#ifndef PFOR_PFOR_USEROP_H
#define PFOR_PFOR_USEROP_H

#include "expression/expression.h"

namespace pfor {

template<typename F>
struct UserOperator {
	F f;

	template<typename... Args, std::enable_if_t<expr::allExpression<Args...>>* = nullptr>
	inline decltype(auto) eval(Args&&... args) {
		return f(std::forward<Args>(args).eval()...);
	}

	template<typename... Args>
	inline decltype(auto) eval(std::size_t i, Args&&... args) {
		return f(std::forward<Args>(args)[i]...);
	}
};

/**
 * @brief make an operator from a function
 *
 * @param[in] f a function
 *
 * @return an operator (UserOperator)
 */
template<typename F>
auto makeOperator(F&& f) {
	return [f = std::forward<F>(f)](auto&&... args) {
		using Op = UserOperator<decltype(f)>;
		using Expr = pfor::expr::Expression<Op, expr::AsExpression<std::remove_reference_t<decltype(args)>>...>;
		return Expr{{f}, decltype(args)(args)...};
	};
}

}

#endif