numutil 0.1.0

Utility for working with Rust's core numeric types. Convenient and fast conversions between core types and other core types, core types and bytes, and vectors of core types and bytes
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217

/// Methods for converting between arrays of `T` and bytes, assuming `T` implements `to_(n/l/b)e_bytes()`.
pub trait VecByteConversion
where
    Self: Sized,
{
    fn to_le_bytes(&self) -> Vec<u8>;
    fn from_le_bytes(bytes: &[u8]) -> Option<Self>;
    fn to_be_bytes(&self) -> Vec<u8>;
    fn from_be_bytes(bytes: &[u8]) -> Option<Self>;
    fn to_ne_bytes(&self) -> Vec<u8>;
    fn from_ne_bytes(bytes: &[u8]) -> Option<Self>;
}

/// Trait useful for accepting any type `T` that implements `(to/from)_(n/l/b)e_bytes()` as a function input.
pub trait ByteConversion<const N: usize> {
    fn to_le_bytes_(self) -> [u8; N];
    fn from_le_bytes_(bytes: [u8; N]) -> Self;
    fn to_be_bytes_(self) -> [u8; N];
    fn from_be_bytes_(bytes: [u8; N]) -> Self;
    fn to_ne_bytes_(self) -> [u8; N];
    fn from_ne_bytes_(bytes: [u8; N]) -> Self;
}

macro_rules! impl_byte_conversion {
    ($x:ty) => (
        impl ByteConversion<{ size_of::<$x>() }> for $x {
            fn to_le_bytes_(self) -> [u8; size_of::<$x>()] {
                <$x>::to_le_bytes(self)
            }

            fn from_le_bytes_(bytes: [u8; size_of::<$x>()]) -> Self {
                <$x>::from_le_bytes(bytes)
            }

            fn to_be_bytes_(self) -> [u8; size_of::<$x>()] {
                <$x>::to_be_bytes(self)
            }

            fn from_be_bytes_(bytes: [u8; size_of::<$x>()]) -> Self {
                <$x>::from_be_bytes(bytes)
            }

            fn to_ne_bytes_(self) -> [u8; size_of::<$x>()] {
                <$x>::to_ne_bytes(self)
            }

            fn from_ne_bytes_(bytes: [u8; size_of::<$x>()]) -> Self {
                <$x>::from_ne_bytes(bytes)
            }
        }
        impl VecByteConversion for Vec<$x> {
            fn to_le_bytes(&self) -> Vec<u8> {
                self.iter().flat_map(|v| v.to_le_bytes()).collect()
            }

            fn from_le_bytes(bytes: &[u8]) -> Option<Self> {
                if bytes.len().is_multiple_of(size_of::<$x>()) {
                    Some(
                        bytes
                            .chunks_exact(size_of::<$x>())
                            .map(|v| {
                                <$x>::from_le_bytes(unsafe {
                                    (v.as_ptr() as *const [u8; size_of::<$x>()]).read()
                                })
                            })
                            .collect(),
                    )
                } else {
                    None
                }
            }
            fn to_be_bytes(&self) -> Vec<u8> {
                self.iter().flat_map(|v| v.to_be_bytes()).collect()
            }

            fn from_be_bytes(bytes: &[u8]) -> Option<Self> {
                if bytes.len().is_multiple_of(size_of::<$x>()) {
                    Some(
                        bytes
                            .chunks_exact(size_of::<$x>())
                            .map(|v| {
                                <$x>::from_be_bytes(unsafe {
                                    (v.as_ptr() as *const [u8; size_of::<$x>()]).read()
                                })
                            })
                            .collect(),
                    )
                } else {
                    None
                }
            }
            fn to_ne_bytes(&self) -> Vec<u8> {
                self.iter().flat_map(|v| v.to_ne_bytes()).collect()
            }

            fn from_ne_bytes(bytes: &[u8]) -> Option<Self> {
                if bytes.len().is_multiple_of(size_of::<$x>()) {
                    Some(
                        bytes
                            .chunks_exact(size_of::<$x>())
                            .map(|v| {
                                <$x>::from_ne_bytes(unsafe {
                                    (v.as_ptr() as *const [u8; size_of::<$x>()]).read()
                                })
                            })
                            .collect(),
                    )
                } else {
                    None
                }
            }
        }
    );
    ($x:ty, $($y:ty),+) => (
        impl_byte_conversion!($x);
        impl_byte_conversion!($($y),+);
    )
}

impl_byte_conversion!(
    usize, isize, i8, u8, i16, i32, i64, i128, u16, u32, u64, u128, f32, f64
);

/// Similar to `num_traits` `as_()` methods, but works in reverse too.
pub trait LossyCast<T> {
    fn _as(self) -> T;
    fn _from(v: T) -> Self;
}

macro_rules! impl_cast {
    ($x:ty, $y:ty) => (
        impl LossyCast<$y> for $x {
            fn _as(self) -> $y {
                self as _
            }
            fn _from(v: $y) -> $x {
                v as _
            }
        }
    );
    ($x:ty,$y:ty, $($z:ty),+) => (
        impl_cast!($x, $y);
        impl_cast!($x, $($z),+);
    )
}

impl_cast!(
    usize, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    isize, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    i8, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    u8, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    i16, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    i32, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    i64, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    u16, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    u32, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    u64, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    f32, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    f64, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    i128, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);
impl_cast!(
    u128, usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
);

#[cfg(test)]
mod tests {
    use crate::VecByteConversion;

    macro_rules! impl_vec_test {
        ($x:ty) => (
                let src_vec = vec![<$x>::MAX/(4 as $x), <$x>::MAX/(2 as $x),<$x>::MAX/(4 as $x)*(3 as $x),<$x>::MAX];
                let round_trip_vec = Vec::<$x>::from_le_bytes(&src_vec.to_le_bytes()).unwrap();
                for idx in 0..4 {
                    assert_eq!(
                        src_vec[idx],
                        Vec::<$x>::from_le_bytes(&src_vec.to_le_bytes()).unwrap()[idx]
                    );
                }
        );
        ($x:ty, $($y:ty),+) => (
            impl_vec_test!($x);
            impl_vec_test!($($y),+);
        )
    }

    #[test]
    fn test_roundtrip() {
        impl_vec_test!(
            usize, isize, i8, u8, i16, i32, i64, u16, u32, u64, i128, u128, f32, f64
        );
    }
}