From 36d22d82aa202bb199967e9512281e9a53db42c9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 21:33:14 +0200 Subject: Adding upstream version 115.7.0esr. Signed-off-by: Daniel Baumann --- xpcom/base/nsISupportsUtils.h | 142 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 xpcom/base/nsISupportsUtils.h (limited to 'xpcom/base/nsISupportsUtils.h') diff --git a/xpcom/base/nsISupportsUtils.h b/xpcom/base/nsISupportsUtils.h new file mode 100644 index 0000000000..a885c5cb14 --- /dev/null +++ b/xpcom/base/nsISupportsUtils.h @@ -0,0 +1,142 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef nsISupportsUtils_h__ +#define nsISupportsUtils_h__ + +#include + +#include "nscore.h" +#include "nsIOutputStream.h" +#include "nsISupports.h" +#include "nsError.h" +#include "nsDebug.h" +#include "nsISupportsImpl.h" +#include "mozilla/RefPtr.h" + +/** + * Macro for adding a reference to an interface. + * @param _ptr The interface pointer. + */ +#define NS_ADDREF(_ptr) (_ptr)->AddRef() + +/** + * Macro for adding a reference to this. This macro should be used + * because NS_ADDREF (when tracing) may require an ambiguous cast + * from the pointers primary type to nsISupports. This macro sidesteps + * that entire problem. + */ +#define NS_ADDREF_THIS() AddRef() + +// Making this a |inline| |template| allows |aExpr| to be evaluated only once, +// yet still denies you the ability to |AddRef()| an |nsCOMPtr|. +template +inline void ns_if_addref(T aExpr) { + if (aExpr) { + aExpr->AddRef(); + } +} + +/** + * Macro for adding a reference to an interface that checks for nullptr. + * @param _expr The interface pointer. + */ +#define NS_IF_ADDREF(_expr) ns_if_addref(_expr) + +/* + * Given these declarations, it explicitly OK and efficient to end a `getter' + * with: + * + * NS_IF_ADDREF(*result = mThing); + * + * even if |mThing| is an |nsCOMPtr|. If |mThing| is an |nsCOMPtr|, however, it + * is still _illegal_ to say |NS_IF_ADDREF(mThing)|. + */ + +/** + * Macro for releasing a reference to an interface. + * @param _ptr The interface pointer. + */ +#define NS_RELEASE(_ptr) \ + do { \ + (_ptr)->Release(); \ + (_ptr) = 0; \ + } while (0) + +/** + * Macro for releasing a reference to this interface. + */ +#define NS_RELEASE_THIS() Release() + +/** + * Macro for releasing a reference to an interface, except that this + * macro preserves the return value from the underlying Release call. + * The interface pointer argument will only be NULLed if the reference count + * goes to zero. + * + * @param _ptr The interface pointer. + * @param _rc The reference count. + */ +#define NS_RELEASE2(_ptr, _rc) \ + do { \ + _rc = (_ptr)->Release(); \ + if (0 == (_rc)) (_ptr) = 0; \ + } while (0) + +/** + * Macro for releasing a reference to an interface that checks for nullptr; + * @param _ptr The interface pointer. + */ +#define NS_IF_RELEASE(_ptr) \ + do { \ + if (_ptr) { \ + (_ptr)->Release(); \ + (_ptr) = 0; \ + } \ + } while (0) + +/* + * Often you have to cast an implementation pointer, e.g., |this|, to an + * |nsISupports*|, but because you have multiple inheritance, a simple cast + * is ambiguous. One could simply say, e.g., (given a base |nsIBase|), + * |static_cast(this)|; but that disguises the fact that what + * you are really doing is disambiguating the |nsISupports|. You could make + * that more obvious with a double cast, e.g., |static_cast + (* + static_cast(this))|, but that is bulky and harder to read... + * + * The following macro is clean, short, and obvious. In the example above, + * you would use it like this: |NS_ISUPPORTS_CAST(nsIBase*, this)|. + */ + +#define NS_ISUPPORTS_CAST(__unambiguousBase, __expr) \ + static_cast(static_cast<__unambiguousBase>(__expr)) + +// a type-safe shortcut for calling the |QueryInterface()| member function +template +inline nsresult CallQueryInterface(T* aSource, DestinationType** aDestination) { + // We permit nsISupports-to-nsISupports here so that one can still obtain + // the canonical nsISupports pointer with CallQueryInterface. + static_assert( + !(std::is_same_v || + std::is_base_of::value) || + std::is_same_v, + "don't use CallQueryInterface for compile-time-determinable casts"); + + MOZ_ASSERT(aSource, "null parameter"); + MOZ_ASSERT(aDestination, "null parameter"); + + return aSource->QueryInterface(NS_GET_TEMPLATE_IID(DestinationType), + reinterpret_cast(aDestination)); +} + +template +inline nsresult CallQueryInterface(RefPtr& aSourcePtr, + DestinationType** aDestPtr) { + return CallQueryInterface(aSourcePtr.get(), aDestPtr); +} + +#endif /* __nsISupportsUtils_h */ -- cgit v1.2.3