libscheaders/functools.hpp

//
// functools.hpp
// libcommon
//
// Created by Bob Polis at 2019-10-19
// Copyright (c) 2019 SwiftCoder. All rights reserved.
//

#ifndef _functools_H_
#define _functools_H_

#include <vector>
#include <functional>
#include <algorithm>
#include <iterator>

namespace sc {

	// std::vector versions

	template<class T, class M>
	std::vector<M> map(const std::vector<T>& seq, std::function<M(T)> fun) {
		std::vector<M> result;
		std::transform(seq.begin(), seq.end(), back_inserter(result), fun);
		return result;
	}

	template<class T>
	std::vector<T> filter(const std::vector<T>& seq, std::function<bool(T)> fun) {
		std::vector<T> result;
		std::copy_if(seq.begin(), seq.end(), back_inserter(result), fun);
		return result;
	}

	template<class T, class R>
	R reduce(const std::vector<T>& seq, R seed, std::function<R(T, R)> fun) {
		R result {seed};
		for (const auto& elem : seq) {
			result = fun(elem, result);
		}
		return result;
	}

	// iterator versions

	template<class T, class M, class FwdIter>
	std::vector<M> map(FwdIter begin, FwdIter end, std::function<M(T)> fun) {
		std::vector<M> result;
		std::transform(begin, end, std::back_inserter(result), fun);
		return result;
	}

	template<class T, class FwdIter>
	std::vector<T> filter(FwdIter begin, FwdIter end, std::function<bool(T)> fun) {
		std::vector<T> result;
		std::copy_if(begin, end, std::back_inserter(result), fun);
		return result;
	}

	template<class T, class R, class FwdIter>
	R reduce(FwdIter begin, FwdIter end, R seed, std::function<R(T, R)> fun) {
		R result {seed};
		for (FwdIter it = begin; it != end; ++it) {
			result = fun(*it, result);
		}
		return result;
	}

}

#endif // _functools_H_