Merge pull request #889 from kamalmarhubi/next-power-of-two

Use checked_next_power_of_two from std instead of custom method

Author: nrc

src/string.rs

@@ -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();

src/utils.rs

@@ -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));
-}