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Implement TrustedLen for iter::Fuse<I: TrustedLen>

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This commit is contained in:
Sebastian Dröge 2021-01-31 18:53:11 +02:00
parent 99893346e8
commit 12b605af88
1 changed files with 9 additions and 1 deletions
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10
library/core/src/iter/adapters/fuse.rs
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@ -1,6 +1,8 @@
use crate::intrinsics; use crate::intrinsics;
use crate::iter::adapters::{zip::try_get_unchecked, InPlaceIterable, SourceIter}; use crate::iter::adapters::{zip::try_get_unchecked, InPlaceIterable, SourceIter};
use crate::iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator, TrustedRandomAccess}; use crate::iter::{
DoubleEndedIterator, ExactSizeIterator, FusedIterator, TrustedLen, TrustedRandomAccess,
};
use crate::ops::Try; use crate::ops::Try;
/// An iterator that yields `None` forever after the underlying iterator /// An iterator that yields `None` forever after the underlying iterator
@ -182,6 +184,12 @@ where
} }
} }
#[unstable(feature = "trusted_len", issue = "37572")]
// SAFETY: `TrustedLen` requires that an accurate length is reported via `size_hint()`. As `Fuse`
// is just forwarding this to the wrapped iterator `I` this property is preserved and it is safe to
// implement `TrustedLen` here.
unsafe impl<I> TrustedLen for Fuse<I> where I: TrustedLen {}
#[doc(hidden)] #[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")] #[unstable(feature = "trusted_random_access", issue = "none")]
// SAFETY: `TrustedRandomAccess` requires that `size_hint()` must be exact and cheap to call, and // SAFETY: `TrustedRandomAccess` requires that `size_hint()` must be exact and cheap to call, and