Struct Column

pub struct Column { /* private fields */ }

A type-erased contiguous container for data of a homogeneous type.

Conceptually, a Column is very similar to a type-erased Vec<T>. It also stores the change detection ticks for its components, kept in two separate contiguous buffers internally. An element shares its data across these buffers by using the same index (i.e. the entity at row 3 has its data at index 3 and its change detection ticks at index 3). A slice to these contiguous blocks of memory can be fetched via Column::get_data_slice, Column::get_added_ticks_slice, and Column::get_changed_ticks_slice.

Like many other low-level storage types, Column has a limited and highly unsafe interface. It’s highly advised to use higher level types and their safe abstractions instead of working directly with Column.

Implementations

impl Column

pub fn item_layout(&self) -> Layout

Fetches the Layout for the underlying type.

pub fn len(&self) -> usize

Gets the current number of elements stored in the column.

pub fn is_empty(&self) -> bool

Checks if the column is empty. Returns true if there are no elements, false otherwise.

pub fn get_data_ptr(&self) -> Ptr<'_>

Fetches the data pointer to the first element of the Column.

The pointer is type erased, so using this function to fetch anything other than the first element will require computing the offset using Column::item_layout.

pub unsafe fn get_data_slice<T>(&self) -> &[UnsafeCell<T>]

Fetches the slice to the Column’s data cast to a given type.

Note: The values stored within are UnsafeCell. Users of this API must ensure that accesses to each individual element adhere to the safety invariants of UnsafeCell.

Safety

The type T must be the type of the items in this column.

pub fn get_added_ticks_slice(&self) -> &[UnsafeCell<Tick>]

Fetches the slice to the Column’s “added” change detection ticks.

Note: The values stored within are UnsafeCell. Users of this API must ensure that accesses to each individual element adhere to the safety invariants of UnsafeCell.

pub fn get_changed_ticks_slice(&self) -> &[UnsafeCell<Tick>]

Fetches the slice to the Column’s “changed” change detection ticks.

Note: The values stored within are UnsafeCell. Users of this API must ensure that accesses to each individual element adhere to the safety invariants of UnsafeCell.

pub fn get(&self, row: TableRow) -> Option<(Ptr<'_>, TickCells<'_>)>

Fetches a reference to the data and change detection ticks at row.

Returns None if row is out of bounds.

pub fn get_data(&self, row: TableRow) -> Option<Ptr<'_>>

Fetches a read-only reference to the data at row.

Returns None if row is out of bounds.

pub unsafe fn get_data_unchecked(&self, row: TableRow) -> Ptr<'_>

Fetches a read-only reference to the data at row. Unlike Column::get this does not do any bounds checking.

Safety

• row must be within the range [0, self.len()).
• no other mutable reference to the data of the same row can exist at the same time

pub fn get_data_mut(&mut self, row: TableRow) -> Option<PtrMut<'_>>

Fetches a mutable reference to the data at row.

Returns None if row is out of bounds.

pub fn get_added_tick(&self, row: TableRow) -> Option<&UnsafeCell<Tick>>

Fetches the “added” change detection tick for the value at row.

Returns None if row is out of bounds.

Note: The values stored within are UnsafeCell. Users of this API must ensure that accesses to each individual element adhere to the safety invariants of UnsafeCell.

pub fn get_changed_tick(&self, row: TableRow) -> Option<&UnsafeCell<Tick>>

Fetches the “changed” change detection tick for the value at row.

Returns None if row is out of bounds.

Note: The values stored within are UnsafeCell. Users of this API must ensure that accesses to each individual element adhere to the safety invariants of UnsafeCell.

pub fn get_ticks(&self, row: TableRow) -> Option<ComponentTicks>

Fetches the change detection ticks for the value at row.

Returns None if row is out of bounds.

pub unsafe fn get_added_tick_unchecked( &self, row: TableRow, ) -> &UnsafeCell<Tick>

Fetches the “added” change detection tick for the value at row. Unlike Column::get_added_tick this function does not do any bounds checking.

Safety

row must be within the range [0, self.len()).

pub unsafe fn get_changed_tick_unchecked( &self, row: TableRow, ) -> &UnsafeCell<Tick>

Fetches the “changed” change detection tick for the value at row. Unlike Column::get_changed_tick this function does not do any bounds checking.

Safety

row must be within the range [0, self.len()).

pub unsafe fn get_ticks_unchecked(&self, row: TableRow) -> ComponentTicks

Fetches the change detection ticks for the value at row. Unlike Column::get_ticks this function does not do any bounds checking.

Safety

row must be within the range [0, self.len()).

pub fn clear(&mut self)

Clears the column, removing all values.

Note that this function has no effect on the allocated capacity of the Column>

Trait Implementations

impl Debug for Column

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

Formats the value using the given formatter.