flat_bytes/
lib.rs

1#![deny(clippy::pedantic)]
2
3pub use flat_bytes_derive::flat_enum;
4pub use flat_bytes_derive::Flat;
5
6pub trait Flat: Sized {
7    fn serialize(&self) -> Vec<u8>;
8    fn deserialize_with_size(data: &[u8]) -> Option<(Self, usize)>;
9    #[must_use]
10    fn deserialize(data: &[u8]) -> Option<Self> {
11        Self::deserialize_with_size(data).map(|(r, _)| r)
12    }
13}
14
15macro_rules! impl_primitive {
16    ($t:ident) => {
17        impl Flat for $t {
18            fn serialize(&self) -> Vec<u8> {
19                self.to_le_bytes().to_vec()
20            }
21
22            fn deserialize_with_size(data: &[u8]) -> Option<(Self, usize)> {
23                if data.len() < std::mem::size_of::<Self>() {
24                    return None;
25                }
26                let mut tmp = [0u8; std::mem::size_of::<Self>()];
27                tmp.copy_from_slice(&data[..::std::mem::size_of::<Self>()]);
28                Some((Self::from_le_bytes(tmp), ::std::mem::size_of::<Self>()))
29            }
30        }
31    };
32}
33
34impl_primitive!(u8);
35impl_primitive!(u16);
36impl_primitive!(u32);
37impl_primitive!(u64);
38impl_primitive!(i8);
39impl_primitive!(i16);
40impl_primitive!(i32);
41impl_primitive!(i64);
42
43impl Flat for bool {
44    fn serialize(&self) -> Vec<u8> {
45        Flat::serialize(&(u8::from(*self)))
46    }
47
48    fn deserialize_with_size(data: &[u8]) -> Option<(Self, usize)> {
49        <u8 as Flat>::deserialize_with_size(data).map(|(v, s)| (v != 0, s))
50    }
51}
52
53macro_rules! impl_array {
54    (@step ($d: ident, $idx:expr,) -> ($($body:tt)*)) => {
55        impl_array!(@as_expr [$($body)*])
56    };
57    (@step ($d: ident, $idx:expr, $t:ident, $($ts:ident,)*) -> ($($body:tt)*)) => {
58        impl_array!(@step ($d, $idx+1, $($ts,)*) -> ($($body)* $t::deserialize(&$d[::std::mem::size_of::<$t>()*($idx)..])?,))
59    };
60    (@as_expr $e:expr) => {$e};
61    {$n:expr, $t:ident $($ts:ident)*}=> {
62        impl<T: Flat> Flat for [T; $n] {
63            fn serialize(&self) -> Vec<u8> {
64                self.iter().map(Flat::serialize).flatten().collect()
65            }
66
67            fn deserialize_with_size(data: &[u8]) -> Option<(Self, usize)> {
68                let res =
69                    impl_array!(@step (data, 0, $t, $($ts,)*) -> ());
70                Some((res, ::std::mem::size_of::<Self>()))
71            }
72        }
73        impl_array!{($n - 1), $($ts)*}
74    };
75    {$n:expr,} => {
76        impl<T: Flat> Flat for [T; $n] {
77            fn serialize(&self) -> Vec<u8> {
78                vec![]
79            }
80
81            fn deserialize_with_size(_data: &[u8]) -> Option<(Self, usize)> {
82                Some(([], 0))
83            }
84        }
85    };
86}
87impl_array! {32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}
88
89#[cfg(test)]
90mod tests {
91    use super::*;
92    use crate as flat_bytes;
93
94    flat_enum! {
95        #[repr(u8)]
96        pub enum Foo {
97            Bar = 1,
98            Baz(bool) = 3,
99            Blubb{a: bool, b: u8},
100        }
101    }
102
103    static FOO: [u16; 4] = [1, 2, 3, 4];
104
105    #[derive(Flat)]
106    struct Header {
107        magic: [u8; 2],
108        size: u16,
109        admin: bool,
110    }
111
112    #[derive(Flat)]
113    struct Wrapper(Foo);
114
115    #[test]
116    fn serialize() {
117        #![allow(clippy::many_single_char_names)]
118
119        let a = Foo::Bar;
120        assert_eq!(a.serialize(), vec![1]);
121        let b = Foo::Baz(true);
122        assert_eq!(b.serialize(), vec![3, 1]);
123        let b = Foo::Baz(false);
124        assert_eq!(b.serialize(), vec![3, 0]);
125        let c = Foo::Blubb { a: true, b: 1 };
126        assert_eq!(c.serialize(), vec![4, 1, 1]);
127        let c = Foo::Blubb { a: false, b: 2 };
128        assert_eq!(c.serialize(), vec![4, 0, 2]);
129
130        assert_eq!(FOO.serialize(), vec![1, 0, 2, 0, 3, 0, 4, 0]);
131
132        let h = Header {
133            magic: *b"AB",
134            size: 123,
135            admin: true,
136        };
137        assert_eq!(h.serialize(), vec![0x41, 0x42, 123, 0, 1]);
138
139        let w = Wrapper(Foo::Bar);
140        assert_eq!(w.serialize(), vec![1]);
141    }
142
143    #[test]
144    fn deserialize() {
145        assert!(Foo::deserialize(&[]).is_none());
146        assert!(Foo::deserialize(&[5]).is_none());
147        assert!(Foo::deserialize(&[0]).is_none());
148        let a = Foo::deserialize(&[1]).unwrap();
149        assert!(matches!(a, Foo::Bar));
150        let b = Foo::deserialize(&[3, 0]).unwrap();
151        assert!(matches!(b, Foo::Baz(false)));
152        let b = Foo::deserialize(&[3, 1]).unwrap();
153        assert!(matches!(b, Foo::Baz(true)));
154        let c = Foo::deserialize(&[4, 1, 1]).unwrap();
155        assert!(matches!(c, Foo::Blubb { a: true, b: 1 }));
156        let c = Foo::deserialize(&[4, 0, 2]).unwrap();
157        assert!(matches!(c, Foo::Blubb { a: false, b: 2 }));
158
159        assert_eq!(
160            <[u16; 4]>::deserialize(&[1, 0, 2, 0, 3, 0, 4, 0]).unwrap(),
161            FOO
162        );
163
164        let w = Wrapper::deserialize(&[1]).unwrap();
165        assert!(matches!(w.0, Foo::Bar));
166    }
167}
flat_bytes/lib.rs

flat_bytes/
lib.rs
