malachite_nz/integer_polynomial/conversion/
from_unsigned_polynomial.rs

1// Copyright © 2026 Mikhail Hogrefe
2//
3// This file is part of Malachite.
4//
5// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
6// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
7// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
8
9use crate::integer::Integer;
10use crate::integer_polynomial::IntegerPolynomial;
11use malachite_base::num::basic::unsigneds::PrimitiveUnsigned;
12use malachite_base::polynomial::Polynomial;
13use malachite_base::unsigned_polynomial::UnsignedPolynomial;
14
15impl<T: PrimitiveUnsigned> From<UnsignedPolynomial<T>> for IntegerPolynomial
16where
17    Integer: From<T>,
18{
19    /// Converts a [`UnsignedPolynomial`] to an [`IntegerPolynomial`].
20    ///
21    /// Every unsigned primitive is an [`Integer`], so nothing is lost and nothing can fail. The
22    /// coefficients are converted one by one, and the leading one stays nonzero, so the degree is
23    /// unchanged.
24    ///
25    /// $f(p) = p$, read on the left over the coefficients and on the right over $\Z$.
26    ///
27    /// # Worst-case complexity
28    /// $T(n) = O(n)$
29    ///
30    /// $M(n) = O(n)$
31    ///
32    /// where $T$ is time, $M$ is additional memory, and $n$ is the number of coefficients.
33    ///
34    /// # Examples
35    /// ```
36    /// use core::str::FromStr;
37    /// use malachite_base::unsigned_polynomial::UnsignedPolynomial;
38    /// use malachite_nz::integer_polynomial::IntegerPolynomial;
39    ///
40    /// let p = UnsignedPolynomial::<u64>::from_str("x^2+3*x+2").unwrap();
41    /// assert_eq!(IntegerPolynomial::from(p).to_string(), "x^2+3*x+2");
42    ///
43    /// assert_eq!(
44    ///     IntegerPolynomial::from(UnsignedPolynomial::<u64>::default()).to_string(),
45    ///     "0"
46    /// );
47    /// ```
48    #[inline]
49    fn from(p: UnsignedPolynomial<T>) -> Self {
50        // The coefficients keep their order and their nonzero leading one, so no trimming is
51        // needed; but going through the constructor costs one comparison and cannot be wrong.
52        Self::from_coefficients_asc(
53            p.into_coefficients_asc()
54                .into_iter()
55                .map(Integer::from)
56                .collect(),
57        )
58    }
59}
malachite_nz/integer_polynomial/conversion/from_unsigned_polynomial.rs

malachite_nz/integer_polynomial/conversion/
from_unsigned_polynomial.rs
