Struct Id 

pub struct Id(/* private fields */);

Widget identifier

All widgets are assigned an identifier which is unique within the window. This type may be tested for equality and order and may be iterated over as a “path” of “key” values.

Formatting an Id via Display prints the the path, for example #1290a4. Here, # represents the root; each following hexadecimal digit represents a path component except that digits 8-f are combined with the following digit(s). Hence, the above path has components 1, 2, 90, a4. To interpret these values, first subtract 8 from each digit but the last digit, then read as base-8: [1, 2, 8, 20].

Representation

This type is small (64-bit) and non-zero: Option<Id> has the same size as Id. It is also very cheap to Clone: usually only one if check, and in the worst case a pointer dereference and ref-count increment. Paths up to 14 digits long (as printed) are represented internally; beyond this limit a reference-counted stack allocation is used.

Id is neither Send nor Sync.

Invalid state

When Id is Default constructed, it uses a special invalid state. Any attempt to use or compare such an invalid state will cause a panic.

Widgets are initially constructed with an invalid Id, then assigned an Id when configured (see Events::configure). In most cases values are persistent but this is not guaranteed (e.g. inserting or removing a child from a List widget will affect the identifiers of all following children). View-widgets assign path components based on the data key, thus possibly making identifiers persistent.

Implementations

impl Id

pub fn is_valid(&self) -> bool

Is the identifier valid?

Default-constructed identifiers are invalid. Comparing invalid ids is considered a logic error and thus will panic in debug builds. This method may be used to check an identifier’s validity.

pub fn iter(&self) -> WidgetPathIter<'_>

Iterate over path components

pub fn path_len(&self) -> usize

Get the path len (number of indices, not storage length)

pub fn is_ancestor_of(&self, id: &Self) -> bool

Returns true if self equals id or if id is a descendant of self

pub fn common_ancestor(&self, id: &Self) -> Self

Find the most-derived common ancestor

pub fn iter_keys_after(&self, id: &Self) -> WidgetPathIter<'_>

pub fn next_key_after(&self, id: &Self) -> Option<usize>

Get first key in path of self path after id

If the path of self starts with the path of id (id.is_ancestor_of(self)) then this returns the next key in self’s path (if any). Otherwise, this returns None.

pub fn parent(&self) -> Option<Id>

Get the parent widget’s identifier, if not root

pub fn make_child(&self, key: usize) -> Self

Make an identifier for the child with the given key

Note: this is not a getter method. Calling multiple times with the same key may or may not return the same value!

pub fn to_nzu64(&self) -> NonZeroU64

Convert to a NonZeroU64 representation

This conversion is infallible but not free.

The result may be used in equality checks (with a very small risk of false positive due to hash collision) and may be passed to Self::try_from_u64.

pub fn try_from_u64(n: u64) -> Option<Id>

Try converting a u64 to an Id

This method is the inverse of Self::to_nzu64. Assuming that the input n is the result of calling id.to_nzu64().get() for some id, then this method will return:

• Some(Id::INVALID) where !id.is_valid()
• Some(id) where id uses the internal (non-allocated) representation
• Some(id) where id uses an allocated representation and the original id still exists (on the same thread).
• Some(id) (probably) where id uses an allocated representation, has been freed then reconstructed (on the same thread) before calling this method. (There is a tiny chance of hash collision in this case.)

This method will return None where:

• n == 0
• The originating id used an allocating representation and has been deallocated without reconstruction
• The originating id used an allocating representation and was constructed on another thread (excepting the case where an Id with the same hash was constructed on this thread)

Bad / random inputs may yield either None or Some(bad_id) and in the latter case operations on bad_id may panic, but are memory safe.

Trait Implementations

impl Clone for Id

fn clone(&self) -> Id

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Id

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

Formats the value using the given formatter.

impl Default for Id

fn default() -> Self

Returns the “default value” for a type.

impl Display for Id

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

Formats the value using the given formatter.

impl From<&Id> for NodeId

Available on crate feature accesskit only.

Convert to a NodeId using Id::to_nzu64

Use Id::try_from_u64 for the inverse conversion.

fn from(id: &Id) -> Self

Converts to this type from the input type.

impl From<Id> for NodeId

Available on crate feature accesskit only.

Convert to a NodeId using Id::to_nzu64

Use Id::try_from_u64 for the inverse conversion.

fn from(id: Id) -> Self

Converts to this type from the input type.

impl From<Id> for TextOrSource<'static>

fn from(id: Id) -> Self

Converts to this type from the input type.

impl HasId for &Id

fn has_id(self) -> Id

impl HasId for &mut Id

fn has_id(self) -> Id

impl HasId for Id

fn has_id(self) -> Id

impl Hash for Id

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 Ord for Id

fn cmp(&self, rhs: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<'a> PartialEq<&'a Id> for Id

fn eq(&self, rhs: &&Id) -> 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<'a> PartialEq<&'a Option<Id>> for Id

fn eq(&self, rhs: &&Option<Id>) -> 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 PartialEq<&str> for Id

fn eq(&self, rhs: &&str) -> 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<'a> PartialEq<Option<&'a Id>> for Id

fn eq(&self, rhs: &Option<&'a Id>) -> 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 PartialEq<Option<Id>> for Id

fn eq(&self, rhs: &Option<Id>) -> 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 PartialEq<str> for Id

fn eq(&self, rhs: &str) -> 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 PartialEq for Id

fn eq(&self, rhs: &Self) -> 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 Id

fn partial_cmp(&self, rhs: &Self) -> 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 Eq for Id