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ImathLimits.h

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
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// *       Redistributions in binary form must reproduce the above
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// distribution.
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// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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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.
//
//-----------------------------------------------------------------


00115 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 <>
00131 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 <>
00142 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 <>
00153 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 <>
00164 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 <>
00175 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 <>
00186 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 <>
00197 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 <>
00208 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 <>
00219 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 <>
00230 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 <>
00241 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 <>
00252 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

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