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/*
* Copyright 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <algorithm>
#include <future>
#include <string>
#include <thread>
#include <vector>
#include <gtest/gtest.h>
#include "Promise.h"
namespace android {
namespace {
using Bytes = std::vector<uint8_t>;
Bytes decrement(Bytes bytes) {
std::transform(bytes.begin(), bytes.end(), bytes.begin(), [](auto b) { return b - 1; });
return bytes;
}
} // namespace
TEST(PromiseTest, yield) {
EXPECT_EQ(42, promise::yield(42).get());
auto ptr = std::make_unique<char>('!');
auto future = promise::yield(std::move(ptr));
EXPECT_EQ('!', *future.get());
}
TEST(PromiseTest, chain) {
std::packaged_task<const char*()> fetchString([] { return "ifmmp-"; });
std::packaged_task<Bytes(std::string)> appendString([](std::string str) {
str += "!xpsme";
return Bytes{str.begin(), str.end()};
});
std::packaged_task<std::future<Bytes>(Bytes)> decrementBytes(
[](Bytes bytes) { return promise::defer(decrement, std::move(bytes)); });
auto fetch = fetchString.get_future();
std::thread fetchThread(std::move(fetchString));
std::thread appendThread, decrementThread;
EXPECT_EQ("hello, world",
promise::chain(std::move(fetch))
.then([](const char* str) { return std::string(str); })
.then([&](std::string str) {
auto append = appendString.get_future();
appendThread = std::thread(std::move(appendString), std::move(str));
return append;
})
.then([&](Bytes bytes) {
auto decrement = decrementBytes.get_future();
decrementThread = std::thread(std::move(decrementBytes),
std::move(bytes));
return decrement;
})
.then([](std::future<Bytes> bytes) { return bytes; })
.then([](const Bytes& bytes) {
return std::string(bytes.begin(), bytes.end());
})
.get());
fetchThread.join();
appendThread.join();
decrementThread.join();
}
} // namespace android
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