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Auto merge of #139 - ollie27:bigint_hash, r=cuviper 

bigint: simplify Hash

There cannot be any leading zeros in a BigUint so just derive Hash which will just hash the Vec directly.
Add Hash to Sign so we can derive it for BigInt as well.
This commit is contained in:
Homu 2015-12-17 15:25:49 +09:00
parent 7593c17fa7 e152bbcb46
commit 9b45e6dd9b
1 changed files with 4 additions and 27 deletions
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31
src/bigint.rs
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@ -66,7 +66,7 @@ use std::iter::repeat;
use std::num::ParseIntError; use std::num::ParseIntError;
use std::ops::{Add, BitAnd, BitOr, BitXor, Div, Mul, Neg, Rem, Shl, Shr, Sub}; use std::ops::{Add, BitAnd, BitOr, BitXor, Div, Mul, Neg, Rem, Shl, Shr, Sub};
use std::str::{self, FromStr}; use std::str::{self, FromStr};
use std::{fmt, hash}; use std::fmt;
use std::cmp::Ordering::{self, Less, Greater, Equal}; use std::cmp::Ordering::{self, Less, Greater, Equal};
use std::{u8, i64, u64}; use std::{u8, i64, u64};
@ -175,7 +175,7 @@ fn div_wide(hi: BigDigit, lo: BigDigit, divisor: BigDigit) -> (BigDigit, BigDigi
/// ///
/// A `BigUint`-typed value `BigUint { data: vec!(a, b, c) }` represents a number /// A `BigUint`-typed value `BigUint { data: vec!(a, b, c) }` represents a number
/// `(a + b * big_digit::BASE + c * big_digit::BASE^2)`. /// `(a + b * big_digit::BASE + c * big_digit::BASE^2)`.
#[derive(Clone, RustcEncodable, RustcDecodable, Debug)] #[derive(Clone, RustcEncodable, RustcDecodable, Debug, Hash)]
pub struct BigUint { pub struct BigUint {
data: Vec<BigDigit> data: Vec<BigDigit>
} }
@ -222,22 +222,6 @@ impl Default for BigUint {
fn default() -> BigUint { Zero::zero() } fn default() -> BigUint { Zero::zero() }
} }
impl hash::Hash for BigUint {
fn hash<H>(&self, state: &mut H) where H: hash::Hasher {
// hash 0 in case it's all 0's
0u32.hash(state);
let mut found_first_value = false;
for elem in self.data.iter().rev() {
// don't hash any leading 0's, they shouldn't affect the hash
if found_first_value || *elem != 0 {
found_first_value = true;
elem.hash(state);
}
}
}
}
impl fmt::Display for BigUint { impl fmt::Display for BigUint {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.to_str_radix(10)) write!(f, "{}", self.to_str_radix(10))
@ -1650,7 +1634,7 @@ fn get_radix_base(radix: u32) -> (DoubleBigDigit, usize) {
} }
/// A Sign is a `BigInt`'s composing element. /// A Sign is a `BigInt`'s composing element.
#[derive(PartialEq, PartialOrd, Eq, Ord, Copy, Clone, Debug, RustcEncodable, RustcDecodable)] #[derive(PartialEq, PartialOrd, Eq, Ord, Copy, Clone, Debug, RustcEncodable, RustcDecodable, Hash)]
pub enum Sign { Minus, NoSign, Plus } pub enum Sign { Minus, NoSign, Plus }
impl Neg for Sign { impl Neg for Sign {
@ -1681,7 +1665,7 @@ impl Mul<Sign> for Sign {
} }
/// A big signed integer type. /// A big signed integer type.
#[derive(Clone, RustcEncodable, RustcDecodable, Debug)] #[derive(Clone, RustcEncodable, RustcDecodable, Debug, Hash)]
pub struct BigInt { pub struct BigInt {
sign: Sign, sign: Sign,
data: BigUint data: BigUint
@ -1728,13 +1712,6 @@ impl fmt::Display for BigInt {
} }
} }
impl hash::Hash for BigInt {
fn hash<H>(&self, state: &mut H) where H: hash::Hasher {
(self.sign == Plus).hash(state);
self.data.hash(state);
}
}
impl FromStr for BigInt { impl FromStr for BigInt {
type Err = ParseBigIntError; type Err = ParseBigIntError;