Struct Permission

pub struct Permission {
    inner: PermissionPriv,
}

Public interface to the state machine that controls read-write permissions. This is the “private enum” pattern.

Fields

inner: PermissionPriv

Implementations

impl Permission

pub fn short_name(self) -> &'static str

Abbreviated name of the permission (uniformly 3 letters for nice alignment).

impl Permission

pub fn is_initial(&self) -> bool

Check if self can be the initial state of a pointer.

pub fn is_disabled(&self) -> bool

Check if self is the terminal state of a pointer (is Disabled).

pub fn is_active(&self) -> bool

Check if self is the post-child-write state of a pointer (is Active).

pub fn is_frozen(&self) -> bool

Check if self is the never-allow-writes-again state of a pointer (is Frozen).

pub fn new_active() -> Self

Default initial permission of the root of a new tree at inbounds positions. Must only be used for the root, this is not in general an “initial” permission!

fn new_reserved_frz() -> Self

Default initial permission of a reborrowed mutable reference that is either protected or not interior mutable.

fn new_reserved_im() -> Self

Default initial permission of an unprotected interior mutable reference.

pub fn new_reserved(ty_is_freeze: bool, protected: bool) -> Self

Wrapper around new_reserved_frz and new_reserved_im that decides which to call based on the interior mutability and the retag kind (whether there is a protector is relevant because being protected takes priority over being interior mutable)

pub fn new_frozen() -> Self

Default initial permission of a reborrowed shared reference.

pub fn new_disabled() -> Self

Default initial permission of the root of a new tree at out-of-bounds positions. Must only be used for the root, this is not in general an “initial” permission!

pub fn compatible_with_protector(&self) -> bool

Reject ReservedIM that cannot exist in the presence of a protector.

pub fn perform_access( kind: AccessKind, rel_pos: AccessRelatedness, old_perm: Self, protected: bool, ) -> Option<PermTransition>

Apply the transition to the inner PermissionPriv.

pub fn can_be_replaced_by_child(self, child: Self) -> bool

During a provenance GC, we want to compact the tree. For this, we want to merge nodes upwards if they have a singleton parent. But we need to be careful: If the parent is Frozen, and the child is Reserved, we can not do such a merge. In general, such a merge is possible if the parent allows similar accesses, and in particular if the parent never causes UB on its own. This is enforced by a test, namely tree_compacting_is_sound. See that test for more information. This method is only sound if the parent is not protected. We never attempt to remove protected parents.

pub fn strongest_idempotent_foreign_access( &self, prot: bool, ) -> IdempotentForeignAccess

Returns the strongest foreign action this node survives (without change), where prot indicates if it is protected. See foreign_access_skipping

Trait Implementations

impl Clone for Permission

fn clone(&self) -> Permission

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Permission

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Permission

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for Permission

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Permission

fn eq(&self, other: &Permission) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Permission

fn partial_cmp(&self, other: &Permission) -> Option<Ordering>

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

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Permission

impl Eq for Permission

impl StructuralPartialEq for Permission

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 1 byte