planus/impls/
slice.rs

1use core::mem::MaybeUninit;
2
3use crate::{builder::Builder, traits::*, Offset, UnionVectorOffset};
4
5impl<T, P: Primitive> WriteAsOffset<[P]> for [T]
6where
7    T: VectorWrite<P>,
8{
9    fn prepare(&self, builder: &mut Builder) -> Offset<[P]> {
10        let mut tmp: alloc::vec::Vec<T::Value> = alloc::vec::Vec::with_capacity(self.len());
11        for v in self.iter() {
12            tmp.push(v.prepare(builder));
13        }
14        // SAFETY: The inner closure always initializes the entire buffer, because it calls `write_values` with `tmp.len()` values each of length `T::STRIDE`.
15        unsafe {
16            builder.write_with(
17                T::STRIDE.checked_mul(tmp.len()).unwrap(),
18                P::ALIGNMENT_MASK.max(u32::ALIGNMENT_MASK),
19                |buffer_position, bytes| {
20                    let bytes = bytes.as_mut_ptr();
21
22                    T::write_values(&tmp, bytes, buffer_position);
23                },
24            );
25        }
26
27        // SAFETY: The inner closure always initializes the entire buffer, because it calls `copy_from_slice` with an array of len 4
28        unsafe {
29            builder.write_with(4, 0, |_buffer_position, bytes| {
30                let len = (self.len() as u32).to_le_bytes().map(MaybeUninit::new);
31                bytes.copy_from_slice(&len);
32            });
33        }
34        builder.current_offset()
35    }
36}
37
38impl<T, P> WriteAs<Offset<[P]>> for [T]
39where
40    [T]: WriteAsOffset<[P]>,
41{
42    type Prepared = Offset<[P]>;
43
44    fn prepare(&self, builder: &mut Builder) -> Offset<[P]> {
45        WriteAsOffset::prepare(&self, builder)
46    }
47}
48
49impl<T, P> WriteAsDefault<Offset<[P]>, ()> for [T]
50where
51    [T]: WriteAsOffset<[P]>,
52{
53    type Prepared = Offset<[P]>;
54
55    fn prepare(&self, builder: &mut Builder, _default: &()) -> Option<Offset<[P]>> {
56        if self.is_empty() {
57            None
58        } else {
59            Some(WriteAsOffset::prepare(&self, builder))
60        }
61    }
62}
63
64impl<T, P> WriteAsOptional<Offset<[P]>> for [T]
65where
66    [T]: WriteAsOffset<[P]>,
67{
68    type Prepared = Offset<[P]>;
69
70    #[inline]
71    fn prepare(&self, builder: &mut Builder) -> Option<Offset<[P]>> {
72        Some(WriteAsOffset::prepare(self, builder))
73    }
74}
75
76impl<T, P> WriteAsUnionVector<P> for [T]
77where
78    T: WriteAsUnion<P>,
79{
80    fn prepare(&self, builder: &mut Builder) -> UnionVectorOffset<P> {
81        let mut tmp_tags: alloc::vec::Vec<MaybeUninit<u8>> =
82            alloc::vec::Vec::with_capacity(self.len());
83        let mut tmp_values: alloc::vec::Vec<Offset<()>> =
84            alloc::vec::Vec::with_capacity(self.len());
85        for v in self.iter() {
86            let union_offset = v.prepare(builder);
87            tmp_tags.push(MaybeUninit::new(union_offset.tag));
88            tmp_values.push(union_offset.offset());
89        }
90
91        // SAFETY: The inner closure always initializes the entire buffer, because it calls `write_values` with `tmp_values.len()` values each of length `T::STRIDE`.
92        unsafe {
93            builder.write_with(
94                Offset::<()>::STRIDE.checked_mul(self.len()).unwrap(),
95                Offset::<()>::ALIGNMENT_MASK,
96                |buffer_position, bytes| {
97                    let bytes = bytes.as_mut_ptr();
98
99                    Offset::<()>::write_values(&tmp_values, bytes, buffer_position);
100                },
101            );
102        }
103
104        // SAFETY: The inner closure always initializes the entire buffer, because it calls `copy_from_slice` with an array of len 4
105        unsafe {
106            builder.write_with(4, 0, |_buffer_position, bytes| {
107                let len = (self.len() as u32).to_le_bytes().map(MaybeUninit::new);
108                bytes.copy_from_slice(&len);
109            });
110        }
111        let values_offset = builder.current_offset();
112
113        // SAFETY: The inner closure always initializes the entire buffer, because it calls `copy_from_slice` using the same length in both places
114        unsafe {
115            builder.write_with(
116                tmp_tags.len(),
117                u32::ALIGNMENT_MASK,
118                |_buffer_position, bytes| {
119                    bytes.copy_from_slice(&tmp_tags);
120                },
121            );
122        }
123
124        // SAFETY: The inner closure always initializes the entire buffer, because it calls `copy_from_slice` with an array of len 4
125        unsafe {
126            builder.write_with(4, 0, |_buffer_position, bytes| {
127                let len = (self.len() as u32).to_le_bytes().map(MaybeUninit::new);
128                bytes.copy_from_slice(&len);
129            });
130        }
131
132        let tags_offset = builder.current_offset();
133        crate::UnionVectorOffset {
134            tags_offset,
135            values_offset,
136            phantom: core::marker::PhantomData,
137        }
138    }
139}
140
141impl<T, P> WriteAsDefaultUnionVector<P> for [T]
142where
143    T: WriteAsUnion<P>,
144{
145    fn prepare(&self, builder: &mut Builder) -> Option<UnionVectorOffset<P>> {
146        if self.is_empty() {
147            None
148        } else {
149            Some(WriteAsUnionVector::prepare(self, builder))
150        }
151    }
152}
153
154impl<T, P> WriteAsOptionalUnionVector<P> for [T]
155where
156    T: WriteAsUnion<P>,
157{
158    #[inline]
159    fn prepare(&self, builder: &mut Builder) -> Option<UnionVectorOffset<P>> {
160        Some(WriteAsUnionVector::prepare(self, builder))
161    }
162}
planus/impls/slice.rs

planus/impls/
slice.rs
