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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use syntax::ast::{Visibility, Attribute, MetaItem, MetaItem_};
use SKIP_ANNOTATION;
#[inline]
pub fn prev_char(s: &str, mut i: usize) -> usize {
if i == 0 { return 0; }
i -= 1;
while !s.is_char_boundary(i) {
i -= 1;
}
i
}
#[inline]
pub fn next_char(s: &str, mut i: usize) -> usize {
if i >= s.len() { return s.len(); }
while !s.is_char_boundary(i) {
i += 1;
}
i
}
#[inline]
pub fn make_indent(width: usize) -> String {
let mut indent = String::with_capacity(width);
for _ in 0..width {
indent.push(' ')
}
indent
}
#[inline]
pub fn format_visibility(vis: Visibility) -> &'static str {
match vis {
Visibility::Public => "pub ",
Visibility::Inherited => ""
}
}
fn is_skip(meta_item: &MetaItem) -> bool {
match meta_item.node {
MetaItem_::MetaWord(ref s) => *s == SKIP_ANNOTATION,
_ => false,
}
}
#[inline]
pub fn contains_skip(attrs: &[Attribute]) -> bool {
attrs.iter().any(|a| is_skip(&a.node.value))
}
#[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 {
( $e:ident, $( $x:ident ),* ) => {
impl ::rustc_serialize::Decodable for $e {
fn decode<D: ::rustc_serialize::Decoder>(d: &mut D) -> Result<Self, D::Error> {
let s = try!(d.read_str());
match &*s {
$(
stringify!($x) => Ok($e::$x),
)*
_ => Err(d.error("Bad variant")),
}
}
}
};
}
// Same as try!, but for Option
#[macro_export]
macro_rules! try_opt {
($expr:expr) => (match $expr {
Some(val) => val,
None => { return None; }
})
}
#[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));
}
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