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rust: alloc: introduce the
VecExt
trait
Make `try_with_capacity`, `try_push`, and `try_extend_from_slice` methods available in `Vec` even though it doesn't implement them. It is implemented with `try_reserve` and `push_within_capacity`. This is in preparation for switching to the upstream `alloc` crate. Reviewed-by: Benno Lossin <[email protected]> Suggested-by: Gary Guo <[email protected]> Signed-off-by: Wedson Almeida Filho <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Miguel Ojeda <[email protected]>
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#[cfg(not(test))] | ||
#[cfg(not(testlib))] | ||
mod allocator; | ||
pub mod vec_ext; |
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// SPDX-License-Identifier: GPL-2.0 | ||
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//! Extensions to [`Vec`] for fallible allocations. | ||
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use alloc::{collections::TryReserveError, vec::Vec}; | ||
use core::result::Result; | ||
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/// Extensions to [`Vec`]. | ||
pub trait VecExt<T>: Sized { | ||
/// Creates a new [`Vec`] instance with at least the given capacity. | ||
fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>; | ||
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/// Appends an element to the back of the [`Vec`] instance. | ||
fn try_push(&mut self, v: T) -> Result<(), TryReserveError>; | ||
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/// Pushes clones of the elements of slice into the [`Vec`] instance. | ||
fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError> | ||
where | ||
T: Clone; | ||
} | ||
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impl<T> VecExt<T> for Vec<T> { | ||
fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError> { | ||
let mut v = Vec::new(); | ||
v.try_reserve(capacity)?; | ||
Ok(v) | ||
} | ||
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fn try_push(&mut self, v: T) -> Result<(), TryReserveError> { | ||
if let Err(retry) = self.push_within_capacity(v) { | ||
self.try_reserve(1)?; | ||
let _ = self.push_within_capacity(retry); | ||
} | ||
Ok(()) | ||
} | ||
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fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError> | ||
where | ||
T: Clone, | ||
{ | ||
self.try_reserve(other.len())?; | ||
for item in other { | ||
self.try_push(item.clone())?; | ||
} | ||
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Ok(()) | ||
} | ||
} |
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