hex_digit(value: u32) -> char1 fn hex_digit(value: u32) -> char {
2     if value < 10 {
3         (b'0' + value as u8) as char
4     } else if value < 0x10 {
5         (b'a' + value as u8 - 10) as char
6     } else {
7         unreachable!()
8     }
9 }
10 
quote_escape_str(s: &str) -> String11 pub fn quote_escape_str(s: &str) -> String {
12     let mut buf = String::new();
13     buf.push('"');
14     buf.extend(s.chars().flat_map(|c| c.escape_default()));
15     buf.push('"');
16     buf
17 }
18 
quote_escape_bytes(bytes: &[u8]) -> String19 pub fn quote_escape_bytes(bytes: &[u8]) -> String {
20     let mut buf = String::new();
21     buf.push('b');
22     buf.push('"');
23     for &b in bytes {
24         match b {
25             b'\n' => buf.push_str(r"\n"),
26             b'\r' => buf.push_str(r"\r"),
27             b'\t' => buf.push_str(r"\t"),
28             b'"' => buf.push_str("\\\""),
29             b'\\' => buf.push_str(r"\\"),
30             b'\x20'..=b'\x7e' => buf.push(b as char),
31             _ => {
32                 buf.push_str(r"\x");
33                 buf.push(hex_digit((b as u32) >> 4));
34                 buf.push(hex_digit((b as u32) & 0x0f));
35             }
36         }
37     }
38     buf.push('"');
39     buf
40 }
41 
42 #[cfg(test)]
43 mod test {
44 
45     use super::*;
46 
47     #[test]
test_quote_escape_bytes()48     fn test_quote_escape_bytes() {
49         assert_eq!("b\"\"", quote_escape_bytes(b""));
50         assert_eq!("b\"xyZW\"", quote_escape_bytes(b"xyZW"));
51         assert_eq!("b\"aa\\\"bb\"", quote_escape_bytes(b"aa\"bb"));
52         assert_eq!("b\"aa\\r\\n\\tbb\"", quote_escape_bytes(b"aa\r\n\tbb"));
53         assert_eq!(
54             "b\"\\x00\\x01\\x12\\xfe\\xff\"",
55             quote_escape_bytes(b"\x00\x01\x12\xfe\xff")
56         );
57     }
58 }
59