59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
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// Copyright 2022 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TEST_RECTIFY_CALLBACK_H_
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#define BASE_TEST_RECTIFY_CALLBACK_H_
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#include <utility>
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#include "base/test/rectify_callback_internal.h"
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namespace base {
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// RectifyCallback:
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//
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// CallbackType<DesiredSignature> RectifyCallback<DesiredSignature>(
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// CallbackType<ActualSignature> callback)
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//
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// DesiredCallbackType RectifyCallback<DesiredCallbackType>(
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// ActualCallbackType callback)
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//
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// Rectifies the signature of `callback` with `DesiredSignature` or
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// `DesiredCallbackType` by ignoring the first N arguments of the desired
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// callback type. Useful when binding callbacks with lots of arguments you don't
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// actually care about.
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//
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// For now, `ActualSignature` and `DesiredSignature` must have the same return
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// type, and the common arguments between the two must match.
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//
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// Example:
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//
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// using CbType = OnceCallback<bool(A, B, C)>;
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// void Fn(CbType);
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//
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// // These all ignore arguments when passing the callback:
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// Fn(RectifyCallback<CbType>(BindOnce([](){ return true; })));
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// Fn(RectifyCallback<CbType>(BindOnce([](C c){ return true; })));
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// Fn(RectifyCallback<CbType>(BindOnce([](B c, C c){ return true; })));
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//
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// // This also works, though it makes no change to the input callback:
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// Fn(RectifyCallback<CbType>(
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// BindOnce([](A a, B c, C c){ return true; })));
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//
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// You can also make RectifyCallback implicit by embedding it in a template
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// version of your function.
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//
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// template <typename T>
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// void Fn(T&& t) { FnImpl(RectifyCallback<CbType>(std::forward<T>(t))); }
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//
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template <typename Desired, typename Actual>
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auto RectifyCallback(Actual&& callback) {
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using Impl = internal::RectifyCallbackImpl<Desired, std::decay_t<Actual>>;
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return Impl::Rectify(std::move(callback));
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}
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} // namespace base
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#endif // BASE_TEST_RECTIFY_CALLBACK_H_
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