use std::fmt::{self, Write};
pub fn escape(string: &str) -> Escaper {
Escaper(string)
}
pub struct Escaper<'a>(&'a str);
const SPECIAL: &[char] = &[
'\n', '\r', '\'', '\\', '\u{2028}', '\u{2029}', ];
impl<'a> fmt::Display for Escaper<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let &Escaper(mut string) = self;
f.write_char('\'')?;
while !string.is_empty() {
if let Some(i) = string.find(SPECIAL) {
if i > 0 {
f.write_str(&string[..i])?;
}
let mut chars = string[i..].chars();
f.write_str(match chars.next().unwrap() {
'\n' => "\\n",
'\r' => "\\r",
'\'' => "\\'",
'\\' => "\\\\",
'\u{2028}' => "\\u2028",
'\u{2029}' => "\\u2029",
_ => unreachable!(),
})?;
string = chars.as_str();
} else {
f.write_str(string)?;
break;
}
}
f.write_char('\'')?;
Ok(())
}
}
#[test]
fn test() {
let plain = "ABC \n\r' abc \\ \u{2028} \u{2029}123";
let escaped = escape(plain).to_string();
assert!(escaped == "'ABC \\n\\r\\' abc \\\\ \\u2028 \\u2029123'");
}