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bigint: Refactor the `parse_bytes` and `from_str_radix`. 

This follows the changes of "Separate string->integer implementation in strconv" (rust-lang/rust@138b76b).
This allows `parse_bytes` to be removed without breaking `libnum` code.
This commit is contained in:
gifnksm 2014-11-04 23:20:37 +09:00
parent c0cf374c4a
commit 436f954627
1 changed files with 48 additions and 47 deletions
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95
src/bigint.rs
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@ -67,7 +67,7 @@ use std::num::{ToPrimitive, FromPrimitive};
use std::num::{Zero, One, FromStrRadix};
use std::str;
use std::string::String;
use std::{uint, i64, u64};
use std::{i64, u64};
/// A `BigDigit` is a `BigUint`'s composing element.
pub type BigDigit = u32;
@ -703,7 +703,39 @@ impl FromStrRadix for BigUint {
/// Creates and initializes a `BigUint`.
#[inline]
fn from_str_radix(s: &str, radix: uint) -> Option<BigUint> {
BigUint::parse_bytes(s.as_bytes(), radix)
let (base, unit_len) = get_radix_base(radix);
let base_num = match base.to_biguint() {
Some(base_num) => base_num,
None => { return None; }
};
let mut end = s.len();
let mut n: BigUint = Zero::zero();
let mut power: BigUint = One::one();
loop {
let start = cmp::max(end, unit_len) - unit_len;
match FromStrRadix::from_str_radix(s.slice(start, end), radix) {
Some(d) => {
let d: Option<BigUint> = FromPrimitive::from_uint(d);
match d {
Some(d) => {
// FIXME(#5992): assignment operator overloads
// n += d * power;
n = n + d * power;
}
None => { return None; }
}
}
None => { return None; }
}
if end <= unit_len {
return Some(n);
}
end -= unit_len;
// FIXME(#5992): assignment operator overloads
// power *= base_num;
power = power * base_num;
}
}
}
@ -728,42 +760,9 @@ impl BigUint {
}
/// Creates and initializes a `BigUint`.
#[inline]
pub fn parse_bytes(buf: &[u8], radix: uint) -> Option<BigUint> {
let (base, unit_len) = get_radix_base(radix);
let base_num = match base.to_biguint() {
Some(base_num) => base_num,
None => { return None; }
};
let mut end = buf.len();
let mut n: BigUint = Zero::zero();
let mut power: BigUint = One::one();
loop {
let start = cmp::max(end, unit_len) - unit_len;
match str::from_utf8(buf.slice(start, end)).and_then(|s| {
FromStrRadix::from_str_radix(s, radix)
}) {
Some(d) => {
let d: Option<BigUint> = FromPrimitive::from_uint(d);
match d {
Some(d) => {
// FIXME(#5992): assignment operator overloads
// n += d * power;
n = n + d * power;
}
None => { return None; }
}
}
None => { return None; }
}
if end <= unit_len {
return Some(n);
}
end -= unit_len;
// FIXME(#5992): assignment operator overloads
// power *= base_num;
power = power * base_num;
}
str::from_utf8(buf).and_then(|s| FromStrRadix::from_str_radix(s, radix))
}
#[inline]
@ -1280,7 +1279,15 @@ impl FromStrRadix for BigInt {
/// Creates and initializes a BigInt.
#[inline]
fn from_str_radix(s: &str, radix: uint) -> Option<BigInt> {
BigInt::parse_bytes(s.as_bytes(), radix)
if s.is_empty() { return None; }
let mut sign = Plus;
let mut start = 0;
if s.starts_with("-") {
sign = Minus;
start = 1;
}
FromStrRadix::from_str_radix(s.slice_from(start), radix)
.map(|bu| BigInt::from_biguint(sign, bu))
}
}
@ -1396,18 +1403,12 @@ impl BigInt {
}
/// Creates and initializes a `BigInt`.
#[inline]
pub fn parse_bytes(buf: &[u8], radix: uint) -> Option<BigInt> {
if buf.is_empty() { return None; }
let mut sign = Plus;
let mut start = 0;
if buf[0] == b'-' {
sign = Minus;
start = 1;
}
return BigUint::parse_bytes(buf.slice(start, buf.len()), radix)
.map(|bu| BigInt::from_biguint(sign, bu));
str::from_utf8(buf).and_then(|s| FromStrRadix::from_str_radix(s, radix))
}
/// Converts this `BigInt` into a `BigUint`, if it's not negative.
#[inline]
pub fn to_biguint(&self) -> Option<BigUint> {