mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
synced 2024-09-13 09:24:08 -07:00
47ed3a3675
The bulk of this commit was generated by running:
run-clang-tidy.py \
-checks='-*,llvm-namespace-comment' \
-header-filter=^/.../mozilla-central/.* \
-fix
88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* Provides DebugOnly, a type for variables used only in debug builds (i.e. by
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* assertions).
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*/
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#ifndef mozilla_DebugOnly_h
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#define mozilla_DebugOnly_h
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#include "mozilla/Attributes.h"
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namespace mozilla {
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/**
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* DebugOnly contains a value of type T, but only in debug builds. In release
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* builds, it does not contain a value. This helper is intended to be used with
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* MOZ_ASSERT()-style macros, allowing one to write:
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*
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* DebugOnly<bool> check = func();
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* MOZ_ASSERT(check);
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*
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* more concisely than declaring |check| conditional on #ifdef DEBUG, but also
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* without allocating storage space for |check| in release builds.
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*
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* DebugOnly instances can only be coerced to T in debug builds. In release
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* builds they don't have a value, so type coercion is not well defined.
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*
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* Note that DebugOnly instances still take up one byte of space, plus padding,
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* when used as members of structs.
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*/
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template<typename T>
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class DebugOnly
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{
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public:
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#ifdef DEBUG
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T value;
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DebugOnly() { }
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MOZ_IMPLICIT DebugOnly(const T& aOther) : value(aOther) { }
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DebugOnly(const DebugOnly& aOther) : value(aOther.value) { }
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DebugOnly& operator=(const T& aRhs) {
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value = aRhs;
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return *this;
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}
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void operator++(int) { value++; }
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void operator--(int) { value--; }
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// Do not define operator+=() or operator-=() here. These will coerce via
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// the implicit cast and built-in operators. Defining explicit methods here
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// will create ambiguity the compiler can't deal with.
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T* operator&() { return &value; }
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operator T&() { return value; }
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operator const T&() const { return value; }
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T& operator->() { return value; }
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const T& operator->() const { return value; }
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#else
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DebugOnly() { }
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MOZ_IMPLICIT DebugOnly(const T&) { }
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DebugOnly(const DebugOnly&) { }
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DebugOnly& operator=(const T&) { return *this; }
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void operator++(int) { }
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void operator--(int) { }
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DebugOnly& operator+=(const T&) { return *this; }
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DebugOnly& operator-=(const T&) { return *this; }
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#endif
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/*
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* DebugOnly must always have a destructor or else it will
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* generate "unused variable" warnings, exactly what it's intended
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* to avoid!
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*/
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~DebugOnly() {}
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};
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} // namespace mozilla
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#endif /* mozilla_DebugOnly_h */
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