easy-cast 0.7.0

Type conversions which are expected to succeed
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

use easy_cast::{Error, traits::*};

#[test]
fn int_to_float_exact_and_inexact() {
    assert_eq!(f32::try_conv(0u32), Ok(0.0));
    assert_eq!(f32::try_conv(1u32), Ok(1.0));
    assert_eq!(f32::try_conv(-0x00FF_FFFFi32), Ok(-16777215.0));
    assert_eq!(f32::try_conv(-0x01FF_FFFFi32), Err(Error::Inexact));
    assert_eq!(f32::try_conv(0xFFFF_FF00u32), Ok(4294967040.0));
    assert_eq!(f32::try_conv(0xFFFF_FF80u32), Err(Error::Inexact));

    assert_eq!(f64::try_conv(-0x0000_000F_FFFF_FFFFi64), Ok(-68719476735.0));
    assert_eq!(
        f64::try_conv(-0x001F_FFFF_FFFF_FFFFi64),
        Ok(-9007199254740991.0)
    );
    assert_eq!(
        f64::try_conv(-0x003F_FFFF_FFFF_FFFFi64),
        Err(Error::Inexact)
    );
    assert_eq!(
        f64::try_conv(0xFFFF_FFFF_FFFF_F800u64),
        Ok(18446744073709549568.0)
    );
    assert_eq!(f64::try_conv(0xFFFF_FFFF_FFFF_FC00u64), Err(Error::Inexact));

    assert_eq!(
        f32::try_conv(0xFFFFFF00_00000000_00000000_00000001_u128),
        Err(Error::Inexact)
    );
}

#[test]
fn int_to_float_approx() {
    // Duplicate the above tests but using try_conv_approx.
    // Note that values on the right may contain more precision than f32/f64
    // supports; the excess precision is discarded before testing for equality.

    assert_eq!(f32::try_conv_approx(0u32), Ok(0.0));
    assert_eq!(f32::try_conv_approx(1u32), Ok(1.0));
    assert_eq!(f32::try_conv_approx(-0x00FF_FFFFi32), Ok(-16777215.0));
    assert_eq!(f32::try_conv_approx(-0x01FF_FFFFi32), Ok(-33554431.0));
    assert_eq!(f32::try_conv_approx(0xFFFF_FF00u32), Ok(4294967040.0));
    assert_eq!(f32::try_conv_approx(0xFFFF_FF80u32), Ok(4294967168.0));

    assert_eq!(
        f64::try_conv_approx(-0x0000_000F_FFFF_FFFFi64),
        Ok(-68719476735.0)
    );
    assert_eq!(
        f64::try_conv_approx(-0x001F_FFFF_FFFF_FFFFi64),
        Ok(-9007199254740991.0)
    );
    assert_eq!(
        f64::try_conv_approx(-0x003F_FFFF_FFFF_FFFFi64),
        Ok(-18014398509481983.0)
    );
    assert_eq!(
        f64::try_conv_approx(0xFFFF_FFFF_FFFF_F800u64),
        Ok(18446744073709549568.0)
    );
    assert_eq!(
        f64::try_conv_approx(0xFFFF_FFFF_FFFF_FC00u64),
        Ok(18446744073709550592.0)
    );

    assert_eq!(
        f32::try_conv_approx(0xFFFFFF00_00000000_00000000_00000001_u128),
        Ok(f32::MAX)
    );
}

#[cfg(any(feature = "std", feature = "libm"))]
#[test]
fn int_to_float_nearest() {
    use easy_cast::Nearest;

    // Repeat a few of the above tests using Nearest rounding (equivalent)
    assert_eq!(f32::try_conv_to(Nearest, 0xFFFF_FF00u32), Ok(4294967040.0));
    assert_eq!(f32::try_conv_to(Nearest, 0xFFFF_FF70u32), Ok(4294967040.0));
    assert_eq!(f32::try_conv_to(Nearest, 0xFFFF_FF80u32), Ok(4294967168.0));
    assert_eq!(
        f32::try_conv_to(Nearest, 0xFFFF_FFFF_FFFF_FC00u64),
        Ok(18446744073709550592.0)
    );
}

#[test]
fn int_to_float_overflow() {
    // f32::MAX as u128
    const MAX: u128 = 0xFFFFFF00_00000000_00000000_00000000_u128;
    // The maximum value approximating to f32::MAX
    const MAX_APPROX: u128 = 0xFFFFFF7F_FFFFFFFF_FFFFFFFF_FFFFFFFF_u128;

    assert_eq!(f32::try_conv(MAX), Ok(f32::MAX));
    assert_eq!(f32::try_conv(MAX + 1), Err(Error::Inexact));
    assert_eq!(f32::try_conv(MAX_APPROX + 1), Err(Error::Range));

    assert_eq!(f32::try_conv_approx(MAX), Ok(f32::MAX));
    assert_eq!(f32::try_conv_approx(MAX_APPROX), Ok(f32::MAX));
    assert_eq!(f32::try_conv_approx(MAX_APPROX + 1), Ok(f32::INFINITY));
    assert_eq!(f32::try_conv_approx(u128::MAX), Ok(f32::INFINITY));
}

#[test]
fn signed_integer_to_float_boundaries() {
    assert_eq!(f32::try_conv(i32::MIN), Ok(i32::MIN as f32));
    assert_eq!(f32::try_conv(i32::MIN + 1), Err(Error::Inexact));
    assert_eq!(f64::try_conv(i64::MIN), Ok(i64::MIN as f64));
    assert_eq!(f64::try_conv(i64::MIN + 1), Err(Error::Inexact));
}

#[test]
fn wide_integer_to_float_boundaries() {
    const F32_EXACT: u64 = 0x00FF_FFFF;
    const F32_INEXACT: u64 = 0x01FF_FFFF;
    const F64_EXACT: u64 = (1u64 << 53) - 1;
    const F64_INEXACT: u64 = (1u64 << 54) - 1;

    assert_eq!(f32::try_conv(F32_EXACT), Ok(F32_EXACT as f32));
    assert_eq!(f32::try_conv(F32_INEXACT), Err(Error::Inexact));
    assert_eq!(f64::try_conv(F64_EXACT), Ok(F64_EXACT as f64));
    assert_eq!(f64::try_conv(F64_INEXACT), Err(Error::Inexact));

    assert_eq!(f32::try_conv(F32_EXACT as i64), Ok(F32_EXACT as f32));
    assert_eq!(f32::try_conv(F32_INEXACT as i64), Err(Error::Inexact));
    assert_eq!(f64::try_conv(F64_EXACT as i128), Ok(F64_EXACT as f64));
    assert_eq!(f64::try_conv(F64_INEXACT as i128), Err(Error::Inexact));

    assert_eq!(f32::try_conv(F32_EXACT as u128), Ok(F32_EXACT as f32));
    assert_eq!(f32::try_conv(F32_INEXACT as u128), Err(Error::Inexact));
    assert_eq!(f64::try_conv(F64_EXACT as u128), Ok(F64_EXACT as f64));
    assert_eq!(f64::try_conv(F64_INEXACT as u128), Err(Error::Inexact));
}

#[test]
fn usize_and_isize_to_float() {
    assert_eq!(f32::try_conv(0usize), Ok(0.0));
    assert_eq!(f64::try_conv(1usize), Ok(1.0));
    assert_eq!(f32::try_conv(0isize), Ok(0.0));
    assert_eq!(f64::try_conv(-1isize), Ok(-1.0));

    if usize::BITS > f32::MANTISSA_DIGITS + 1 {
        let inexact = (1usize << ((f32::MANTISSA_DIGITS + 1) as usize)) - 1;
        assert_eq!(f32::try_conv(inexact), Err(Error::Inexact));
    }

    if isize::BITS > f64::MANTISSA_DIGITS + 1 {
        let inexact = (1isize << ((f64::MANTISSA_DIGITS + 1) as usize)) - 1;
        assert_eq!(f64::try_conv(inexact), Err(Error::Inexact));
        assert_eq!(f64::try_conv(-inexact), Err(Error::Inexact));
    }
}

#[test]
#[should_panic(expected = "cast x: u64 to f32: inexact for x = 33554431")]
fn integer_to_float_conv_panics_on_inexact_conversion() {
    f32::conv(0x01FF_FFFFu64);
}