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#![cfg_attr(feature = "nightly", feature(pattern))]
#![warn(missing_docs)]
extern crate memchr;
use std::{fmt, ops::Deref};
#[cfg(not(feature = "nightly"))]
pub mod pattern;
#[cfg(feature = "nightly")]
pub use std::str::pattern;
use self::pattern::{Pattern, SearchStep, Searcher};
pub struct ReplacedString<'a, P, D> {
haystack: &'a str,
needle: P,
replacement: D,
}
impl<'a, P, D> ReplacedString<'a, P, D> {
pub fn new(haystack: &'a str, needle: P, replacement: D) -> Self {
ReplacedString {
haystack,
needle,
replacement,
}
}
}
pub trait LazyReplace {
fn lazy_replace<P, D>(&self, pat: P, replacement: D) -> ReplacedString<'_, P, D>;
}
impl<T> LazyReplace for T
where
T: Deref<Target = str>,
{
fn lazy_replace<P, D>(&self, needle: P, replacement: D) -> ReplacedString<'_, P, D> {
ReplacedString {
needle,
replacement,
haystack: &*self,
}
}
}
impl LazyReplace for str {
fn lazy_replace<P, D>(&self, needle: P, replacement: D) -> ReplacedString<'_, P, D> {
ReplacedString {
needle,
replacement,
haystack: &*self,
}
}
}
impl<'a, P, D> fmt::Display for ReplacedString<'a, P, D>
where
P: Pattern<'a> + Clone,
D: fmt::Display,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let mut searcher = self.needle.clone().into_searcher(self.haystack);
loop {
match searcher.next() {
SearchStep::Match(_, _) => write!(f, "{}", self.replacement)?,
SearchStep::Reject(start, end) => write!(f, "{}", &self.haystack[start..end])?,
SearchStep::Done => break,
}
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::LazyReplace;
#[test]
fn it_works() {
assert_eq!(
"onetwothree",
format!("{}", "one!HERE!three".lazy_replace("!HERE!", "two"))
);
assert_eq!(
"onetwothree",
format!("{}", "onetwo!HERE!".lazy_replace("!HERE!", "three"))
);
assert_eq!(
"onetwothreethree",
format!("{}", "onetwo!HERE!!HERE!".lazy_replace("!HERE!", "three"))
);
}
}