Struct rc_box::RcBox

source · [−]
#[repr(transparent)]
pub struct RcBox<T: ?Sized> { /* private fields */ }
Expand description

Known unique version of Rc.

This type is guaranteed to have the same repr as Box<T>. (The heap layout is that of Rc<T>.)

Implementations

Attempt to downcast the box to a concrete type.

Examples
use std::any::Any;

fn print_if_string(value: RcBox<dyn Any>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
let my_string: Rc<dyn Any> = Rc::new(my_string); 
print_if_string(my_string.try_into().unwrap());
let my_number: Rc<dyn Any> = Rc::new(0i8);
print_if_string(my_number.try_into().unwrap());

The unsizing as Rc is required until DST coercions are stabilized. Alternatively, activate the unsize feature to convert the pointer via an explicit method call.

Attempt to downcast the box to a concrete type.

Examples
use std::any::Any;

fn print_if_string(value: RcBox<dyn Any + Send>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
let my_string: Rc<dyn Any + Send> = Rc::new(my_string); 
print_if_string(my_string.try_into().unwrap());
let my_number: Rc<dyn Any + Send> = Rc::new(0i8);
print_if_string(my_number.try_into().unwrap());

The unsizing as Rc is required until DST coercions are stabilized. Alternatively, activate the unsize feature to convert the pointer via an explicit method call.

Attempt to downcast the box to a concrete type.

Examples
use std::any::Any;

fn print_if_string(value: RcBox<dyn Any + Send + Sync>) {
    if let Ok(string) = value.downcast::<String>() {
        println!("String ({}): {}", string.len(), string);
    }
}

let my_string = "Hello World".to_string();
let my_string: Rc<dyn Any + Send + Sync> = Rc::new(my_string); 
print_if_string(my_string.try_into().unwrap());
let my_number: Rc<dyn Any + Send + Sync> = Rc::new(0i8);
print_if_string(my_number.try_into().unwrap());

The unsizing as Rc is required until DST coercions are stabilized. Alternatively, activate the unsize feature to convert the pointer via an explicit method call.

Construct an RcBox from a raw pointer.

Safety

The raw pointer must have previously been acquired by a call to RcBox::into_raw, or Rc::into_raw where the Rc is known unique.

👎 Deprecated:

Use DerefMut instead

Get a mutable reference into the RcBox.

This method exists only for API compatibility with Rc. Use DerefMut instead.

👎 Deprecated:

Use DerefMut instead

Get a mutable reference into the RcBox.

This method exists only for API compatibility with Rc. Use DerefMut instead.

Returns a raw pointer to the object T pointed to by this RcBox.

Note that this returns a ptr::NonNull, not a raw pointer. That makes this function equivalent to as_raw_non_null.

Consume the RcBox, returning the wrapped pointer.

To avoid a memory leak, the pointer must be converted back to a RcBox, using RcBox::from_raw, or directly into a Rc, using Rc::from_raw.

Note that this returns a ptr::NonNull, not a raw pointer. That makes this function equivalent to into_raw_non_null.

Consume and leak the RcBox.

Create a new RcBox.

Construct a new Pin<RcBox<T>>. If T does not implement Unpin, then the data will be pinned in memory and unable to be moved.

Deconstruct this RcBox, returning the inner value.

Trait Implementations

Create a new custom slice DST. Read more

Performs the conversion.

Performs the conversion.

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Unsizes a pointer using the unsize crate.

Usage

use unsize::{Coercion, CoerceUnsize};

let unique = RcBox::new(|| 42u32);
let unique:RcBox<dyn Fn() -> u32> =
    unique.unsize(Coercion::<_, dyn Fn() -> u32>::to_fn());

let value = (*unique)();
assert_eq!(value, 42);

Another common usage would be to create a dyn Any.

fn print_if_string(value: RcBox) { if let Ok(string) = value.downcast::() { println!(“String ({}): {}”, string.len(), string); } }

let my_string = “Hello World”.to_string(); let my_string: RcBox = RcBox::new(my_string).unsize(Coercion::to_any()); print_if_string(my_string); let my_number: RcBox = RcBox::new(0i8).unsize(Coercion::to_any()); print_if_string(my_number);

The type we point to. This influences which kinds of unsizing are possible. Read more

The output type when unsizing the pointee to U.

Get the raw inner pointer.

Replace the container inner pointer with an unsized version. Read more

Formats the value using the given formatter. Read more

The resulting type after dereferencing.

Dereferences the value.

Mutably dereferences the value.

Formats the value using the given formatter. Read more

Removes and returns an element from the end of the iterator. Read more

Returns the nth element from the end of the iterator. Read more

🔬 This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator from the back by n elements. Read more

This is the reverse version of Iterator::try_fold(): it takes elements starting from the back of the iterator. Read more

An iterator method that reduces the iterator’s elements to a single, final value, starting from the back. Read more

Searches for an element of an iterator from the back that satisfies a predicate. Read more

Executes the destructor for this type. Read more

Turn this erasable pointer into an erased pointer. Read more

Unerase this erased pointer. Read more

Returns the exact length of the iterator. Read more

🔬 This is a nightly-only experimental API. (exact_size_is_empty)

Returns true if the iterator is empty. Read more

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Performs the conversion.

Creates a value from an iterator. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

Returns the hash value for the values written so far. Read more

Writes some data into this Hasher. Read more

Writes a single u8 into this hasher.

Writes a single u16 into this hasher.

Writes a single u32 into this hasher.

Writes a single u64 into this hasher.

Writes a single u128 into this hasher.

Writes a single usize into this hasher.

Writes a single i8 into this hasher.

Writes a single i16 into this hasher.

Writes a single i32 into this hasher.

Writes a single i64 into this hasher.

Writes a single i128 into this hasher.

Writes a single isize into this hasher.

The type of the elements being iterated over.

Advances the iterator and returns the next value. Read more

Returns the bounds on the remaining length of the iterator. Read more

Returns the nth element of the iterator. Read more

Consumes the iterator, counting the number of iterations and returning it. Read more

Consumes the iterator, returning the last element. Read more

🔬 This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator by n elements. Read more

Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more

Takes two iterators and creates a new iterator over both in sequence. Read more

‘Zips up’ two iterators into a single iterator of pairs. Read more

🔬 This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places a copy of separator between adjacent items of the original iterator. Read more

🔬 This is a nightly-only experimental API. (iter_intersperse)

Creates a new iterator which places an item generated by separator between adjacent items of the original iterator. Read more

Takes a closure and creates an iterator which calls that closure on each element. Read more

Calls a closure on each element of an iterator. Read more

Creates an iterator which uses a closure to determine if an element should be yielded. Read more

Creates an iterator that both filters and maps. Read more

Creates an iterator which gives the current iteration count as well as the next value. Read more

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information. Read more

Creates an iterator that skips elements based on a predicate. Read more

Creates an iterator that yields elements based on a predicate. Read more

Creates an iterator that both yields elements based on a predicate and maps. Read more

Creates an iterator that skips the first n elements. Read more

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner. Read more

An iterator adapter similar to fold that holds internal state and produces a new iterator. Read more

Creates an iterator that works like map, but flattens nested structure. Read more

Creates an iterator that flattens nested structure. Read more

Creates an iterator which ends after the first None. Read more

Does something with each element of an iterator, passing the value on. Read more

Borrows an iterator, rather than consuming it. Read more

Transforms an iterator into a collection. Read more

🔬 This is a nightly-only experimental API. (iterator_try_collect)

Fallibly transforms an iterator into a collection, short circuiting if a failure is encountered. Read more

🔬 This is a nightly-only experimental API. (iter_collect_into)

Collects all the items from an iterator into a collection. Read more

Consumes an iterator, creating two collections from it. Read more

🔬 This is a nightly-only experimental API. (iter_partition_in_place)

Reorders the elements of this iterator in-place according to the given predicate, such that all those that return true precede all those that return false. Returns the number of true elements found. Read more

🔬 This is a nightly-only experimental API. (iter_is_partitioned)

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false. Read more

An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more

Folds every element into an accumulator by applying an operation, returning the final result. Read more

Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more

🔬 This is a nightly-only experimental API. (iterator_try_reduce)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more

Tests if every element of the iterator matches a predicate. Read more

Tests if any element of the iterator matches a predicate. Read more

Searches for an element of an iterator that satisfies a predicate. Read more

Applies function to the elements of iterator and returns the first non-none result. Read more

🔬 This is a nightly-only experimental API. (try_find)

Applies function to the elements of iterator and returns the first true result or the first error. Read more

Searches for an element in an iterator, returning its index. Read more

Searches for an element in an iterator from the right, returning its index. Read more

Returns the maximum element of an iterator. Read more

Returns the minimum element of an iterator. Read more

Returns the element that gives the maximum value from the specified function. Read more

Returns the element that gives the maximum value with respect to the specified comparison function. Read more

Returns the element that gives the minimum value from the specified function. Read more

Returns the element that gives the minimum value with respect to the specified comparison function. Read more

Reverses an iterator’s direction. Read more

Converts an iterator of pairs into a pair of containers. Read more

Creates an iterator which copies all of its elements. Read more

Creates an iterator which clones all of its elements. Read more

Repeats an iterator endlessly. Read more

Sums the elements of an iterator. Read more

Iterates over the entire iterator, multiplying all the elements Read more

Lexicographically compares the elements of this Iterator with those of another. Read more

🔬 This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more

Lexicographically compares the elements of this Iterator with those of another. Read more

🔬 This is a nightly-only experimental API. (iter_order_by)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more

Determines if the elements of this Iterator are equal to those of another. Read more

🔬 This is a nightly-only experimental API. (iter_order_by)

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function. Read more

Determines if the elements of this Iterator are unequal to those of another. Read more

Determines if the elements of this Iterator are lexicographically less than those of another. Read more

Determines if the elements of this Iterator are lexicographically less or equal to those of another. Read more

Determines if the elements of this Iterator are lexicographically greater than those of another. Read more

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another. Read more

🔬 This is a nightly-only experimental API. (is_sorted)

Checks if the elements of this iterator are sorted. Read more

🔬 This is a nightly-only experimental API. (is_sorted)

Checks if the elements of this iterator are sorted using the given comparator function. Read more

🔬 This is a nightly-only experimental API. (is_sorted)

Checks if the elements of this iterator are sorted using the given key extraction function. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Formats the value using the given formatter.

Create a new custom slice DST with a fallible initialization function. Read more

The type returned in the event of a conversion error.

Performs the conversion.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Convert a pointer, as if with unsize coercion. Read more

Unerase this erased pointer. Read more

Whether this implementor has acknowledged the 1.1.0 update to unerase’s documented implementation requirements. Read more

Turn this erasable pointer into an erased pointer. Read more

Performs the conversion.

Returns the argument unchanged.

Calls U::from(self).

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

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

Converts the given value to a String. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.