extension/lib/utils.coffee

   1 ###
   2 # Copyright Anton Khodakivskiy 2012, 2013, 2014.
   3 # Copyright Simon Lydell 2013, 2014, 2015, 2016.
   4 # Copyright Wang Zhuochun 2013.
   5 # Copyright Alan Wu 2016.
   6 #
   7 # This file is part of VimFx.
   8 #
   9 # VimFx is free software: you can redistribute it and/or modify
  10 # it under the terms of the GNU General Public License as published by
  11 # the Free Software Foundation, either version 3 of the License, or
  12 # (at your option) any later version.
  13 #
  14 # VimFx is distributed in the hope that it will be useful,
  15 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 # GNU General Public License for more details.
  18 #
  19 # You should have received a copy of the GNU General Public License
  20 # along with VimFx.  If not, see <http://www.gnu.org/licenses/>.
  21 ###
  22
  23 # This file contains lots of different helper functions.
  24
  25 {OS} = Components.utils.import('resource://gre/modules/osfile.jsm', {})
  26
  27 nsIClipboardHelper = Cc['@mozilla.org/widget/clipboardhelper;1']
  28   .getService(Ci.nsIClipboardHelper)
  29 nsIDomUtils = Cc['@mozilla.org/inspector/dom-utils;1']
  30   .getService(Ci.inIDOMUtils)
  31 nsIEventListenerService = Cc['@mozilla.org/eventlistenerservice;1']
  32   .getService(Ci.nsIEventListenerService)
  33 nsIFocusManager = Cc['@mozilla.org/focus-manager;1']
  34   .getService(Ci.nsIFocusManager)
  35 nsIStyleSheetService = Cc['@mozilla.org/content/style-sheet-service;1']
  36   .getService(Ci.nsIStyleSheetService)
  37 nsIWindowMediator = Cc['@mozilla.org/appshell/window-mediator;1']
  38   .getService(Ci.nsIWindowMediator)
  39
  40 # For XUL, `instanceof` checks are often better than `.localName` checks,
  41 # because some of the below interfaces are extended by many elements.
  42 XULDocument = Ci.nsIDOMXULDocument
  43 XULButtonElement = Ci.nsIDOMXULButtonElement
  44 XULControlElement = Ci.nsIDOMXULControlElement
  45 XULMenuListElement = Ci.nsIDOMXULMenuListElement
  46 XULTextBoxElement = Ci.nsIDOMXULTextBoxElement
  47
  48 # Full chains of events for different mouse actions. Note: 'click' is fired
  49 # by Firefox automatically after 'mousedown' and 'mouseup'. Similarly,
  50 # 'command' is fired automatically after 'click' on xul pages.
  51 EVENTS_CLICK       = ['mousedown', 'mouseup']
  52 EVENTS_CLICK_XUL   = ['click']
  53 EVENTS_CONTEXT     = ['contextmenu']
  54 EVENTS_HOVER_START = ['mouseover', 'mouseenter', 'mousemove']
  55 EVENTS_HOVER_END   = ['mouseout',  'mouseleave']
  56
  57
  58
  59 # Element classification helpers
  60
  61 hasMarkableTextNode = (element) ->
  62   return Array.some(element.childNodes, (node) ->
  63     # Ignore whitespace-only text nodes, and single-letter ones (which are
  64     # common in many syntax highlighters).
  65     return node.nodeType == 3 and node.data.trim().length > 1
  66   )
  67
  68 isActivatable = (element) ->
  69   return element.localName in ['a', 'button'] or
  70          (element.localName == 'input' and element.type in [
  71            'button', 'submit', 'reset', 'image'
  72          ]) or
  73          element instanceof XULButtonElement
  74
  75 isAdjustable = (element) ->
  76   return element.localName == 'input' and element.type in [
  77            'checkbox', 'radio', 'file', 'color'
  78            'date', 'time', 'datetime', 'datetime-local', 'month', 'week'
  79          ] or
  80          element.localName in ['video', 'audio', 'embed', 'object'] or
  81          element instanceof XULControlElement or
  82          # Custom video players.
  83          includes(element.className, 'video') or
  84          includes(element.className, 'player') or
  85          # Youtube special case.
  86          element.classList?.contains('ytp-button') or
  87          # Allow navigating object inspection trees in th devtools with the
  88          # arrow keys, even if the arrow keys are used as VimFx shortcuts.
  89          isDevtoolsElement(element)
  90
  91 isContentEditable = (element) ->
  92   return element.isContentEditable or
  93          isIframeEditor(element) or
  94          # Google.
  95          element.getAttribute?('g_editable') == 'true' or
  96          element.ownerDocument?.body?.getAttribute?('g_editable') == 'true' or
  97          # Codeacademy terminals.
  98          element.classList?.contains('real-terminal')
  99
 100 isDevtoolsElement = (element) ->
 101   return false unless element.ownerGlobal
 102   return Array.some(element.ownerGlobal.top.frames, isDevtoolsWindow)
 103
 104 isDevtoolsWindow = (window) ->
 105   return window.location?.href in [
 106     'about:devtools-toolbox'
 107     'chrome://devtools/content/framework/toolbox.xul'
 108   ]
 109
 110 isFocusable = (element) ->
 111   # Focusable elements have `.tabIndex > 1` (but not necessarily a
 112   # `tabindex="…"` attribute) …
 113   return (element.tabIndex > -1 or
 114           # … or an explicit `tabindex="-1"` attribute (which means that it is
 115           # focusable, but not reachable with `<tab>`).
 116           element.getAttribute?('tabindex') == '-1') and
 117          not (element.localName?.endsWith?('box') and
 118               element.localName != 'checkbox') and
 119          not (element.localName == 'toolbarbutton' and
 120               element.parentNode?.localName == 'toolbarbutton') and
 121          element.localName not in ['tabs', 'menuitem', 'menuseparator']
 122
 123 isIframeEditor = (element) ->
 124   return false unless element.localName == 'body'
 125   return \
 126          # Etherpad.
 127          element.id == 'innerdocbody' or
 128          # XpressEditor.
 129          (element.classList?.contains('xe_content') and
 130           element.classList?.contains('editable')) or
 131          # vBulletin.
 132          element.classList?.contains('wysiwyg') or
 133          # TYPO3 CMS.
 134          element.classList?.contains('htmlarea-content-body') or
 135          # The wasavi extension.
 136          element.hasAttribute?('data-wasavi-state')
 137
 138 isIgnoreModeFocusType = (element) ->
 139   return \
 140     # The wasavi extension.
 141     element.hasAttribute?('data-wasavi-state') or
 142     element.closest?('#wasavi_container') or
 143     # CodeMirror in Vim mode.
 144     (element.localName == 'textarea' and
 145      element.closest?('.CodeMirror') and _hasVimEventListener(element))
 146
 147 # CodeMirror’s Vim mode is really sucky to detect. The only way seems to be to
 148 # check if the there are any event listener functions with Vim-y words in them.
 149 _hasVimEventListener = (element) ->
 150   for listener in nsIEventListenerService.getListenerInfoFor(element)
 151     if listener.listenerObject and
 152        /\bvim\b|insertmode/i.test(String(listener.listenerObject))
 153       return true
 154   return false
 155
 156 isProperLink = (element) ->
 157   # `.getAttribute` is used below instead of `.hasAttribute` to exclude `<a
 158   # href="">`s used as buttons on some sites.
 159   return element.getAttribute?('href') and
 160          (element.localName == 'a' or
 161           element.ownerDocument instanceof XULDocument) and
 162          not element.href?.endsWith?('#') and
 163          not element.href?.endsWith?('#?') and
 164          not element.href?.startsWith?('javascript:')
 165
 166 isTextInputElement = (element) ->
 167   return (element.localName == 'input' and element.type in [
 168            'text', 'search', 'tel', 'url', 'email', 'password', 'number'
 169          ]) or
 170          element.localName == 'textarea' or
 171          element instanceof XULTextBoxElement or
 172          isContentEditable(element)
 173
 174 isTypingElement = (element) ->
 175   return isTextInputElement(element) or
 176          # `<select>` elements can also receive text input: You may type the
 177          # text of an item to select it.
 178          element.localName == 'select' or
 179          element instanceof XULMenuListElement
 180
 181
 182
 183 # Active/focused element helpers
 184
 185 blurActiveBrowserElement = (vim) ->
 186   # - Blurring in the next tick allows to pass `<escape>` to the location bar to
 187   #   reset it, for example.
 188   # - Focusing the current browser afterwards allows to pass `<escape>` as well
 189   #   as unbound keys to the page. However, focusing the browser also triggers
 190   #   focus events on `document` and `window` in the current page. Many pages
 191   #   re-focus some text input on those events, making it impossible to blur
 192   #   those! Therefore we tell the frame script to suppress those events.
 193   {window} = vim
 194   activeElement = getActiveElement(window)
 195   activeElement.closest('tabmodalprompt')?.abortPrompt()
 196   vim._send('browserRefocus')
 197   nextTick(window, ->
 198     activeElement.blur()
 199     window.gBrowser.selectedBrowser.focus()
 200   )
 201
 202 blurActiveElement = (window) ->
 203   # Blurring a frame element also blurs any active elements inside it. Recursing
 204   # into the frames and blurring the “real” active element directly would give
 205   # focus to the `<body>` of its containing frame, while blurring the top-most
 206   # frame gives focus to the top-most `<body>`. This allows to blur fancy text
 207   # editors which use an `<iframe>` as their text area.
 208   window.document.activeElement?.blur()
 209
 210 # Focus an element and tell Firefox that the focus happened because of a user
 211 # action (not just because some random programmatic focus). `.FLAG_BYKEY` might
 212 # look more appropriate, but it unconditionally selects all text, which
 213 # `.FLAG_BYMOUSE` does not.
 214 focusElement = (element, options = {}) ->
 215   nsIFocusManager.setFocus(element, options.flag ? 'FLAG_BYMOUSE')
 216   element.select?() if options.select
 217
 218 # NOTE: In frame scripts, `document.activeElement` may be `null` when the page
 219 # is loading. Therefore always check if anything was returned, such as:
 220 #
 221 #     return unless activeElement = utils.getActiveElement(window)
 222 getActiveElement = (window) ->
 223   {activeElement} = window.document
 224   return null unless activeElement
 225   # If the active element is a frame, recurse into it. The easiest way to detect
 226   # a frame that works both in browser UI and in web page content is to check
 227   # for the presence of `.contentWindow`. However, in non-multi-process,
 228   # `<browser>` (sometimes `<xul:browser>`) elements have a `.contentWindow`
 229   # pointing to the web page content `window`, which we don’t want to recurse
 230   # into. The problem is that there are _some_ `<browser>`s which we _want_ to
 231   # recurse into, such as the sidebar (for instance the history sidebar), and
 232   # dialogs in `about:preferences`. Checking the `contextmenu` attribute seems
 233   # to be a reliable test, catching both the main tab `<browser>`s and bookmarks
 234   # opened in the sidebar.
 235   if (activeElement.localName == 'browser' and
 236       activeElement.getAttribute?('contextmenu') == 'contentAreaContextMenu') or
 237      not activeElement.contentWindow
 238     return activeElement
 239   else
 240     return getActiveElement(activeElement.contentWindow)
 241
 242 getFocusType = (element) -> switch
 243   when isIgnoreModeFocusType(element)
 244     'ignore'
 245   when isTypingElement(element)
 246     if element.closest?('findbar') then 'findbar' else 'editable'
 247   when isActivatable(element)
 248     'activatable'
 249   when isAdjustable(element)
 250     'adjustable'
 251   else
 252     'none'
 253
 254
 255
 256 # Event helpers
 257
 258 listen = (element, eventName, listener, useCapture = true) ->
 259   element.addEventListener(eventName, listener, useCapture)
 260   module.onShutdown(->
 261     element.removeEventListener(eventName, listener, useCapture)
 262   )
 263
 264 listenOnce = (element, eventName, listener, useCapture = true) ->
 265   fn = (event) ->
 266     listener(event)
 267     element.removeEventListener(eventName, fn, useCapture)
 268   listen(element, eventName, fn, useCapture)
 269
 270 onRemoved = (element, fn) ->
 271   window = element.ownerGlobal
 272
 273   disconnected = false
 274   disconnect = ->
 275     return if disconnected
 276     disconnected = true
 277     mutationObserver.disconnect() unless Cu.isDeadWrapper(mutationObserver)
 278
 279   mutationObserver = new window.MutationObserver((changes) ->
 280     for change in changes then for removedElement in change.removedNodes
 281       if removedElement.contains?(element)
 282         disconnect()
 283         fn()
 284         return
 285   )
 286   mutationObserver.observe(window.document.documentElement, {
 287     childList: true
 288     subtree: true
 289   })
 290   module.onShutdown(disconnect)
 291
 292   return disconnect
 293
 294 simulateMouseEvents = (element, sequence, browserOffset) ->
 295   window = element.ownerGlobal
 296   rect = element.getBoundingClientRect()
 297   topOffset = getTopOffset(element)
 298
 299   eventSequence = switch sequence
 300     when 'click'
 301       EVENTS_CLICK
 302     when 'click-xul'
 303       EVENTS_CLICK_XUL
 304     when 'context'
 305       EVENTS_CONTEXT
 306     when 'hover-start'
 307       EVENTS_HOVER_START
 308     when 'hover-end'
 309       EVENTS_HOVER_END
 310     else
 311       sequence
 312
 313   for type in eventSequence
 314     buttonNum = switch
 315       when type in EVENTS_CONTEXT
 316         2
 317       when type in EVENTS_CLICK
 318         1
 319       else
 320         0
 321
 322     mouseEvent = new window.MouseEvent(type, {
 323       # Let the event bubble in order to trigger delegated event listeners.
 324       bubbles: type not in ['mouseenter', 'mouseleave']
 325       # Make the event cancelable so that `<a href="#">` can be used as a
 326       # JavaScript-powered button without scrolling to the top of the page.
 327       cancelable: type not in ['mouseenter', 'mouseleave']
 328       # These properties are just here for mimicing a real click as much as
 329       # possible.
 330       buttons: buttonNum
 331       detail: buttonNum
 332       view: window
 333       # `page{X,Y}` are set automatically to the correct values when setting
 334       # `client{X,Y}`. `{offset,layer,movement}{X,Y}` are not worth the trouble
 335       # to set.
 336       clientX: rect.left
 337       clientY: rect.top + rect.height / 2
 338       screenX: browserOffset.x + topOffset.x
 339       screenY: browserOffset.y + topOffset.y + rect.height / 2
 340     })
 341
 342     if type == 'mousemove'
 343       # If the below technique is used for this event, the “URL popup” (shown
 344       # when hovering or focusing links) does not appear.
 345       element.dispatchEvent(mouseEvent)
 346     else
 347       # The last `true` below marks the event as trusted, which some APIs
 348       # require, such as `requestFullscreen()`.
 349       # (`element.dispatchEvent(mouseEvent)` is not able to do this.)
 350       window
 351         .QueryInterface(Ci.nsIInterfaceRequestor)
 352         .getInterface(Ci.nsIDOMWindowUtils)
 353         .dispatchDOMEventViaPresShell(element, mouseEvent, true)
 354
 355   return
 356
 357 suppressEvent = (event) ->
 358   event.preventDefault()
 359   event.stopPropagation()
 360
 361
 362
 363 # DOM helpers
 364
 365 area = (element) ->
 366   return element.clientWidth * element.clientHeight
 367
 368 checkElementOrAncestor = (element, fn) ->
 369   window = element.ownerGlobal
 370   while element.parentElement
 371     return true if fn(element)
 372     element = element.parentElement
 373   return false
 374
 375 clearSelectionDeep = (window, {blur = true} = {}) ->
 376   # The selection might be `null` in hidden frames.
 377   selection = window.getSelection()
 378   selection?.removeAllRanges()
 379   for frame in window.frames
 380     clearSelectionDeep(frame, {blur})
 381     # Allow parents to re-gain control of text selection.
 382     frame.frameElement.blur() if blur
 383   return
 384
 385 containsDeep = (parent, element) ->
 386   parentWindow = parent.ownerGlobal
 387   elementWindow = element.ownerGlobal
 388
 389   # Owner windows might be missing when opening the devtools.
 390   while elementWindow and parentWindow and
 391         elementWindow != parentWindow and elementWindow.top != elementWindow
 392     element = elementWindow.frameElement
 393     elementWindow = element.ownerGlobal
 394
 395   return parent.contains(element)
 396
 397 createBox = (document, className = '', parent = null, text = null) ->
 398   box = document.createElement('box')
 399   box.className = "#{className} vimfx-box"
 400   box.textContent = text if text?
 401   parent.appendChild(box) if parent?
 402   return box
 403
 404 # In quirks mode (when the page lacks a doctype), such as on Hackernews,
 405 # `<body>` is considered the root element rather than `<html>`.
 406 getRootElement = (document) ->
 407   if document.compatMode == 'BackCompat' and document.body?
 408     return document.body
 409   else
 410     return document.documentElement
 411
 412 getText = (element) ->
 413   text = element.textContent or element.value or element.placeholder or ''
 414   return text.trim().replace(/\s+/, ' ')
 415
 416 getTopOffset = (element) ->
 417   window = element.ownerGlobal
 418
 419   {left: x, top: y} = element.getBoundingClientRect()
 420   while window.frameElement
 421     frame = window.frameElement
 422     frameRect = frame.getBoundingClientRect()
 423     x += frameRect.left
 424     y += frameRect.top
 425
 426     computedStyle = frame.ownerGlobal.getComputedStyle(frame)
 427     if computedStyle
 428       x +=
 429         parseFloat(computedStyle.getPropertyValue('border-left-width')) +
 430         parseFloat(computedStyle.getPropertyValue('padding-left'))
 431       y +=
 432         parseFloat(computedStyle.getPropertyValue('border-top-width')) +
 433         parseFloat(computedStyle.getPropertyValue('padding-top'))
 434
 435     window = window.parent
 436   return {x, y}
 437
 438 injectTemporaryPopup = (document, contents) ->
 439   popup = document.createElement('menupopup')
 440   popup.appendChild(contents)
 441   document.getElementById('mainPopupSet').appendChild(popup)
 442   listenOnce(popup, 'popuphidden', popup.remove.bind(popup))
 443   return popup
 444
 445 insertText = (input, value) ->
 446   {selectionStart, selectionEnd} = input
 447   input.value =
 448     input.value[0...selectionStart] + value + input.value[selectionEnd..]
 449   input.selectionStart = input.selectionEnd = selectionStart + value.length
 450
 451 isDetached = (element) ->
 452   return not element.ownerDocument?.documentElement?.contains?(element)
 453
 454 isNonEmptyTextNode = (node) ->
 455   return node.nodeType == 3 and node.data.trim() != ''
 456
 457 querySelectorAllDeep = (window, selector) ->
 458   elements = Array.from(window.document.querySelectorAll(selector))
 459   for frame in window.frames
 460     elements.push(querySelectorAllDeep(frame, selector)...)
 461   return elements
 462
 463 selectAllSubstringMatches = (element, substring, {caseSensitive = true} = {}) ->
 464   window = element.ownerGlobal
 465   selection = window.getSelection()
 466   {textContent} = element
 467
 468   format = (string) -> if caseSensitive then string else string.toLowerCase()
 469   offsets =
 470     getAllNonOverlappingRangeOffsets(format(textContent), format(substring))
 471   offsetsLength = offsets.length
 472   return if offsetsLength == 0
 473
 474   textIndex = 0
 475   offsetsIndex = 0
 476   [currentOffset] = offsets
 477   searchIndex = currentOffset.start
 478   start = null
 479
 480   walkTextNodes(element, (textNode) ->
 481     {length} = textNode.data
 482     return false if length == 0
 483
 484     while textIndex + length > searchIndex
 485       if start
 486         range = window.document.createRange()
 487         range.setStart(start.textNode, start.offset)
 488         range.setEnd(textNode, currentOffset.end - textIndex)
 489         selection.addRange(range)
 490
 491         offsetsIndex += 1
 492         return true if offsetsIndex >= offsetsLength
 493         currentOffset = offsets[offsetsIndex]
 494
 495         start = null
 496         searchIndex = currentOffset.start
 497
 498       else
 499         start = {textNode, offset: currentOffset.start - textIndex}
 500         searchIndex = currentOffset.end - 1
 501
 502     textIndex += length
 503     return false
 504   )
 505
 506 selectElement = (element) ->
 507   window = element.ownerGlobal
 508   selection = window.getSelection()
 509   range = window.document.createRange()
 510   range.selectNodeContents(element)
 511   selection.addRange(range)
 512
 513 setAttributes = (element, attributes) ->
 514   for attribute, value of attributes
 515     element.setAttribute(attribute, value)
 516   return
 517
 518 setHover = (element, hover) ->
 519   method = if hover then 'addPseudoClassLock' else 'removePseudoClassLock'
 520   while element.parentElement
 521     nsIDomUtils[method](element, ':hover')
 522     element = element.parentElement
 523   return
 524
 525 walkTextNodes = (element, fn) ->
 526   for node in element.childNodes then switch node.nodeType
 527     when 3 # TextNode.
 528       stop = fn(node)
 529       return true if stop
 530     when 1 # Element.
 531       stop = walkTextNodes(node, fn)
 532       return true if stop
 533   return false
 534
 535
 536
 537 # Language helpers
 538
 539 class Counter
 540   constructor: ({start: @value = 0, @step = 1}) ->
 541   tick: -> @value += @step
 542
 543 class EventEmitter
 544   constructor: ->
 545     @listeners = {}
 546
 547   on: (event, listener) ->
 548     (@listeners[event] ?= new Set()).add(listener)
 549
 550   off: (event, listener) ->
 551     @listeners[event]?.delete(listener)
 552
 553   emit: (event, data) ->
 554     @listeners[event]?.forEach((listener) ->
 555       listener(data)
 556     )
 557
 558 # Returns `[nonMatch, adjacentMatchAfter]`, where `adjacentMatchAfter - nonMatch
 559 # == 1`. `fn(n)` is supposed to return `false` for `n <= nonMatch` and `true`
 560 # for `n >= adjacentMatchAfter`. Both `nonMatch` and `adjacentMatchAfter` may be
 561 # `null` if they cannot be found. Otherwise they’re in the range `min <= n <=
 562 # max`. `[null, null]` is returned in non-sensical cases. This function is
 563 # intended to be used as a faster alternative to something like this:
 564 #
 565 #     adjacentMatchAfter = null
 566 #     for n in [min..max]
 567 #       if fn(n)
 568 #         adjacentMatchAfter = n
 569 #         break
 570 bisect = (min, max, fn) ->
 571   return [null, null] unless max - min >= 0 and min % 1 == 0 and max % 1 == 0
 572
 573   while max - min > 1
 574     mid = min + (max - min) // 2
 575     match = fn(mid)
 576     if match
 577       max = mid
 578     else
 579       min = mid
 580
 581   matchMin = fn(min)
 582   matchMax = fn(max)
 583
 584   return switch
 585     when matchMin and matchMax
 586       [null, min]
 587     when not matchMin and not matchMax
 588       [max, null]
 589     when not matchMin and matchMax
 590       [min, max]
 591     else
 592       [null, null]
 593
 594 getAllNonOverlappingRangeOffsets = (string, substring) ->
 595   {length} = substring
 596   return [] if length == 0
 597
 598   offsets = []
 599   lastOffset = {start: -Infinity, end: -Infinity}
 600   index = -1
 601
 602   loop
 603     index = string.indexOf(substring, index + 1)
 604     break if index == -1
 605     if index > lastOffset.end
 606       lastOffset = {start: index, end: index + length}
 607       offsets.push(lastOffset)
 608     else
 609       lastOffset.end = index + length
 610
 611   return offsets
 612
 613 has = (obj, prop) -> Object::hasOwnProperty.call(obj, prop)
 614
 615 # Check if `search` exists in `string` (case insensitively). Returns `false` if
 616 # `string` doesn’t exist or isn’t a string, such as `<SVG element>.className`.
 617 includes = (string, search) ->
 618   return false unless typeof string == 'string'
 619   return string.toLowerCase().includes(search)
 620
 621 # Calls `fn` repeatedly, with at least `interval` ms between each call.
 622 interval = (window, interval, fn) ->
 623   stopped = false
 624   currentIntervalId = null
 625   next = ->
 626     return if stopped
 627     currentIntervalId = window.setTimeout((-> fn(next)), interval)
 628   clearInterval = ->
 629     stopped = true
 630     window.clearTimeout(currentIntervalId)
 631   next()
 632   return clearInterval
 633
 634 nextTick = (window, fn) -> window.setTimeout((-> fn()) , 0)
 635
 636 overlaps = (rectA, rectB) ->
 637   return \
 638     Math.round(rectA.right) >= Math.round(rectB.left) and
 639     Math.round(rectA.left) <= Math.round(rectB.right) and
 640     Math.round(rectA.bottom) >= Math.round(rectB.top) and
 641     Math.round(rectA.top) <= Math.round(rectB.bottom)
 642
 643 partition = (array, fn) ->
 644   matching = []
 645   nonMatching = []
 646   for item, index in array
 647     if fn(item, index, array)
 648       matching.push(item)
 649     else
 650       nonMatching.push(item)
 651   return [matching, nonMatching]
 652
 653 regexEscape = (s) -> s.replace(/[|\\{}()[\]^$+*?.]/g, '\\$&')
 654
 655 removeDuplicateChars = (string) -> removeDuplicates(string.split('')).join('')
 656
 657 removeDuplicates = (array) -> Array.from(new Set(array))
 658
 659 sum = (numbers) -> numbers.reduce(((sum, number) -> sum + number), 0)
 660
 661
 662
 663 # Misc helpers
 664
 665 expandPath = (path) ->
 666   if path.startsWith('~/') or path.startsWith('~\\')
 667     return OS.Constants.Path.homeDir + path[1..]
 668   else
 669     return path
 670
 671 getCurrentLocation = ->
 672   return unless window = getCurrentWindow()
 673   return new window.URL(window.gBrowser.selectedBrowser.currentURI.spec)
 674
 675 # This function might return `null` on startup.
 676 getCurrentWindow = -> nsIWindowMediator.getMostRecentWindow('navigator:browser')
 677
 678 hasEventListeners = (element, type) ->
 679   for listener in nsIEventListenerService.getListenerInfoFor(element)
 680     if listener.listenerObject and listener.type == type
 681       return true
 682   return false
 683
 684 loadCss = (uriString) ->
 685   uri = Services.io.newURI(uriString, null, null)
 686   method = nsIStyleSheetService.AUTHOR_SHEET
 687   unless nsIStyleSheetService.sheetRegistered(uri, method)
 688     nsIStyleSheetService.loadAndRegisterSheet(uri, method)
 689   module.onShutdown(->
 690     nsIStyleSheetService.unregisterSheet(uri, method)
 691   )
 692
 693 observe = (topic, observer) ->
 694   observer = {observe: observer} if typeof observer == 'function'
 695   Services.obs.addObserver(observer, topic, false)
 696   module.onShutdown(->
 697     Services.obs.removeObserver(observer, topic, false)
 698   )
 699
 700 # Try to open a button’s dropdown menu, if any.
 701 openDropdown = (element) ->
 702   if element.ownerDocument instanceof XULDocument and
 703      element.getAttribute?('type') == 'menu' and
 704      element.open == false # Only change `.open` if it is already a boolean.
 705     element.open = true
 706
 707 openPopup = (popup) ->
 708   window = popup.ownerGlobal
 709   # Show the popup so it gets a height and width.
 710   popup.openPopupAtScreen(0, 0)
 711   # Center the popup inside the window.
 712   popup.moveTo(
 713     window.screenX + window.outerWidth  / 2 - popup.clientWidth  / 2,
 714     window.screenY + window.outerHeight / 2 - popup.clientHeight / 2
 715   )
 716
 717 writeToClipboard = (text) -> nsIClipboardHelper.copyString(text)
 718
 719
 720
 721 module.exports = {
 722   hasMarkableTextNode
 723   isActivatable
 724   isAdjustable
 725   isContentEditable
 726   isDevtoolsElement
 727   isDevtoolsWindow
 728   isFocusable
 729   isIframeEditor
 730   isIgnoreModeFocusType
 731   isProperLink
 732   isTextInputElement
 733   isTypingElement
 734
 735   blurActiveBrowserElement
 736   blurActiveElement
 737   focusElement
 738   getActiveElement
 739   getFocusType
 740
 741   listen
 742   listenOnce
 743   onRemoved
 744   simulateMouseEvents
 745   suppressEvent
 746
 747   area
 748   checkElementOrAncestor
 749   clearSelectionDeep
 750   containsDeep
 751   createBox
 752   getRootElement
 753   getText
 754   getTopOffset
 755   injectTemporaryPopup
 756   insertText
 757   isDetached
 758   isNonEmptyTextNode
 759   querySelectorAllDeep
 760   selectAllSubstringMatches
 761   selectElement
 762   setAttributes
 763   setHover
 764   walkTextNodes
 765
 766   Counter
 767   EventEmitter
 768   bisect
 769   getAllNonOverlappingRangeOffsets
 770   has
 771   includes
 772   interval
 773   nextTick
 774   overlaps
 775   partition
 776   regexEscape
 777   removeDuplicateChars
 778   removeDuplicates
 779   sum
 780
 781   expandPath
 782   getCurrentLocation
 783   getCurrentWindow
 784   hasEventListeners
 785   loadCss
 786   observe
 787   openDropdown
 788   openPopup
 789   writeToClipboard
 790 }