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
// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::integer::Integer;
use crate::natural::Natural;
use core::cmp::Ordering;
use malachite_base::num::conversion::from::{SignedFromFloatError, UnsignedFromFloatError};
use malachite_base::num::conversion::traits::{ConvertibleFrom, RoundingFrom};
use malachite_base::rounding_modes::RoundingMode;
macro_rules! float_impls {
($f: ident) => {
impl RoundingFrom<$f> for Integer {
/// Converts a primitive float to an [`Integer`], using the specified rounding mode. An
/// [`Ordering`] is also returned, indicating whether the returned value is less than,
/// equal to, or greater than the original value.
///
/// The floating-point value cannot be NaN or infinite.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.sci_exponent()`.
///
/// # Panics
/// Panics if `value` is NaN or infinite or if the rounding mode is `Exact` and `value`
/// is not an integer.
///
/// # Examples
/// See [here](super::from_primitive_float#rounding_from).
fn rounding_from(value: $f, rm: RoundingMode) -> (Self, Ordering) {
if value >= 0.0 {
let (abs, o) = Natural::rounding_from(value, rm);
(Integer { sign: true, abs }, o)
} else {
let (n, o) = Natural::rounding_from(-value, -rm);
(-n, o.reverse())
}
}
}
impl TryFrom<$f> for Integer {
type Error = SignedFromFloatError;
/// Converts a primitive float to an [`Integer`].
///
/// If the input isn't exactly equal to some [`Integer`], an error is returned.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `value.sci_exponent()`.
///
/// # Examples
/// See [here](super::from_primitive_float#try_from).
fn try_from(value: $f) -> Result<Integer, Self::Error> {
Natural::try_from(value.abs())
.map(|n| Integer {
sign: value >= 0.0,
abs: n,
})
.map_err(|e| match e {
UnsignedFromFloatError::FloatInfiniteOrNan => {
SignedFromFloatError::FloatInfiniteOrNan
}
UnsignedFromFloatError::FloatNonIntegerOrOutOfRange => {
SignedFromFloatError::FloatNonIntegerOrOutOfRange
}
_ => unreachable!(),
})
}
}
impl ConvertibleFrom<$f> for Integer {
/// Determines whether a primitive float can be exactly converted to an [`Integer`].
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// See [here](super::from_primitive_float#convertible_from).
fn convertible_from(value: $f) -> bool {
Natural::convertible_from(value.abs())
}
}
};
}
apply_to_primitive_floats!(float_impls);