add debounce operator

6 files changed, 494 insertions, 0 deletions

diff --git a/Rx/v2/examples/doxygen/debounce.cpp b/Rx/v2/examples/doxygen/debounce.cpp
new file mode 100644
index 0000000..b90183d
--- /dev/null
+++ b/Rx/v2/examples/doxygen/debounce.cpp
@@ -0,0 +1,20 @@
+#include "rxcpp/rx.hpp"
+
+#include "rxcpp/rx-test.hpp"
+#include "catch.hpp"
+
+SCENARIO("debounce sample"){
+    printf("//! [debounce sample]\n");
+    using namespace std::chrono;
+    auto scheduler = rxcpp::identity_current_thread();
+    auto start = scheduler.now();
+    auto period = milliseconds(10);
+    auto values = rxcpp::observable<>::interval(start, period, scheduler).
+        take(4).
+        debounce(period);
+    values.
+        subscribe(
+            [](long v) { printf("OnNext: %ld\n", v); },
+            []() { printf("OnCompleted\n"); });
+    printf("//! [debounce sample]\n");
+}
\ No newline at end of file
diff --git a/Rx/v2/src/rxcpp/operators/rx-debounce.hpp b/Rx/v2/src/rxcpp/operators/rx-debounce.hpp
new file mode 100644
index 0000000..bd8ec60
--- /dev/null
+++ b/Rx/v2/src/rxcpp/operators/rx-debounce.hpp
@@ -0,0 +1,216 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+#pragma once
+
+#if !defined(RXCPP_OPERATORS_RX_DEBOUNCE_HPP)
+#define RXCPP_OPERATORS_RX_DEBOUNCE_HPP
+
+#include "../rx-includes.hpp"
+
+namespace rxcpp {
+
+namespace operators {
+
+namespace detail {
+
+template<class T, class Duration, class Coordination>
+struct debounce
+{
+    typedef rxu::decay_t<T> source_value_type;
+    typedef rxu::decay_t<Coordination> coordination_type;
+    typedef typename coordination_type::coordinator_type coordinator_type;
+    typedef rxu::decay_t<Duration> duration_type;
+
+    struct debounce_values
+    {
+        debounce_values(duration_type p, coordination_type c)
+            : period(p)
+            , coordination(c)
+        {
+        }
+
+        duration_type period;
+        coordination_type coordination;
+    };
+    debounce_values initial;
+
+    debounce(duration_type period, coordination_type coordination)
+        : initial(period, coordination)
+    {
+    }
+
+    template<class Subscriber>
+    struct debounce_observer
+    {
+        typedef debounce_observer<Subscriber> this_type;
+        typedef rxu::decay_t<T> value_type;
+        typedef rxu::decay_t<Subscriber> dest_type;
+        typedef observer<T, this_type> observer_type;
+
+        struct debounce_subscriber_values : public debounce_values
+        {
+            debounce_subscriber_values(composite_subscription cs, dest_type d, debounce_values v, coordinator_type c)
+                : debounce_values(v)
+                , cs(std::move(cs))
+                , dest(std::move(d))
+                , coordinator(std::move(c))
+                , worker(coordinator.get_worker())
+                , index(0)
+            {
+            }
+
+            composite_subscription cs;
+            dest_type dest;
+            coordinator_type coordinator;
+            rxsc::worker worker;
+            mutable std::size_t index;
+            mutable rxu::maybe<value_type> value;
+        };
+        typedef std::shared_ptr<debounce_subscriber_values> state_type;
+        state_type state;
+
+        debounce_observer(composite_subscription cs, dest_type d, debounce_values v, coordinator_type c)
+            : state(std::make_shared<debounce_subscriber_values>(debounce_subscriber_values(std::move(cs), std::move(d), v, std::move(c))))
+        {
+            auto localState = state;
+
+            auto disposer = [=](const rxsc::schedulable&){
+                localState->cs.unsubscribe();
+                localState->dest.unsubscribe();
+                localState->worker.unsubscribe();
+            };
+            auto selectedDisposer = on_exception(
+                [&](){ return localState->coordinator.act(disposer); },
+                localState->dest);
+            if (selectedDisposer.empty()) {
+                return;
+            }
+
+            localState->dest.add([=](){
+                localState->worker.schedule(selectedDisposer.get());
+            });
+            localState->cs.add([=](){
+                localState->worker.schedule(selectedDisposer.get());
+            });
+        }
+
+        static std::function<void(const rxsc::schedulable&)> produce_item(std::size_t id, state_type state) {
+            auto produce = [id, state](const rxsc::schedulable&) {
+                if(id != state->index)
+                    return;
+
+                state->dest.on_next(*state->value);
+                state->value.reset();
+            };
+
+            auto selectedProduce = on_exception(
+                    [&](){ return state->coordinator.act(produce); },
+                    state->dest);
+            if (selectedProduce.empty()) {
+                return std::function<void(const rxsc::schedulable&)>();
+            }
+
+            return std::function<void(const rxsc::schedulable&)>(selectedProduce.get());
+        }
+
+        void on_next(T v) const {
+            auto localState = state;
+            auto work = [v, localState](const rxsc::schedulable&) {
+                auto new_id = ++localState->index;
+                auto produce_time = localState->worker.now() + localState->period;
+
+                localState->value.reset(v);
+                localState->worker.schedule(produce_time, produce_item(new_id, localState));
+            };
+            auto selectedWork = on_exception(
+                [&](){return localState->coordinator.act(work);},
+                localState->dest);
+            if (selectedWork.empty()) {
+                return;
+            }
+            localState->worker.schedule(selectedWork.get());
+        }
+
+        void on_error(std::exception_ptr e) const {
+            auto localState = state;
+            auto work = [e, localState](const rxsc::schedulable&) {
+                localState->dest.on_error(e);
+                localState->value.reset();
+            };
+            auto selectedWork = on_exception(
+                [&](){ return localState->coordinator.act(work); },
+                localState->dest);
+            if (selectedWork.empty()) {
+                return;
+            }
+            localState->worker.schedule(selectedWork.get());
+        }
+
+        void on_completed() const {
+            auto localState = state;
+            auto work = [localState](const rxsc::schedulable&) {
+                if(!localState->value.empty()) {
+                    localState->dest.on_next(*localState->value);
+                }
+                localState->dest.on_completed();
+            };
+            auto selectedWork = on_exception(
+                [&](){ return localState->coordinator.act(work); },
+                localState->dest);
+            if (selectedWork.empty()) {
+                return;
+            }
+            localState->worker.schedule(selectedWork.get());
+        }
+
+        static subscriber<T, observer_type> make(dest_type d, debounce_values v) {
+            auto cs = composite_subscription();
+            auto coordinator = v.coordination.create_coordinator();
+
+            return make_subscriber<T>(cs, observer_type(this_type(cs, std::move(d), std::move(v), std::move(coordinator))));
+        }
+    };
+
+    template<class Subscriber>
+    auto operator()(Subscriber dest) const
+        -> decltype(debounce_observer<Subscriber>::make(std::move(dest), initial)) {
+        return      debounce_observer<Subscriber>::make(std::move(dest), initial);
+    }
+};
+
+template<class Duration, class Coordination>
+class debounce_factory
+{
+    typedef rxu::decay_t<Duration> duration_type;
+    typedef rxu::decay_t<Coordination> coordination_type;
+
+    duration_type period;
+    coordination_type coordination;
+public:
+    debounce_factory(duration_type p, coordination_type c) : period(p), coordination(c) {}
+    template<class Observable>
+    auto operator()(Observable&& source)
+        -> decltype(source.template lift<rxu::value_type_t<rxu::decay_t<Observable>>>(debounce<rxu::value_type_t<rxu::decay_t<Observable>>, Duration, Coordination>(period, coordination))) {
+        return      source.template lift<rxu::value_type_t<rxu::decay_t<Observable>>>(debounce<rxu::value_type_t<rxu::decay_t<Observable>>, Duration, Coordination>(period, coordination));
+    }
+};
+
+}
+
+template<class Duration, class Coordination>
+inline auto debounce(Duration period, Coordination coordination)
+    ->      detail::debounce_factory<Duration, Coordination> {
+    return  detail::debounce_factory<Duration, Coordination>(period, coordination);
+}
+
+template<class Duration>
+inline auto debounce(Duration period)
+    ->      detail::debounce_factory<Duration, identity_one_worker> {
+    return  detail::debounce_factory<Duration, identity_one_worker>(period, identity_current_thread());
+}
+
+}
+
+}
+
+#endif
diff --git a/Rx/v2/src/rxcpp/rx-observable.hpp b/Rx/v2/src/rxcpp/rx-observable.hpp
index e2646ed..08071ef 100644
--- a/Rx/v2/src/rxcpp/rx-observable.hpp
+++ b/Rx/v2/src/rxcpp/rx-observable.hpp
@@ -838,6 +838,50 @@ public:
         return                    lift<rxu::value_type_t<rxo::detail::map<T, Selector>>>(rxo::detail::map<T, Selector>(std::move(s)));
     }
 
+    /*! Return an observable that emits an item if a particular timespan has passed without emitting another item from the source ovservable.
+
+        \tparam Duration      the type of time interval
+        \tparam Coordination  the type of the scheduler
+
+        \param period        the period of time to suppress any emitted items
+        \param coordination  the scheduler to manage timeout for each event
+
+        \return  Observable that emits an item if a particular timespan has passed without emitting another item from the source ovservable.
+
+        \sample
+        \snippet debounce.cpp debounce sample
+        \snippet output.txt debounce sample
+    */
+    template<class Duration, class Coordination>
+    auto debounce(Duration period, Coordination coordination) const
+        /// \cond SHOW_SERVICE_MEMBERS
+        -> decltype(EXPLICIT_THIS lift<T>(rxo::detail::debounce<T, Duration, Coordination>(period, coordination)))
+        /// \endcond
+    {
+        return                    lift<T>(rxo::detail::debounce<T, Duration, Coordination>(period, coordination));
+    }
+
+    /*! Return an observable that emits an item if a particular timespan has passed without emitting another item from the source ovservable.
+
+        \tparam Duration      the type of time interval
+
+        \param period        the period of time to suppress any emitted items
+
+        \return  Observable that emits an item if a particular timespan has passed without emitting another item from the source ovservable.
+
+        \sample
+        \snippet debounce.cpp debounce sample
+        \snippet output.txt debounce sample
+    */
+    template<class Duration>
+    auto debounce(Duration period) const
+        /// \cond SHOW_SERVICE_MEMBERS
+        -> decltype(EXPLICIT_THIS lift<T>(rxo::detail::debounce<T, Duration, identity_one_worker>(period, identity_current_thread())))
+        /// \endcond
+    {
+        return                    lift<T>(rxo::detail::debounce<T, Duration, identity_one_worker>(period, identity_current_thread()));
+    }
+
     /*! Return an observable that emits each item emitted by the source observable after the specified delay.
 
         \tparam Duration      the type of time interval
diff --git a/Rx/v2/src/rxcpp/rx-operators.hpp b/Rx/v2/src/rxcpp/rx-operators.hpp
index 81e5b1f..21c7bf8 100644
--- a/Rx/v2/src/rxcpp/rx-operators.hpp
+++ b/Rx/v2/src/rxcpp/rx-operators.hpp
@@ -42,6 +42,7 @@ namespace rxo=operators;
 #include "operators/rx-concat.hpp"
 #include "operators/rx-concat_map.hpp"
 #include "operators/rx-connect_forever.hpp"
+#include "operators/rx-debounce.hpp"
 #include "operators/rx-delay.hpp"
 #include "operators/rx-distinct.hpp"
 #include "operators/rx-distinct_until_changed.hpp"
diff --git a/Rx/v2/test/CMakeLists.txt b/Rx/v2/test/CMakeLists.txt
index 43a942d..8b9b100 100644
--- a/Rx/v2/test/CMakeLists.txt
+++ b/Rx/v2/test/CMakeLists.txt
@@ -33,6 +33,7 @@ set(TEST_SOURCES
     ${TEST_DIR}/operators/combine_latest.cpp
     ${TEST_DIR}/operators/concat.cpp
     ${TEST_DIR}/operators/concat_map.cpp
+    ${TEST_DIR}/operators/debounce.cpp
     ${TEST_DIR}/operators/delay.cpp
     ${TEST_DIR}/operators/distinct.cpp
     ${TEST_DIR}/operators/distinct_until_changed.cpp
diff --git a/Rx/v2/test/operators/debounce.cpp b/Rx/v2/test/operators/debounce.cpp
new file mode 100644
index 0000000..8b542c7
--- /dev/null
+++ b/Rx/v2/test/operators/debounce.cpp
@@ -0,0 +1,212 @@
+#include "../test.h"
+
+using namespace std::chrono;
+
+SCENARIO("debounce - never", "[debounce][operators]"){
+    GIVEN("a source"){
+        auto sc = rxsc::make_test();
+        auto so = rx::synchronize_in_one_worker(sc);
+        auto w = sc.create_worker();
+        const rxsc::test::messages<int> on;
+
+        auto xs = sc.make_hot_observable({
+            on.next(150, 1)
+        });
+
+        WHEN("values are debounceed"){
+
+            auto res = w.start(
+                [so, xs]() {
+                    return xs.debounce(milliseconds(10), so);
+                }
+            );
+
+            THEN("the output is empty"){
+                auto required = std::vector<rxsc::test::messages<int>::recorded_type>();
+                auto actual = res.get_observer().messages();
+                REQUIRE(required == actual);
+            }
+
+            THEN("there was 1 subscription/unsubscription to the source"){
+                auto required = rxu::to_vector({
+                    on.subscribe(200, 1001)
+                });
+                auto actual = xs.subscriptions();
+                REQUIRE(required == actual);
+            }
+        }
+    }
+}
+
+SCENARIO("debounce - empty", "[debounce][operators]"){
+    GIVEN("a source"){
+        auto sc = rxsc::make_test();
+        auto so = rx::synchronize_in_one_worker(sc);
+        auto w = sc.create_worker();
+        const rxsc::test::messages<int> on;
+
+        auto xs = sc.make_hot_observable({
+            on.next(150, 1),
+            on.completed(250)
+        });
+
+        WHEN("values are debounceed"){
+
+            auto res = w.start(
+                [so, xs]() {
+                    return xs.debounce(milliseconds(10), so);
+                }
+            );
+
+            THEN("the output only contains complete message"){
+                auto required = rxu::to_vector({
+                    on.completed(251)
+                });
+                auto actual = res.get_observer().messages();
+                REQUIRE(required == actual);
+            }
+
+            THEN("there was 1 subscription/unsubscription to the source"){
+                auto required = rxu::to_vector({
+                    on.subscribe(200, 250)
+                });
+                auto actual = xs.subscriptions();
+                REQUIRE(required == actual);
+            }
+
+        }
+    }
+}
+
+SCENARIO("debounce - no overlap", "[debounce][operators]"){
+    GIVEN("a source"){
+        auto sc = rxsc::make_test();
+        auto so = rx::synchronize_in_one_worker(sc);
+        auto w = sc.create_worker();
+        const rxsc::test::messages<int> on;
+
+        auto xs = sc.make_hot_observable({
+            on.next(150, 1),
+            on.next(210, 2),
+            on.next(240, 3),
+            on.completed(300)
+        });
+
+        WHEN("values are debounceed"){
+
+            auto res = w.start(
+                [so, xs]() {
+                    return xs.debounce(milliseconds(10), so);
+                }
+            );
+
+            THEN("the output only contains debounced items sent while subscribed"){
+                auto required = rxu::to_vector({
+                    on.next(221, 2),
+                    on.next(251, 3),
+                    on.completed(301)
+                });
+                auto actual = res.get_observer().messages();
+                REQUIRE(required == actual);
+            }
+
+            THEN("there was 1 subscription/unsubscription to the source"){
+                auto required = rxu::to_vector({
+                    on.subscribe(200, 300)
+                });
+                auto actual = xs.subscriptions();
+                REQUIRE(required == actual);
+            }
+
+        }
+    }
+}
+
+SCENARIO("debounce - overlap", "[debounce][operators]"){
+    GIVEN("a source"){
+        auto sc = rxsc::make_test();
+        auto so = rx::synchronize_in_one_worker(sc);
+        auto w = sc.create_worker();
+        const rxsc::test::messages<int> on;
+
+        auto xs = sc.make_hot_observable({
+            on.next(150, 1),
+            on.next(215, 2),
+            on.next(225, 3),
+            on.next(235, 4),
+            on.next(245, 5),
+            on.next(255, 6),
+            on.next(265, 7),
+            on.completed(300)
+        });
+
+        WHEN("values are debounceed"){
+
+            auto res = w.start(
+                [so, xs]() {
+                    return xs.debounce(milliseconds(30), so);
+                }
+            );
+
+            THEN("the output only contains debounced items sent while subscribed"){
+                auto required = rxu::to_vector({
+                    on.next(296, 7),
+                    on.completed(301)
+                });
+                auto actual = res.get_observer().messages();
+                REQUIRE(required == actual);
+            }
+
+            THEN("there was 1 subscription/unsubscription to the source"){
+                auto required = rxu::to_vector({
+                    on.subscribe(200, 300)
+                });
+                auto actual = xs.subscriptions();
+                REQUIRE(required == actual);
+            }
+
+        }
+    }
+}
+
+SCENARIO("debounce - throw", "[debounce][operators]"){
+    GIVEN("a source"){
+        auto sc = rxsc::make_test();
+        auto so = rx::synchronize_in_one_worker(sc);
+        auto w = sc.create_worker();
+        const rxsc::test::messages<int> on;
+
+        std::runtime_error ex("debounce on_error from source");
+
+        auto xs = sc.make_hot_observable({
+            on.next(150, 1),
+            on.error(250, ex)
+        });
+
+        WHEN("values are debounceed"){
+
+            auto res = w.start(
+                [so, xs]() {
+                    return xs.debounce(milliseconds(10), so);
+                }
+            );
+
+            THEN("the output only contains only error"){
+                auto required = rxu::to_vector({
+                    on.error(251, ex)
+                });
+                auto actual = res.get_observer().messages();
+                REQUIRE(required == actual);
+            }
+
+            THEN("there was 1 subscription/unsubscription to the source"){
+                auto required = rxu::to_vector({
+                    on.subscribe(200, 250)
+                });
+                auto actual = xs.subscriptions();
+                REQUIRE(required == actual);
+            }
+
+        }
+    }
+}