1 // Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
2
3 #pragma once
4
5 /*! \file rx-on_error_resume_next.hpp
6
7 \brief If an error occurs, take the result from the Selector and subscribe to that instead.
8
9 \tparam Selector the actual type of a function of the form `observable<T>(rxu::error_ptr)`
10
11 \param s the function of the form `observable<T>(rxu::error_ptr)`
12
13 \return Observable that emits the items from the source observable and switches to a new observable on error.
14
15 \sample
16 \snippet on_error_resume_next.cpp on_error_resume_next sample
17 \snippet output.txt on_error_resume_next sample
18 */
19
20 #if !defined(RXCPP_OPERATORS_RX_ON_ERROR_RESUME_NEXT_HPP)
21 #define RXCPP_OPERATORS_RX_ON_ERROR_RESUME_NEXT_HPP
22
23 #include "../rx-includes.hpp"
24
25 namespace rxcpp {
26
27 namespace operators {
28
29 namespace detail {
30
31 template<class... AN>
32 struct on_error_resume_next_invalid_arguments {};
33
34 template<class... AN>
35 struct on_error_resume_next_invalid : public rxo::operator_base<on_error_resume_next_invalid_arguments<AN...>> {
36 using type = observable<on_error_resume_next_invalid_arguments<AN...>, on_error_resume_next_invalid<AN...>>;
37 };
38 template<class... AN>
39 using on_error_resume_next_invalid_t = typename on_error_resume_next_invalid<AN...>::type;
40
41
42 template<class T, class Selector>
43 struct on_error_resume_next
44 {
45 typedef rxu::decay_t<T> value_type;
46 typedef rxu::decay_t<Selector> select_type;
47 typedef decltype((*(select_type*)nullptr)(rxu::error_ptr())) fallback_type;
48 select_type selector;
49
on_error_resume_nextrxcpp::operators::detail::on_error_resume_next50 on_error_resume_next(select_type s)
51 : selector(std::move(s))
52 {
53 }
54
55 template<class Subscriber>
56 struct on_error_resume_next_observer
57 {
58 typedef on_error_resume_next_observer<Subscriber> this_type;
59 typedef rxu::decay_t<T> value_type;
60 typedef rxu::decay_t<Selector> select_type;
61 typedef decltype((*(select_type*)nullptr)(rxu::error_ptr())) fallback_type;
62 typedef rxu::decay_t<Subscriber> dest_type;
63 typedef observer<T, this_type> observer_type;
64 dest_type dest;
65 composite_subscription lifetime;
66 select_type selector;
67
on_error_resume_next_observerrxcpp::operators::detail::on_error_resume_next::on_error_resume_next_observer68 on_error_resume_next_observer(dest_type d, composite_subscription cs, select_type s)
69 : dest(std::move(d))
70 , lifetime(std::move(cs))
71 , selector(std::move(s))
72 {
73 dest.add(lifetime);
74 }
on_nextrxcpp::operators::detail::on_error_resume_next::on_error_resume_next_observer75 void on_next(value_type v) const {
76 dest.on_next(std::move(v));
77 }
on_errorrxcpp::operators::detail::on_error_resume_next::on_error_resume_next_observer78 void on_error(rxu::error_ptr e) const {
79 auto selected = on_exception(
80 [&](){
81 return this->selector(std::move(e));},
82 dest);
83 if (selected.empty()) {
84 return;
85 }
86 selected->subscribe(dest);
87 }
on_completedrxcpp::operators::detail::on_error_resume_next::on_error_resume_next_observer88 void on_completed() const {
89 dest.on_completed();
90 }
91
makerxcpp::operators::detail::on_error_resume_next::on_error_resume_next_observer92 static subscriber<T, observer_type> make(dest_type d, select_type s) {
93 auto cs = composite_subscription();
94 return make_subscriber<T>(cs, observer_type(this_type(std::move(d), cs, std::move(s))));
95 }
96 };
97
98 template<class Subscriber>
operator ()rxcpp::operators::detail::on_error_resume_next99 auto operator()(Subscriber dest) const
100 -> decltype(on_error_resume_next_observer<Subscriber>::make(std::move(dest), selector)) {
101 return on_error_resume_next_observer<Subscriber>::make(std::move(dest), selector);
102 }
103 };
104
105 }
106
107 /*! @copydoc rx-on_error_resume_next.hpp
108 */
109 template<class... AN>
on_error_resume_next(AN &&...an)110 auto on_error_resume_next(AN&&... an)
111 -> operator_factory<on_error_resume_next_tag, AN...> {
112 return operator_factory<on_error_resume_next_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
113 }
114
115 /*! @copydoc rx-on_error_resume_next.hpp
116 */
117 template<class... AN>
switch_on_error(AN &&...an)118 auto switch_on_error(AN&&... an)
119 -> operator_factory<on_error_resume_next_tag, AN...> {
120 return operator_factory<on_error_resume_next_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
121 }
122
123 }
124
125 template<>
126 struct member_overload<on_error_resume_next_tag>
127 {
128 template<class Observable, class Selector,
129 class SourceValue = rxu::value_type_t<Observable>,
130 class OnErrorResumeNext = rxo::detail::on_error_resume_next<SourceValue, rxu::decay_t<Selector>>,
131 class Value = rxu::value_type_t<OnErrorResumeNext>>
memberrxcpp::member_overload132 static auto member(Observable&& o, Selector&& p)
133 -> decltype(o.template lift<Value>(OnErrorResumeNext(std::forward<Selector>(p)))) {
134 return o.template lift<Value>(OnErrorResumeNext(std::forward<Selector>(p)));
135 }
136
137 template<class... AN>
memberrxcpp::member_overload138 static operators::detail::on_error_resume_next_invalid_t<AN...> member(const AN&...) {
139 std::terminate();
140 return {};
141 static_assert(sizeof...(AN) == 10000, "on_error_resume_next takes (Selector)");
142 }
143 };
144
145 }
146
147 #endif
148