prelude.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Boost Software License - Version 1.0 - August 17th, 2003
 *
 * Permission is hereby granted, free of charge, to any person or organization
 * obtaining a copy of the software and accompanying documentation covered by
 * this license (the "Software") to use, reproduce, display, distribute,
 * execute, and transmit the Software, and to prepare derivative works of the
 * Software, and to permit third-parties to whom the Software is furnished to
 * do so, all subject to the following:
 *
 * The copyright notices in the Software and this entire statement, including
 * the above license grant, this restriction and the following disclaimer,
 * must be included in all copies of the Software, in whole or in part, and
 * all derivative works of the Software, unless such copies or derivative
 * works are solely in the form of machine-executable object code generated by
 * a source language processor.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 **********************************************************************/

#pragma once

#include <type_traits>
#include <iterator>
#include <QPair>
#include <QStringList>
#include <boost/optional.hpp>
#include "oldcppkludges.h"

namespace LeechCraft
{
namespace Util
{
    template<typename T>
    struct WrapType
    {
        using type = T;
    };

    template<typename T>
    using WrapType_t = typename WrapType<T>::type;

    template<>
    struct WrapType<QList<QString>>
    {
        using type = QStringList;
    };

    template<typename T1, typename T2, template<typename U> class Container, typename F>
    auto ZipWith (const Container<T1>& c1, const Container<T2>& c2, F f) -> WrapType_t<Container<std::decay_t<std::result_of_t<F (T1, T2)>>>>
    {
        WrapType_t<Container<std::decay_t<std::result_of_t<F (T1, T2)>>>> result;

        using std::begin;
        using std::end;

        auto i1 = begin (c1), e1 = end (c1);
        auto i2 = begin (c2), e2 = end (c2);
        for ( ; i1 != e1 && i2 != e2; ++i1, ++i2)
            result.push_back (f (*i1, *i2));
        return result;
    }

    template<typename T1, typename T2,
        template<typename U> class Container,
        template<typename U1, typename U2> class Pair = QPair>
    auto Zip (const Container<T1>& c1, const Container<T2>& c2) -> Container<Pair<T1, T2>>
    {
        return ZipWith (c1, c2,
                [] (const T1& t1, const T2& t2) -> Pair<T1, T2>
                    { return { t1, t2}; });
    }

    namespace detail
    {
        template<typename Res, typename T>
        void Append (Res& result, T&& val, decltype (result.push_back (std::forward<T> (val)))* = nullptr)
        {
            result.push_back (std::forward<T> (val));
        }

        template<typename Res, typename T>
        void Append (Res& result, T&& val, decltype (result.insert (std::forward<T> (val)))* = nullptr)
        {
            result.insert (std::forward<T> (val));
        }

        template<typename T, typename F>
        constexpr bool IsInvokableWithConstImpl (std::result_of_t<F (const T&)>*)
        {
            return true;
        }

        template<typename T, typename F>
        constexpr bool IsInvokableWithConstImpl (...)
        {
            return false;
        }

        template<typename T, typename F>
        constexpr bool IsInvokableWithConst ()
        {
            return IsInvokableWithConstImpl<std::decay_t<T>, F> (0);
        }

        template<typename>
        struct CountArgs
        {
            static const size_t ArgsCount = 0;
        };

        template<template<typename...> class Container, typename... Args>
        struct CountArgs<Container<Args...>>
        {
            static const size_t ArgsCount = sizeof... (Args);
        };

        template<typename C>
        constexpr bool IsSimpleContainer ()
        {
            return CountArgs<std::decay_t<C>>::ArgsCount == 1;
        }

        template<typename F, typename Cont>
        constexpr bool DoesReturnVoid ()
        {
            using Ret_t = decltype (Invoke (std::declval<F> (), *std::declval<Cont> ().begin ()));
            return std::is_same<void, Ret_t>::value;
        }
    }

    template<
            typename T,
            template<typename U> class Container,
            typename F,
            typename = std::enable_if_t<detail::IsSimpleContainer<Container<T>> ()>,
            typename = std::enable_if_t<!detail::DoesReturnVoid<F, Container<T>> ()>
        >
    auto Map (const Container<T>& c, F f)
    {
        WrapType_t<Container<std::decay_t<decltype (Invoke (f, *c.begin ()))>>> result;
        for (auto&& t : c)
            detail::Append (result, Invoke (f, t));
        return result;
    }

    template<
            typename Container,
            typename F,
            template<typename> class ResultCont = QList,
            typename = std::enable_if_t<!detail::IsSimpleContainer<Container> ()>,
            typename = std::enable_if_t<!detail::DoesReturnVoid<F, Container> ()>
        >
    auto Map (const Container& c, F f)
    {
        WrapType_t<ResultCont<std::decay_t<decltype (Invoke (f, *c.begin ()))>>> cont;
        for (auto&& t : c)
            detail::Append (cont, Invoke (f, t));
        return cont;
    }

    template<
            typename Container,
            typename F,
            typename = std::enable_if_t<detail::DoesReturnVoid<F, Container> ()>
        >
    auto Map (const Container& c, F f)
    {
        for (auto&& t : c)
            Invoke (f, t);
    }

    template<
            typename Container,
            typename F,
            typename = std::enable_if_t<detail::DoesReturnVoid<F, Container> ()>
        >
    auto Map (Container& c, F f)
    {
        for (auto&& t : c)
            Invoke (f, t);
    }

    template<typename T, template<typename U> class Container, typename F>
    Container<T> Filter (const Container<T>& c, F f)
    {
        Container<T> result;
        for (const auto& item : c)
            if (Invoke (f, item))
                detail::Append (result, item);
        return result;
    }

    template<template<typename> class Container, typename T>
    Container<T> Concat (const Container<Container<T>>& containers)
    {
        Container<T> result;
        for (const auto& cont : containers)
            std::copy (cont.begin (), cont.end (), std::back_inserter (result));
        return result;
    }

    template<template<typename...> class Container, typename... ContArgs>
    auto Concat (const Container<ContArgs...>& containers) -> std::decay_t<decltype (*containers.begin ())>
    {
        std::decay_t<decltype (*containers.begin ())> result;
        for (const auto& cont : containers)
            std::copy (cont.begin (), cont.end (), std::back_inserter (result));
        return result;
    }

    template<typename Cont, typename F>
    auto ConcatMap (Cont&& c, F&& f) -> decltype (Concat (Map (std::forward<Cont> (c), std::forward<F> (f))))
    {
        return Concat (Map (std::forward<Cont> (c), std::forward<F> (f)));
    }

    template<template<typename> class Container, typename T>
    Container<Container<T>> SplitInto (size_t numChunks, const Container<T>& container)
    {
        Container<Container<T>> result;

        const size_t chunkSize = container.size () / numChunks;
        for (size_t i = 0; i < numChunks; ++i)
        {
            Container<T> subcont;
            const auto start = container.begin () + chunkSize * i;
            const auto end = start + chunkSize;
            std::copy (start, end, std::back_inserter (subcont));
            result.push_back (subcont);
        }

        const auto lastStart = container.begin () + chunkSize * numChunks;
        const auto lastEnd = container.end ();
        std::copy (lastStart, lastEnd, std::back_inserter (result.front ()));

        return result;
    }

    template<template<typename Pair, typename... Rest> class Cont, template<typename K, typename V> class Pair, typename K, typename V, typename KV, typename... Rest>
    boost::optional<V> Lookup (const KV& key, const Cont<Pair<K, V>, Rest...>& cont)
    {
        for (const auto& pair : cont)
            if (pair.first == key)
                return pair.second;

        return {};
    }

    template<typename Cont>
    Cont Sorted (Cont&& cont)
    {
        std::sort (cont.begin (), cont.end ());
        return cont;
    }

    const auto Id = [] (const auto& t) { return t; };

    template<typename R>
    auto ComparingBy (R r)
    {
        return [r] (const auto& left, const auto& right) { return Invoke (r, left) < Invoke (r, right); };
    }

    const auto Apply = [] (const auto& t) { return t (); };

    const auto Fst = [] (const auto& pair) { return pair.first; };

    const auto Snd = [] (const auto& pair) { return pair.second; };

    template<typename F>
    auto First (F&& f)
    {
        return [f = std::forward<F> (f)] (const auto& pair) { return Invoke (f, pair.first); };
    }

    template<typename F>
    auto Second (F&& f)
    {
        return [f = std::forward<F> (f)] (const auto& pair) { return Invoke (f, pair.second); };
    }

    template<typename F>
    auto Flip (F&& f)
    {
        return [f = std::move (f)] (auto&& left, auto&& right)
        {
            return f (std::forward<decltype (right)> (right),
                    std::forward<decltype (left)> (left));
        };
    }
}
}