feat add rxcpp

3party/rxcpp/operators/rx-element_at.hpp

@@ -0,0 +1,137 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+#pragma once
+
+/*! \file rx-element_at.hpp
+  
+    \brief Pulls an item located at a specified index location in the sequence of items and emits that item as its own sole emission.
+
+    \param index  the index of the element to return.
+
+    \return An observable that emit an item located at a specified index location.
+
+    \sample
+    \snippet element_at.cpp element_at sample
+    \snippet output.txt element_at sample
+*/
+
+#if !defined(RXCPP_OPERATORS_RX_ELEMENT_AT_HPP)
+#define RXCPP_OPERATORS_RX_ELEMENT_AT_HPP
+
+#include "../rx-includes.hpp"
+
+namespace rxcpp {
+
+namespace operators {
+
+namespace detail {
+
+template<class... AN>
+struct element_at_invalid_arguments {};
+
+template<class... AN>
+struct element_at_invalid : public rxo::operator_base<element_at_invalid_arguments<AN...>> {
+    using type = observable<element_at_invalid_arguments<AN...>, element_at_invalid<AN...>>;
+};
+template<class... AN>
+using element_at_invalid_t = typename element_at_invalid<AN...>::type;
+    
+template<class T>
+struct element_at {
+    typedef rxu::decay_t<T> source_value_type;
+
+    struct element_at_values {
+        element_at_values(int i)
+            : index(i)
+        {
+        }
+        int index;
+    };
+
+    element_at_values initial;
+    
+    element_at(int i)
+        : initial(i)
+    {
+    }
+
+    template<class Subscriber>
+    struct element_at_observer : public element_at_values
+    {
+        typedef element_at_observer<Subscriber> this_type;
+        typedef source_value_type value_type;
+        typedef rxu::decay_t<Subscriber> dest_type;
+        typedef observer<value_type, this_type> observer_type;
+        dest_type dest;
+        mutable int current;
+
+        element_at_observer(dest_type d, element_at_values v)
+            : element_at_values(v),
+              dest(d),
+              current(0)
+        {
+        }
+        void on_next(source_value_type v) const {
+            if (current++ == this->index) {
+                dest.on_next(v);
+                dest.on_completed();
+            }
+        }
+        void on_error(rxu::error_ptr e) const {
+            dest.on_error(e);
+        }
+        void on_completed() const {
+            if(current <= this->index) {
+                dest.on_error(rxu::make_error_ptr(std::range_error("index is out of bounds")));
+            }
+        }
+
+        static subscriber<value_type, observer_type> make(dest_type d, element_at_values v) {
+            return make_subscriber<value_type>(d, this_type(d, v));
+        }
+    };
+
+    template<class Subscriber>
+    auto operator()(Subscriber dest) const
+        -> decltype(element_at_observer<Subscriber>::make(std::move(dest), initial)) {
+        return      element_at_observer<Subscriber>::make(std::move(dest), initial);
+    }
+};
+
+}
+
+/*! @copydoc rx-element_at.hpp
+*/
+template<class... AN>
+auto element_at(AN&&... an)
+    ->      operator_factory<element_at_tag, AN...> {
+     return operator_factory<element_at_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
+}
+
+}
+
+template<>
+struct member_overload<element_at_tag>
+{
+    template<class Observable,
+        class Enabled = rxu::enable_if_all_true_type_t<
+            is_observable<Observable>
+            >,
+        class SourceValue = rxu::value_type_t<Observable>,
+        class element_at = rxo::detail::element_at<SourceValue>>
+    static auto member(Observable&& o, int index)
+        -> decltype(o.template lift<SourceValue>(element_at(index))) {
+        return      o.template lift<SourceValue>(element_at(index));
+    }
+
+    template<class... AN>
+    static operators::detail::element_at_invalid_t<AN...> member(const AN...) {
+        std::terminate();
+        return {};
+        static_assert(sizeof...(AN) == 10000, "element_at takes (required int)");
+    }
+};
+    
+}
+
+#endif