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Summary: To add more code there. Reviewed By: JakobDegen Differential Revision: D61058558 fbshipit-source-id: 4fa7f3519a3c49b61dce8771d0997de7f5299666
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| /* | ||
| * Copyright 2019 The Starlark in Rust Authors. | ||
| * Copyright (c) Facebook, Inc. and its affiliates. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * https://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| use std::fmt; | ||
| use std::fmt::Formatter; | ||
| use std::ops::Deref; | ||
|
|
||
| use allocative::Allocative; | ||
| use dupe::Dupe; | ||
|
|
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| use crate::values::FrozenHeapRef; | ||
| use crate::values::FrozenRef; | ||
|
|
||
| /// Same as a `FrozenRef`, but it keeps itself alive by storing a reference to the owning heap. | ||
| /// | ||
| /// Usually constructed from an `OwnedFrozenValueTyped`. | ||
| #[derive(Clone, Dupe, Allocative)] | ||
| pub struct OwnedFrozenRef<T: ?Sized + 'static> { | ||
| owner: FrozenHeapRef, | ||
| // Invariant: this FrozenValue must be kept alive by the `owner` field. | ||
| value: FrozenRef<'static, T>, | ||
| } | ||
|
|
||
| impl<T: ?Sized> OwnedFrozenRef<T> { | ||
| /// Creates a new `OwnedFrozenRef` pointing at the given value. | ||
| /// | ||
| /// ## Safety | ||
| /// | ||
| /// The reference must be kept alive by the owning heap | ||
| pub unsafe fn new_unchecked(value: &'static T, owner: FrozenHeapRef) -> OwnedFrozenRef<T> { | ||
| OwnedFrozenRef { | ||
| owner, | ||
| value: FrozenRef::new(value), | ||
| } | ||
| } | ||
|
|
||
| /// Returns a reference to the underlying value. | ||
| pub fn as_ref<'a>(&'a self) -> &'a T { | ||
| self.value.as_ref() | ||
| } | ||
|
|
||
| /// Converts `self` into a new reference that points at something reachable from the previous. | ||
| /// | ||
| /// See the caveats on `[starlark::values::OwnedFrozenValue::map]` | ||
| pub fn map<F, U: ?Sized>(self, f: F) -> OwnedFrozenRef<U> | ||
| where | ||
| for<'v> F: FnOnce(&'v T) -> &'v U, | ||
| { | ||
| OwnedFrozenRef { | ||
| owner: self.owner, | ||
| value: self.value.map(f), | ||
| } | ||
| } | ||
|
|
||
| /// Fallible map the reference to another one. | ||
| pub fn try_map_result<F, U: ?Sized, E>(self, f: F) -> Result<OwnedFrozenRef<U>, E> | ||
| where | ||
| for<'v> F: FnOnce(&'v T) -> Result<&'v U, E>, | ||
| { | ||
| Ok(OwnedFrozenRef { | ||
| owner: self.owner, | ||
| value: self.value.try_map_result(f)?, | ||
| }) | ||
| } | ||
|
|
||
| /// Optionally map the reference to another one. | ||
| pub fn try_map_option<F, U: ?Sized>(self, f: F) -> Option<OwnedFrozenRef<U>> | ||
| where | ||
| for<'v> F: FnOnce(&'v T) -> Option<&'v U>, | ||
| { | ||
| Some(OwnedFrozenRef { | ||
| owner: self.owner, | ||
| value: self.value.try_map_option(f)?, | ||
| }) | ||
| } | ||
|
|
||
| /// Get a reference to the owning frozen heap | ||
| pub fn owner(&self) -> &FrozenHeapRef { | ||
| &self.owner | ||
| } | ||
| } | ||
|
|
||
| impl<T: ?Sized + fmt::Debug> fmt::Debug for OwnedFrozenRef<T> { | ||
| fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { | ||
| fmt::Debug::fmt(&self.value, f) | ||
| } | ||
| } | ||
|
|
||
| impl<T: ?Sized + fmt::Display> fmt::Display for OwnedFrozenRef<T> { | ||
| fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { | ||
| fmt::Display::fmt(&self.value, f) | ||
| } | ||
| } | ||
|
|
||
| impl<T: ?Sized> Deref for OwnedFrozenRef<T> { | ||
| type Target = T; | ||
|
|
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| fn deref(&self) -> &T { | ||
| self.as_ref() | ||
| } | ||
| } |