gcd.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_GCD_HH
#define DUNE_GCD_HH
 
namespace Dune
{
#ifndef DOXYGEN
  template<long a, long b, bool bo>
  struct GcdHelper
  {};
 
 
  template<long a, long b>
  struct GcdHelper<a,b,true>
  {
    static void conceptCheck()
    {
      static_assert(b<a, "b<a must hold!");
      static_assert(0<b, "b must be positive");
    }
 
 
    const static long gcd = GcdHelper<b,a%b,true>::gcd;
  };
 
  template<long a, long b>
  struct GcdHelper<a,b,false>
  {
    const static long gcd = GcdHelper<b,a,true>::gcd;
  };
  template<long a>
  struct GcdHelper<a,0,true>
  {
    const static long gcd=a;
  };
 
#endif
 
  template<long a, long b>
  struct Gcd
  {
    const static long value = GcdHelper<a,b,(a>b)>::gcd;
  };
 
}
 
#endif