Function display_utf8_lossy

aiscript-vm/src/string/utils.rs:8–38

Display potentially non-UTF8 string in a lossy way, *without* allocating a new buffer to hold the string.

(input: &[u8])

/// Display potentially non-UTF8 string in a lossy way, *without* allocating a new buffer to hold
/// the string.
pub fn display_utf8_lossy(input: &[u8]) -> impl fmt::Display + '_ {
    struct StringDisplay<'a>(&'a [u8]);

    impl fmt::Display for StringDisplay<'_> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            let mut input = self.0;
            loop {
                match str::from_utf8(input) {
                    Ok(valid) => {
                        f.write_str(valid)?;
                        break;
                    }
                    Err(error) => {
                        let (valid, after_valid) = input.split_at(error.valid_up_to());
                        f.write_str(str::from_utf8(valid).unwrap())?;
                        f.write_str("\u{FFFD}")?;

                        if let Some(invalid_sequence_length) = error.error_len() {
                            input = &after_valid[invalid_sequence_length..]
                        } else {
                            break;
                        }
                    }
                }
            }
            Ok(())
        }
    }

    StringDisplay(input)
}

/// Like [`display_utf8_lossy`], returns an `impl fmt::Debug` type that uses debug character escapes
/// and surrounds the string by '"' characters.