зеркало из https://github.com/mozilla/gecko-dev.git
68 строки
2.0 KiB
C++
68 строки
2.0 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 fallible = 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);
|
|
* }
|
|
*
|
|
*/
|
|
namespace mozilla {
|
|
|
|
struct fallible_t { };
|
|
|
|
/* This symbol is kept unexported, such that in corner cases where the
|
|
* compiler can't remove its use (essentially, cross compilation-unit
|
|
* calls), the smallest machine code is used.
|
|
* Depending how the linker packs symbols, it will consume between 1 and
|
|
* 8 bytes of read-only data in each executable or shared library, but
|
|
* only in those where it's actually not optimized out by the compiler.
|
|
*/
|
|
extern const fallible_t fallible;
|
|
|
|
} // namespace mozilla
|
|
#endif
|
|
|
|
#endif // mozilla_fallible_h
|