proc_macro/
escape.rs

1#[derive(Copy, Clone)]
2pub(crate) struct EscapeOptions {
3    /// Produce \'.
4    pub escape_single_quote: bool,
5    /// Produce \".
6    pub escape_double_quote: bool,
7    /// Produce \x escapes for non-ASCII, and use \x rather than \u for ASCII
8    /// control characters.
9    pub escape_nonascii: bool,
10}
11
12pub(crate) fn escape_bytes(bytes: &[u8], opt: EscapeOptions) -> String {
13    let mut repr = String::new();
14
15    if opt.escape_nonascii {
16        for &byte in bytes {
17            escape_single_byte(byte, opt, &mut repr);
18        }
19    } else {
20        let mut chunks = bytes.utf8_chunks();
21        while let Some(chunk) = chunks.next() {
22            for ch in chunk.valid().chars() {
23                escape_single_char(ch, opt, &mut repr);
24            }
25            for &byte in chunk.invalid() {
26                escape_single_byte(byte, opt, &mut repr);
27            }
28        }
29    }
30
31    repr
32}
33
34fn escape_single_byte(byte: u8, opt: EscapeOptions, repr: &mut String) {
35    if byte == b'\0' {
36        repr.push_str("\\0");
37    } else if (byte == b'\'' && !opt.escape_single_quote)
38        || (byte == b'"' && !opt.escape_double_quote)
39    {
40        repr.push(byte as char);
41    } else {
42        // Escapes \t, \r, \n, \\, \', \", and uses \x## for non-ASCII and
43        // for ASCII control characters.
44        repr.extend(byte.escape_ascii().map(char::from));
45    }
46}
47
48fn escape_single_char(ch: char, opt: EscapeOptions, repr: &mut String) {
49    if (ch == '\'' && !opt.escape_single_quote) || (ch == '"' && !opt.escape_double_quote) {
50        repr.push(ch);
51    } else {
52        // Escapes \0, \t, \r, \n, \\, \', \", and uses \u{...} for
53        // non-printable characters and for Grapheme_Extend characters, which
54        // includes things like U+0300 "Combining Grave Accent".
55        repr.extend(ch.escape_debug());
56    }
57}