ometa W {
    oneOf :a ?(a.length == 1) = apply(a.pop()),
    oneOf :a ?(a.length > 1) = apply(a.pop()) | oneOf(a),
    bla = oneOf([`b, `i]):c -> [`one, c],

    escapedChar = '~' char:c -> c,
    escaped = escapedChar+:c -> [`escaped, c.join('')],

    b = seq('**'),
    i = seq('//'),
    s = seq('--'),
    nl = '\n' ((~'\n' space)* '\n')+,
    special = (b | i | s | nl):c -> [`special, c],

    between :t :n = apply(t) (~oneOf(n) inline(W.add(n, t)))*:c apply(t) -> c,
    between_ :t = apply(t) (~special text)*:c (~~special | end) -> c,

    bold :n = between(`b, n):c -> [`bold, c],
    bold_ = between_(`b):c -> [`bold_, c],

    italic :n = between(`i, n):c -> [`italic, c],
    italic_ = between_(`i):c -> [`italic_, c],

    strike :n = between(`s, n):c -> [`strike, c],
    strike_ = between_(`s):c -> [`strike_, c],

    text = (~special ~escapedChar char)+:c -> c.join('')
           | escaped:c -> c,

    inline :n = bold([`b]) | italic([`i]) | strike([`s]) | text,
    inline :n ?(n.length > 0) = bold(n) | italic(n) | strike(n) | text,
    inline_ = bold_ | italic_ | strike_,

    allInline = inline([]) | (~inline([]) inline_),

    para = (~nl allInline)+:c (nl | end) -> [`para, c],

    allBlock = para,

    topLevel = (allInline)+
}
W.without = function(arr, elem) {
    var newArr = [];
    for (var i = 0; i < arr.length; i++) {
       if (arr[i] != elem) newArr[newArr.length] = arr[i];
    }
    return newArr;
}

W.add = function(arr, elem) {
    for (var i = 0, l = arr.length; i < l; i++) {
       if (arr[i] == elem) return arr;
    }
    arr[arr.length] = elem;
    return arr;
}
alert(W.matchAll('1ad', 'topLevel'));