UncheckedRef

Struct UncheckedRef 

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pub struct UncheckedRef<'b, T: ?Sized + 'b> { /* private fields */ }
Expand description

Wraps a borrowed reference to a value in a RefCell box. A wrapper type for an immutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

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impl<'b, T: ?Sized> UncheckedRef<'b, T>

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pub fn clone(orig: &UncheckedRef<'b, T>) -> UncheckedRef<'b, T>

Copies a UncheckedRef.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as UncheckedRef::clone(...). A Clone implementation or a method would interfere with the widespread use of r.borrow().clone() to clone the contents of a RefCell.

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pub fn map<U: ?Sized, F>(orig: UncheckedRef<'b, T>, f: F) -> UncheckedRef<'b, U>
where F: FnOnce(&T) -> &U,

Makes a new UncheckedRef for a component of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as UncheckedRef::map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use unchecked_refcell::{UncheckedRefCell, UncheckedRef};

let c = UncheckedRefCell::new((5, 'b'));
let b1: UncheckedRef<'_, (u32, char)> = c.borrow();
let b2: UncheckedRef<'_, u32> = UncheckedRef::map(b1, |t| &t.0);
assert_eq!(*b2, 5)
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pub fn filter_map<U: ?Sized, F>( orig: UncheckedRef<'b, T>, f: F, ) -> Result<UncheckedRef<'b, U>, Self>
where F: FnOnce(&T) -> Option<&U>,

Makes a new UncheckedRef for an optional component of the borrowed data. The original guard is returned as an Err(..) if the closure returns None.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as UncheckedRef::filter_map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use unchecked_refcell::{UncheckedRefCell, UncheckedRef};

let c = UncheckedRefCell::new(vec![1, 2, 3]);
let b1: UncheckedRef<'_, Vec<u32>> = c.borrow();
let b2: Result<UncheckedRef<'_, u32>, _> = UncheckedRef::filter_map(b1, |v| v.get(1));
assert_eq!(*b2.unwrap(), 2);
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pub fn try_map<U: ?Sized, E>( orig: UncheckedRef<'b, T>, f: impl FnOnce(&T) -> Result<&U, E>, ) -> Result<UncheckedRef<'b, U>, (Self, E)>

Tries to makes a new UncheckedRef for a component of the borrowed data. On failure, the original guard is returned alongside with the error returned by the closure.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as UncheckedRef::try_map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use unchecked_refcell::{UncheckedRefCell, UncheckedRef};
use std::str::{from_utf8, Utf8Error};

let c = UncheckedRefCell::new(vec![0xF0, 0x9F, 0xA6 ,0x80]);
let b1: UncheckedRef<'_, Vec<u8>> = c.borrow();
let b2: Result<UncheckedRef<'_, str>, _> = UncheckedRef::try_map(b1, |v| from_utf8(v));
assert_eq!(&*b2.unwrap(), "🦀");

let c = UncheckedRefCell::new(vec![0xF0, 0x9F, 0xA6]);
let b1: UncheckedRef<'_, Vec<u8>> = c.borrow();
let b2: Result<_, (UncheckedRef<'_, Vec<u8>>, Utf8Error)> = UncheckedRef::try_map(b1, |v| from_utf8(v));
let (b3, e) = b2.unwrap_err();
assert_eq!(*b3, vec![0xF0, 0x9F, 0xA6]);
assert_eq!(e.valid_up_to(), 0);
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pub fn map_split<U: ?Sized, V: ?Sized, F>( orig: UncheckedRef<'b, T>, f: F, ) -> (UncheckedRef<'b, U>, UncheckedRef<'b, V>)
where F: FnOnce(&T) -> (&U, &V),

Splits a UncheckedRef into multiple UncheckedRefs for different components of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as UncheckedRef::map_split(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use unchecked_refcell::{UncheckedRefCell, UncheckedRef};

let cell = UncheckedRefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow();
let (begin, end) = UncheckedRef::map_split(borrow, |slice| slice.split_at(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
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pub fn leak(orig: UncheckedRef<'b, T>) -> &'b T

Converts into a reference to the underlying data.

The underlying RefCell can never be mutably borrowed from again and will always appear already immutably borrowed. It is not a good idea to leak more than a constant number of references. The RefCell can be immutably borrowed again if only a smaller number of leaks have occurred in total.

This is an associated function that needs to be used as UncheckedRef::leak(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use unchecked_refcell::{UncheckedRefCell, UncheckedRef};
let cell = UncheckedRefCell::new(0);

let value = UncheckedRef::leak(cell.borrow());
assert_eq!(*value, 0);

assert!(cell.try_borrow().is_ok());
assert!(cell.try_borrow_mut().is_err());

Trait Implementations§

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impl<T: ?Sized + Debug> Debug for UncheckedRef<'_, T>

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

Formats the value using the given formatter. Read more
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impl<T: ?Sized> Deref for UncheckedRef<'_, T>

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
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impl<T: ?Sized + Display> Display for UncheckedRef<'_, T>

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

Formats the value using the given formatter. Read more

Auto Trait Implementations§

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impl<'b, T> Freeze for UncheckedRef<'b, T>
where T: ?Sized,

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impl<'b, T> !RefUnwindSafe for UncheckedRef<'b, T>

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impl<'b, T> !Send for UncheckedRef<'b, T>

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impl<'b, T> !Sync for UncheckedRef<'b, T>

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impl<'b, T> Unpin for UncheckedRef<'b, T>
where T: ?Sized,

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impl<'b, T> !UnwindSafe for UncheckedRef<'b, T>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<P, T> Receiver for P
where P: Deref<Target = T> + ?Sized, T: ?Sized,

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type Target = T

🔬This is a nightly-only experimental API. (arbitrary_self_types)
The target type on which the method may be called.
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impl<T> ToString for T
where T: Display + ?Sized,

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fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.