source: NonGTP/OpenEXR/include/Imath/ImathLimits.h @ 855

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// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
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#ifndef INCLUDED_IMATHLIMITS_H
#define INCLUDED_IMATHLIMITS_H

//----------------------------------------------------------------
//
//      Limitations of the basic C++ numerical data types
//
//----------------------------------------------------------------

#include <float.h>
#include <limits.h>

//------------------------------------------
// In Windows, min and max are macros.  Yay.
//------------------------------------------

#ifdef PLATFORM_WINDOWS
    #ifdef min
        #undef min
    #endif
    #ifdef max
        #undef max
    #endif
#endif

namespace Imath {


//-----------------------------------------------------------------
//
// Template class limits<T> returns information about the limits
// of numerical data type T:
//
//      min()           largest possible negative value of type T
//
//      max()           largest possible positive value of type T
//
//      smallest()      smallest possible positive value of type T
//
//      epsilon()       smallest possible e of type T, for which
//                      1 + e != 1
//
//      isIntegral()    returns true if T is an integral type
//
//      isSigned()      returns true if T is signed
//
// Class limits<T> is useful to implement template classes or
// functions which depend on the limits of a numerical type
// which is not known in advance; for example:
//
//      template <class T> max (T x[], int n)
//      {
//          T m = limits<T>::min();
//
//          for (int i = 0; i < n; i++)
//              if (m < x[i])
//                  m = x[i];
//
//          return m;
//      }
//
// Class limits<T> has been implemented for the following types:
//
//      char, signed char, unsigned char
//      short, unsigned short
//      int, unsigned int
//      long, unsigned long
//      float
//      double
//      long double
//
// Class limits<T> has only static member functions, all of which
// are implemented as inlines.  No objects of type limits<T> are
// ever created.
//
//-----------------------------------------------------------------


template <class T> struct limits
{
    static T    min();
    static T    max();
    static T    smallest();
    static T    epsilon();
    static bool isIntegral();
    static bool isSigned();
};


//---------------
// Implementation
//---------------

template <>
struct limits <char>
{
    static char                 min()           {return CHAR_MIN;}
    static char                 max()           {return CHAR_MAX;}
    static char                 smallest()      {return 1;}
    static char                 epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return (char) ~0 < 0;}
};

template <>
struct limits <signed char>
{
    static signed char          min()           {return SCHAR_MIN;}
    static signed char          max()           {return SCHAR_MAX;}
    static signed char          smallest()      {return 1;}
    static signed char          epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <unsigned char>
{
    static unsigned char        min()           {return 0;}
    static unsigned char        max()           {return UCHAR_MAX;}
    static unsigned char        smallest()      {return 1;}
    static unsigned char        epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return false;}
};

template <>
struct limits <short>
{
    static short                min()           {return SHRT_MIN;}
    static short                max()           {return SHRT_MAX;}
    static short                smallest()      {return 1;}
    static short                epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <unsigned short>
{
    static unsigned short       min()           {return 0;}
    static unsigned short       max()           {return USHRT_MAX;}
    static unsigned short       smallest()      {return 1;}
    static unsigned short       epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return false;}
};

template <>
struct limits <int>
{
    static int                  min()           {return INT_MIN;}
    static int                  max()           {return INT_MAX;}
    static int                  smallest()      {return 1;}
    static int                  epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <unsigned int>
{
    static unsigned int         min()           {return 0;}
    static unsigned int         max()           {return UINT_MAX;}
    static unsigned int         smallest()      {return 1;}
    static unsigned int         epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return false;}
};

template <>
struct limits <long>
{
    static long                 min()           {return LONG_MIN;}
    static long                 max()           {return LONG_MAX;}
    static long                 smallest()      {return 1;}
    static long                 epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <unsigned long>
{
    static unsigned long        min()           {return 0;}
    static unsigned long        max()           {return ULONG_MAX;}
    static unsigned long        smallest()      {return 1;}
    static unsigned long        epsilon()       {return 1;}
    static bool                 isIntegral()    {return true;}
    static bool                 isSigned()      {return false;}
};

template <>
struct limits <float>
{
    static float                min()           {return -FLT_MAX;}
    static float                max()           {return FLT_MAX;}
    static float                smallest()      {return FLT_MIN;}
    static float                epsilon()       {return FLT_EPSILON;}
    static bool                 isIntegral()    {return false;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <double>
{
    static double               min()           {return -DBL_MAX;}
    static double               max()           {return DBL_MAX;}
    static double               smallest()      {return DBL_MIN;}
    static double               epsilon()       {return DBL_EPSILON;}
    static bool                 isIntegral()    {return false;}
    static bool                 isSigned()      {return true;}
};

template <>
struct limits <long double>
{
    static long double          min()           {return -LDBL_MAX;}
    static long double          max()           {return LDBL_MAX;}
    static long double          smallest()      {return LDBL_MIN;}
    static long double          epsilon()       {return LDBL_EPSILON;}
    static bool                 isIntegral()    {return false;}
    static bool                 isSigned()      {return true;}
};


} // namespace Imath

#endif