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Use checked_next_power_of_two from std instead of custom method

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NB The custom method returned 0 on an input of 0, which is arguably
incorrect: 0 is not a power of two; the method in `std` returns 1 in
that case.
This commit is contained in:
Kamal Marhubi 2016-03-28 23:30:08 -04:00
parent 6526533745
commit 8168c7c44c
2 changed files with 3 additions and 37 deletions
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5
src/string.rs
View File

@ -15,7 +15,6 @@ use regex::Regex;
use Indent;
use config::Config;
use utils::round_up_to_power_of_two;
use MIN_STRING;
@ -41,7 +40,9 @@ pub fn rewrite_string<'a>(orig: &str, fmt: &StringFormat<'a>) -> Option<String>
let punctuation = ":,;.";
let mut cur_start = 0;
let mut result = String::with_capacity(round_up_to_power_of_two(stripped_str.len()));
let mut result = String::with_capacity(stripped_str.len()
.checked_next_power_of_two()
.unwrap_or(usize::max_value()));
result.push_str(fmt.opener);
let ender_length = fmt.line_end.len();

35
src/utils.rs
View File

@ -180,33 +180,6 @@ pub fn trim_newlines(input: &str) -> &str {
}
}
#[inline]
#[cfg(target_pointer_width="64")]
// Based on the trick layed out at
// http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
pub fn round_up_to_power_of_two(mut x: usize) -> usize {
x = x.wrapping_sub(1);
x |= x >> 1;
x |= x >> 2;
x |= x >> 4;
x |= x >> 8;
x |= x >> 16;
x |= x >> 32;
x.wrapping_add(1)
}
#[inline]
#[cfg(target_pointer_width="32")]
pub fn round_up_to_power_of_two(mut x: usize) -> usize {
x = x.wrapping_sub(1);
x |= x >> 1;
x |= x >> 2;
x |= x >> 4;
x |= x >> 8;
x |= x >> 16;
x.wrapping_add(1)
}
// Macro for deriving implementations of Decodable for enums
#[macro_export]
macro_rules! impl_enum_decodable {
@ -344,11 +317,3 @@ fn bin_search_test() {
assert_eq!(Some(()), binary_search(4, 125, &closure));
assert_eq!(None, binary_search(6, 100, &closure));
}
#[test]
fn power_rounding() {
assert_eq!(0, round_up_to_power_of_two(0));
assert_eq!(1, round_up_to_power_of_two(1));
assert_eq!(64, round_up_to_power_of_two(33));
assert_eq!(256, round_up_to_power_of_two(256));
}