tokio_dbus/
alignment.rs

1use crate::ty;
2
3/// The alignment of a D-Bus type, as a runtime value.
4///
5/// D-Bus values are padded to the alignment of their type, which for the static
6/// writers in this crate is derived from a [`ty::Marker`]. Code which works with
7/// types that are only known at runtime needs to pass it explicitly instead.
8///
9/// # Examples
10///
11/// ```
12/// use tokio_dbus::{ty, Alignment};
13///
14/// assert_eq!(Alignment::of::<u8>(), Alignment::BYTE);
15/// assert_eq!(Alignment::of::<ty::Str>(), Alignment::U32);
16/// assert_eq!(Alignment::of::<(u8, u8)>(), Alignment::U64);
17/// ```
18#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
19#[non_exhaustive]
20pub enum Alignment {
21    /// Alignment of one byte, used by `y`, `g` and `v`.
22    BYTE,
23    /// Alignment of two bytes, used by `n` and `q`.
24    U16,
25    /// Alignment of four bytes, used by `b`, `i`, `u`, `h`, `s`, `o` and by the
26    /// length prefix of an array.
27    U32,
28    /// Alignment of eight bytes, used by `x`, `t`, `d`, structs and dict
29    /// entries.
30    U64,
31}
32
33impl Alignment {
34    /// The alignment of the type described by the [`ty::Marker`] `T`.
35    ///
36    /// # Examples
37    ///
38    /// ```
39    /// use tokio_dbus::{ty, Alignment};
40    ///
41    /// assert_eq!(Alignment::of::<u64>(), Alignment::U64);
42    /// assert_eq!(Alignment::of::<ty::Variant>(), Alignment::BYTE);
43    /// ```
44    pub const fn of<T>() -> Self
45    where
46        T: ty::Aligned,
47    {
48        match align_of::<T::Alignment>() {
49            1 => Alignment::BYTE,
50            2 => Alignment::U16,
51            4 => Alignment::U32,
52            _ => Alignment::U64,
53        }
54    }
55
56    /// The alignment as a number of bytes, which is always a power of two.
57    ///
58    /// # Examples
59    ///
60    /// ```
61    /// use tokio_dbus::Alignment;
62    ///
63    /// assert_eq!(Alignment::BYTE.in_bytes(), 1);
64    /// assert_eq!(Alignment::U64.in_bytes(), 8);
65    /// ```
66    pub const fn in_bytes(self) -> usize {
67        match self {
68            Alignment::BYTE => 1,
69            Alignment::U16 => 2,
70            Alignment::U32 => 4,
71            Alignment::U64 => 8,
72        }
73    }
74}
tokio_dbus/alignment.rs

tokio_dbus/
alignment.rs
