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// 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_SCAN_HPP)
#define RXCPP_OPERATORS_RX_SCAN_HPP
#include "../rx-includes.hpp"
namespace rxcpp {
namespace operators {
namespace detail {
template<class T, class Observable, class Accumulator, class Seed>
struct scan : public operator_base<rxu::decay_t<Seed>>
{
typedef rxu::decay_t<Observable> source_type;
typedef rxu::decay_t<Accumulator> accumulator_type;
typedef rxu::decay_t<Seed> seed_type;
struct scan_initial_type
{
scan_initial_type(source_type o, accumulator_type a, seed_type s)
: source(std::move(o))
, accumulator(std::move(a))
, seed(s)
{
}
source_type source;
accumulator_type accumulator;
seed_type seed;
};
scan_initial_type initial;
template<class CT, class CS, class CP>
static auto check(int) -> decltype((*(CP*)nullptr)(*(CS*)nullptr, *(CT*)nullptr));
template<class CT, class CS, class CP>
static void check(...);
scan(source_type o, accumulator_type a, seed_type s)
: initial(std::move(o), a, s)
{
static_assert(std::is_convertible<decltype(check<T, seed_type, accumulator_type>(0)), seed_type>::value, "scan Accumulator must be a function with the signature Seed(Seed, T)");
}
template<class Subscriber>
void on_subscribe(Subscriber o) const {
struct scan_state_type
: public scan_initial_type
, public std::enable_shared_from_this<scan_state_type>
{
scan_state_type(scan_initial_type i, Subscriber scrbr)
: scan_initial_type(i)
, result(scan_initial_type::seed)
, out(std::move(scrbr))
{
}
seed_type result;
Subscriber out;
};
auto state = std::make_shared<scan_state_type>(initial, std::move(o));
state->source.subscribe(
state->out,
// on_next
[state](T t) {
auto result = on_exception(
[&](){return state->accumulator(state->result, t);},
state->out);
if (result.empty()) {
return;
}
state->result = result.get();
state->out.on_next(state->result);
},
// on_error
[state](std::exception_ptr e) {
state->out.on_error(e);
},
// on_completed
[state]() {
state->out.on_completed();
}
);
}
};
template<class Accumulator, class Seed>
class scan_factory
{
typedef rxu::decay_t<Accumulator> accumulator_type;
typedef rxu::decay_t<Seed> seed_type;
accumulator_type accumulator;
seed_type seed;
public:
scan_factory(accumulator_type a, Seed s)
: accumulator(std::move(a))
, seed(s)
{
}
template<class Observable>
auto operator()(Observable&& source)
-> observable<rxu::decay_t<Seed>, scan<rxu::value_type_t<rxu::decay_t<Observable>>, Observable, Accumulator, Seed>> {
return observable<rxu::decay_t<Seed>, scan<rxu::value_type_t<rxu::decay_t<Observable>>, Observable, Accumulator, Seed>>(
scan<rxu::value_type_t<rxu::decay_t<Observable>>, Observable, Accumulator, Seed>(std::forward<Observable>(source), accumulator, seed));
}
};
}
template<class Seed, class Accumulator>
auto scan(Seed s, Accumulator&& a)
-> detail::scan_factory<Accumulator, Seed> {
return detail::scan_factory<Accumulator, Seed>(std::forward<Accumulator>(a), s);
}
}
}
#endif
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