Trait kernel::list::ListItem

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pub unsafe trait ListItem<const ID: u64 = 0>: ListArcSafe<ID> {
    // Required methods
    unsafe fn view_links(me: *const Self) -> *mut ListLinks<ID>;
    unsafe fn view_value(me: *mut ListLinks<ID>) -> *const Self;
    unsafe fn prepare_to_insert(me: *const Self) -> *mut ListLinks<ID>;
    unsafe fn post_remove(me: *mut ListLinks<ID>) -> *const Self;
}
Expand description

Implemented by types where a ListArc<Self> can be inserted into a List.

§Safety

Implementers must ensure that they provide the guarantees documented on methods provided by this trait.

Required Methods§

Views the ListLinks for this value.

§Guarantees

If there is a previous call to prepare_to_insert and there is no call to post_remove since the most recent such call, then this returns the same pointer as the one returned by the most recent call to prepare_to_insert.

Otherwise, the returned pointer points at a read-only ListLinks with two null pointers.

§Safety

The provided pointer must point at a valid value. (It need not be in an Arc.)

source

unsafe fn view_value(me: *mut ListLinks<ID>) -> *const Self

View the full value given its ListLinks field.

Can only be used when the value is in a list.

§Guarantees
  • Returns the same pointer as the one passed to the most recent call to prepare_to_insert.
  • The returned pointer is valid until the next call to post_remove.
§Safety
  • The provided pointer must originate from the most recent call to prepare_to_insert, or from a call to view_links that happened after the most recent call to prepare_to_insert.
  • Since the most recent call to prepare_to_insert, the post_remove method must not have been called.
source

unsafe fn prepare_to_insert(me: *const Self) -> *mut ListLinks<ID>

This is called when an item is inserted into a List.

§Guarantees

The caller is granted exclusive access to the returned ListLinks until post_remove is called.

§Safety
  • The provided pointer must point at a valid value in an Arc.
  • Calls to prepare_to_insert and post_remove on the same value must alternate.
  • The caller must own the ListArc for this value.
  • The caller must not give up ownership of the ListArc unless post_remove has been called after this call to prepare_to_insert.
source

unsafe fn post_remove(me: *mut ListLinks<ID>) -> *const Self

This undoes a previous call to prepare_to_insert.

§Guarantees

The returned pointer is the pointer that was originally passed to prepare_to_insert.

§Safety

The provided pointer must be the pointer returned by the most recent call to prepare_to_insert.

Object Safety§

This trait is not object safe.

Implementors§