tmux-lib 0.5.0

Tmux helper functions.
Documentation 
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/// Trim each line of the buffer.
fn buf_trim_trailing(buf: &[u8]) -> Vec<&[u8]> {
    buf.split(|c| *c == b'\n')
        .map(|line| line.trim_ascii_end())
        .collect()
}

/// Drop all the last empty lines.
fn drop_last_empty_lines<'a>(lines: &[&'a [u8]]) -> Vec<&'a [u8]> {
    if let Some(last) = lines.iter().rposition(|line| !line.is_empty()) {
        lines[0..=last].to_vec()
    } else {
        lines.to_vec()
    }
}

/// Process a pane captured buffer.
///
/// - All lines are trimmed after capture because tmux does not allow capturing escape codes and
///   trimming lines.
/// - If `drop_n_last_lines` is greater than 0, the n last lines are not captured. This is used only
///   for panes with a zsh prompt, in order to avoid polluting the history with new prompts on
///   restore.
/// - In addition, the last line has an additional ascii reset escape code because tmux does not
///   capture it.
///
/// ```
/// use tmux_lib::utils::cleanup_captured_buffer;
///
/// let buffer = b"line1  \nline2\t\n\n\n";
/// let result = cleanup_captured_buffer(buffer, 0);
/// let output = String::from_utf8(result).unwrap();
///
/// // trailing whitespace trimmed, empty trailing lines dropped, reset code appended
/// assert_eq!(output, "line1\nline2\x1b[0m\n");
/// ```
pub fn cleanup_captured_buffer(buffer: &[u8], drop_n_last_lines: usize) -> Vec<u8> {
    let trimmed_lines: Vec<&[u8]> = buf_trim_trailing(buffer);
    let mut buffer: Vec<&[u8]> = drop_last_empty_lines(&trimmed_lines);
    buffer.truncate(buffer.len() - drop_n_last_lines);

    // Join the lines with `b'\n'`, add reset code to the last line
    let mut final_buffer: Vec<u8> = Vec::with_capacity(buffer.len());
    for (idx, &line) in buffer.iter().enumerate() {
        final_buffer.extend_from_slice(line);

        let is_last_line = idx == buffer.len() - 1;
        if is_last_line {
            let reset = "\u{001b}[0m".as_bytes();
            final_buffer.extend_from_slice(reset);
            final_buffer.push(b'\n');
        } else {
            final_buffer.push(b'\n');
        }
    }

    final_buffer
}

#[cfg(test)]
mod tests {
    use super::{buf_trim_trailing, cleanup_captured_buffer, drop_last_empty_lines};

    #[test]
    fn trims_trailing_whitespaces() {
        let input = "  text   ".as_bytes();
        let expected = "  text".as_bytes();

        let actual = input.trim_ascii_end();
        assert_eq!(actual, expected);
    }

    #[test]
    fn trims_whitespaces() {
        let input = "  text   ".as_bytes();
        let expected = "text".as_bytes();

        let actual = input.trim_ascii();
        assert_eq!(actual, expected);
    }

    #[test]
    fn test_buf_trim_trailing() {
        let text = "line1\n\nline3   ";
        let actual = buf_trim_trailing(text.as_bytes());
        let expected = vec!["line1".as_bytes(), "".as_bytes(), "line3".as_bytes()];
        assert_eq!(actual, expected);
    }

    #[test]
    fn test_buf_drop_last_empty_lines() {
        let text = "line1\nline2\n\nline3   ";

        let trimmed_lines = buf_trim_trailing(text.as_bytes());
        let actual = drop_last_empty_lines(&trimmed_lines);
        let expected = trimmed_lines;
        assert_eq!(actual, expected);

        //

        let text = "line1\nline2\n\n\n     ";

        let trimmed_lines = buf_trim_trailing(text.as_bytes());
        let actual = drop_last_empty_lines(&trimmed_lines);
        let expected = vec!["line1".as_bytes(), "line2".as_bytes()];
        assert_eq!(actual, expected);
    }

    #[test]
    fn test_trim_only_whitespace() {
        let input = "   \t  ".as_bytes();
        assert_eq!(input.trim_ascii(), &[]);
        assert_eq!(input.trim_ascii_end(), &[]);
    }

    #[test]
    fn test_trim_empty() {
        let input = "".as_bytes();
        assert_eq!(input.trim_ascii(), &[]);
        assert_eq!(input.trim_ascii_end(), &[]);
    }

    #[test]
    fn test_trim_tabs() {
        let input = "\t\ttext\t\t".as_bytes();
        assert_eq!(input.trim_ascii(), "text".as_bytes());
        assert_eq!(input.trim_ascii_end(), "\t\ttext".as_bytes());
    }

    #[test]
    fn test_cleanup_captured_buffer_basic() {
        let input = "line1\nline2\n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);

        // Should have lines with reset code on last line
        let result_str = String::from_utf8(result).unwrap();
        assert!(result_str.contains("line1\n"));
        assert!(result_str.contains("line2"));
        assert!(result_str.contains("\u{001b}[0m")); // reset code
    }

    #[test]
    fn test_cleanup_captured_buffer_trims_trailing_spaces() {
        let input = "line1   \nline2   \n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);

        let result_str = String::from_utf8(result).unwrap();
        // Lines should be trimmed of trailing spaces
        assert!(result_str.starts_with("line1\n"));
        assert!(result_str.contains("line2\u{001b}[0m\n"));
    }

    #[test]
    fn test_cleanup_captured_buffer_drops_empty_trailing_lines() {
        let input = "line1\nline2\n\n\n   \n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);

        let result_str = String::from_utf8(result).unwrap();
        // Should only have line1 and line2, no trailing empty lines
        assert_eq!(result_str, "line1\nline2\u{001b}[0m\n");
    }

    #[test]
    fn test_cleanup_captured_buffer_drop_n_last_lines() {
        let input = "line1\nline2\nline3\nline4\n";
        let result = cleanup_captured_buffer(input.as_bytes(), 2);

        let result_str = String::from_utf8(result).unwrap();
        // Should drop last 2 lines (line3 and line4)
        assert_eq!(result_str, "line1\nline2\u{001b}[0m\n");
    }

    #[test]
    fn test_cleanup_captured_buffer_single_line() {
        let input = "single line   \n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);

        let result_str = String::from_utf8(result).unwrap();
        assert_eq!(result_str, "single line\u{001b}[0m\n");
    }

    #[test]
    fn test_cleanup_captured_buffer_preserves_escape_codes() {
        // Simulate content with existing escape codes
        let input = "\u{001b}[32mgreen text\u{001b}[0m\n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);

        let result_str = String::from_utf8(result).unwrap();
        // Should preserve existing escape codes and add reset at end
        assert!(result_str.contains("\u{001b}[32m"));
        assert!(result_str.ends_with("\u{001b}[0m\n"));
    }

    #[test]
    fn test_drop_last_empty_lines_all_empty() {
        let lines: Vec<&[u8]> = vec![b"", b"", b""];
        let result = drop_last_empty_lines(&lines);
        // When all lines are empty, should return as-is
        assert_eq!(result, lines);
    }

    #[test]
    fn test_drop_last_empty_lines_no_empty() {
        let lines: Vec<&[u8]> = vec![b"a", b"b", b"c"];
        let result = drop_last_empty_lines(&lines);
        assert_eq!(result, lines);
    }

    #[test]
    fn test_cleanup_captured_buffer_tabs_are_trimmed() {
        let input = "line1\t\t\nline2\t\n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);
        let result_str = String::from_utf8(result).unwrap();
        assert_eq!(result_str, "line1\nline2\u{001b}[0m\n");
    }

    #[test]
    fn test_cleanup_captured_buffer_mixed_trailing_whitespace() {
        let input = "line1 \t \nline2\t  \t\n";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);
        let result_str = String::from_utf8(result).unwrap();
        assert_eq!(result_str, "line1\nline2\u{001b}[0m\n");
    }

    #[test]
    fn test_cleanup_captured_buffer_no_trailing_newline() {
        let input = "line1\nline2";
        let result = cleanup_captured_buffer(input.as_bytes(), 0);
        let result_str = String::from_utf8(result).unwrap();
        assert_eq!(result_str, "line1\nline2\u{001b}[0m\n");
    }

    #[test]
    fn test_buf_trim_trailing_preserves_leading_whitespace() {
        let text = "  indented\n\tnested\n";
        let actual = buf_trim_trailing(text.as_bytes());
        assert_eq!(actual[0], "  indented".as_bytes());
        assert_eq!(actual[1], "\tnested".as_bytes());
    }
}