devela/data/list/array/
ext.rs

Help
1// devela::data::list::array::ext
2//
3//!
4//
5
6use crate::{Debug, Display, FmtResult, Formatter};
7
8/// A formatting wrapper for core [arrays][array], implementing [`Display`] and [`Debug`].
9///
10/// It is created by the [`ExtArray::fmt`] method.
11#[repr(transparent)]
12pub struct ArrayFmt<'a, T: ExtArray>(&'a T);
13
14/// Private trait for arrays with elements that implement [`Display`].
15trait ArrayDisplay: ExtArray {
16    fn fmt_display(&self, f: &mut Formatter) -> FmtResult<()>;
17}
18
19/// Private trait for arrays with elements that implement [`Debug`].
20///
21/// This trait is a bit redundant since arrays of any size can impl `Debug`,
22/// nevertheless it's better if we can offer the same api in both cases.
23trait ArrayDebug: ExtArray {
24    fn fmt_debug(&self, f: &mut Formatter) -> FmtResult<()>;
25}
26
27impl<T: ArrayDisplay> Display for ArrayFmt<'_, T> {
28    fn fmt(&self, f: &mut Formatter) -> FmtResult<()> {
29        self.0.fmt_display(f)
30    }
31}
32impl<T: ArrayDebug> Debug for ArrayFmt<'_, T> {
33    fn fmt(&self, f: &mut Formatter) -> FmtResult<()> {
34        self.0.fmt_debug(f)
35    }
36}
37
38/// Marker trait to prevent downstream implementations of the [`ExtArray`] trait.
39trait Sealed {}
40impl<T, const LEN: usize> Sealed for [T; LEN] {}
41
42/// Extension trait providing convenience methods for [`[T; N]`][array] arrays.
43///
44/// This trait is sealed and cannot be implemented for any other type.
45#[expect(private_bounds, reason = "Sealed")]
46pub trait ExtArray: Sealed {
47    /// The length of this array.
48    const LEN: usize;
49
50    /// Wraps the array in an [`ArrayFmt`] for formatting purposes.
51    #[rustfmt::skip]
52    fn fmt(&self) -> ArrayFmt<Self> where Self: Sized { ArrayFmt(self) }
53}
54
55impl<T, const LEN: usize> ExtArray for [T; LEN] {
56    const LEN: usize = LEN;
57}
58
59impl<T: Display, const LEN: usize> ArrayDisplay for [T; LEN] {
60    fn fmt_display(&self, f: &mut Formatter) -> FmtResult<()> {
61        write!(f, "[")?;
62        for (index, element) in self.iter().enumerate() {
63            if index > 0 {
64                write!(f, ", ")?;
65            }
66            Display::fmt(element, f)?;
67        }
68        write!(f, "]")
69    }
70}
71impl<T: Debug, const LEN: usize> ArrayDebug for [T; LEN] {
72    fn fmt_debug(&self, f: &mut Formatter) -> FmtResult<()> {
73        f.debug_list().entries(self.iter()).finish()
74    }
75}
devela/data/list/array/ext.rs

devela/data/list/array/
ext.rs
