163 lines
4.3 KiB
C++
163 lines
4.3 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-skip.hpp
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\brief Make new observable with skipped first count items from this observable.
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\tparam Count the type of the items counter
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\param t the number of items to skip
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\return An observable that is identical to the source observable except that it does not emit the first t items that the source observable emits.
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\sample
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\snippet skip.cpp skip sample
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\snippet output.txt skip sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_SKIP_HPP)
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#define RXCPP_OPERATORS_RX_SKIP_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 skip_invalid_arguments {};
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template<class... AN>
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struct skip_invalid : public rxo::operator_base<skip_invalid_arguments<AN...>> {
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using type = observable<skip_invalid_arguments<AN...>, skip_invalid<AN...>>;
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};
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template<class... AN>
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using skip_invalid_t = typename skip_invalid<AN...>::type;
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template<class T, class Observable, class Count>
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struct skip : public operator_base<T>
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{
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typedef rxu::decay_t<Observable> source_type;
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typedef rxu::decay_t<Count> count_type;
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struct values
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{
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values(source_type s, count_type t)
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: source(std::move(s))
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, count(std::move(t))
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{
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}
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source_type source;
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count_type count;
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};
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values initial;
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skip(source_type s, count_type t)
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: initial(std::move(s), std::move(t))
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{
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}
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struct mode
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{
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enum type {
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skipping, // ignore messages
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triggered, // capture messages
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errored, // error occured
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stopped // observable completed
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};
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};
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template<class Subscriber>
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void on_subscribe(const Subscriber& s) const {
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typedef Subscriber output_type;
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struct state_type
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: public std::enable_shared_from_this<state_type>
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, public values
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{
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state_type(const values& i, const output_type& oarg)
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: values(i)
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, mode_value(i.count > 0 ? mode::skipping : mode::triggered)
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, out(oarg)
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{
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}
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typename mode::type mode_value;
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output_type out;
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};
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// take a copy of the values for each subscription
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auto state = std::make_shared<state_type>(initial, s);
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composite_subscription source_lifetime;
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s.add(source_lifetime);
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state->source.subscribe(
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// split subscription lifetime
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source_lifetime,
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// on_next
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[state](T t) {
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if (state->mode_value == mode::skipping) {
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if (--state->count == 0) {
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state->mode_value = mode::triggered;
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}
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} else {
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state->out.on_next(t);
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}
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},
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// on_error
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[state](rxu::error_ptr e) {
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state->mode_value = mode::errored;
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state->out.on_error(e);
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},
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// on_completed
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[state]() {
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state->mode_value = mode::stopped;
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state->out.on_completed();
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}
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);
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}
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};
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}
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/*! @copydoc rx-skip.hpp
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*/
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template<class... AN>
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auto skip(AN&&... an)
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-> operator_factory<skip_tag, AN...> {
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return operator_factory<skip_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<skip_tag>
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{
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template<class Observable,
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class Count,
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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 Skip = rxo::detail::skip<SourceValue, rxu::decay_t<Observable>, rxu::decay_t<Count>>,
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class Value = rxu::value_type_t<Skip>,
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class Result = observable<Value, Skip>>
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static Result member(Observable&& o, Count&& c) {
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return Result(Skip(std::forward<Observable>(o), std::forward<Count>(c)));
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}
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template<class... AN>
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static operators::detail::skip_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, "skip takes (optional Count)");
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}
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};
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}
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#endif
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