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// Copyright 2020 Google LLC
//
// 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
//
// https://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.
#ifndef CORE_PAYLOAD_H_
#define CORE_PAYLOAD_H_
#include <cstdint>
#include <functional>
#include <memory>
#include <utility>
#include "platform/base/byte_array.h"
#include "platform/base/input_stream.h"
#include "platform/base/payload_id.h"
#include "platform/base/prng.h"
#include "platform/public/file.h"
#include "absl/types/variant.h"
namespace location {
namespace nearby {
namespace connections {
// Payload is default-constructible, and moveable, but not copyable container
// that holds at most one instance of one of:
// ByteArray, InputStream, or InputFile.
class Payload {
public:
using Id = PayloadId;
// Order of types in variant, and values in Type enum is important.
// Enum values must match respective variant types.
using Content = absl::variant<absl::monostate, ByteArray,
std::function<InputStream&()>, InputFile>;
enum class Type { kUnknown = 0, kBytes = 1, kStream = 2, kFile = 3 };
Payload(Payload&& other) = default;
~Payload() = default;
Payload& operator=(Payload&& other) = default;
// Default (invalid) payload.
Payload() : content_(absl::monostate()) {}
// Constructors for outgoing payloads.
explicit Payload(ByteArray&& bytes) : content_(std::move(bytes)) {}
explicit Payload(const ByteArray& bytes) : content_(bytes) {}
explicit Payload(std::function<InputStream&()> stream)
: content_(std::move(stream)) {}
// Constructors for incoming payloads.
Payload(Id id, ByteArray&& bytes) : content_(std::move(bytes)), id_(id) {}
Payload(Id id, const ByteArray& bytes) : content_(bytes), id_(id) {}
Payload(Id id, std::function<InputStream&()> stream)
: content_(std::move(stream)), id_(id) {}
// Constructor for incoming and outgoing file payloads.
Payload(Id id, InputFile file) : content_(std::move(file)), id_(id) {}
// Returns ByteArray payload, if it has been defined, or empty ByteArray.
const ByteArray& AsBytes() const& {
static const ByteArray empty; // NOLINT: function-level static is OK.
auto* result = absl::get_if<ByteArray>(&content_);
return result ? *result : empty;
}
ByteArray&& AsBytes() && {
auto* result = absl::get_if<ByteArray>(&content_);
return result ? std::move(*result) : std::move(ByteArray());
}
// Returns InputStream* payload, if it has been defined, or nullptr.
InputStream* AsStream() {
auto* result = absl::get_if<std::function<InputStream&()>>(&content_);
return result ? &(*result)() : nullptr;
}
// Returns InputFile* payload, if it has been defined, or nullptr.
InputFile* AsFile() { return absl::get_if<InputFile>(&content_); }
// Returns Payload unique ID.
Id GetId() const { return id_; }
// Returns Payload type.
Type GetType() const { return type_; }
// Generate Payload Id; to be passed to outgoing file constructor.
static Id GenerateId() { return Prng().NextInt64(); }
private:
Type FindType(const Content& content) const {
return static_cast<Type>(content_.index());
}
Content content_;
Id id_{GenerateId()};
Type type_{FindType(content_)};
};
} // namespace connections
} // namespace nearby
} // namespace location
#endif // CORE_PAYLOAD_H_