mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
f3ea548a3e
The new enum makes keeping track of what flavor of lifetime values ought to have a little bit type-safer.
72 lines
2.5 KiB
C++
72 lines
2.5 KiB
C++
//===---- Lifetime.h - How long a value should be kept alive ----*- C++ -*-===//
|
|
//
|
|
// This source file is part of the Swift.org open source project
|
|
//
|
|
// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
|
|
// Licensed under Apache License v2.0 with Runtime Library Exception
|
|
//
|
|
// See https://swift.org/LICENSE.txt for license information
|
|
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Defines a simple type-safe wrapper type to indicate the kind of lifetime that
|
|
// a value has--whether it is tied to a lexical scope or not.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "swift/AST/LifetimeAnnotation.h"
|
|
|
|
#ifndef SWIFT_SIL_LIFETIME_H
|
|
#define SWIFT_SIL_LIFETIME_H
|
|
|
|
namespace swift {
|
|
|
|
/// How long a value (such as instances of a type) should be kept alive--how
|
|
/// aggressively its destroys may be hoisted.
|
|
///
|
|
/// By default, types have lifetimes inferred from their structure, see
|
|
/// TypeLowering::RecursiveProperties::isLexical. It can be overridden both on
|
|
/// the type level and the value level via attributes.
|
|
struct Lifetime {
|
|
enum Storage : uint8_t {
|
|
/// No lifetime. Applicable to values which aren't destroyed.
|
|
None,
|
|
/// A lifetime independent from the lexical scope of the value: its
|
|
/// releases are hoisted without respect to deinit barriers.
|
|
EagerMove,
|
|
/// A lifetime tied to the lexical scope of the value: its releases are
|
|
/// not hoisted over deinit barriers.
|
|
Lexical,
|
|
} value;
|
|
|
|
Lifetime(decltype(value) newValue) : value(newValue) {}
|
|
|
|
operator Storage() const { return value; }
|
|
|
|
bool isLexical() { return value == Lifetime::Lexical; }
|
|
|
|
bool isEagerMove() { return value == Lifetime::EagerMove; }
|
|
|
|
/// Given a lifetime for a type and the lifetime annotation on a value of that
|
|
/// type, the lifetime appropriate for that value.
|
|
///
|
|
/// Value annotations override a type's lifetime, so the result is just the
|
|
/// lifetime indicated by the annotation, if there is one; otherwise its the
|
|
/// lifetime from the type.
|
|
Lifetime getLifetimeForAnnotatedValue(LifetimeAnnotation annotation) const {
|
|
switch (annotation) {
|
|
case LifetimeAnnotation::None:
|
|
return *this;
|
|
case LifetimeAnnotation::EagerMove:
|
|
return Lifetime::EagerMove;
|
|
case LifetimeAnnotation::Lexical:
|
|
return Lifetime::Lexical;
|
|
}
|
|
}
|
|
};
|
|
|
|
} // end swift namespace
|
|
|
|
#endif
|