ImathLimits.h

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//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
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// 
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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.
//------------------------------------------

#if defined _WIN32 || defined _WIN64
    #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
//          (for float and double: smallest normalized
//          positive value)
//
//  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