Can C 0x Metaprogramming Techniques be Used to Programmatically Assign Values to Static Arrays at Compile Time?

Programmatically Generating Static Arrays at Compile Time in C

Given the ability to define static arrays at compile time in C , is it possible to programmatically assign their values using metaprogramming techniques?

Question 1: Programmatic Assignment of Array Values

Yes, using C 0x features, it is feasible to initialize array elements "programmatically" at compile time. Consider the following example:

template<unsigned... args>
struct ArrayHolder {
    static const unsigned data[sizeof...(args)];
};

template<unsigned... args>
const unsigned ArrayHolder<args...>::data[sizeof...(args)] = { args... };

Question 2: Selective Assignment of Array Values

Assuming the array contains recurring values with some exceptions, it is possible to selectively assign values programmatically:

template<size_t N, template<size_t> class F, unsigned... args>
struct generate_array_impl {
    typedef typename generate_array_impl<N-1, F, F<N>::value, args...>::result result;
};

template<template<size_t> class F, unsigned... args>
struct generate_array_impl<0, F, args...> {
    typedef ArrayHolder<F<0>::value, args...> result;
};

template<size_t N, template<size_t> class F>
struct generate_array {
    typedef typename generate_array_impl<N-1, F>::result result;
};

Usage for the array with recurring zeros except for elements 2 and 3:

template<size_t index>
struct MetaFunc {
    enum { value = index == 2 || index == 3 ? index + 1 : 0 };
};

void test() {
    const size_t count = 7;
    typedef generate_array<count, MetaFunc>::result A;

    for (size_t i=0; i<count; ++i)
        std::cout << A::data[i] << "\n";
}

While these solutions are limited by the maximum template instantiation depth, they demonstrate the potential of C 0x for programmatic array creation and initialization.

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