write_fonts/
collections.rs

1//! helpers related to collection types
2
3use std::collections::BTreeSet;
4
5use crate::{NullableOffsetMarker, OffsetMarker};
6
7/// A helper trait for array-like fields, where we need to know
8/// the length in order to populate another field.
9pub trait HasLen {
10    fn len(&self) -> usize;
11}
12
13impl<T> HasLen for [T] {
14    fn len(&self) -> usize {
15        self.len()
16    }
17}
18
19impl<T> HasLen for BTreeSet<T> {
20    fn len(&self) -> usize {
21        self.len()
22    }
23}
24
25impl<T> HasLen for Vec<T> {
26    fn len(&self) -> usize {
27        self.len()
28    }
29}
30
31impl<T: HasLen> HasLen for Option<T> {
32    fn len(&self) -> usize {
33        match &self {
34            Some(t) => t.len(),
35            None => 0,
36        }
37    }
38}
39
40impl<T: HasLen, const N: usize> HasLen for OffsetMarker<T, N> {
41    fn len(&self) -> usize {
42        T::len(self)
43    }
44}
45
46impl<T: HasLen, const N: usize> HasLen for NullableOffsetMarker<T, N> {
47    fn len(&self) -> usize {
48        self.as_ref().map(HasLen::len).unwrap_or(0)
49    }
50}
write_fonts/collections.rs

write_fonts/
collections.rs
