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|
//! Missing batteries for standard libraries.
use std::{
sync::atomic::{AtomicUsize, Ordering},
time::Instant,
};
mod macros;
#[inline(always)]
pub fn is_ci() -> bool {
option_env!("CI").is_some()
}
#[must_use]
pub fn timeit(label: &'static str) -> impl Drop {
struct Guard {
label: &'static str,
start: Instant,
}
impl Drop for Guard {
fn drop(&mut self) {
eprintln!("{}: {:.2?}", self.label, self.start.elapsed())
}
}
Guard { label, start: Instant::now() }
}
pub fn to_lower_snake_case(s: &str) -> String {
let mut buf = String::with_capacity(s.len());
let mut prev = false;
for c in s.chars() {
if c.is_ascii_uppercase() && prev {
buf.push('_')
}
prev = true;
buf.push(c.to_ascii_lowercase());
}
buf
}
pub fn replace(buf: &mut String, from: char, to: &str) {
if !buf.contains(from) {
return;
}
// FIXME: do this in place.
*buf = buf.replace(from, to)
}
// https://github.com/rust-lang/rust/issues/74773
pub fn split_once(haystack: &str, delim: char) -> Option<(&str, &str)> {
let mut split = haystack.splitn(2, delim);
let prefix = split.next()?;
let suffix = split.next()?;
Some((prefix, suffix))
}
pub fn rsplit_once(haystack: &str, delim: char) -> Option<(&str, &str)> {
let mut split = haystack.rsplitn(2, delim);
let suffix = split.next()?;
let prefix = split.next()?;
Some((prefix, suffix))
}
pub fn trim_indent(mut text: &str) -> String {
if text.starts_with('\n') {
text = &text[1..];
}
let indent = text
.lines()
.filter(|it| !it.trim().is_empty())
.map(|it| it.len() - it.trim_start().len())
.min()
.unwrap_or(0);
lines_with_ends(text)
.map(
|line| {
if line.len() <= indent {
line.trim_start_matches(' ')
} else {
&line[indent..]
}
},
)
.collect()
}
pub fn lines_with_ends(text: &str) -> LinesWithEnds {
LinesWithEnds { text }
}
pub struct LinesWithEnds<'a> {
text: &'a str,
}
impl<'a> Iterator for LinesWithEnds<'a> {
type Item = &'a str;
fn next(&mut self) -> Option<&'a str> {
if self.text.is_empty() {
return None;
}
let idx = self.text.find('\n').map_or(self.text.len(), |it| it + 1);
let (res, next) = self.text.split_at(idx);
self.text = next;
Some(res)
}
}
// https://github.com/rust-lang/rust/issues/73831
pub fn partition_point<T, P>(slice: &[T], mut pred: P) -> usize
where
P: FnMut(&T) -> bool,
{
let mut left = 0;
let mut right = slice.len();
while left != right {
let mid = left + (right - left) / 2;
// SAFETY:
// When left < right, left <= mid < right.
// Therefore left always increases and right always decreases,
// and either of them is selected.
// In both cases left <= right is satisfied.
// Therefore if left < right in a step,
// left <= right is satisfied in the next step.
// Therefore as long as left != right, 0 <= left < right <= len is satisfied
// and if this case 0 <= mid < len is satisfied too.
let value = unsafe { slice.get_unchecked(mid) };
if pred(value) {
left = mid + 1;
} else {
right = mid;
}
}
left
}
pub struct RacyFlag(AtomicUsize);
impl RacyFlag {
pub const fn new() -> RacyFlag {
RacyFlag(AtomicUsize::new(0))
}
pub fn get(&self, init: impl FnMut() -> bool) -> bool {
let mut init = Some(init);
self.get_impl(&mut || init.take().map_or(false, |mut f| f()))
}
fn get_impl(&self, init: &mut dyn FnMut() -> bool) -> bool {
match self.0.load(Ordering::Relaxed) {
0 => false,
1 => true,
_ => {
let res = init();
self.0.store(if res { 1 } else { 0 }, Ordering::Relaxed);
res
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_trim_indent() {
assert_eq!(trim_indent(""), "");
assert_eq!(
trim_indent(
"
hello
world
"
),
"hello\nworld\n"
);
assert_eq!(
trim_indent(
"
hello
world"
),
"hello\nworld"
);
assert_eq!(trim_indent(" hello\n world\n"), "hello\nworld\n");
assert_eq!(
trim_indent(
"
fn main() {
return 92;
}
"
),
"fn main() {\n return 92;\n}\n"
);
}
}
|
