Files
platform-external-webrtc/rtc_base/cancer_stick_castle.h
Karl Wiberg 8d875587d5 Cancer Stick Castle: Clarify copyability and movability
Because the style guide wants it:
https://google.github.io/styleguide/cppguide.html#Copyable_Movable_Types

Bug: webrtc:11943
Change-Id: I17373f870496c6411b5edd80e7d50dbb15a7fbc0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/184511
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32135}
2020-09-18 09:08:37 +00:00

92 lines
3.1 KiB
C++

/*
* Copyright 2020 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_CANCER_STICK_CASTLE_H_
#define RTC_BASE_CANCER_STICK_CASTLE_H_
#include <utility>
#include <vector>
#include "api/function_view.h"
#include "rtc_base/function.h"
#include "rtc_base/system/assume.h"
namespace webrtc {
namespace cancer_stick_castle_impl {
class CancerStickCastleReceivers {
public:
CancerStickCastleReceivers();
CancerStickCastleReceivers(const CancerStickCastleReceivers&) = delete;
CancerStickCastleReceivers& operator=(const CancerStickCastleReceivers&) =
delete;
CancerStickCastleReceivers(CancerStickCastleReceivers&&) = delete;
CancerStickCastleReceivers& operator=(CancerStickCastleReceivers&&) = delete;
~CancerStickCastleReceivers();
void AddReceiver(UntypedFunction&& f) {
AddReceiverImpl(&f);
// Assume that f was moved from and is now trivially destructible.
// This helps the compiler optimize away the destructor call.
RTC_ASSUME(f.IsTriviallyDestructible());
}
void Foreach(rtc::FunctionView<void(UntypedFunction&)> fv);
private:
void AddReceiverImpl(UntypedFunction* f);
std::vector<UntypedFunction> receivers_;
};
} // namespace cancer_stick_castle_impl
// A collection of receivers (callable objects) that can be called all at once.
// Optimized for minimal binary size.
//
// Neither copyable nor movable. Could easily be made movable if necessary.
//
// TODO(kwiberg): Add support for removing receivers, if necessary. AddReceiver
// would have to return some sort of ID that the caller could save and then pass
// to RemoveReceiver. Alternatively, the callable objects could return one value
// if they wish to stay in the CSC and another value if they wish to be removed.
// It depends on what's convenient for the callers...
template <typename... ArgT>
class CancerStickCastle {
public:
CancerStickCastle() = default;
CancerStickCastle(const CancerStickCastle&) = delete;
CancerStickCastle& operator=(const CancerStickCastle&) = delete;
CancerStickCastle(CancerStickCastle&&) = delete;
CancerStickCastle& operator=(CancerStickCastle&&) = delete;
// Adds a new receiver. The receiver (a callable object or a function pointer)
// must be movable, but need not be copyable. Its call signature should be
// `void(ArgT...)`.
template <typename F>
void AddReceiver(F&& f) {
receivers_.AddReceiver(
UntypedFunction::Create<void(ArgT...)>(std::forward<F>(f)));
}
// Calls all receivers with the given arguments.
void Send(ArgT&&... args) {
receivers_.Foreach([&](UntypedFunction& f) {
f.Call<void(ArgT...)>(std::forward<ArgT>(args)...);
});
}
private:
cancer_stick_castle_impl::CancerStickCastleReceivers receivers_;
};
} // namespace webrtc
#endif // RTC_BASE_CANCER_STICK_CASTLE_H_