84 lines
2.4 KiB
C++
84 lines
2.4 KiB
C++
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// 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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#if !defined(RXCPP_SOURCES_RX_DEFER_HPP)
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#define RXCPP_SOURCES_RX_DEFER_HPP
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#include "../rx-includes.hpp"
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/*! \file rx-defer.hpp
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\brief Returns an observable that calls the specified observable factory to create an observable for each new observer that subscribes.
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\tparam ObservableFactory the type of the observable factory
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\param of the observable factory function to invoke for each observer that subscribes to the resulting observable
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\return observable whose observers' subscriptions trigger an invocation of the given observable factory function
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\sample
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\snippet defer.cpp defer sample
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\snippet output.txt defer sample
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*/
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namespace rxcpp {
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namespace sources {
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namespace detail {
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template<class ObservableFactory>
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struct defer_traits
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{
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typedef rxu::decay_t<ObservableFactory> observable_factory_type;
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typedef decltype((*(observable_factory_type*)nullptr)()) collection_type;
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typedef typename collection_type::value_type value_type;
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};
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template<class ObservableFactory>
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struct defer : public source_base<rxu::value_type_t<defer_traits<ObservableFactory>>>
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{
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typedef defer<ObservableFactory> this_type;
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typedef defer_traits<ObservableFactory> traits;
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typedef typename traits::observable_factory_type observable_factory_type;
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typedef typename traits::collection_type collection_type;
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observable_factory_type observable_factory;
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defer(observable_factory_type of)
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: observable_factory(std::move(of))
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{
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}
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template<class Subscriber>
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void on_subscribe(Subscriber o) const {
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auto selectedCollection = on_exception(
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[this](){return this->observable_factory();},
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o);
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if (selectedCollection.empty()) {
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return;
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}
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selectedCollection->subscribe(o);
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}
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};
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}
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/*! @copydoc rx-defer.hpp
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*/
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template<class ObservableFactory>
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auto defer(ObservableFactory of)
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-> observable<rxu::value_type_t<detail::defer_traits<ObservableFactory>>, detail::defer<ObservableFactory>> {
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return observable<rxu::value_type_t<detail::defer_traits<ObservableFactory>>, detail::defer<ObservableFactory>>(
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detail::defer<ObservableFactory>(std::move(of)));
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}
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}
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}
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#endif
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