127 lines
3.6 KiB
C++
127 lines
3.6 KiB
C++
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
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#pragma once
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/*! \file rx-pairwise.hpp
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\brief Take values pairwise from this observable.
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\return Observable that emits tuples of two the most recent items emitted by the source observable.
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\sample
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\snippet pairwise.cpp pairwise sample
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\snippet output.txt pairwise sample
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If the source observable emits less than two items, no pairs are emitted by the source observable:
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\snippet pairwise.cpp pairwise short sample
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\snippet output.txt pairwise short sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_PAIRWISE_HPP)
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#define RXCPP_OPERATORS_RX_PAIRWISE_HPP
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#include "../rx-includes.hpp"
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namespace rxcpp {
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namespace operators {
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namespace detail {
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template<class... AN>
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struct pairwise_invalid_arguments {};
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template<class... AN>
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struct pairwise_invalid : public rxo::operator_base<pairwise_invalid_arguments<AN...>> {
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using type = observable<pairwise_invalid_arguments<AN...>, pairwise_invalid<AN...>>;
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};
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template<class... AN>
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using pairwise_invalid_t = typename pairwise_invalid<AN...>::type;
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template<class T>
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struct pairwise
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{
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typedef rxu::decay_t<T> source_value_type;
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typedef std::tuple<source_value_type, source_value_type> value_type;
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template<class Subscriber>
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struct pairwise_observer
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{
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typedef pairwise_observer<Subscriber> this_type;
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typedef std::tuple<source_value_type, source_value_type> value_type;
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typedef rxu::decay_t<Subscriber> dest_type;
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typedef observer<T, this_type> observer_type;
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dest_type dest;
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mutable rxu::detail::maybe<source_value_type> remembered;
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pairwise_observer(dest_type d)
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: dest(std::move(d))
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{
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}
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void on_next(source_value_type v) const {
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if (remembered.empty()) {
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remembered.reset(v);
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return;
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}
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dest.on_next(std::make_tuple(remembered.get(), v));
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remembered.reset(v);
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}
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void on_error(rxu::error_ptr e) const {
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dest.on_error(e);
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}
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void on_completed() const {
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dest.on_completed();
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}
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static subscriber<T, observer_type> make(dest_type d) {
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auto cs = d.get_subscription();
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return make_subscriber<T>(std::move(cs), observer_type(this_type(std::move(d))));
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}
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};
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template<class Subscriber>
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auto operator()(Subscriber dest) const
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-> decltype(pairwise_observer<Subscriber>::make(std::move(dest))) {
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return pairwise_observer<Subscriber>::make(std::move(dest));
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}
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};
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}
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/*! @copydoc rx-pairwise.hpp
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*/
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template<class... AN>
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auto pairwise(AN&&... an)
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-> operator_factory<pairwise_tag, AN...> {
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return operator_factory<pairwise_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
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}
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}
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template<>
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struct member_overload<pairwise_tag>
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{
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template<class Observable,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_observable<Observable>>,
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class SourceValue = rxu::value_type_t<Observable>,
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class Pairwise = rxo::detail::pairwise<SourceValue>,
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class Value = rxu::value_type_t<Pairwise>>
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static auto member(Observable&& o)
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-> decltype(o.template lift<Value>(Pairwise())) {
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return o.template lift<Value>(Pairwise());
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}
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template<class... AN>
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static operators::detail::pairwise_invalid_t<AN...> member(AN...) {
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std::terminate();
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return {};
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static_assert(sizeof...(AN) == 10000, "pairwise takes no arguments");
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}
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};
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}
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#endif
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