rx-buffer_count.hpp

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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.

#pragma once

#if !defined(RXCPP_OPERATORS_RX_BUFFER_COUNT_HPP)
#define RXCPP_OPERATORS_RX_BUFFER_COUNT_HPP

#include "../rx-includes.hpp"

namespace rxcpp {

namespace operators {

namespace detail {

template<class... AN>
struct buffer_count_invalid_arguments {};

template<class... AN>
struct buffer_count_invalid : public rxo::operator_base<buffer_count_invalid_arguments<AN...>> {
    using type = observable<buffer_count_invalid_arguments<AN...>, buffer_count_invalid<AN...>>;
};
template<class... AN>
using buffer_count_invalid_t = typename buffer_count_invalid<AN...>::type;

template<class T>
struct buffer_count
{
    typedef rxu::decay_t<T> source_value_type;
    typedef std::vector<source_value_type> value_type;

    struct buffer_count_values
    {
        buffer_count_values(int c, int s)
            : count(c)
            , skip(s)
        {
        }
        int count;
        int skip;
    };

    buffer_count_values initial;

    buffer_count(int count, int skip)
        : initial(count, skip)
    {
    }

    template<class Subscriber>
    struct buffer_count_observer : public buffer_count_values
    {
        typedef buffer_count_observer<Subscriber> this_type;
        typedef std::vector<T> value_type;
        typedef rxu::decay_t<Subscriber> dest_type;
        typedef observer<value_type, this_type> observer_type;
        dest_type dest;
        mutable int cursor;
        mutable std::deque<value_type> chunks;

        buffer_count_observer(dest_type d, buffer_count_values v)
            : buffer_count_values(v)
            , dest(std::move(d))
            , cursor(0)
        {
        }
        void on_next(T v) const {
            if (cursor++ % this->skip == 0) {
                chunks.emplace_back();
            }
            for(auto& chunk : chunks) {
                chunk.push_back(v);
            }
            while (!chunks.empty() && int(chunks.front().size()) == this->count) {
                dest.on_next(std::move(chunks.front()));
                chunks.pop_front();
            }
        }
        void on_error(std::exception_ptr e) const {
            dest.on_error(e);
        }
        void on_completed() const {
            auto done = on_exception(
                [&](){
                    while (!chunks.empty()) {
                        dest.on_next(std::move(chunks.front()));
                        chunks.pop_front();
                    }
                    return true;
                },
                dest);
            if (done.empty()) {
                return;
            }
            dest.on_completed();
        }

        static subscriber<T, observer<T, this_type>> make(dest_type d, buffer_count_values v) {
            auto cs = d.get_subscription();
            return make_subscriber<T>(std::move(cs), this_type(std::move(d), std::move(v)));
        }
    };

    template<class Subscriber>
    auto operator()(Subscriber dest) const
        -> decltype(buffer_count_observer<Subscriber>::make(std::move(dest), initial)) {
        return      buffer_count_observer<Subscriber>::make(std::move(dest), initial);
    }
};

}

template<class... AN>
auto buffer(AN&&... an)
    ->      operator_factory<buffer_count_tag, AN...> {
     return operator_factory<buffer_count_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
}

}

template<>
struct member_overload<buffer_count_tag>
{
    template<class Observable,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class BufferCount = rxo::detail::buffer_count<SourceValue>,
        class Value = rxu::value_type_t<BufferCount>>
    static auto member(Observable&& o, int count, int skip)
        -> decltype(o.template lift<Value>(BufferCount(count, skip))) {
        return      o.template lift<Value>(BufferCount(count, skip));
    }

     template<class Observable,
        class Enabled = rxu::enable_if_all_true_type_t<
            is_observable<Observable>>,
        class SourceValue = rxu::value_type_t<Observable>,
        class BufferCount = rxo::detail::buffer_count<SourceValue>,
        class Value = rxu::value_type_t<BufferCount>>
    static auto member(Observable&& o, int count)
        -> decltype(o.template lift<Value>(BufferCount(count, count))) {
        return      o.template lift<Value>(BufferCount(count, count));
    }

    template<class... AN>
    static operators::detail::buffer_count_invalid_t<AN...> member(AN...) {
        std::terminate();
        return {};
        static_assert(sizeof...(AN) == 10000, "buffer takes (Count, optional Skip)");
    }
};

}

#endif