gecko-dev/mfbt/fallible.h

65 lines
1.7 KiB
C++

/* 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 mozilla_fallible_h
#define mozilla_fallible_h
#if defined(__cplusplus)
/* Explicit fallible allocation
*
* Memory allocation (normally) defaults to abort in case of failed
* allocation. That is, it never returns NULL, and crashes instead.
*
* Code can explicitely request for fallible memory allocation thanks
* to the declarations below.
*
* The typical use of the mozilla::fallible const is with placement new,
* like the following:
*
* foo = new (mozilla::fallible) Foo();
*
* The following forms, or derivatives, are also possible but deprecated:
*
* foo = new ((mozilla::fallible_t())) Foo();
*
* const mozilla::fallible_t f = mozilla::fallible_t();
* bar = new (f) Bar();
*
* It is also possible to declare method overloads with fallible allocation
* alternatives, like so:
*
* class Foo {
* public:
* void Method(void *);
* void Method(void *, const mozilla::fallible_t&);
* };
*
* Foo foo;
* foo.Method(nullptr, mozilla::fallible);
*
* If that last method call is in a method that itself takes a const
* fallible_t& argument, it is recommended to propagate that argument
* instead of using mozilla::fallible:
*
* void Func(Foo &foo, const mozilla::fallible_t& aFallible) {
* foo.Method(nullptr, aFallible);
* }
*
*/
# include <new>
namespace mozilla {
using fallible_t = std::nothrow_t;
static const fallible_t& fallible = std::nothrow;
} // namespace mozilla
#endif
#endif // mozilla_fallible_h