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//! Utilities.
pub mod fat;
mod buffer;
pub use buffer::Buffer;
use std::fmt::{self, Debug, Formatter};
use std::hash::Hash;
use std::num::NonZeroUsize;
use std::path::{Component, Path, PathBuf};
use std::sync::Arc;
use siphasher::sip128::{Hasher128, SipHasher};
/// Turn a closure into a struct implementing [`Debug`].
pub fn debug<F>(f: F) -> impl Debug
where
F: Fn(&mut Formatter) -> fmt::Result,
{
struct Wrapper<F>(F);
impl<F> Debug for Wrapper<F>
where
F: Fn(&mut Formatter) -> fmt::Result,
{
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
self.0(f)
}
}
Wrapper(f)
}
/// Calculate a 128-bit siphash of a value.
pub fn hash128<T: Hash + ?Sized>(value: &T) -> u128 {
let mut state = SipHasher::new();
value.hash(&mut state);
state.finish128().as_u128()
}
/// An extra constant for [`NonZeroUsize`].
pub trait NonZeroExt {
/// The number `1`.
const ONE: Self;
}
impl NonZeroExt for NonZeroUsize {
const ONE: Self = match Self::new(1) {
Some(v) => v,
None => unreachable!(),
};
}
/// Extra methods for [`str`].
pub trait StrExt {
/// The number of code units this string would use if it was encoded in
/// UTF16. This runs in linear time.
fn len_utf16(&self) -> usize;
}
impl StrExt for str {
fn len_utf16(&self) -> usize {
self.chars().map(char::len_utf16).sum()
}
}
/// Extra methods for [`Arc`].
pub trait ArcExt<T> {
/// Takes the inner value if there is exactly one strong reference and
/// clones it otherwise.
fn take(self) -> T;
}
impl<T: Clone> ArcExt<T> for Arc<T> {
fn take(self) -> T {
match Arc::try_unwrap(self) {
Ok(v) => v,
Err(rc) => (*rc).clone(),
}
}
}
/// Extra methods for [`[T]`](slice).
pub trait SliceExt<T> {
/// Split a slice into consecutive runs with the same key and yield for
/// each such run the key and the slice of elements with that key.
fn group_by_key<K, F>(&self, f: F) -> GroupByKey<'_, T, F>
where
F: FnMut(&T) -> K,
K: PartialEq;
}
impl<T> SliceExt<T> for [T] {
fn group_by_key<K, F>(&self, f: F) -> GroupByKey<'_, T, F> {
GroupByKey { slice: self, f }
}
}
/// This struct is created by [`SliceExt::group_by_key`].
pub struct GroupByKey<'a, T, F> {
slice: &'a [T],
f: F,
}
impl<'a, T, K, F> Iterator for GroupByKey<'a, T, F>
where
F: FnMut(&T) -> K,
K: PartialEq,
{
type Item = (K, &'a [T]);
fn next(&mut self) -> Option<Self::Item> {
let mut iter = self.slice.iter();
let key = (self.f)(iter.next()?);
let count = 1 + iter.take_while(|t| (self.f)(t) == key).count();
let (head, tail) = self.slice.split_at(count);
self.slice = tail;
Some((key, head))
}
}
/// Extra methods for [`Path`].
pub trait PathExt {
/// Lexically normalize a path.
fn normalize(&self) -> PathBuf;
}
impl PathExt for Path {
fn normalize(&self) -> PathBuf {
let mut out = PathBuf::new();
for component in self.components() {
match component {
Component::CurDir => {}
Component::ParentDir => match out.components().next_back() {
Some(Component::Normal(_)) => {
out.pop();
}
_ => out.push(component),
},
_ => out.push(component),
}
}
out
}
}
/// Format pieces separated with commas and a final "and" or "or".
pub fn separated_list(pieces: &[impl AsRef<str>], last: &str) -> String {
let mut buf = String::new();
for (i, part) in pieces.iter().enumerate() {
match i {
0 => {}
1 if pieces.len() == 2 => {
buf.push(' ');
buf.push_str(last);
buf.push(' ');
}
i if i + 1 == pieces.len() => {
buf.push_str(", ");
buf.push_str(last);
buf.push(' ');
}
_ => buf.push_str(", "),
}
buf.push_str(part.as_ref());
}
buf
}
/// Format a comma-separated list.
///
/// Tries to format horizontally, but falls back to vertical formatting if the
/// pieces are too long.
pub fn pretty_comma_list(pieces: &[impl AsRef<str>], trailing_comma: bool) -> String {
const MAX_WIDTH: usize = 50;
let mut buf = String::new();
let len = pieces.iter().map(|s| s.as_ref().len()).sum::<usize>()
+ 2 * pieces.len().saturating_sub(1);
if len <= MAX_WIDTH {
for (i, piece) in pieces.iter().enumerate() {
if i > 0 {
buf.push_str(", ");
}
buf.push_str(piece.as_ref());
}
if trailing_comma {
buf.push(',');
}
} else {
for piece in pieces {
buf.push_str(piece.as_ref().trim());
buf.push_str(",\n");
}
}
buf
}
/// Format an array-like construct.
///
/// Tries to format horizontally, but falls back to vertical formatting if the
/// pieces are too long.
pub fn pretty_array_like(parts: &[impl AsRef<str>], trailing_comma: bool) -> String {
let list = pretty_comma_list(&parts, trailing_comma);
let mut buf = String::new();
buf.push('(');
if list.contains('\n') {
buf.push('\n');
for (i, line) in list.lines().enumerate() {
if i > 0 {
buf.push('\n');
}
buf.push_str(" ");
buf.push_str(line);
}
buf.push('\n');
} else {
buf.push_str(&list);
}
buf.push(')');
buf
}
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