBL_EPSILON)#define float_equal(a, b) (fabs((a)-(b)) <= FLOAT_EPSILON(a,b))#define double_equal(a, b) (fabs((a)-(b)) <= DOUBLE_EPSILON(a,b))#define INT64_MAX 0x7fffffffffffffffLLtypedef struct{ size_t operator()(const double & dValue) const  {       int e = 0 ;    double tmp = dValue;    if (dValue<0)    {     tmp = -dValue;    }    e = ceil (log (dValue));    return size_t(( INT64_MAX+ 1.0) * tmp * exp (-e));  }} hash_double;typedef struct{  bool operator()(const double &value1,const double &value2) const   {     return double_equal(value1,value2);   }} hash_double_cmp;typedef struct{   size_t operator()(const string & str) const   {     size_t h=0;for(size_t i=0;i<str.length();++i)     {      h = ( h<<5 ) - h + str[i];     }     return h;     //return __stl_hash_string(str.c_str());   }} hash_string;typedef struct{   bool operator()(const string &str1,const string &str2) const   {     return str1.compare(str2) == 0;    }} hash_str_cmp;hash_map<double, vector,hash_double,hash_double_cmp> m_doubleMap;hash_map<string, vector,hash_string,hash_str_cmp> m_strMap;