meta.h

/*
http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Int-To-Type
Template meta-programming extras.
*/

#ifndef META_H_
#define META_H_


/** @ingroup util
Enables you to instantiate a template based on an integer value.
For example, this is used in StateVariable.h to choose a different next()
function for each kind of filter, LOWPASS, BANDPASS, HIGHPASS or NOTCH, which are simple
integer values 0,1,2,3 provided to the StateVariable template on instantiation.
Fantastic!
It's in C++11, but not yet available in avr-gcc.
See "c++ enable_if"
*/
template <int I>
struct Int2Type
{
  enum {
    value = I      };
};


/*
//from http://en.wikibooks.org/wiki/C%2B%2B_Programming/Templates/Template_Meta-Programming#Compile-time_programming

//First, the general (unspecialized) template says that factorial<n>::value is given by n*factorial<n-1>::value:
template <unsigned n>
struct factorial
{
  enum { value = n * factorial<n-1>::value };
};


//Next, the specialization for zero says that factorial<0>::value evaluates to 1:
template <>
struct factorial<0>
{
  enum { value = 1 };
};


//And now some code that "calls" the factorial template at compile-time:
// Because calculations are done at compile-time, they can be
// used for things such as array sizes, eg.
//  int array[ factorial<7>::value ];

*/
  
#endif /* META_H_ */