tuigram-cli 0.6.0

//! Text from other people, made safe to show and copy.

/// Characters left out of text from Telegram:
/// - control characters other than line breaks and tabs. The screen drops
///   them anyway, but copied text keeps them, and a hidden `\r` or escape
///   can run a command when pasted into a shell or vim.
/// - bidi overrides and isolates, which can make text read backwards:
///   "invoice<U+202E>fdp.exe" shows as `invoiceexe.pdf` in some terminals.
pub fn is_hidden(c: char) -> bool {
    (c.is_control() && c != '\n' && c != '\t')
        || matches!(c, '\u{202A}'..='\u{202E}' | '\u{2066}'..='\u{2069}')
}

/// `text` without the characters [`is_hidden`] leaves out.
pub fn clean(text: &str) -> String {
    text.chars().filter(|&c| !is_hidden(c)).collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn controls_and_bidi_overrides_are_dropped_but_line_breaks_and_tabs_stay() {
        assert_eq!(clean("invoice\u{202E}fdp.exe"), "invoicefdp.exe");
        assert_eq!(clean("a\u{1b}[2Jb\rc\u{7}d\u{9b}e"), "a[2Jbcde");
        assert_eq!(clean("one\ntwo\tthree"), "one\ntwo\tthree");
        assert_eq!(clean("עברית and العربية"), "עברית and العربية");
    }
}