148 lines
4.8 KiB
C++
148 lines
4.8 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-on_error_resume_next.hpp
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\brief If an error occurs, take the result from the Selector and subscribe to that instead.
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\tparam Selector the actual type of a function of the form `observable<T>(rxu::error_ptr)`
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\param s the function of the form `observable<T>(rxu::error_ptr)`
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\return Observable that emits the items from the source observable and switches to a new observable on error.
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\sample
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\snippet on_error_resume_next.cpp on_error_resume_next sample
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\snippet output.txt on_error_resume_next sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_ON_ERROR_RESUME_NEXT_HPP)
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#define RXCPP_OPERATORS_RX_ON_ERROR_RESUME_NEXT_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 on_error_resume_next_invalid_arguments {};
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template<class... AN>
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struct on_error_resume_next_invalid : public rxo::operator_base<on_error_resume_next_invalid_arguments<AN...>> {
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using type = observable<on_error_resume_next_invalid_arguments<AN...>, on_error_resume_next_invalid<AN...>>;
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};
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template<class... AN>
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using on_error_resume_next_invalid_t = typename on_error_resume_next_invalid<AN...>::type;
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template<class T, class Selector>
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struct on_error_resume_next
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{
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typedef rxu::decay_t<T> value_type;
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typedef rxu::decay_t<Selector> select_type;
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typedef decltype((*(select_type*)nullptr)(rxu::error_ptr())) fallback_type;
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select_type selector;
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on_error_resume_next(select_type s)
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: selector(std::move(s))
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{
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}
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template<class Subscriber>
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struct on_error_resume_next_observer
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{
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typedef on_error_resume_next_observer<Subscriber> this_type;
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typedef rxu::decay_t<T> value_type;
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typedef rxu::decay_t<Selector> select_type;
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typedef decltype((*(select_type*)nullptr)(rxu::error_ptr())) fallback_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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composite_subscription lifetime;
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select_type selector;
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on_error_resume_next_observer(dest_type d, composite_subscription cs, select_type s)
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: dest(std::move(d))
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, lifetime(std::move(cs))
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, selector(std::move(s))
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{
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dest.add(lifetime);
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}
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void on_next(value_type v) const {
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dest.on_next(std::move(v));
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}
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void on_error(rxu::error_ptr e) const {
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auto selected = on_exception(
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[&](){
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return this->selector(std::move(e));},
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dest);
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if (selected.empty()) {
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return;
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}
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selected->subscribe(dest);
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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, select_type s) {
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auto cs = composite_subscription();
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return make_subscriber<T>(cs, observer_type(this_type(std::move(d), cs, std::move(s))));
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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(on_error_resume_next_observer<Subscriber>::make(std::move(dest), selector)) {
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return on_error_resume_next_observer<Subscriber>::make(std::move(dest), selector);
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}
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};
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}
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/*! @copydoc rx-on_error_resume_next.hpp
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*/
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template<class... AN>
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auto on_error_resume_next(AN&&... an)
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-> operator_factory<on_error_resume_next_tag, AN...> {
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return operator_factory<on_error_resume_next_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
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}
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/*! @copydoc rx-on_error_resume_next.hpp
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*/
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template<class... AN>
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auto switch_on_error(AN&&... an)
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-> operator_factory<on_error_resume_next_tag, AN...> {
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return operator_factory<on_error_resume_next_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<on_error_resume_next_tag>
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{
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template<class Observable, class Selector,
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class SourceValue = rxu::value_type_t<Observable>,
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class OnErrorResumeNext = rxo::detail::on_error_resume_next<SourceValue, rxu::decay_t<Selector>>,
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class Value = rxu::value_type_t<OnErrorResumeNext>>
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static auto member(Observable&& o, Selector&& p)
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-> decltype(o.template lift<Value>(OnErrorResumeNext(std::forward<Selector>(p)))) {
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return o.template lift<Value>(OnErrorResumeNext(std::forward<Selector>(p)));
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}
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template<class... AN>
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static operators::detail::on_error_resume_next_invalid_t<AN...> member(const AN&...) {
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std::terminate();
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return {};
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static_assert(sizeof...(AN) == 10000, "on_error_resume_next takes (Selector)");
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}
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};
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}
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#endif
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