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#![feature(float_extras)] extern crate num; use num::integer::Integer; use num::{BigInt, One, abs}; use num::cast::ToPrimitive; use num::bigint::ToBigInt; use std::ops::{Add, AddAssign, Sub, SubAssign, Mul, MulAssign, Div, DivAssign, Neg}; fn reduce(a: &BigInt, b: &BigInt) -> (BigInt, BigInt) { let gcd = a.gcd(&b); (a / gcd.clone(), b / gcd) } pub trait ExactFloatNumber { fn from_integer(self) -> ExactFloat; } impl ExactFloatNumber for ExactFloat { fn from_integer(self) -> ExactFloat {self} } impl ExactFloatNumber for u8 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for u16 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for u32 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for u64 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for i8 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for i16 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for i32 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for i64 { fn from_integer(self) -> ExactFloat {ExactFloat::from_bigint(self.to_bigint().unwrap())} } impl ExactFloatNumber for f32 { fn from_integer(self) -> ExactFloat { let (mantissa, exponent, sign) = self.integer_decode(); let (numerator, denominator) = if exponent > 0 { (mantissa * 2u64.pow(exponent as u32), 1) } else { (mantissa, 2u64.pow((-exponent) as u32)) }; ExactFloat { numerator: (numerator * sign as u64).to_bigint().unwrap(), denominator: denominator.to_bigint().unwrap() } } } impl ExactFloatNumber for f64 { fn from_integer(self) -> ExactFloat { let (mantissa, exponent, sign) = self.integer_decode(); println!("{:?}, {:?}", mantissa, exponent); let (numerator, denominator) = if exponent > 0 { (mantissa * 2u64.pow(exponent as u32), 1) } else { (mantissa, 2u64.pow((-exponent) as u32)) }; ExactFloat { numerator: (numerator * sign as u64).to_bigint().unwrap(), denominator: denominator.to_bigint().unwrap() } } } #[derive(Clone, Debug)] pub struct ExactFloat { pub numerator: BigInt, pub denominator: BigInt } impl ExactFloat { pub fn new<T: ExactFloatNumber>(x: T) -> ExactFloat { x.from_integer() } fn from_bigint(a: BigInt) -> ExactFloat { ExactFloat { numerator: a, denominator: One::one() } } pub fn pre_calculate(&mut self) { let (numerator, denominator) = reduce(&self.numerator, &self.denominator); self.numerator = numerator; self.denominator = denominator; } pub fn calculate(&self) -> Option<f64> { let (numerator, denominator) = reduce(&self.numerator, &self.denominator); match (numerator.to_f64(), denominator.to_f64()) { (Some(numerator), Some(denominator)) => Some(numerator / denominator), _ => None } } pub fn abs(&self) -> ExactFloat { ExactFloat { numerator: abs(self.numerator.clone()), denominator: abs(self.denominator.clone()) } } } impl<T: ExactFloatNumber> Add<T> for ExactFloat { type Output = ExactFloat; fn add(self, other: T) -> ExactFloat { let as_exact_float = other.from_integer(); ExactFloat { numerator: &as_exact_float.denominator * self.numerator + &self.denominator * as_exact_float.numerator, denominator: self.denominator * as_exact_float.denominator } } } impl<T: ExactFloatNumber> AddAssign<T> for ExactFloat { fn add_assign(&mut self, other: T) { let as_exact_float = other.from_integer(); self.numerator = &as_exact_float.denominator * &self.numerator + &self.denominator * as_exact_float.numerator; self.denominator = &self.denominator * as_exact_float.denominator; } } impl<T: ExactFloatNumber> Sub<T> for ExactFloat { type Output = ExactFloat; fn sub(self, other: T) -> ExactFloat { let as_exact_float = other.from_integer(); ExactFloat { numerator: &as_exact_float.denominator * self.numerator - &self.denominator * as_exact_float.numerator, denominator: &self.denominator * &as_exact_float.denominator } } } impl<T: ExactFloatNumber> SubAssign<T> for ExactFloat { fn sub_assign(&mut self, other: T) { let as_exact_float = other.from_integer(); self.numerator = &as_exact_float.denominator * &self.numerator - &self.denominator * as_exact_float.numerator; self.denominator = &self.denominator * &as_exact_float.denominator; } } impl<T: ExactFloatNumber> Mul<T> for ExactFloat { type Output = ExactFloat; fn mul(self, other: T) -> ExactFloat { let as_exact_float = other.from_integer(); ExactFloat { numerator: self.numerator * as_exact_float.numerator, denominator: self.denominator * as_exact_float.denominator } } } impl<T: ExactFloatNumber> MulAssign<T> for ExactFloat { fn mul_assign(&mut self, other: T) { let as_exact_float = other.from_integer(); self.numerator = &self.numerator * as_exact_float.numerator; self.denominator = &self.denominator * as_exact_float.denominator; } } impl<T: ExactFloatNumber> Div<T> for ExactFloat { type Output = ExactFloat; fn div(self, other: T) -> ExactFloat { let as_exact_float = other.from_integer(); ExactFloat { numerator: self.numerator * as_exact_float.denominator, denominator: self.denominator * as_exact_float.numerator } } } impl<T: ExactFloatNumber> DivAssign<T> for ExactFloat { fn div_assign(&mut self, other: T) { let as_exact_float = other.from_integer(); self.numerator = &self.numerator * as_exact_float.denominator; self.denominator = &self.denominator * as_exact_float.numerator; } } impl Neg for ExactFloat { type Output = ExactFloat; fn neg(self) -> ExactFloat { ExactFloat { numerator: -self.numerator, denominator: self.denominator } } }