pub struct Cursor<'list, T: Linked<Links<T>> + ?Sized> { /* private fields */ }
Expand description
A cursor over a List
.
A Cursor
is like a by-reference Iterator
(and it implements the
Iterator
trait), except that it can freely seek
back and forth, and can safely mutate the list during iteration. This is
because the lifetime of its yielded references is tied to its own lifetime,
instead of that of the underlying underlying list. This means cursors cannot
yield multiple elements at once.
Cursors always rest between two elements in the list, and index in a logically circular way — once a cursor has advanced past the end of the list, advancing it again will “wrap around” to the first element, and seeking past the first element will wrap the cursor around to the end.
To accommodate this, there is a null non-element that yields None
between
the head and tail of the list. This indicates that the cursor has reached
an end of the list.
This type implements the same interface as the
alloc::collections::linked_list::Cursor
type, and should behave
similarly.
For a mutable cursor, see the CursorMut
type.
Implementations§
source§impl<'list, T: Linked<Links<T>> + ?Sized> Cursor<'list, T>
impl<'list, T: Linked<Links<T>> + ?Sized> Cursor<'list, T>
sourcepub fn index(&self) -> Option<usize>
pub fn index(&self) -> Option<usize>
Returns the index of this cursor’s position in the List
.
This returns None
if the cursor is currently pointing to the
null element.
sourcepub fn current(&self) -> Option<Pin<&T>>
pub fn current(&self) -> Option<Pin<&T>>
Borrows the element that the cursor is currently pointing at.
This returns None
if the cursor is currently pointing to the
null element.
Trait Implementations§
source§impl<'list, T: Linked<Links<T>> + ?Sized> Iterator for Cursor<'list, T>
impl<'list, T: Linked<Links<T>> + ?Sized> Iterator for Cursor<'list, T>
source§fn size_hint(&self) -> (usize, Option<usize>)
fn size_hint(&self) -> (usize, Option<usize>)
A Cursor
can never return an accurate size_hint
— its lower
bound is always 0 and its upper bound is always None
.
This is because the cursor may be moved around within the list through
methods outside of its Iterator
implementation. This would make any
size_hint
s a Cursor
] returns inaccurate.
source§fn next(&mut self) -> Option<Self::Item>
fn next(&mut self) -> Option<Self::Item>
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