(Re)number lines

script

(() => {
    'use strict';

    // MAIN ------------------------------------------------
    // Line numbering (followed by colon and space) updated.
    const main = () =>
        draftOrLinesUpdated(
            xs => {
                const
                    iLast = xs.length - 1,
                    intDigits = iLast.toString().length,
                    rgxNum = /^(\s*\d+:\s*|)(.*)$/;
                return map(
                    (x, i) => justifyRight(
                        intDigits, ' ',
                        (1 + i).toString(),
                    ) + ':  ' + rgxNum.exec(x)[2],
                    xs
                );
            }
        );

    // REUSABLE FUNCTION FOR DRAFTS:
    //
    // Update the editor with selected (or otherwise all) lines
    // transformed by a function on a list of (line) strings
    // which returns another list of strings.

    // draftOrLinesUpdated :: IO () -> ([String] -> [String]) -> IO ()
    const draftOrLinesUpdated = f => {
        const
            functionName = f.name, // Used for logging.
            // Selected lines or whole of draft.
            [intStart, intLength] = editor.getSelectedLineRange(),
            [intFrom, intChars] = (
                editor.getSelectedText()
                .length > 0 ? (
                    [intStart, intLength]
                ) : [0, editor.getText().length]
            ),
            // Concatenated result of applying f to the list of lines
            strUpdated = unlines(f(lines(
                editor.getTextInRange(intFrom, intChars)
            )));
        return (
            // Various channels, for testing and use.
            editor.setTextInRange(intFrom, intChars, strUpdated),
            console.log(functionName, strUpdated),
            strUpdated
        );
    };

    // GENERIC FUNCTIONS -----------------------------

    // justifyRight :: Int -> Char -> String -> String
    const justifyRight = (n, cFiller, strText) =>
        n > strText.length ? (
            (cFiller.repeat(n) + strText)
            .slice(-n)
        ) : strText;

    // lines :: String -> [String]
    const lines = s => s.split(/[\r\n]/);

    // map :: (a -> b) -> [a] -> [b]
    const map = (f, xs) => xs.map(f);

    // unlines :: [String] -> String
    const unlines = xs => xs.join('\n');

    // MAIN ------------------------------
    return main();
})();