Toggle numbered lists

script

(() => {
    'use strict';

    // Toggle list item numbering of selected lines on ⇄ off
    const main = () => {
        const
            e = editor,
            rgxOL = /^(\s*)\d+\. (.*)/,
            rgxOther = /^(\s*)(\S.*)/,
            [pres, selns, posts] = selectionTriagedLines(),
            dcts = map(
                x => {
                    const
                        mOL = rgxOL.exec(x),
                        mOther = mOL ? null : rgxOther.exec(x),
                        blnOther = Boolean(mOther);
                    return mOL ? {
                        ol: true,
                        indent: mOL[1],
                        txt: mOL[2]
                    } : {
                        ol: false,
                        indent: blnOther ? mOther[1] : '',
                        txt: blnOther ? mOther[2] : ''
                    };
                },
                selns
            ),
            blnToOL = !dcts.some(dct => dct.ol),
            strPre = unlines(pres),
            strToggled = unlines(map(
                blnToOL ? (
                    (x, i) => `${x.indent}${i + 1}. ${x.txt}`
                ) : x => x.indent + x.txt,
                dcts
            ));

        return (
            e.setText(
                unlines(
                    [strPre, strToggled, unlines(posts)]
                    .filter(x => 0 < x.length)
                )
            ),
            selns.length > 1 ? (
                e.setSelectedRange(
                    1 + (strPre.length || -1),
                    strToggled.length
                )
            ) : e.setSelectedRange(
                1 + (strPre.length || -1) +
                strToggled.length,
                0
            )
        );
    };

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

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

    // showLog :: a -> Console String
    const showLog = (...args) =>
        alert(
            args.map(JSON.stringify)
            .join(' -> ')
        );

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

    // DRAFTS ---

    // selectionTriagedLines :: () ->
    //                 ([String],[String],[String])
    const selectionTriagedLines = () => {
        const
            e = editor,
            [from, lng] = e.getSelectedLineRange(),
            last = from + lng,
            clng = draft.content.length,
            blnLast = clng === last;
        return map(
            rng => rng.length > 0 ? (
                e.getTextInRange(...rng).split('\n')
            ) : [], [
                from > 0 ? [0, from - 1] : [],
                [from, blnLast ? lng : lng - 1],
                blnLast ? [] : [last, clng - last]
            ]
        );
    };

    // MAIN ...
    main();
})();