120 lines
3.5 KiB
C++
120 lines
3.5 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-distinct.hpp
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\brief For each item from this observable, filter out repeated values and emit only items that have not already been emitted.
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\return Observable that emits those items from the source observable that are distinct.
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\note istinct keeps an unordered_set<T> of past values. Due to an issue in multiple implementations of std::hash<T>, rxcpp maintains a whitelist of hashable types. new types can be added by specializing rxcpp::filtered_hash<T>
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\sample
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\snippet distinct.cpp distinct sample
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\snippet output.txt distinct sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_DISTINCT_HPP)
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#define RXCPP_OPERATORS_RX_DISTINCT_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 distinct_invalid_arguments {};
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template<class... AN>
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struct distinct_invalid : public rxo::operator_base<distinct_invalid_arguments<AN...>> {
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using type = observable<distinct_invalid_arguments<AN...>, distinct_invalid<AN...>>;
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};
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template<class... AN>
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using distinct_invalid_t = typename distinct_invalid<AN...>::type;
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template<class T>
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struct distinct
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{
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typedef rxu::decay_t<T> source_value_type;
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template<class Subscriber>
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struct distinct_observer
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{
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typedef distinct_observer<Subscriber> this_type;
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typedef source_value_type value_type;
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typedef rxu::decay_t<Subscriber> dest_type;
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typedef observer<value_type, this_type> observer_type;
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dest_type dest;
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mutable std::unordered_set<source_value_type, rxcpp::filtered_hash<source_value_type>> remembered;
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distinct_observer(dest_type d)
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: dest(d)
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{
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}
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void on_next(source_value_type v) const {
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if (remembered.empty() || remembered.count(v) == 0) {
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remembered.insert(v);
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dest.on_next(v);
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}
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}
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void on_error(rxu::error_ptr e) const {
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dest.on_error(e);
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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<value_type, observer<value_type, this_type>> make(dest_type d) {
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return make_subscriber<value_type>(d, this_type(d));
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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(distinct_observer<Subscriber>::make(std::move(dest))) {
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return distinct_observer<Subscriber>::make(std::move(dest));
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}
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};
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}
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/*! @copydoc rx-distinct.hpp
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*/
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template<class... AN>
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auto distinct(AN&&... an)
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-> operator_factory<distinct_tag, AN...> {
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return operator_factory<distinct_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<distinct_tag>
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{
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template<class Observable,
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class SourceValue = rxu::value_type_t<Observable>,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_observable<Observable>,
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is_hashable<SourceValue>>,
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class Distinct = rxo::detail::distinct<SourceValue>>
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static auto member(Observable&& o)
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-> decltype(o.template lift<SourceValue>(Distinct())) {
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return o.template lift<SourceValue>(Distinct());
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}
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template<class... AN>
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static operators::detail::distinct_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, "distinct takes no arguments");
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}
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};
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}
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#endif
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