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

//! This module implements the `BigInt` operations.

use num_traits::cast::ToPrimitive;
use num_traits::pow::Pow;

use super::BigInt;

impl BigInt {
    #[inline]
    pub fn pow(self, other: &Self) -> Result<Self, String> {
        Ok(Self(self.0.pow(
            other.0.to_biguint().ok_or("BigInt negative exponent")?,
        )))
    }

    #[inline]
    pub fn shift_right(mut self, other: Self) -> Result<Self, String> {
        use std::ops::ShlAssign;
        use std::ops::ShrAssign;

        if let Some(n) = other.0.to_i32() {
            if n > 0 {
                self.0.shr_assign(n as usize)
            } else {
                self.0.shl_assign(n.abs() as usize)
            }

            Ok(self)
        } else {
            Err("Maximum BigInt size exceeded".into())
        }
    }

    #[inline]
    pub fn shift_left(mut self, other: Self) -> Result<Self, String> {
        use std::ops::ShlAssign;
        use std::ops::ShrAssign;

        if let Some(n) = other.0.to_i32() {
            if n > 0 {
                self.0.shl_assign(n as usize)
            } else {
                self.0.shr_assign(n.abs() as usize)
            }

            Ok(self)
        } else {
            Err("Maximum BigInt size exceeded".into())
        }
    }

    /// Floored integer modulo.
    ///
    /// # Examples
    /// ```
    /// # use num_integer::Integer;
    /// assert_eq!((8).mod_floor(&3), 2);
    /// assert_eq!((8).mod_floor(&-3), -1);
    /// ```
    #[inline]
    pub fn mod_floor(self, other: &Self) -> Self {
        use num_integer::Integer;
        Self(self.0.mod_floor(&other.0))
    }
}

macro_rules! impl_bigint_operator {
    ($op:ident, $op_method:ident, $assign_op:ident, $assign_op_method:ident) => {
        impl std::ops::$op for BigInt {
            type Output = Self;

            fn $op_method(mut self, other: Self) -> Self {
                std::ops::$assign_op::$assign_op_method(&mut self.0, other.0);
                self
            }
        }
    };
}

impl_bigint_operator!(Add, add, AddAssign, add_assign);
impl_bigint_operator!(Sub, sub, SubAssign, sub_assign);
impl_bigint_operator!(Mul, mul, MulAssign, mul_assign);
impl_bigint_operator!(Div, div, DivAssign, div_assign);
impl_bigint_operator!(Rem, rem, RemAssign, rem_assign);
impl_bigint_operator!(BitAnd, bitand, BitAndAssign, bitand_assign);
impl_bigint_operator!(BitOr, bitor, BitOrAssign, bitor_assign);
impl_bigint_operator!(BitXor, bitxor, BitXorAssign, bitxor_assign);

impl std::ops::Neg for BigInt {
    type Output = Self;

    fn neg(self) -> Self::Output {
        Self(-self.0)
    }
}

impl std::fmt::Debug for BigInt {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl std::fmt::Display for BigInt {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}