devela/data/
absence.rs

1// devela::data::absence
2//
3//! Implements traits for the unit type [`()`] to represent the absence of data.
4//
5
6#[cfg(all(not(feature = "safe_data"), feature = "unsafe_layout"))]
7use super::DataRaw;
8use crate::{DataType, DataTypeCopy, DataValue, DataValueCopy};
9
10/// Represents the absence of some data.
11pub type NoData = ();
12
13#[rustfmt::skip]
14impl DataType for NoData {
15    type Value = NoData;
16
17    fn data_values_are_copy() -> bool { true }
18
19    fn data_value_is_copy(&self) -> bool { true }
20    fn data_value_default(&self) -> Option<Self::Value> { Some(()) }
21    fn data_value_align(&self) -> usize { align_of::<NoData>() }
22    fn data_value_size(&self) -> usize { size_of::<NoData>() }
23}
24#[rustfmt::skip]
25impl DataValue for NoData {
26    type Type = NoData;
27
28    fn data_values_are_copy() -> bool { true }
29
30    fn data_type(&self) -> Self::Type {}
31    fn data_value_is_copy(&self) -> bool { true }
32}
33
34impl DataTypeCopy for NoData {}
35impl DataValueCopy for NoData {}
36
37#[cfg(all(not(feature = "safe_data"), feature = "unsafe_layout"))]
38#[cfg_attr(feature = "nightly", doc(cfg(feature = "unsafe_layout")))]
39unsafe impl DataRaw for NoData {}