154 lines
4.2 KiB
C++
154 lines
4.2 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_last.hpp
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\brief Make new observable with skipped last 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 last items to skip.
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\return An observable that is identical to the source observable except that it does not emit the last t items that the source observable emits.
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\sample
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\snippet skip_last.cpp skip_last sample
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\snippet output.txt skip_last sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_SKIP_LAST_HPP)
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#define RXCPP_OPERATORS_RX_SKIP_LAST_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_last_invalid_arguments {};
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template<class... AN>
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struct skip_last_invalid : public rxo::operator_base<skip_last_invalid_arguments<AN...>> {
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using type = observable<skip_last_invalid_arguments<AN...>, skip_last_invalid<AN...>>;
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};
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template<class... AN>
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using skip_last_invalid_t = typename skip_last_invalid<AN...>::type;
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template<class T, class Observable, class Count>
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struct skip_last : 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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typedef std::queue<T> queue_type;
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typedef typename queue_type::size_type queue_size_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(static_cast<queue_size_type>(t))
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{
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}
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source_type source;
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queue_size_type count;
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};
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values initial;
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skip_last(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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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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, out(oarg)
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{
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}
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queue_type items;
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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->count > 0) {
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if (state->items.size() == state->count) {
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state->out.on_next(std::move(state->items.front()));
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state->items.pop();
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}
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state->items.push(t);
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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->out.on_error(e);
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},
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// on_completed
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[state]() {
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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_last.hpp
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*/
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template<class... AN>
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auto skip_last(AN&&... an)
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-> operator_factory<skip_last_tag, AN...> {
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return operator_factory<skip_last_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_last_tag>
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{
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template<class Observable, 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 SkipLast = rxo::detail::skip_last<SourceValue, rxu::decay_t<Observable>, rxu::decay_t<Count>>,
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class Value = rxu::value_type_t<SkipLast>,
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class Result = observable<Value, SkipLast>>
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static Result member(Observable&& o, Count&& c) {
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return Result(SkipLast(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_last_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_last takes (Count)");
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}
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};
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}
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#endif
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