143 lines
4.9 KiB
C++
143 lines
4.9 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_until_changed.hpp
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\brief For each item from this observable, filter out consequentially repeated values and emit only changes from the new observable that is returned.
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\tparam BinaryPredicate (optional) the type of the value comparing function. The signature should be equivalent to the following: bool pred(const T1& a, const T2& b);
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\param pred (optional) the function that implements comparison of two values.
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\return Observable that emits those items from the source observable that are distinct from their immediate predecessors.
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\sample
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\snippet distinct_until_changed.cpp distinct_until_changed sample
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\snippet output.txt distinct_until_changed sample
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*/
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#if !defined(RXCPP_OPERATORS_RX_DISTINCT_UNTIL_CHANGED_HPP)
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#define RXCPP_OPERATORS_RX_DISTINCT_UNTIL_CHANGED_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_until_changed_invalid_arguments {};
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template<class... AN>
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struct distinct_until_changed_invalid : public rxo::operator_base<distinct_until_changed_invalid_arguments<AN...>> {
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using type = observable<distinct_until_changed_invalid_arguments<AN...>, distinct_until_changed_invalid<AN...>>;
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};
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template<class... AN>
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using distinct_until_changed_invalid_t = typename distinct_until_changed_invalid<AN...>::type;
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template<class T, class BinaryPredicate>
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struct distinct_until_changed
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{
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typedef rxu::decay_t<T> source_value_type;
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typedef rxu::decay_t<BinaryPredicate> predicate_type;
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predicate_type pred;
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distinct_until_changed(predicate_type p)
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: pred(std::move(p))
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{
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}
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template<class Subscriber>
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struct distinct_until_changed_observer
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{
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typedef distinct_until_changed_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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predicate_type pred;
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mutable rxu::detail::maybe<source_value_type> remembered;
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distinct_until_changed_observer(dest_type d, predicate_type pred)
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: dest(std::move(d))
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, pred(std::move(pred))
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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() || !pred(v, remembered.get())) {
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remembered.reset(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_type> make(dest_type d, predicate_type p) {
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return make_subscriber<value_type>(d, this_type(d, std::move(p)));
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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_until_changed_observer<Subscriber>::make(std::move(dest), pred)) {
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return distinct_until_changed_observer<Subscriber>::make(std::move(dest), pred);
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}
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};
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}
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/*! @copydoc rx-distinct_until_changed.hpp
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*/
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template<class... AN>
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auto distinct_until_changed(AN&&... an)
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-> operator_factory<distinct_until_changed_tag, AN...> {
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return operator_factory<distinct_until_changed_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_until_changed_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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class DistinctUntilChanged = rxo::detail::distinct_until_changed<SourceValue, rxu::equal_to<>>>
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static auto member(Observable&& o)
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-> decltype(o.template lift<SourceValue>(DistinctUntilChanged(rxu::equal_to<>()))) {
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return o.template lift<SourceValue>(DistinctUntilChanged(rxu::equal_to<>()));
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}
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template<class Observable,
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class BinaryPredicate,
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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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class DistinctUntilChanged = rxo::detail::distinct_until_changed<SourceValue, BinaryPredicate>>
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static auto member(Observable&& o, BinaryPredicate&& pred)
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-> decltype(o.template lift<SourceValue>(DistinctUntilChanged(std::forward<BinaryPredicate>(pred)))) {
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return o.template lift<SourceValue>(DistinctUntilChanged(std::forward<BinaryPredicate>(pred)));
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}
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template<class... AN>
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static operators::detail::distinct_until_changed_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_until_changed takes (optional BinaryPredicate)");
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}
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};
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}
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#endif
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