Struct starlark::values::OwnedFrozenValue

pub struct OwnedFrozenValue { /* private fields */ }

A FrozenValue along with a FrozenHeapRef that ensures it is kept alive. Obtained from FrozenModule::get or OwnedFrozenValue::alloc.

While it is possible to obtain the underlying FrozenValue with unchecked_frozen_value, that approach is strongly discouraged. See the other methods which unpack the code, access it as a Value (which has a suitable lifetime) or add references to other heaps.

Implementations

impl OwnedFrozenValue

pub unsafe fn new(owner: FrozenHeapRef, value: FrozenValue) -> Self

Create an OwnedFrozenValue - generally OwnedFrozenValues are obtained from FrozenModule::get. Safe provided the value (and any values it points at) are kept alive by the owner, typically because the value was created on the heap.

use starlark::values::FrozenHeap;
use starlark::values::OwnedFrozenValue;
let heap = FrozenHeap::new();
let value = heap.alloc("test");
unsafe { OwnedFrozenValue::new(heap.into_ref(), value) };

pub fn alloc(x: impl AllocFrozenValue) -> Self

Create an OwnedFrozenValue in a new heap.

pub fn unpack_bool(&self) -> Option<bool>

Unpack the boolean contained in the underlying value, or None if it is not a boolean.

pub fn unpack_i32(&self) -> Option<i32>

Obtain the underlying integer if it fits in an i32. Note floats are not considered integers, i. e. unpack_i32 for 1.0 will return None.

pub fn unpack_str(&self) -> Option<&str>

Unpack the string contained in the underlying value, or None if it is not an string.

pub fn downcast<T: StarlarkValue<'static>>( self ) -> Result<OwnedFrozenValueTyped<T>, Self>

Check if self references <T>.

pub fn downcast_anyhow<T: StarlarkValue<'static>>( self ) -> Result<OwnedFrozenValueTyped<T>>

downcast, but return an error for human instead of original value.

pub fn value<'v>(&'v self) -> Value<'v>

Obtain the Value stored inside.

pub fn owned_value<'v>(&self, heap: &'v FrozenHeap) -> Value<'v>

Extract a Value by passing the FrozenHeap which will promise to keep it alive. When using with a Module, see the frozen_heap function. If you don’t care about the resulting lifetime the value method is easier.

pub fn map(&self, f: impl FnOnce(FrozenValue) -> FrozenValue) -> Self

Operate on the FrozenValue stored inside. Safe provided you don’t store the argument FrozenValue after the closure has returned. Using this function is discouraged when possible.

pub fn try_map<E>( &self, f: impl FnOnce(FrozenValue) -> Result<FrozenValue, E> ) -> Result<Self, E>

Same as map above but with Result

pub fn owner(&self) -> &FrozenHeapRef

Obtain a reference to the FrozenHeap that owns this value.

pub unsafe fn unchecked_frozen_value(&self) -> FrozenValue

Obtain direct access to the FrozenValue that lives inside. If you drop all references to the FrozenHeap keeping it alive, any code using the FrozenValue is likely to segfault. If possible use value or owned_frozen_value.

pub unsafe fn owned_frozen_value(&self, heap: &FrozenHeap) -> FrozenValue

Extract a FrozenValue by passing the FrozenHeap which will keep it alive. Provided the argument heap does indeed stay alive for the lifetime of the result, all will be fine. Unsafe if you pass the wrong heap, or don’t keep the heap alive long enough. Where possible, use value or owned_value.

Trait Implementations

impl AllocFrozenValue for OwnedFrozenValue

fn alloc_frozen_value(self, heap: &FrozenHeap) -> FrozenValue

Allocate a value in the frozen heap and return a reference to the allocated value.

impl Allocative for OwnedFrozenValue

fn visit<'allocative_a, 'allocative_b: 'allocative_a>( &self, visitor: &'allocative_a mut Visitor<'allocative_b> )

impl Clone for OwnedFrozenValue

fn clone(&self) -> OwnedFrozenValue

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OwnedFrozenValue

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for OwnedFrozenValue

fn default() -> Self

Returns the “default value” for a type.

impl Display for OwnedFrozenValue

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Dupe for OwnedFrozenValue

fn dupe(&self) -> Self

impl StarlarkTypeRepr for OwnedFrozenValue

fn starlark_type_repr() -> Ty

The representation of a type that a user would use verbatim in starlark type annotations