kitodo / kitodo-publication

// Distributed under an MIT license: http://codemirror.net/LICENSE

// This is CodeMirror (http://codemirror.net), a code editor

// implemented in JavaScript on top of the browser's DOM.

//

// You can find some technical background for some of the code below

// at http://marijnhaverbeke.nl/blog/#cm-internals .

  if (typeof exports == "object" && typeof module == "object") // CommonJS

    return define([], mod);

  else // Plain browser env

})(function() {

  "use strict";

  // BROWSER SNIFFING

  // Kludges for bugs and behavior differences that can't be feature

  // detected are enabled based on userAgent etc sniffing.

  var ie_upto10 = /MSIE \d/.test(navigator.userAgent);

  var ie_11up = /Trident\/(?:[7-9]|\d{2,})\..*rv:(\d+)/.exec(navigator.userAgent);

  var ie = ie_upto10 || ie_11up;

  var ie_version = ie && (ie_upto10 ? document.documentMode || 6 : ie_11up[1]);

  var webkit = /WebKit\//.test(navigator.userAgent);

  var qtwebkit = webkit && /Qt\/\d+\.\d+/.test(navigator.userAgent);

  var chrome = /Chrome\//.test(navigator.userAgent);

  var presto = /Opera\//.test(navigator.userAgent);

  var safari = /Apple Computer/.test(navigator.vendor);

  var mac_geMountainLion = /Mac OS X 1\d\D([8-9]|\d\d)\D/.test(navigator.userAgent);

  var phantom = /PhantomJS/.test(navigator.userAgent);

  var ios = /AppleWebKit/.test(navigator.userAgent) && /Mobile\/\w+/.test(navigator.userAgent);

  // This is woefully incomplete. Suggestions for alternative methods welcome.

  var mobile = ios || /Android|webOS|BlackBerry|Opera Mini|Opera Mobi|IEMobile/i.test(navigator.userAgent);

  var mac = ios || /Mac/.test(navigator.platform);

  var windows = /win/i.test(navigator.platform);

  var presto_version = presto && navigator.userAgent.match(/Version\/(\d*\.\d*)/);

  if (presto_version) presto_version = Number(presto_version[1]);

  if (presto_version && presto_version >= 15) { presto = false; webkit = true; }

  // Some browsers use the wrong event properties to signal cmd/ctrl on OS X

  var captureRightClick = gecko || (ie && ie_version >= 9);

  // Optimize some code when these features are not used.

  var sawReadOnlySpans = false, sawCollapsedSpans = false;

  // EDITOR CONSTRUCTOR

  // A CodeMirror instance represents an editor. This is the object

  // that user code is usually dealing with.

  function CodeMirror(place, options) {

    if (!(this instanceof CodeMirror)) return new CodeMirror(place, options);

    this.options = options = options ? copyObj(options) : {};

    // Determine effective options based on given values and defaults.

    copyObj(defaults, options, false);

    setGuttersForLineNumbers(options);

    var doc = options.value;

    if (typeof doc == "string") doc = new Doc(doc, options.mode);

    this.doc = doc;

    var input = new CodeMirror.inputStyles[options.inputStyle](this);

    var display = this.display = new Display(place, doc, input);

    display.wrapper.CodeMirror = this;

    updateGutters(this);

    themeChanged(this);

    if (options.lineWrapping)

      this.display.wrapper.className += " CodeMirror-wrap";

    if (options.autofocus && !mobile) display.input.focus();

    initScrollbars(this);

    this.state = {

      keyMaps: [],  // stores maps added by addKeyMap

      overlays: [], // highlighting overlays, as added by addOverlay

      modeGen: 0,   // bumped when mode/overlay changes, used to invalidate highlighting info

      overwrite: false, focused: false,

      suppressEdits: false, // used to disable editing during key handlers when in readOnly mode

      pasteIncoming: false, cutIncoming: false, // help recognize paste/cut edits in input.poll

      draggingText: false,

      highlight: new Delayed(), // stores highlight worker timeout

      keySeq: null  // Unfinished key sequence

    };

    var cm = this;

    // Override magic textarea content restore that IE sometimes does

    // on our hidden textarea on reload

    if (ie && ie_version < 11) setTimeout(function() { cm.display.input.reset(true); }, 20);

    registerEventHandlers(this);

    ensureGlobalHandlers();

    startOperation(this);

    this.curOp.forceUpdate = true;

    attachDoc(this, doc);

    if ((options.autofocus && !mobile) || cm.hasFocus())

      setTimeout(bind(onFocus, this), 20);

    else

      onBlur(this);

    for (var opt in optionHandlers) if (optionHandlers.hasOwnProperty(opt))

      optionHandlers[opt](this, options[opt], Init);

    maybeUpdateLineNumberWidth(this);

    if (options.finishInit) options.finishInit(this);

    for (var i = 0; i < initHooks.length; ++i) initHooks[i](this);

    endOperation(this);

    // Suppress optimizelegibility in Webkit, since it breaks text

    // measuring on line wrapping boundaries.

        getComputedStyle(display.lineDiv).textRendering == "optimizelegibility")

  }

  // DISPLAY CONSTRUCTOR

  // The display handles the DOM integration, both for input reading

  // and content drawing. It holds references to DOM nodes and

  // display-related state.

  function Display(place, doc, input) {

    var d = this;

    this.input = input;

    // Covers bottom-right square when both scrollbars are present.

    d.scrollbarFiller = elt("div", null, "CodeMirror-scrollbar-filler");

    d.scrollbarFiller.setAttribute("cm-not-content", "true");

    // Covers bottom of gutter when coverGutterNextToScrollbar is on

    // and h scrollbar is present.

    d.gutterFiller = elt("div", null, "CodeMirror-gutter-filler");

    d.gutterFiller.setAttribute("cm-not-content", "true");

    // Will contain the actual code, positioned to cover the viewport.

    d.lineDiv = elt("div", null, "CodeMirror-code");

    // Elements are added to these to represent selection and cursors.

    d.selectionDiv = elt("div", null, null, "position: relative; z-index: 1");

    d.cursorDiv = elt("div", null, "CodeMirror-cursors");

    // A visibility: hidden element used to find the size of things.

    d.measure = elt("div", null, "CodeMirror-measure");

    // When lines outside of the viewport are measured, they are drawn in this.

    d.lineMeasure = elt("div", null, "CodeMirror-measure");

    // Wraps everything that needs to exist inside the vertically-padded coordinate system

    d.lineSpace = elt("div", [d.measure, d.lineMeasure, d.selectionDiv, d.cursorDiv, d.lineDiv],

                      null, "position: relative; outline: none");

    // Moved around its parent to cover visible view.

    d.mover = elt("div", [elt("div", [d.lineSpace], "CodeMirror-lines")], null, "position: relative");

    // Set to the height of the document, allowing scrolling.

    d.sizer = elt("div", [d.mover], "CodeMirror-sizer");

    d.sizerWidth = null;

    // Behavior of elts with overflow: auto and padding is

    // inconsistent across browsers. This is used to ensure the

    // scrollable area is big enough.

    d.heightForcer = elt("div", null, null, "position: absolute; height: " + scrollerGap + "px; width: 1px;");

    // Will contain the gutters, if any.

    d.gutters = elt("div", null, "CodeMirror-gutters");

    d.lineGutter = null;

    // Actual scrollable element.

    d.scroller = elt("div", [d.sizer, d.heightForcer, d.gutters], "CodeMirror-scroll");

    d.scroller.setAttribute("tabIndex", "-1");

    // The element in which the editor lives.

    d.wrapper = elt("div", [d.scrollbarFiller, d.gutterFiller, d.scroller], "CodeMirror");

    // Work around IE7 z-index bug (not perfect, hence IE7 not really being supported)

    if (ie && ie_version < 8) { d.gutters.style.zIndex = -1; d.scroller.style.paddingRight = 0; }

    if (!webkit && !(gecko && mobile)) d.scroller.draggable = true;

    if (place) {

      if (place.appendChild) place.appendChild(d.wrapper);

      else place(d.wrapper);

    }

    // Current rendered range (may be bigger than the view window).

    d.viewFrom = d.viewTo = doc.first;

    d.reportedViewFrom = d.reportedViewTo = doc.first;

    // Information about the rendered lines.

    d.view = [];

    d.renderedView = null;

    // Holds info about a single rendered line when it was rendered

    // for measurement, while not in view.

    d.externalMeasured = null;

    // Empty space (in pixels) above the view

    d.viewOffset = 0;

    d.lastWrapHeight = d.lastWrapWidth = 0;

    d.updateLineNumbers = null;

    d.nativeBarWidth = d.barHeight = d.barWidth = 0;

    d.scrollbarsClipped = false;

    // Used to only resize the line number gutter when necessary (when

    // the amount of lines crosses a boundary that makes its width change)

    d.lineNumWidth = d.lineNumInnerWidth = d.lineNumChars = null;

    // Set to true when a non-horizontal-scrolling line widget is

    // added. As an optimization, line widget aligning is skipped when

    // this is false.

    d.alignWidgets = false;

    d.cachedCharWidth = d.cachedTextHeight = d.cachedPaddingH = null;

    // Tracks the maximum line length so that the horizontal scrollbar

    // can be kept static when scrolling.

    d.maxLine = null;

    d.maxLineLength = 0;

    d.maxLineChanged = false;

    // Used for measuring wheel scrolling granularity

    d.wheelDX = d.wheelDY = d.wheelStartX = d.wheelStartY = null;

    // True when shift is held down.

    d.shift = false;

    // Used to track whether anything happened since the context menu

    // was opened.

    d.selForContextMenu = null;

    d.activeTouch = null;

    input.init(d);

  }

  // STATE UPDATES

  // Used to get the editor into a consistent state again when options change.

  function loadMode(cm) {

    cm.doc.mode = CodeMirror.getMode(cm.options, cm.doc.modeOption);

    resetModeState(cm);

  }

  function resetModeState(cm) {

    cm.doc.iter(function(line) {

      if (line.stateAfter) line.stateAfter = null;

      if (line.styles) line.styles = null;

    });

    cm.doc.frontier = cm.doc.first;

    startWorker(cm, 100);

    cm.state.modeGen++;

    if (cm.curOp) regChange(cm);

  }

  function wrappingChanged(cm) {

    if (cm.options.lineWrapping) {

      addClass(cm.display.wrapper, "CodeMirror-wrap");

      cm.display.sizer.style.minWidth = "";

      cm.display.sizerWidth = null;

    } else {

      rmClass(cm.display.wrapper, "CodeMirror-wrap");

      findMaxLine(cm);

    }

    estimateLineHeights(cm);

    regChange(cm);

    clearCaches(cm);

    setTimeout(function(){updateScrollbars(cm);}, 100);

  }

  // Returns a function that estimates the height of a line, to use as

  // first approximation until the line becomes visible (and is thus

  // properly measurable).

  function estimateHeight(cm) {

    var th = textHeight(cm.display), wrapping = cm.options.lineWrapping;

    var perLine = wrapping && Math.max(5, cm.display.scroller.clientWidth / charWidth(cm.display) - 3);

    return function(line) {

      if (lineIsHidden(cm.doc, line)) return 0;

      var widgetsHeight = 0;

      if (line.widgets) for (var i = 0; i < line.widgets.length; i++) {

        if (line.widgets[i].height) widgetsHeight += line.widgets[i].height;

      }

      if (wrapping)

        return widgetsHeight + (Math.ceil(line.text.length / perLine) || 1) * th;

      else

    };

  }

  function estimateLineHeights(cm) {

    var doc = cm.doc, est = estimateHeight(cm);

    doc.iter(function(line) {

      var estHeight = est(line);

      if (estHeight != line.height) updateLineHeight(line, estHeight);

    });

  }

  function themeChanged(cm) {

    cm.display.wrapper.className = cm.display.wrapper.className.replace(/\s*cm-s-\S+/g, "") +

      cm.options.theme.replace(/(^|\s)\s*/g, " cm-s-");

    clearCaches(cm);

  }

  function guttersChanged(cm) {

    updateGutters(cm);

    regChange(cm);

    setTimeout(function(){alignHorizontally(cm);}, 20);

  }

  // Rebuild the gutter elements, ensure the margin to the left of the

  // code matches their width.

  function updateGutters(cm) {

    var gutters = cm.display.gutters, specs = cm.options.gutters;

    removeChildren(gutters);

    for (var i = 0; i < specs.length; ++i) {

      var gutterClass = specs[i];

      var gElt = gutters.appendChild(elt("div", null, "CodeMirror-gutter " + gutterClass));

      if (gutterClass == "CodeMirror-linenumbers") {

        cm.display.lineGutter = gElt;

        gElt.style.width = (cm.display.lineNumWidth || 1) + "px";

      }

    }

    gutters.style.display = i ? "" : "none";

    updateGutterSpace(cm);

  }

  function updateGutterSpace(cm) {

    var width = cm.display.gutters.offsetWidth;

    cm.display.sizer.style.marginLeft = width + "px";

  }

  // Compute the character length of a line, taking into account

  // collapsed ranges (see markText) that might hide parts, and join

  // other lines onto it.

  function lineLength(line) {

    var len = line.text.length, merged, cur = line;

    while (merged = collapsedSpanAtStart(cur)) {

      var found = merged.find(0, true);

      cur = found.from.line;

      len += found.from.ch - found.to.ch;

    }

    cur = line;

    while (merged = collapsedSpanAtEnd(cur)) {

      len -= cur.text.length - found.from.ch;

      cur = found.to.line;

      len += cur.text.length - found.to.ch;

    }

    return len;

  }

  // Find the longest line in the document.

  function findMaxLine(cm) {

    var d = cm.display, doc = cm.doc;

    d.maxLine = getLine(doc, doc.first);

    d.maxLineLength = lineLength(d.maxLine);

    d.maxLineChanged = true;

    doc.iter(function(line) {

      var len = lineLength(line);

      if (len > d.maxLineLength) {

        d.maxLineLength = len;

        d.maxLine = line;

      }

    });

  }

  // Make sure the gutters options contains the element

  // "CodeMirror-linenumbers" when the lineNumbers option is true.

  function setGuttersForLineNumbers(options) {

    var found = indexOf(options.gutters, "CodeMirror-linenumbers");

    if (found == -1 && options.lineNumbers) {

      options.gutters = options.gutters.concat(["CodeMirror-linenumbers"]);

    } else if (found > -1 && !options.lineNumbers) {

      options.gutters = options.gutters.slice(0);

      options.gutters.splice(found, 1);

    }

  }

  // SCROLLBARS

  // Prepare DOM reads needed to update the scrollbars. Done in one

  // shot to minimize update/measure roundtrips.

  function measureForScrollbars(cm) {

    var d = cm.display, gutterW = d.gutters.offsetWidth;

    var docH = Math.round(cm.doc.height + paddingVert(cm.display));

    return {

      clientHeight: d.scroller.clientHeight,

      viewHeight: d.wrapper.clientHeight,

      scrollWidth: d.scroller.scrollWidth, clientWidth: d.scroller.clientWidth,

      viewWidth: d.wrapper.clientWidth,

      barLeft: cm.options.fixedGutter ? gutterW : 0,

      docHeight: docH,

      scrollHeight: docH + scrollGap(cm) + d.barHeight,

      nativeBarWidth: d.nativeBarWidth,

      gutterWidth: gutterW

    };

  }

  function NativeScrollbars(place, scroll, cm) {

    this.cm = cm;

    var vert = this.vert = elt("div", [elt("div", null, null, "min-width: 1px")], "CodeMirror-vscrollbar");

    var horiz = this.horiz = elt("div", [elt("div", null, null, "height: 100%; min-height: 1px")], "CodeMirror-hscrollbar");

    place(vert); place(horiz);

    on(vert, "scroll", function() {

      if (vert.clientHeight) scroll(vert.scrollTop, "vertical");

    });

    on(horiz, "scroll", function() {

      if (horiz.clientWidth) scroll(horiz.scrollLeft, "horizontal");

    });

    this.checkedOverlay = false;

    // Need to set a minimum width to see the scrollbar on IE7 (but must not set it on IE8).

    if (ie && ie_version < 8) this.horiz.style.minHeight = this.vert.style.minWidth = "18px";

  }

  NativeScrollbars.prototype = copyObj({

    update: function(measure) {

      var needsH = measure.scrollWidth > measure.clientWidth + 1;

      var needsV = measure.scrollHeight > measure.clientHeight + 1;

      var sWidth = measure.nativeBarWidth;

      if (needsV) {

        this.vert.style.display = "block";

        this.vert.style.bottom = needsH ? sWidth + "px" : "0";

        var totalHeight = measure.viewHeight - (needsH ? sWidth : 0);

        // A bug in IE8 can cause this value to be negative, so guard it.

        this.vert.firstChild.style.height =

          Math.max(0, measure.scrollHeight - measure.clientHeight + totalHeight) + "px";

      } else {

        this.vert.style.display = "";

        this.vert.firstChild.style.height = "0";

      }

      if (needsH) {

        this.horiz.style.display = "block";

        this.horiz.style.right = needsV ? sWidth + "px" : "0";

        this.horiz.style.left = measure.barLeft + "px";

        var totalWidth = measure.viewWidth - measure.barLeft - (needsV ? sWidth : 0);

        this.horiz.firstChild.style.width =

          (measure.scrollWidth - measure.clientWidth + totalWidth) + "px";

      } else {

        this.horiz.style.display = "";

        this.horiz.firstChild.style.width = "0";

      }

      if (!this.checkedOverlay && measure.clientHeight > 0) {

        this.checkedOverlay = true;

      }

      return {right: needsV ? sWidth : 0, bottom: needsH ? sWidth : 0};

    },

    setScrollLeft: function(pos) {

      if (this.horiz.scrollLeft != pos) this.horiz.scrollLeft = pos;

    },

    setScrollTop: function(pos) {

      if (this.vert.scrollTop != pos) this.vert.scrollTop = pos;

    },

    overlayHack: function() {

      var w = mac && !mac_geMountainLion ? "12px" : "18px";

      this.horiz.style.minHeight = this.vert.style.minWidth = w;

      var self = this;

      var barMouseDown = function(e) {

        if (e_target(e) != self.vert && e_target(e) != self.horiz)

          operation(self.cm, onMouseDown)(e);

      };

      on(this.vert, "mousedown", barMouseDown);

      on(this.horiz, "mousedown", barMouseDown);

    },

    clear: function() {

      var parent = this.horiz.parentNode;

      parent.removeChild(this.horiz);

      parent.removeChild(this.vert);

    }

  }, NativeScrollbars.prototype);

  function NullScrollbars() {}

  NullScrollbars.prototype = copyObj({

    update: function() { return {bottom: 0, right: 0}; },

    setScrollLeft: function() {},

    setScrollTop: function() {},

    clear: function() {}

  }, NullScrollbars.prototype);

  CodeMirror.scrollbarModel = {"native": NativeScrollbars, "null": NullScrollbars};

  function initScrollbars(cm) {

    if (cm.display.scrollbars) {

      cm.display.scrollbars.clear();

      if (cm.display.scrollbars.addClass)

        rmClass(cm.display.wrapper, cm.display.scrollbars.addClass);

    }

    cm.display.scrollbars = new CodeMirror.scrollbarModel[cm.options.scrollbarStyle](function(node) {

      cm.display.wrapper.insertBefore(node, cm.display.scrollbarFiller);

      // Prevent clicks in the scrollbars from killing focus

      on(node, "mousedown", function() {

        if (cm.state.focused) setTimeout(function() { cm.display.input.focus(); }, 0);

      });

      node.setAttribute("cm-not-content", "true");

    }, function(pos, axis) {

      if (axis == "horizontal") setScrollLeft(cm, pos);

      else setScrollTop(cm, pos);

    }, cm);

    if (cm.display.scrollbars.addClass)

      addClass(cm.display.wrapper, cm.display.scrollbars.addClass);

  }

  function updateScrollbars(cm, measure) {

    if (!measure) measure = measureForScrollbars(cm);

    var startWidth = cm.display.barWidth, startHeight = cm.display.barHeight;

    updateScrollbarsInner(cm, measure);

    for (var i = 0; i < 4 && startWidth != cm.display.barWidth || startHeight != cm.display.barHeight; i++) {

      if (startWidth != cm.display.barWidth && cm.options.lineWrapping)

        updateHeightsInViewport(cm);

      updateScrollbarsInner(cm, measureForScrollbars(cm));

      startWidth = cm.display.barWidth; startHeight = cm.display.barHeight;

    }

  }

  // Re-synchronize the fake scrollbars with the actual size of the

  // content.

  function updateScrollbarsInner(cm, measure) {

    var d = cm.display;

    var sizes = d.scrollbars.update(measure);

    d.sizer.style.paddingRight = (d.barWidth = sizes.right) + "px";

    d.sizer.style.paddingBottom = (d.barHeight = sizes.bottom) + "px";

    if (sizes.right && sizes.bottom) {

      d.scrollbarFiller.style.display = "block";

      d.scrollbarFiller.style.height = sizes.bottom + "px";

      d.scrollbarFiller.style.width = sizes.right + "px";

    } else d.scrollbarFiller.style.display = "";

    if (sizes.bottom && cm.options.coverGutterNextToScrollbar && cm.options.fixedGutter) {

      d.gutterFiller.style.display = "block";

      d.gutterFiller.style.height = sizes.bottom + "px";

      d.gutterFiller.style.width = measure.gutterWidth + "px";

    } else d.gutterFiller.style.display = "";

  }

  // Compute the lines that are visible in a given viewport (defaults

  // the the current scroll position). viewport may contain top,

  // height, and ensure (see op.scrollToPos) properties.

  function visibleLines(display, doc, viewport) {

    top = Math.floor(top - paddingTop(display));

    var from = lineAtHeight(doc, top), to = lineAtHeight(doc, bottom);

    // Ensure is a {from: {line, ch}, to: {line, ch}} object, and

    // forces those lines into the viewport (if possible).

    if (viewport && viewport.ensure) {

      var ensureFrom = viewport.ensure.from.line, ensureTo = viewport.ensure.to.line;

      if (ensureFrom < from) {

        from = ensureFrom;

        to = lineAtHeight(doc, heightAtLine(getLine(doc, ensureFrom)) + display.wrapper.clientHeight);

      } else if (Math.min(ensureTo, doc.lastLine()) >= to) {

        from = lineAtHeight(doc, heightAtLine(getLine(doc, ensureTo)) - display.wrapper.clientHeight);

        to = ensureTo;

      }

    }

    return {from: from, to: Math.max(to, from + 1)};

  }

  // LINE NUMBERS

  // Re-align line numbers and gutter marks to compensate for

  // horizontal scrolling.

  function alignHorizontally(cm) {

    var display = cm.display, view = display.view;

    if (!display.alignWidgets && (!display.gutters.firstChild || !cm.options.fixedGutter)) return;

    var comp = compensateForHScroll(display) - display.scroller.scrollLeft + cm.doc.scrollLeft;

    var gutterW = display.gutters.offsetWidth, left = comp + "px";

    for (var i = 0; i < view.length; i++) if (!view[i].hidden) {

      if (cm.options.fixedGutter && view[i].gutter)

        view[i].gutter.style.left = left;

      var align = view[i].alignable;

      if (align) for (var j = 0; j < align.length; j++)

        align[j].style.left = left;

    }

    if (cm.options.fixedGutter)

      display.gutters.style.left = (comp + gutterW) + "px";

  }

  // Used to ensure that the line number gutter is still the right

  // size for the current document size. Returns true when an update

  // is needed.

  function maybeUpdateLineNumberWidth(cm) {

    if (!cm.options.lineNumbers) return false;

    var doc = cm.doc, last = lineNumberFor(cm.options, doc.first + doc.size - 1), display = cm.display;

    if (last.length != display.lineNumChars) {

      var test = display.measure.appendChild(elt("div", [elt("div", last)],

                                                 "CodeMirror-linenumber CodeMirror-gutter-elt"));

      var innerW = test.firstChild.offsetWidth, padding = test.offsetWidth - innerW;

      display.lineGutter.style.width = "";

      display.lineNumInnerWidth = Math.max(innerW, display.lineGutter.offsetWidth - padding);

      display.lineNumWidth = display.lineNumInnerWidth + padding;

      display.lineNumChars = display.lineNumInnerWidth ? last.length : -1;

      display.lineGutter.style.width = display.lineNumWidth + "px";

      updateGutterSpace(cm);

      return true;

    }

    return false;

  }

  function lineNumberFor(options, i) {

    return String(options.lineNumberFormatter(i + options.firstLineNumber));

  }

  // Computes display.scroller.scrollLeft + display.gutters.offsetWidth,

  // but using getBoundingClientRect to get a sub-pixel-accurate

  // result.

  function compensateForHScroll(display) {

    return display.scroller.getBoundingClientRect().left - display.sizer.getBoundingClientRect().left;

  }

  // DISPLAY DRAWING

  function DisplayUpdate(cm, viewport, force) {

    var display = cm.display;

    this.viewport = viewport;

    // Store some values that we'll need later (but don't want to force a relayout for)

    this.visible = visibleLines(display, cm.doc, viewport);

    this.editorIsHidden = !display.wrapper.offsetWidth;

    this.wrapperHeight = display.wrapper.clientHeight;

    this.wrapperWidth = display.wrapper.clientWidth;

    this.oldDisplayWidth = displayWidth(cm);

    this.force = force;

    this.dims = getDimensions(cm);

    this.events = [];

  }

  DisplayUpdate.prototype.signal = function(emitter, type) {

    if (hasHandler(emitter, type))

      this.events.push(arguments);

  };

  DisplayUpdate.prototype.finish = function() {

    for (var i = 0; i < this.events.length; i++)

      signal.apply(null, this.events[i]);

  };

  function maybeClipScrollbars(cm) {

    var display = cm.display;

    if (!display.scrollbarsClipped && display.scroller.offsetWidth) {

      display.nativeBarWidth = display.scroller.offsetWidth - display.scroller.clientWidth;

      display.heightForcer.style.height = scrollGap(cm) + "px";

      display.sizer.style.marginBottom = -display.nativeBarWidth + "px";

      display.sizer.style.borderRightWidth = scrollGap(cm) + "px";

      display.scrollbarsClipped = true;

    }

  }

  // Does the actual updating of the line display. Bails out

  // (returning false) when there is nothing to be done and forced is

  // false.

  function updateDisplayIfNeeded(cm, update) {

    var display = cm.display, doc = cm.doc;

    if (update.editorIsHidden) {

      resetView(cm);

      return false;

    }

    // Bail out if the visible area is already rendered and nothing changed.

    if (!update.force &&

        update.visible.from >= display.viewFrom && update.visible.to <= display.viewTo &&

      return false;

    if (maybeUpdateLineNumberWidth(cm)) {

      resetView(cm);

      update.dims = getDimensions(cm);

    }

    // Compute a suitable new viewport (from & to)

    var end = doc.first + doc.size;

    var from = Math.max(update.visible.from - cm.options.viewportMargin, doc.first);

    var to = Math.min(end, update.visible.to + cm.options.viewportMargin);

    if (display.viewFrom < from && from - display.viewFrom < 20) from = Math.max(doc.first, display.viewFrom);

    if (display.viewTo > to && display.viewTo - to < 20) to = Math.min(end, display.viewTo);

    if (sawCollapsedSpans) {

      from = visualLineNo(cm.doc, from);

      to = visualLineEndNo(cm.doc, to);

    }

    var different = from != display.viewFrom || to != display.viewTo ||

      display.lastWrapHeight != update.wrapperHeight || display.lastWrapWidth != update.wrapperWidth;

    adjustView(cm, from, to);

    display.viewOffset = heightAtLine(getLine(cm.doc, display.viewFrom));

    // Position the mover div to align with the current scroll position

    cm.display.mover.style.top = display.viewOffset + "px";

    var toUpdate = countDirtyView(cm);

        (display.updateLineNumbers == null || display.updateLineNumbers >= display.viewTo))

      return false;

    // For big changes, we hide the enclosing element during the

    // update, since that speeds up the operations on most browsers.

    var focused = activeElt();

    if (toUpdate > 4) display.lineDiv.style.display = "none";

    patchDisplay(cm, display.updateLineNumbers, update.dims);

    if (toUpdate > 4) display.lineDiv.style.display = "";

    display.renderedView = display.view;

    // There might have been a widget with a focused element that got

    // hidden or updated, if so re-focus it.

    if (focused && activeElt() != focused && focused.offsetHeight) focused.focus();

    // Prevent selection and cursors from interfering with the scroll

    // width and height.

    removeChildren(display.cursorDiv);

    removeChildren(display.selectionDiv);

    display.gutters.style.height = 0;

    if (different) {

      display.lastWrapHeight = update.wrapperHeight;

      display.lastWrapWidth = update.wrapperWidth;

      startWorker(cm, 400);

    }

    display.updateLineNumbers = null;

    return true;

  }

  function postUpdateDisplay(cm, update) {

    for (var first = true;; first = false) {

      if (first && cm.options.lineWrapping && update.oldDisplayWidth != displayWidth(cm)) {

        force = true;

      } else {

        force = false;

        // Clip forced viewport to actual scrollable area.

          viewport = {top: Math.min(cm.doc.height + paddingVert(cm.display) - displayHeight(cm), viewport.top)};

        // Updated line heights might result in the drawn area not

        // actually covering the viewport. Keep looping until it does.

        update.visible = visibleLines(cm.display, cm.doc, viewport);

        if (update.visible.from >= cm.display.viewFrom && update.visible.to <= cm.display.viewTo)

          break;

      }

      if (!updateDisplayIfNeeded(cm, update)) break;

      updateHeightsInViewport(cm);

      var barMeasure = measureForScrollbars(cm);

      updateSelection(cm);

      setDocumentHeight(cm, barMeasure);

      updateScrollbars(cm, barMeasure);

    }

    update.signal(cm, "update", cm);

    if (cm.display.viewFrom != cm.display.reportedViewFrom || cm.display.viewTo != cm.display.reportedViewTo) {

      update.signal(cm, "viewportChange", cm, cm.display.viewFrom, cm.display.viewTo);

      cm.display.reportedViewFrom = cm.display.viewFrom; cm.display.reportedViewTo = cm.display.viewTo;

    }

  }

  function updateDisplaySimple(cm, viewport) {

    var update = new DisplayUpdate(cm, viewport);

    if (updateDisplayIfNeeded(cm, update)) {

      updateHeightsInViewport(cm);

      postUpdateDisplay(cm, update);

      var barMeasure = measureForScrollbars(cm);

      updateSelection(cm);

      setDocumentHeight(cm, barMeasure);

      updateScrollbars(cm, barMeasure);

      update.finish();

    }

  }

  function setDocumentHeight(cm, measure) {

    cm.display.sizer.style.minHeight = measure.docHeight + "px";

    var total = measure.docHeight + cm.display.barHeight;

    cm.display.heightForcer.style.top = total + "px";

    cm.display.gutters.style.height = Math.max(total + scrollGap(cm), measure.clientHeight) + "px";

  }

  // Read the actual heights of the rendered lines, and update their

  // stored heights to match.

  function updateHeightsInViewport(cm) {

    var display = cm.display;

    var prevBottom = display.lineDiv.offsetTop;

    for (var i = 0; i < display.view.length; i++) {

      var cur = display.view[i], height;

      if (cur.hidden) continue;

      if (ie && ie_version < 8) {

        var bot = cur.node.offsetTop + cur.node.offsetHeight;

        height = bot - prevBottom;

        prevBottom = bot;

      } else {

        var box = cur.node.getBoundingClientRect();

        height = box.bottom - box.top;

      }

      var diff = cur.line.height - height;

      if (height < 2) height = textHeight(display);

      if (diff > .001 || diff < -.001) {

        updateLineHeight(cur.line, height);

        updateWidgetHeight(cur.line);

        if (cur.rest) for (var j = 0; j < cur.rest.length; j++)

          updateWidgetHeight(cur.rest[j]);

      }

    }

  }

  // Read and store the height of line widgets associated with the

  // given line.

  function updateWidgetHeight(line) {

    if (line.widgets) for (var i = 0; i < line.widgets.length; ++i)

      line.widgets[i].height = line.widgets[i].node.offsetHeight;

  }

  // Do a bulk-read of the DOM positions and sizes needed to draw the

  // view, so that we don't interleave reading and writing to the DOM.

  function getDimensions(cm) {

    var d = cm.display, left = {}, width = {};

    var gutterLeft = d.gutters.clientLeft;

    for (var n = d.gutters.firstChild, i = 0; n; n = n.nextSibling, ++i) {

      left[cm.options.gutters[i]] = n.offsetLeft + n.clientLeft + gutterLeft;

      width[cm.options.gutters[i]] = n.clientWidth;

    }

    return {fixedPos: compensateForHScroll(d),

            gutterTotalWidth: d.gutters.offsetWidth,

            gutterLeft: left,

            gutterWidth: width,

            wrapperWidth: d.wrapper.clientWidth};

  }

  // Sync the actual display DOM structure with display.view, removing

  // nodes for lines that are no longer in view, and creating the ones

  // that are not there yet, and updating the ones that are out of

  // date.

  function patchDisplay(cm, updateNumbersFrom, dims) {

    var display = cm.display, lineNumbers = cm.options.lineNumbers;

    var container = display.lineDiv, cur = container.firstChild;

    function rm(node) {

      var next = node.nextSibling;

      // Works around a throw-scroll bug in OS X Webkit

      if (webkit && mac && cm.display.currentWheelTarget == node)

        node.style.display = "none";

      else

        node.parentNode.removeChild(node);

      return next;

    }

    var view = display.view, lineN = display.viewFrom;

    // Loop over the elements in the view, syncing cur (the DOM nodes

    // in display.lineDiv) with the view as we go.

    for (var i = 0; i < view.length; i++) {

      var lineView = view[i];

      } else if (!lineView.node || lineView.node.parentNode != container) { // Not drawn yet

        var node = buildLineElement(cm, lineView, lineN, dims);

        container.insertBefore(node, cur);

      } else { // Already drawn

        while (cur != lineView.node) cur = rm(cur);

          updateNumbersFrom <= lineN && lineView.lineNumber;

        if (lineView.changes) {

          if (indexOf(lineView.changes, "gutter") > -1) updateNumber = false;

          updateLineForChanges(cm, lineView, lineN, dims);

        }

        if (updateNumber) {

          removeChildren(lineView.lineNumber);

          lineView.lineNumber.appendChild(document.createTextNode(lineNumberFor(cm.options, lineN)));

        }

        cur = lineView.node.nextSibling;

      }

      lineN += lineView.size;

    }

    while (cur) cur = rm(cur);

  }

  // When an aspect of a line changes, a string is added to

  // lineView.changes. This updates the relevant part of the line's

  // DOM structure.

  function updateLineForChanges(cm, lineView, lineN, dims) {

    for (var j = 0; j < lineView.changes.length; j++) {

      var type = lineView.changes[j];

      if (type == "text") updateLineText(cm, lineView);

      else if (type == "gutter") updateLineGutter(cm, lineView, lineN, dims);

      else if (type == "class") updateLineClasses(lineView);

      else if (type == "widget") updateLineWidgets(cm, lineView, dims);

    }

    lineView.changes = null;

  }

  // Lines with gutter elements, widgets or a background class need to

  // be wrapped, and have the extra elements added to the wrapper div

  function ensureLineWrapped(lineView) {

    if (lineView.node == lineView.text) {

      lineView.node = elt("div", null, null, "position: relative");

      if (lineView.text.parentNode)

        lineView.text.parentNode.replaceChild(lineView.node, lineView.text);

      lineView.node.appendChild(lineView.text);

      if (ie && ie_version < 8) lineView.node.style.zIndex = 2;

    }

    return lineView.node;

  }

  function updateLineBackground(lineView) {

    var cls = lineView.bgClass ? lineView.bgClass + " " + (lineView.line.bgClass || "") : lineView.line.bgClass;

    if (cls) cls += " CodeMirror-linebackground";

    if (lineView.background) {

      if (cls) lineView.background.className = cls;

      else { lineView.background.parentNode.removeChild(lineView.background); lineView.background = null; }

    } else if (cls) {

      var wrap = ensureLineWrapped(lineView);

      lineView.background = wrap.insertBefore(elt("div", null, cls), wrap.firstChild);

    }

  }

  // Wrapper around buildLineContent which will reuse the structure

  // in display.externalMeasured when possible.

  function getLineContent(cm, lineView) {

    var ext = cm.display.externalMeasured;

    if (ext && ext.line == lineView.line) {

      cm.display.externalMeasured = null;

      lineView.measure = ext.measure;

      return ext.built;

    }

    return buildLineContent(cm, lineView);

  }

  // Redraw the line's text. Interacts with the background and text

  // classes because the mode may output tokens that influence these

  // classes.

  function updateLineText(cm, lineView) {

    var cls = lineView.text.className;

    var built = getLineContent(cm, lineView);

    if (lineView.text == lineView.node) lineView.node = built.pre;

    lineView.text.parentNode.replaceChild(built.pre, lineView.text);

    lineView.text = built.pre;

    if (built.bgClass != lineView.bgClass || built.textClass != lineView.textClass) {

      lineView.bgClass = built.bgClass;

      lineView.textClass = built.textClass;

      updateLineClasses(lineView);

    } else if (cls) {

      lineView.text.className = cls;

    }

  }

  function updateLineClasses(lineView) {

    updateLineBackground(lineView);

    if (lineView.line.wrapClass)

      ensureLineWrapped(lineView).className = lineView.line.wrapClass;

    else if (lineView.node != lineView.text)

      lineView.node.className = "";

    var textClass = lineView.textClass ? lineView.textClass + " " + (lineView.line.textClass || "") : lineView.line.textClass;

    lineView.text.className = textClass || "";

  }

  function updateLineGutter(cm, lineView, lineN, dims) {

    if (lineView.gutter) {

      lineView.node.removeChild(lineView.gutter);

      lineView.gutter = null;

    }

    var markers = lineView.line.gutterMarkers;

    if (cm.options.lineNumbers || markers) {

      var wrap = ensureLineWrapped(lineView);

      var gutterWrap = lineView.gutter = elt("div", null, "CodeMirror-gutter-wrapper", "left: " +

                                             (cm.options.fixedGutter ? dims.fixedPos : -dims.gutterTotalWidth) +

                                             "px; width: " + dims.gutterTotalWidth + "px");

      cm.display.input.setUneditable(gutterWrap);

      wrap.insertBefore(gutterWrap, lineView.text);

      if (lineView.line.gutterClass)

        gutterWrap.className += " " + lineView.line.gutterClass;

      if (cm.options.lineNumbers && (!markers || !markers["CodeMirror-linenumbers"]))

        lineView.lineNumber = gutterWrap.appendChild(

          elt("div", lineNumberFor(cm.options, lineN),

              "CodeMirror-linenumber CodeMirror-gutter-elt",

              "left: " + dims.gutterLeft["CodeMirror-linenumbers"] + "px; width: "

              + cm.display.lineNumInnerWidth + "px"));