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//! Missing batteries for standard libraries.
use std::{cell::Cell, fmt};
/// Appends formatted string to a `String`.
#[macro_export]
macro_rules! format_to {
($buf:expr) => ();
($buf:expr, $lit:literal $($arg:tt)*) => {
{ use ::std::fmt::Write as _; let _ = ::std::write!($buf, $lit $($arg)*); }
};
}
pub trait SepBy: Sized {
/// Returns an `impl fmt::Display`, which joins elements via a separator.
fn sep_by<'a>(self, sep: &'a str) -> SepByBuilder<'a, Self>;
}
impl<I> SepBy for I
where
I: Iterator,
I::Item: fmt::Display,
{
fn sep_by<'a>(self, sep: &'a str) -> SepByBuilder<'a, Self> {
SepByBuilder::new(sep, self)
}
}
pub struct SepByBuilder<'a, I> {
sep: &'a str,
prefix: &'a str,
suffix: &'a str,
iter: Cell<Option<I>>,
}
impl<'a, I> SepByBuilder<'a, I> {
fn new(sep: &'a str, iter: I) -> SepByBuilder<'a, I> {
SepByBuilder { sep, prefix: "", suffix: "", iter: Cell::new(Some(iter)) }
}
pub fn prefix(mut self, prefix: &'a str) -> Self {
self.prefix = prefix;
self
}
pub fn suffix(mut self, suffix: &'a str) -> Self {
self.suffix = suffix;
self
}
/// Set both suffix and prefix.
pub fn surround_with(self, prefix: &'a str, suffix: &'a str) -> Self {
self.prefix(prefix).suffix(suffix)
}
}
impl<I> fmt::Display for SepByBuilder<'_, I>
where
I: Iterator,
I::Item: fmt::Display,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(self.prefix)?;
let mut first = true;
for item in self.iter.take().unwrap() {
if !first {
f.write_str(self.sep)?;
}
first = false;
fmt::Display::fmt(&item, f)?;
}
f.write_str(self.suffix)?;
Ok(())
}
}
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