fold.hpp

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/*
Copyright© 2014 Akihiro Nishimura

This software is released under the MIT License.
http://opensource.org/licenses/mit-license.php
*/

#ifndef SIG_UTIL_FOLD_HPP
#define SIG_UTIL_FOLD_HPP

#include "../helper/helper_modules.hpp"
#include "../helper/container_helper.hpp"


namespace sig
{

template <class F, class T, class C>
auto foldl(F&& func, T&& init, C&& list)
{
    using CR = typename impl::remove_const_reference<C>::type;
    using R = decltype(std::forward<F>(func)(std::forward<T>(init), std::declval<typename impl::container_traits<CR>::value_type>()));

    return std::accumulate(impl::begin(std::forward<C>(list)), impl::end(std::forward<C>(list)), static_cast<R>(init), std::forward<F>(func));
}

#if SIG_ENABLE_FOLDR

template <class F, class T, class C>
auto foldr(F&& func, T&& init, C&& list)
{
    using CR = typename impl::remove_const_reference<C>::type;
    using R = decltype(impl::eval(std::forward<F>(func), std::forward<T>(init), std::declval<typename impl::container_traits<CR>::value_type>()));

    return std::accumulate(impl::rbegin(std::forward<C>(list)), impl::rend(std::forward<C>(list)), static_cast<R>(std::forward<T>(init)), std::bind(std::forward<F>(func), _2, _1));
}
#endif



template <class F1, class F2, class T, class... Cs>
auto dotProduct(F1&& fold_func, F2&& oper_func, T&& init, Cs&&... lists)
{
    using R = decltype(impl::eval(
        std::forward<F1>(fold_func),
        std::forward<T>(init),
        impl::eval(
            std::forward<F2>(oper_func),
            std::declval<typename impl::container_traits<typename impl::remove_const_reference<Cs>::type>::value_type>()...)
        )
    );
    R result = std::forward<T>(init);
    const uint length = min(lists.size()...);

    iterative_fold(length, result, std::forward<F2>(oper_func), std::forward<F1>(fold_func), impl::begin(std::forward<Cs>(lists))...);

    return result;
}

}
#endif