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#[allow(clippy::missing_panics_doc)]
pub fn escape_string(input: &str, out: &mut String) {
for ch in input.chars() {
match ch {
'\\' => out.push_str("\\\\"),
'"' => out.push_str("\\\""),
'\n' => out.push_str("\\n"),
'\r' => out.push_str("\\r"),
'\t' => out.push_str("\\t"),
'\x20'..='\x7e' => out.push(ch),
_ => {
let mut buf = [0; 2];
for &mut code_unit in ch.encode_utf16(&mut buf) {
out.push_str("\\u");
out.push(char::from_digit(u32::from(code_unit) / 0x1000, 16).unwrap());
out.push(char::from_digit(u32::from(code_unit) % 0x1000 / 0x100, 16).unwrap());
out.push(char::from_digit(u32::from(code_unit) % 0x100 / 0x10, 16).unwrap());
out.push(char::from_digit(u32::from(code_unit) % 0x10, 16).unwrap());
}
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[track_caller]
fn test_json_str(input: &str, expected: &str) {
let mut out = String::new();
escape_string(input, &mut out);
assert_eq!(out, expected);
}
#[test]
fn json_string_encoding() {
test_json_str("abc", "abc");
test_json_str("fancy string\n", "fancy string\\n");
test_json_str("\n\t\r\0\\\'\"", "\\n\\t\\r\\u0000\\\\'\\\"");
test_json_str("\u{1d54a}", "\\ud835\\udd4a");
}
}