function_traits.h

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#pragma once
 
#include "fl/stl/stdint.h"
#include "fl/stl/tuple.h"
 
namespace fl {
 
// =============================================================================
// Function signature traits - extract return type and argument types
// =============================================================================
 
template <typename T>
struct function_traits;
 
// For free functions
template <typename R, typename... Args>
struct function_traits<R(Args...)> {
    using return_type = R;
    using args_tuple = fl::tuple<Args...>;
    static constexpr fl::size arity = sizeof...(Args);
 
    template <fl::size N>
    using arg = typename fl::tuple_element<N, args_tuple>::type;
};
 
// For function pointers
template <typename R, typename... Args>
struct function_traits<R(*)(Args...)> : function_traits<R(Args...)> {};
 
// For fl::function
template <typename R, typename... Args>
struct function_traits<fl::function<R(Args...)>> : function_traits<R(Args...)> {};
 
} // namespace fl