yet another Hit-a-Hint implementation

hit@hint.ubiq.user.js

// ==UserScript== function cmd_
// @name          hit@hint
// @description   pseudo Hit-a-Hint for Ubiquity/Greasemonkey
// @namespace     http://d.hatena.ne.jp/murky-satyr
// @include       *
// ==/UserScript==
function pageLoad_HatH(doc, win){ if((win = doc.defaultView) === win.top){{}
HatH(win, doc, {
  key: 'asdfghjkl',
  bind: {
    go: ['C_\\', 29 /* unconvert */],
    ok: 'S_return C_return', //does default action, then continues hint-mode
    bs: ['back_space', 29],  //undo
    click: ';', dblclick: ':',
    mouseup: '[', mousedown: ']',
    mouseover: ',', mouseout: '.',
  },
  css: ''+<><![CDATA[
    $pan {
      position:absolute; z-index:2147483647;
      color:#000; background-color:#ef7; opacity:0.7;
      font:bold 9pt/1 "Consolas",monospace; text-transform:uppercase;
      margin:0; padding:0 1px; border:1px solid #aaa}
    $pan.hit {background-color:#fcf}
    ]]></>,
  /// each hint's offset from its associated element
  offset: {x: -3, y: -2},
  /// base point of screen (set negative values to allow overflowed elements)
  origin: {x: -6, y: -4},
  /// xpath fragments for specific URIs
  xpath: {
    '^':
    'a[@href] img[@onclick] input[not(@type="hidden")] textarea select button',
    '^http://\\w\\.hatena\\.ne\\.jp/':
    ['img[@class="hatena-star-comment-button"]', 'img[@title="Add Star"]'],
    '^http://www\\.google\\.com/reader/':
    ['div[contains(concat(" ",@class," ")," lhn-button ")'+
     ' or contains(concat(" ",@class," ")," goog-button ")]'],
  },
  /// guide
  //sign: {__noSuchMethod__: isNaN},
})}}
this.CmdUtils || pageLoad_HatH(document);

function HatH(window, document,
              {id, key, css, bind, sign, xpath, offset, origin}){
  const KeyEvent = document.createEvent('KeyEvents'),
  K = (key || 'asdfghjkl').split(''), L = K.length;
  Bind = bind || {go: 'C_z', ok: 'RETURN'},
  ID = id || 'HatH', IDD = ID +'Div', IDS = ID +'Style',
  {x: OffsetX, y: OffsetY} = offset || {x: -8, y: -8},
  {x: OriginX, y: OriginY} = origin || {x: -4, y: -4},
  XPath = mixpath(xpath).map(function(s) this + s +'|'+ this +'xhtml:' + s,
                             '/html/body/descendant::').join('|'),
  CSS = (css.replace(/\$/g, '#'+ IDD +'>s')
         .replace(/([^;\s])\s*\}/g, '$1;}').replace(/;/g, ' !important;')),
  Sign = sign || {
    new: function SNew(){ this._ = document.title; this.put('') },
    put: function SPut(txt, lmn){
      var msg = '@'+ txt;
      if(lmn){
        var name = lmn.nodeName.toUpperCase();
        msg += (' '+ (name === 'INPUT' ? lmn.type.toUpperCase() : name) +
                ' '+ (lmn.href || lmn.src || lmn.value || '') +
                ' '+ (lmn.title || lmn.alt || lmn.textContent || ''));
      }
      document.title = msg;
    },
    end: function SEnd(){ document.title = this._ },
  },
  Hints = {
    Hint: {
      set on(b)(this.span.className = b ? (this.item.focus(), 'hit') : '', b),
    },
    txt: '',
    new: function HNew(){ this.dic = {}, this.len = 0 },
    end: function HEnd(){ this.dic = this.len = null },
    add: function HAdd(span, item){
      var n = this.len++;
      this.dic[span.textContent = K[n] || (K[n] = K[~-(n / L)] + K[n % L])]
        = {__proto__: this.Hint, span: span, item: item};
    },
    get now() this.dic[this.txt],
    set: function HSet(t){
      var h = this.now;
      if(h) h.on = false;
      return this.txt = (h = this.dic[t]) ? h.on = t : '';
    },
    spray: function HSpray(win, doc){
      this.css(doc);
      var box = doc.createElement('div'), {max} = Math, i = -1,
      xpr = doc.evaluate(XPath, doc, nsr, 7, null), l = xpr.snapshotLength;
      while(++i < l){
        var lmn = xpr.snapshotItem(i), stl = win.getComputedStyle(lmn, null);
        if(stl.visibility === 'hidden' || stl.opacity === '0') continue;
        var {top, right, bottom, left} = lmn.getBoundingClientRect();
        if(left >= right || top >= bottom ||
           OriginX > left || OriginY > top ||
           right > win.innerWidth - OriginX ||
           bottom > win.innerHeight - OriginY) continue;
        var spn = doc.createElement('span');
        spn.setAttribute(
          'style', ('left:'+ max(0, left + win.scrollX + OffsetX) +'px'+
                    ';top:'+ max(0, top  + win.scrollY + OffsetY) +'px'));
        this.add(box.appendChild(spn), lmn);
      }
      box.id = IDD;
      doc.body.appendChild(box);
    },
    sweep: function HSweep(doc){
      var box = doc.getElementById(IDD);
      box && doc.body.removeChild(box);
    },
    css: function HCss(doc){
      if(doc.getElementById(IDS)) return;
      var style = doc.createElement('style');
      style.innerHTML = CSS,
      doc.body.appendChild(style).id = IDS;
    },
  },
  Do = (['click', 'dblclick', 'mouseup', 'mousedown', 'mouseover', 'mouseout']
        .reduce(function(d, h)(d[h] = mouser(h), d),
                {$: input, go: begin, ok: unhit, bs: back})),
  Runner = handler({go: Bind.go});
  Hitter = (function()(delete Bind.go,
                       Bind.$ = [k.charCodeAt() for each(k in K)],
                       handler(Bind, end)))();
  cast(function(win){ win.addEventListener('keypress', Runner, true) });

  function start(win, doc){
    win.removeEventListener('keypress', Runner, true);
    doc.getElementsByTagName('frameset').length || Hints.spray(win, doc);
    win.addEventListener('keypress', Hitter, true);
  }
  function reset(win, doc){
    win.removeEventListener('keypress', Hitter, true);
    Hints.sweep(doc);
    win.addEventListener('keypress', Runner, true);
  }
  function begin(){
    Sign.new();
    Hints.new();
    cast(start);
  }
  function end(){
    cast(reset);
    Hints.end();
    Sign.end();
    return true;
  }
  function hit(txt)(Hints.set(txt)
                    ? (Sign.put(Hints.txt, Hints.now.item), true)
                    : (Sign.put(''), false));
  function input(e){
    var key = String.fromCharCode(e.keyCode || e.which);
    hit(Hints.txt + key) || hit(key);
  }
  function unhit() !hit();
  function back(){ Hints.txt ? hit(Hints.txt.slice(0, -1)) : end() }
  function mouser(type){
    var detail = type === 'dblclick' ? 2 : 1;
    return function mouse(e){
      var lm = Hints.now.item;
      var me = document.createEvent('MouseEvents');
      me.initMouseEvent(type, 1, 1, e.view, detail,
                        e.screenX, e.screenY, e.clientX, e.clientY,
                        e.ctrlKey, e.altKey, e.shiftKey, e.metaKey,
                        1, lm);
      lm.dispatchEvent(me);
    }
  }

  function cast(fn){
    fn(window, document);
    Array.forEach(window.frames, function(window){
      try { var {document} = window } catch(_){ return }
      fn(window, document);
    });
  }
  function handler(dic, els){
    const F = {__noSuchMethod__: els || function() true},
    C = 9, A = 10, S = 11, M = 12, Modic = {C_:1<<C,A_:1<<A,S_:1<<S,M_:1<<M};
    for(var d in dic) for each(var k in arr(dic[d]))
      F[typeof k === 'number' ? k : translate(k)] = Do[d];
    return function(e){
      with(e) F[ctrlKey << C | altKey << A | shiftKey << S | metaKey << M |
                (keyCode || which)](e) || preventDefault(stopPropagation());
    }
    function translate(key){
      if(/^(?:[CAM]_)*[A-Z!\"#$%&\'()=~|`+*{}<>?]$/.test(key)) key = 'S_'+ key;
      return key.match(/[CASM]_|.+/giy).reduce(acc, 0);
    }
    function acc(n, k) n | (k.length === 1 && k.charCodeAt() ||
                            Modic[k = k.toUpperCase()] ||
                            KeyEvent['DOM_VK_'+ k]);
  }
  function arr(x) x == null ? [] : x.map ? x : x.match ? x.match(/\S+/g) : [x];
  function nsr(p) p === 'xhtml' && 'http://www.w3.org/1999/xhtml';
  function mixpath(xps){
    var {URL} = document, a = [], {push} = a;
    for(var k in xps) ~URL.search(k) && push.apply(a, arr(xps[k]));
    return a;
  }
}