text: // CodeMirror, copyright (c) by Marijn Haverbeke and others
  // Distributed under an MIT license: http://codemirror.net/LICENSE
  
  // declare global: diff_match_patch, DIFF_INSERT, DIFF_DELETE, DIFF_EQUAL
  
  (function(mod) {
    if (typeof exports == "object" && typeof module == "object") // CommonJS
      mod(require("../../lib/codemirror")); // Note non-packaged dependency diff_match_patch
    else if (typeof define == "function" && define.amd) // AMD
      define(["../../lib/codemirror", "diff_match_patch"], mod);
    else // Plain browser env
      mod(CodeMirror);
  })(function(CodeMirror) {
    "use strict";
    var Pos = CodeMirror.Pos;
    var svgNS = "http://www.w3.org/2000/svg";
  
    function DiffView(mv, type) {
      this.mv = mv;
      this.type = type;
      this.classes = type == "left"
        ? {chunk: "CodeMirror-merge-l-chunk",
           start: "CodeMirror-merge-l-chunk-start",
           end: "CodeMirror-merge-l-chunk-end",
           insert: "CodeMirror-merge-l-inserted",
           del: "CodeMirror-merge-l-deleted",
           connect: "CodeMirror-merge-l-connect"}
        : {chunk: "CodeMirror-merge-r-chunk",
           start: "CodeMirror-merge-r-chunk-start",
           end: "CodeMirror-merge-r-chunk-end",
           insert: "CodeMirror-merge-r-inserted",
           del: "CodeMirror-merge-r-deleted",
           connect: "CodeMirror-merge-r-connect"};
    }
  
    DiffView.prototype = {
      constructor: DiffView,
      init: function(pane, orig, options) {
        this.edit = this.mv.edit;
        ;(this.edit.state.diffViews || (this.edit.state.diffViews = [])).push(this);
        this.orig = CodeMirror(pane, copyObj({value: orig, readOnly: !this.mv.options.allowEditingOriginals}, copyObj(options)));
        if (this.mv.options.connect == "align") {
          if (!this.edit.state.trackAlignable) this.edit.state.trackAlignable = new TrackAlignable(this.edit)
          this.orig.state.trackAlignable = new TrackAlignable(this.orig)
        }
  
        this.orig.state.diffViews = [this];
        var classLocation = options.chunkClassLocation || "background";
        if (Object.prototype.toString.call(classLocation) != "[object Array]") classLocation = [classLocation]
        this.classes.classLocation = classLocation
  
        this.diff = getDiff(asString(orig), asString(options.value), this.mv.options.ignoreWhitespace);
        this.chunks = getChunks(this.diff);
        this.diffOutOfDate = this.dealigned = false;
        this.needsScrollSync = null
  
        this.showDifferences = options.showDifferences !== false;
      },
      registerEvents: function(otherDv) {
        this.forceUpdate = registerUpdate(this);
        setScrollLock(this, true, false);
        registerScroll(this, otherDv);
      },
      setShowDifferences: function(val) {
        val = val !== false;
        if (val != this.showDifferences) {
          this.showDifferences = val;
          this.forceUpdate("full");
        }
      }
    };
  
    function ensureDiff(dv) {
      if (dv.diffOutOfDate) {
        dv.diff = getDiff(dv.orig.getValue(), dv.edit.getValue(), dv.mv.options.ignoreWhitespace);
        dv.chunks = getChunks(dv.diff);
        dv.diffOutOfDate = false;
        CodeMirror.signal(dv.edit, "updateDiff", dv.diff);
      }
    }
  
    var updating = false;
    function registerUpdate(dv) {
      var edit = {from: 0, to: 0, marked: []};
      var orig = {from: 0, to: 0, marked: []};
      var debounceChange, updatingFast = false;
      function update(mode) {
        updating = true;
        updatingFast = false;
        if (mode == "full") {
          if (dv.svg) clear(dv.svg);
          if (dv.copyButtons) clear(dv.copyButtons);
          clearMarks(dv.edit, edit.marked, dv.classes);
          clearMarks(dv.orig, orig.marked, dv.classes);
          edit.from = edit.to = orig.from = orig.to = 0;
        }
        ensureDiff(dv);
        if (dv.showDifferences) {
          updateMarks(dv.edit, dv.diff, edit, DIFF_INSERT, dv.classes);
          updateMarks(dv.orig, dv.diff, orig, DIFF_DELETE, dv.classes);
        }
  
        if (dv.mv.options.connect == "align")
          alignChunks(dv);
        makeConnections(dv);
        if (dv.needsScrollSync != null) syncScroll(dv, dv.needsScrollSync)
  
        updating = false;
      }
      function setDealign(fast) {
        if (updating) return;
        dv.dealigned = true;
        set(fast);
      }
      function set(fast) {
        if (updating || updatingFast) return;
        clearTimeout(debounceChange);
        if (fast === true) updatingFast = true;
        debounceChange = setTimeout(update, fast === true ? 20 : 250);
      }
      function change(_cm, change) {
        if (!dv.diffOutOfDate) {
          dv.diffOutOfDate = true;
          edit.from = edit.to = orig.from = orig.to = 0;
        }
        // Update faster when a line was added/removed
        setDealign(change.text.length - 1 != change.to.line - change.from.line);
      }
      function swapDoc() {
        dv.diffOutOfDate = true;
        dv.dealigned = true;
        update("full");
      }
      dv.edit.on("change", change);
      dv.orig.on("change", change);
      dv.edit.on("swapDoc", swapDoc);
      dv.orig.on("swapDoc", swapDoc);
      if (dv.mv.options.connect == "align") {
        CodeMirror.on(dv.edit.state.trackAlignable, "realign", setDealign)
        CodeMirror.on(dv.orig.state.trackAlignable, "realign", setDealign)
      }
      dv.edit.on("viewportChange", function() { set(false); });
      dv.orig.on("viewportChange", function() { set(false); });
      update();
      return update;
    }
  
    function registerScroll(dv, otherDv) {
      dv.edit.on("scroll", function() {
        syncScroll(dv, true) && makeConnections(dv);
      });
      dv.orig.on("scroll", function() {
        syncScroll(dv, false) && makeConnections(dv);
        if (otherDv) syncScroll(otherDv, true) && makeConnections(otherDv);
      });
    }
  
    function syncScroll(dv, toOrig) {
      // Change handler will do a refresh after a timeout when diff is out of date
      if (dv.diffOutOfDate) {
        if (dv.lockScroll && dv.needsScrollSync == null) dv.needsScrollSync = toOrig
        return false
      }
      dv.needsScrollSync = null
      if (!dv.lockScroll) return true;
      var editor, other, now = +new Date;
      if (toOrig) { editor = dv.edit; other = dv.orig; }
      else { editor = dv.orig; other = dv.edit; }
      // Don't take action if the position of this editor was recently set
      // (to prevent feedback loops)
      if (editor.state.scrollSetBy == dv && (editor.state.scrollSetAt || 0) + 250 > now) return false;
  
      var sInfo = editor.getScrollInfo();
      if (dv.mv.options.connect == "align") {
        targetPos = sInfo.top;
      } else {
        var halfScreen = .5 * sInfo.clientHeight, midY = sInfo.top + halfScreen;
        var mid = editor.lineAtHeight(midY, "local");
        var around = chunkBoundariesAround(dv.chunks, mid, toOrig);
        var off = getOffsets(editor, toOrig ? around.edit : around.orig);
        var offOther = getOffsets(other, toOrig ? around.orig : around.edit);
        var ratio = (midY - off.top) / (off.bot - off.top);
        var targetPos = (offOther.top - halfScreen) + ratio * (offOther.bot - offOther.top);
  
        var botDist, mix;
        // Some careful tweaking to make sure no space is left out of view
        // when scrolling to top or bottom.
        if (targetPos > sInfo.top && (mix = sInfo.top / halfScreen) < 1) {
          targetPos = targetPos * mix + sInfo.top * (1 - mix);
        } else if ((botDist = sInfo.height - sInfo.clientHeight - sInfo.top) < halfScreen) {
          var otherInfo = other.getScrollInfo();
          var botDistOther = otherInfo.height - otherInfo.clientHeight - targetPos;
          if (botDistOther > botDist && (mix = botDist / halfScreen) < 1)
            targetPos = targetPos * mix + (otherInfo.height - otherInfo.clientHeight - botDist) * (1 - mix);
        }
      }
  
      other.scrollTo(sInfo.left, targetPos);
      other.state.scrollSetAt = now;
      other.state.scrollSetBy = dv;
      return true;
    }
  
    function getOffsets(editor, around) {
      var bot = around.after;
      if (bot == null) bot = editor.lastLine() + 1;
      return {top: editor.heightAtLine(around.before || 0, "local"),
              bot: editor.heightAtLine(bot, "local")};
    }
  
    function setScrollLock(dv, val, action) {
      dv.lockScroll = val;
      if (val && action != false) syncScroll(dv, DIFF_INSERT) && makeConnections(dv);
      (val ? CodeMirror.addClass : CodeMirror.rmClass)(dv.lockButton, "CodeMirror-merge-scrolllock-enabled");
    }
  
    // Updating the marks for editor content
  
    function removeClass(editor, line, classes) {
      var locs = classes.classLocation
      for (var i = 0; i < locs.length; i++) {
        editor.removeLineClass(line, locs[i], classes.chunk);
        editor.removeLineClass(line, locs[i], classes.start);
        editor.removeLineClass(line, locs[i], classes.end);
      }
    }
  
    function clearMarks(editor, arr, classes) {
      for (var i = 0; i < arr.length; ++i) {
        var mark = arr[i];
        if (mark instanceof CodeMirror.TextMarker)
          mark.clear();
        else if (mark.parent)
          removeClass(editor, mark, classes);
      }
      arr.length = 0;
    }
  
    // FIXME maybe add a margin around viewport to prevent too many updates
    function updateMarks(editor, diff, state, type, classes) {
      var vp = editor.getViewport();
      editor.operation(function() {
        if (state.from == state.to || vp.from - state.to > 20 || state.from - vp.to > 20) {
          clearMarks(editor, state.marked, classes);
          markChanges(editor, diff, type, state.marked, vp.from, vp.to, classes);
          state.from = vp.from; state.to = vp.to;
        } else {
          if (vp.from < state.from) {
            markChanges(editor, diff, type, state.marked, vp.from, state.from, classes);
            state.from = vp.from;
          }
          if (vp.to > state.to) {
            markChanges(editor, diff, type, state.marked, state.to, vp.to, classes);
            state.to = vp.to;
          }
        }
      });
    }
  
    function addClass(editor, lineNr, classes, main, start, end) {
      var locs = classes.classLocation, line = editor.getLineHandle(lineNr);
      for (var i = 0; i < locs.length; i++) {
        if (main) editor.addLineClass(line, locs[i], classes.chunk);
        if (start) editor.addLineClass(line, locs[i], classes.start);
        if (end) editor.addLineClass(line, locs[i], classes.end);
      }
      return line;
    }
  
    function markChanges(editor, diff, type, marks, from, to, classes) {
      var pos = Pos(0, 0);
      var top = Pos(from, 0), bot = editor.clipPos(Pos(to - 1));
      var cls = type == DIFF_DELETE ? classes.del : classes.insert;
      function markChunk(start, end) {
        var bfrom = Math.max(from, start), bto = Math.min(to, end);
        for (var i = bfrom; i < bto; ++i)
          marks.push(addClass(editor, i, classes, true, i == start, i == end - 1));
        // When the chunk is empty, make sure a horizontal line shows up
        if (start == end && bfrom == end && bto == end) {
          if (bfrom)
            marks.push(addClass(editor, bfrom - 1, classes, false, false, true));
          else
            marks.push(addClass(editor, bfrom, classes, false, true, false));
        }
      }
  
      var chunkStart = 0, pending = false;
      for (var i = 0; i < diff.length; ++i) {
        var part = diff[i], tp = part[0], str = part[1];
        if (tp == DIFF_EQUAL) {
          var cleanFrom = pos.line + (startOfLineClean(diff, i) ? 0 : 1);
          moveOver(pos, str);
          var cleanTo = pos.line + (endOfLineClean(diff, i) ? 1 : 0);
          if (cleanTo > cleanFrom) {
            if (pending) { markChunk(chunkStart, cleanFrom); pending = false }
            chunkStart = cleanTo;
          }
        } else {
          pending = true
          if (tp == type) {
            var end = moveOver(pos, str, true);
            var a = posMax(top, pos), b = posMin(bot, end);
            if (!posEq(a, b))
              marks.push(editor.markText(a, b, {className: cls}));
            pos = end;
          }
        }
      }
      if (pending) markChunk(chunkStart, pos.line + 1);
    }
  
    // Updating the gap between editor and original
  
    function makeConnections(dv) {
      if (!dv.showDifferences) return;
  
      if (dv.svg) {
        clear(dv.svg);
        var w = dv.gap.offsetWidth;
        attrs(dv.svg, "width", w, "height", dv.gap.offsetHeight);
      }
      if (dv.copyButtons) clear(dv.copyButtons);
  
      var vpEdit = dv.edit.getViewport(), vpOrig = dv.orig.getViewport();
      var outerTop = dv.mv.wrap.getBoundingClientRect().top
      var sTopEdit = outerTop - dv.edit.getScrollerElement().getBoundingClientRect().top + dv.edit.getScrollInfo().top
      var sTopOrig = outerTop - dv.orig.getScrollerElement().getBoundingClientRect().top + dv.orig.getScrollInfo().top;
      for (var i = 0; i < dv.chunks.length; i++) {
        var ch = dv.chunks[i];
        if (ch.editFrom <= vpEdit.to && ch.editTo >= vpEdit.from &&
            ch.origFrom <= vpOrig.to && ch.origTo >= vpOrig.from)
          drawConnectorsForChunk(dv, ch, sTopOrig, sTopEdit, w);
      }
    }
  
    function getMatchingOrigLine(editLine, chunks) {
      var editStart = 0, origStart = 0;
      for (var i = 0; i < chunks.length; i++) {
        var chunk = chunks[i];
        if (chunk.editTo > editLine && chunk.editFrom <= editLine) return null;
        if (chunk.editFrom > editLine) break;
        editStart = chunk.editTo;
        origStart = chunk.origTo;
      }
      return origStart + (editLine - editStart);
    }
  
    // Combines information about chunks and widgets/markers to return
    // an array of lines, in a single editor, that probably need to be
    // aligned with their counterparts in the editor next to it.
    function alignableFor(cm, chunks, isOrig) {
      var tracker = cm.state.trackAlignable
      var start = cm.firstLine(), trackI = 0
      var result = []
      for (var i = 0;; i++) {
        var chunk = chunks[i]
        var chunkStart = !chunk ? 1e9 : isOrig ? chunk.origFrom : chunk.editFrom
        for (; trackI < tracker.alignable.length; trackI += 2) {
          var n = tracker.alignable[trackI] + 1
          if (n <= start) continue
          if (n <= chunkStart) result.push(n)
          else break
        }
        if (!chunk) break
        result.push(start = isOrig ? chunk.origTo : chunk.editTo)
      }
      return result
    }
  
    // Given information about alignable lines in two editors, fill in
    // the result (an array of three-element arrays) to reflect the
    // lines that need to be aligned with each other.
    function mergeAlignable(result, origAlignable, chunks, setIndex) {
      var rI = 0, origI = 0, chunkI = 0, diff = 0
      outer: for (;; rI++) {
        var nextR = result[rI], nextO = origAlignable[origI]
        if (!nextR && nextO == null) break
  
        var rLine = nextR ? nextR[0] : 1e9, oLine = nextO == null ? 1e9 : nextO
        while (chunkI < chunks.length) {
          var chunk = chunks[chunkI]
          if (chunk.origFrom <= oLine && chunk.origTo > oLine) {
            origI++
            rI--
            continue outer;
          }
          if (chunk.editTo > rLine) {
            if (chunk.editFrom <= rLine) continue outer;
            break
          }
          diff += (chunk.origTo - chunk.origFrom) - (chunk.editTo - chunk.editFrom)
          chunkI++
        }
        if (rLine == oLine - diff) {
          nextR[setIndex] = oLine
          origI++
        } else if (rLine < oLine - diff) {
          nextR[setIndex] = rLine + diff
        } else {
          var record = [oLine - diff, null, null]
          record[setIndex] = oLine
          result.splice(rI, 0, record)
          origI++
        }
      }
    }
  
    function findAlignedLines(dv, other) {
      var alignable = alignableFor(dv.edit, dv.chunks, false), result = []
      if (other) for (var i = 0, j = 0; i < other.chunks.length; i++) {
        var n = other.chunks[i].editTo
        while (j < alignable.length && alignable[j] < n) j++
        if (j == alignable.length || alignable[j] != n) alignable.splice(j++, 0, n)
      }
      for (var i = 0; i < alignable.length; i++)
        result.push([alignable[i], null, null])
  
      mergeAlignable(result, alignableFor(dv.orig, dv.chunks, true), dv.chunks, 1)
      if (other)
        mergeAlignable(result, alignableFor(other.orig, other.chunks, true), other.chunks, 2)
  
      return result
    }
  
    function alignChunks(dv, force) {
      if (!dv.dealigned && !force) return;
      if (!dv.orig.curOp) return dv.orig.operation(function() {
        alignChunks(dv, force);
      });
  
      dv.dealigned = false;
      var other = dv.mv.left == dv ? dv.mv.right : dv.mv.left;
      if (other) {
        ensureDiff(other);
        other.dealigned = false;
      }
      var linesToAlign = findAlignedLines(dv, other);
  
      // Clear old aligners
      var aligners = dv.mv.aligners;
      for (var i = 0; i < aligners.length; i++)
        aligners[i].clear();
      aligners.length = 0;
  
      var cm = [dv.edit, dv.orig], scroll = [];
      if (other) cm.push(other.orig);
      for (var i = 0; i < cm.length; i++)
        scroll.push(cm[i].getScrollInfo().top);
  
      for (var ln = 0; ln < linesToAlign.length; ln++)
        alignLines(cm, linesToAlign[ln], aligners);
  
      for (var i = 0; i < cm.length; i++)
        cm[i].scrollTo(null, scroll[i]);
    }
  
    function alignLines(cm, lines, aligners) {
      var maxOffset = 0, offset = [];
      for (var i = 0; i < cm.length; i++) if (lines[i] != null) {
        var off = cm[i].heightAtLine(lines[i], "local");
        offset[i] = off;
        maxOffset = Math.max(maxOffset, off);
      }
      for (var i = 0; i < cm.length; i++) if (lines[i] != null) {
        var diff = maxOffset - offset[i];
        if (diff > 1)
          aligners.push(padAbove(cm[i], lines[i], diff));
      }
    }
  
    function padAbove(cm, line, size) {
      var above = true;
      if (line > cm.lastLine()) {
        line--;
        above = false;
      }
      var elt = document.createElement("div");
      elt.className = "CodeMirror-merge-spacer";
      elt.style.height = size + "px"; elt.style.minWidth = "1px";
      return cm.addLineWidget(line, elt, {height: size, above: above, mergeSpacer: true, handleMouseEvents: true});
    }
  
    function drawConnectorsForChunk(dv, chunk, sTopOrig, sTopEdit, w) {
      var flip = dv.type == "left";
      var top = dv.orig.heightAtLine(chunk.origFrom, "local", true) - sTopOrig;
      if (dv.svg) {
        var topLpx = top;
        var topRpx = dv.edit.heightAtLine(chunk.editFrom, "local", true) - sTopEdit;
        if (flip) { var tmp = topLpx; topLpx = topRpx; topRpx = tmp; }
        var botLpx = dv.orig.heightAtLine(chunk.origTo, "local", true) - sTopOrig;
        var botRpx = dv.edit.heightAtLine(chunk.editTo, "local", true) - sTopEdit;
        if (flip) { var tmp = botLpx; botLpx = botRpx; botRpx = tmp; }
        var curveTop = " C " + w/2 + " " + topRpx + " " + w/2 + " " + topLpx + " " + (w + 2) + " " + topLpx;
        var curveBot = " C " + w/2 + " " + botLpx + " " + w/2 + " " + botRpx + " -1 " + botRpx;
        attrs(dv.svg.appendChild(document.createElementNS(svgNS, "path")),
              "d", "M -1 " + topRpx + curveTop + " L " + (w + 2) + " " + botLpx + curveBot + " z",
              "class", dv.classes.connect);
      }
      if (dv.copyButtons) {
        var copy = dv.copyButtons.appendChild(elt("div", dv.type == "left" ? "\u21dd" : "\u21dc",
                                                  "CodeMirror-merge-copy"));
        var editOriginals = dv.mv.options.allowEditingOriginals;
        copy.title = editOriginals ? "Push to left" : "Revert chunk";
        copy.chunk = chunk;
        copy.style.top = (chunk.origTo > chunk.origFrom ? top : dv.edit.heightAtLine(chunk.editFrom, "local") - sTopEdit) + "px";
  
        if (editOriginals) {
          var topReverse = dv.edit.heightAtLine(chunk.editFrom, "local") - sTopEdit;
          var copyReverse = dv.copyButtons.appendChild(elt("div", dv.type == "right" ? "\u21dd" : "\u21dc",
                                                           "CodeMirror-merge-copy-reverse"));
          copyReverse.title = "Push to right";
          copyReverse.chunk = {editFrom: chunk.origFrom, editTo: chunk.origTo,
                               origFrom: chunk.editFrom, origTo: chunk.editTo};
          copyReverse.style.top = topReverse + "px";
          dv.type == "right" ? copyReverse.style.left = "2px" : copyReverse.style.right = "2px";
        }
      }
    }
  
    function copyChunk(dv, to, from, chunk) {
      if (dv.diffOutOfDate) return;
      var origStart = chunk.origTo > from.lastLine() ? Pos(chunk.origFrom - 1) : Pos(chunk.origFrom, 0)
      var origEnd = Pos(chunk.origTo, 0)
      var editStart = chunk.editTo > to.lastLine() ? Pos(chunk.editFrom - 1) : Pos(chunk.editFrom, 0)
      var editEnd = Pos(chunk.editTo, 0)
      var handler = dv.mv.options.revertChunk
      if (handler)
        handler(dv.mv, from, origStart, origEnd, to, editStart, editEnd)
      else
        to.replaceRange(from.getRange(origStart, origEnd), editStart, editEnd)
    }
  
    // Merge view, containing 0, 1, or 2 diff views.
  
    var MergeView = CodeMirror.MergeView = function(node, options) {
      if (!(this instanceof MergeView)) return new MergeView(node, options);
  
      this.options = options;
      var origLeft = options.origLeft, origRight = options.origRight == null ? options.orig : options.origRight;
  
      var hasLeft = origLeft != null, hasRight = origRight != null;
      var panes = 1 + (hasLeft ? 1 : 0) + (hasRight ? 1 : 0);
      var wrap = [], left = this.left = null, right = this.right = null;
      var self = this;
  
      if (hasLeft) {
        left = this.left = new DiffView(this, "left");
        var leftPane = elt("div", null, "CodeMirror-merge-pane CodeMirror-merge-left");
        wrap.push(leftPane);
        wrap.push(buildGap(left));
      }
  
      var editPane = elt("div", null, "CodeMirror-merge-pane CodeMirror-merge-editor");
      wrap.push(editPane);
  
      if (hasRight) {
        right = this.right = new DiffView(this, "right");
        wrap.push(buildGap(right));
        var rightPane = elt("div", null, "CodeMirror-merge-pane CodeMirror-merge-right");
        wrap.push(rightPane);
      }
  
      (hasRight ? rightPane : editPane).className += " CodeMirror-merge-pane-rightmost";
  
      wrap.push(elt("div", null, null, "height: 0; clear: both;"));
  
      var wrapElt = this.wrap = node.appendChild(elt("div", wrap, "CodeMirror-merge CodeMirror-merge-" + panes + "pane"));
      this.edit = CodeMirror(editPane, copyObj(options));
  
      if (left) left.init(leftPane, origLeft, options);
      if (right) right.init(rightPane, origRight, options);
      if (options.collapseIdentical)
        this.editor().operation(function() {
          collapseIdenticalStretches(self, options.collapseIdentical);
        });
      if (options.connect == "align") {
        this.aligners = [];
        alignChunks(this.left || this.right, true);
      }
      if (left) left.registerEvents(right)
      if (right) right.registerEvents(left)
  
  
      var onResize = function() {
        if (left) makeConnections(left);
        if (right) makeConnections(right);
      };
      CodeMirror.on(window, "resize", onResize);
      var resizeInterval = setInterval(function() {
        for (var p = wrapElt.parentNode; p && p != document.body; p = p.parentNode) {}
        if (!p) { clearInterval(resizeInterval); CodeMirror.off(window, "resize", onResize); }
      }, 5000);
    };
  
    function buildGap(dv) {
      var lock = dv.lockButton = elt("div", null, "CodeMirror-merge-scrolllock");
      lock.title = "Toggle locked scrolling";
      var lockWrap = elt("div", [lock], "CodeMirror-merge-scrolllock-wrap");
      CodeMirror.on(lock, "click", function() { setScrollLock(dv, !dv.lockScroll); });
      var gapElts = [lockWrap];
      if (dv.mv.options.revertButtons !== false) {
        dv.copyButtons = elt("div", null, "CodeMirror-merge-copybuttons-" + dv.type);
        CodeMirror.on(dv.copyButtons, "click", function(e) {
          var node = e.target || e.srcElement;
          if (!node.chunk) return;
          if (node.className == "CodeMirror-merge-copy-reverse") {
            copyChunk(dv, dv.orig, dv.edit, node.chunk);
            return;
          }
          copyChunk(dv, dv.edit, dv.orig, node.chunk);
        });
        gapElts.unshift(dv.copyButtons);
      }
      if (dv.mv.options.connect != "align") {
        var svg = document.createElementNS && document.createElementNS(svgNS, "svg");
        if (svg && !svg.createSVGRect) svg = null;
        dv.svg = svg;
        if (svg) gapElts.push(svg);
      }
  
      return dv.gap = elt("div", gapElts, "CodeMirror-merge-gap");
    }
  
    MergeView.prototype = {
      constructor: MergeView,
      editor: function() { return this.edit; },
      rightOriginal: function() { return this.right && this.right.orig; },
      leftOriginal: function() { return this.left && this.left.orig; },
      setShowDifferences: function(val) {
        if (this.right) this.right.setShowDifferences(val);
        if (this.left) this.left.setShowDifferences(val);
      },
      rightChunks: function() {
        if (this.right) { ensureDiff(this.right); return this.right.chunks; }
      },
      leftChunks: function() {
        if (this.left) { ensureDiff(this.left); return this.left.chunks; }
      }
    };
  
    function asString(obj) {
      if (typeof obj == "string") return obj;
      else return obj.getValue();
    }
  
    // Operations on diffs
    var dmp;
    function getDiff(a, b, ignoreWhitespace) {
      if (!dmp) dmp = new diff_match_patch();
  
      var diff = dmp.diff_main(a, b);
      // The library sometimes leaves in empty parts, which confuse the algorithm
      for (var i = 0; i < diff.length; ++i) {
        var part = diff[i];
        if (ignoreWhitespace ? !/[^ \t]/.test(part[1]) : !part[1]) {
          diff.splice(i--, 1);
        } else if (i && diff[i - 1][0] == part[0]) {
          diff.splice(i--, 1);
          diff[i][1] += part[1];
        }
      }
      return diff;
    }
  
    function getChunks(diff) {
      var chunks = [];
      var startEdit = 0, startOrig = 0;
      var edit = Pos(0, 0), orig = Pos(0, 0);
      for (var i = 0; i < diff.length; ++i) {
        var part = diff[i], tp = part[0];
        if (tp == DIFF_EQUAL) {
          var startOff = !startOfLineClean(diff, i) || edit.line < startEdit || orig.line < startOrig ? 1 : 0;
          var cleanFromEdit = edit.line + startOff, cleanFromOrig = orig.line + startOff;
          moveOver(edit, part[1], null, orig);
          var endOff = endOfLineClean(diff, i) ? 1 : 0;
          var cleanToEdit = edit.line + endOff, cleanToOrig = orig.line + endOff;
          if (cleanToEdit > cleanFromEdit) {
            if (i) chunks.push({origFrom: startOrig, origTo: cleanFromOrig,
                                editFrom: startEdit, editTo: cleanFromEdit});
            startEdit = cleanToEdit; startOrig = cleanToOrig;
          }
        } else {
          moveOver(tp == DIFF_INSERT ? edit : orig, part[1]);
        }
      }
      if (startEdit <= edit.line || startOrig <= orig.line)
        chunks.push({origFrom: startOrig, origTo: orig.line + 1,
                     editFrom: startEdit, editTo: edit.line + 1});
      return chunks;
    }
  
    function endOfLineClean(diff, i) {
      if (i == diff.length - 1) return true;
      var next = diff[i + 1][1];
      if ((next.length == 1 && i < diff.length - 2) || next.charCodeAt(0) != 10) return false;
      if (i == diff.length - 2) return true;
      next = diff[i + 2][1];
      return (next.length > 1 || i == diff.length - 3) && next.charCodeAt(0) == 10;
    }
  
    function startOfLineClean(diff, i) {
      if (i == 0) return true;
      var last = diff[i - 1][1];
      if (last.charCodeAt(last.length - 1) != 10) return false;
      if (i == 1) return true;
      last = diff[i - 2][1];
      return last.charCodeAt(last.length - 1) == 10;
    }
  
    function chunkBoundariesAround(chunks, n, nInEdit) {
      var beforeE, afterE, beforeO, afterO;
      for (var i = 0; i < chunks.length; i++) {
        var chunk = chunks[i];
        var fromLocal = nInEdit ? chunk.editFrom : chunk.origFrom;
        var toLocal = nInEdit ? chunk.editTo : chunk.origTo;
        if (afterE == null) {
          if (fromLocal > n) { afterE = chunk.editFrom; afterO = chunk.origFrom; }
          else if (toLocal > n) { afterE = chunk.editTo; afterO = chunk.origTo; }
        }
        if (toLocal <= n) { beforeE = chunk.editTo; beforeO = chunk.origTo; }
        else if (fromLocal <= n) { beforeE = chunk.editFrom; beforeO = chunk.origFrom; }
      }
      return {edit: {before: beforeE, after: afterE}, orig: {before: beforeO, after: afterO}};
    }
  
    function collapseSingle(cm, from, to) {
      cm.addLineClass(from, "wrap", "CodeMirror-merge-collapsed-line");
      var widget = document.createElement("span");
      widget.className = "CodeMirror-merge-collapsed-widget";
      widget.title = "Identical text collapsed. Click to expand.";
      var mark = cm.markText(Pos(from, 0), Pos(to - 1), {
        inclusiveLeft: true,
        inclusiveRight: true,
        replacedWith: widget,
        clearOnEnter: true
      });
      function clear() {
        mark.clear();
        cm.removeLineClass(from, "wrap", "CodeMirror-merge-collapsed-line");
      }
      if (mark.explicitlyCleared) clear();
      CodeMirror.on(widget, "click", clear);
      mark.on("clear", clear);
      CodeMirror.on(widget, "click", clear);
      return {mark: mark, clear: clear};
    }
  
    function collapseStretch(size, editors) {
      var marks = [];
      function clear() {
        for (var i = 0; i < marks.length; i++) marks[i].clear();
      }
      for (var i = 0; i < editors.length; i++) {
        var editor = editors[i];
        var mark = collapseSingle(editor.cm, editor.line, editor.line + size);
        marks.push(mark);
        mark.mark.on("clear", clear);
      }
      return marks[0].mark;
    }
  
    function unclearNearChunks(dv, margin, off, clear) {
      for (var i = 0; i < dv.chunks.length; i++) {
        var chunk = dv.chunks[i];
        for (var l = chunk.editFrom - margin; l < chunk.editTo + margin; l++) {
          var pos = l + off;
          if (pos >= 0 && pos < clear.length) clear[pos] = false;
        }
      }
    }
  
    function collapseIdenticalStretches(mv, margin) {
      if (typeof margin != "number") margin = 2;
      var clear = [], edit = mv.editor(), off = edit.firstLine();
      for (var l = off, e = edit.lastLine(); l <= e; l++) clear.push(true);
      if (mv.left) unclearNearChunks(mv.left, margin, off, clear);
      if (mv.right) unclearNearChunks(mv.right, margin, off, clear);
  
      for (var i = 0; i < clear.length; i++) {
        if (clear[i]) {
          var line = i + off;
          for (var size = 1; i < clear.length - 1 && clear[i + 1]; i++, size++) {}
          if (size > margin) {
            var editors = [{line: line, cm: edit}];
            if (mv.left) editors.push({line: getMatchingOrigLine(line, mv.left.chunks), cm: mv.left.orig});
            if (mv.right) editors.push({line: getMatchingOrigLine(line, mv.right.chunks), cm: mv.right.orig});
            var mark = collapseStretch(size, editors);
            if (mv.options.onCollapse) mv.options.onCollapse(mv, line, size, mark);
          }
        }
      }
    }
  
    // General utilities
  
    function elt(tag, content, className, style) {
      var e = document.createElement(tag);
      if (className) e.className = className;
      if (style) e.style.cssText = style;
      if (typeof content == "string") e.appendChild(document.createTextNode(content));
      else if (content) for (var i = 0; i < content.length; ++i) e.appendChild(content[i]);
      return e;
    }
  
    function clear(node) {
      for (var count = node.childNodes.length; count > 0; --count)
        node.removeChild(node.firstChild);
    }
  
    function attrs(elt) {
      for (var i = 1; i < arguments.length; i += 2)
        elt.setAttribute(arguments[i], arguments[i+1]);
    }
  
    function copyObj(obj, target) {
      if (!target) target = {};
      for (var prop in obj) if (obj.hasOwnProperty(prop)) target[prop] = obj[prop];
      return target;
    }
  
    function moveOver(pos, str, copy, other) {
      var out = copy ? Pos(pos.line, pos.ch) : pos, at = 0;
      for (;;) {
        var nl = str.indexOf("\n", at);
        if (nl == -1) break;
        ++out.line;
        if (other) ++other.line;
        at = nl + 1;
      }
      out.ch = (at ? 0 : out.ch) + (str.length - at);
      if (other) other.ch = (at ? 0 : other.ch) + (str.length - at);
      return out;
    }
  
    // Tracks collapsed markers and line widgets, in order to be able to
    // accurately align the content of two editors.
  
    var F_WIDGET = 1, F_WIDGET_BELOW = 2, F_MARKER = 4
  
    function TrackAlignable(cm) {
      this.cm = cm
      this.alignable = []
      this.height = cm.doc.height
      var self = this
      cm.on("markerAdded", function(_, marker) {
        if (!marker.collapsed) return
        var found = marker.find(1)
        if (found != null) self.set(found.line, F_MARKER)
      })
      cm.on("markerCleared", function(_, marker, _min, max) {
        if (max != null && marker.collapsed)
          self.check(max, F_MARKER, self.hasMarker)
      })
      cm.on("markerChanged", this.signal.bind(this))
      cm.on("lineWidgetAdded", function(_, widget, lineNo) {
        if (widget.mergeSpacer) return
        if (widget.above) self.set(lineNo - 1, F_WIDGET_BELOW)
        else self.set(lineNo, F_WIDGET)
      })
      cm.on("lineWidgetCleared", function(_, widget, lineNo) {
        if (widget.mergeSpacer) return
        if (widget.above) self.check(lineNo - 1, F_WIDGET_BELOW, self.hasWidgetBelow)
        else self.check(lineNo, F_WIDGET, self.hasWidget)
      })
      cm.on("lineWidgetChanged", this.signal.bind(this))
      cm.on("change", function(_, change) {
        var start = change.from.line, nBefore = change.to.line - change.from.line
        var nAfter = change.text.length - 1, end = start + nAfter
        if (nBefore || nAfter) self.map(start, nBefore, nAfter)
        self.check(end, F_MARKER, self.hasMarker)
        if (nBefore || nAfter) self.check(change.from.line, F_MARKER, self.hasMarker)
      })
      cm.on("viewportChange", function() {
        if (self.cm.doc.height != self.height) self.signal()
      })
    }
  
    TrackAlignable.prototype = {
      signal: function() {
        CodeMirror.signal(this, "realign")
        this.height = this.cm.doc.height
      },
  
      set: function(n, flags) {
        var pos = -1
        for (; pos < this.alignable.length; pos += 2) {
          var diff = this.alignable[pos] - n
          if (diff == 0) {
            if ((this.alignable[pos + 1] & flags) == flags) return
            this.alignable[pos + 1] |= flags
            this.signal()
            return
          }
          if (diff > 0) break
        }
        this.signal()
        this.alignable.splice(pos, 0, n, flags)
      },
  
      find: function(n) {
        for (var i = 0; i < this.alignable.length; i += 2)
          if (this.alignable[i] == n) return i
        return -1
      },
  
      check: function(n, flag, pred) {
        var found = this.find(n)
        if (found == -1 || !(this.alignable[found + 1] & flag)) return
        if (!pred.call(this, n)) {
          this.signal()
          var flags = this.alignable[found + 1] & ~flag
          if (flags) this.alignable[found + 1] = flags
          else this.alignable.splice(found, 2)
        }
      },
  
      hasMarker: function(n) {
        var handle = this.cm.getLineHandle(n)
        if (handle.markedSpans) for (var i = 0; i < handle.markedSpans.length; i++)
          if (handle.markedSpans[i].mark.collapsed && handle.markedSpans[i].to != null)
            return true
        return false
      },
  
      hasWidget: function(n) {
        var handle = this.cm.getLineHandle(n)
        if (handle.widgets) for (var i = 0; i < handle.widgets.length; i++)
          if (!handle.widgets[i].above && !handle.widgets[i].mergeSpacer) return true
        return false
      },
  
      hasWidgetBelow: function(n) {
        if (n == this.cm.lastLine()) return false
        var handle = this.cm.getLineHandle(n + 1)
        if (handle.widgets) for (var i = 0; i < handle.widgets.length; i++)
          if (handle.widgets[i].above && !handle.widgets[i].mergeSpacer) return true
        return false
      },
  
      map: function(from, nBefore, nAfter) {
        var diff = nAfter - nBefore, to = from + nBefore, widgetFrom = -1, widgetTo = -1
        for (var i = 0; i < this.alignable.length; i += 2) {
          var n = this.alignable[i]
          if (n == from && (this.alignable[i + 1] & F_WIDGET_BELOW)) widgetFrom = i
          if (n == to && (this.alignable[i + 1] & F_WIDGET_BELOW)) widgetTo = i
          if (n <= from) continue
          else if (n < to) this.alignable.splice(i--, 2)
          else this.alignable[i] += diff
        }
        if (widgetFrom > -1) {
          var flags = this.alignable[widgetFrom + 1]
          if (flags == F_WIDGET_BELOW) this.alignable.splice(widgetFrom, 2)
          else this.alignable[widgetFrom + 1] = flags & ~F_WIDGET_BELOW
        }
        if (widgetTo > -1 && nAfter)
          this.set(from + nAfter, F_WIDGET_BELOW)
      }
    }
  
    function posMin(a, b) { return (a.line - b.line || a.ch - b.ch) < 0 ? a : b; }
    function posMax(a, b) { return (a.line - b.line || a.ch - b.ch) > 0 ? a : b; }
    function posEq(a, b) { return a.line == b.line && a.ch == b.ch; }
  
    function findPrevDiff(chunks, start, isOrig) {
      for (var i = chunks.length - 1; i >= 0; i--) {
        var chunk = chunks[i];
        var to = (isOrig ? chunk.origTo : chunk.editTo) - 1;
        if (to < start) return to;
      }
    }
  
    function findNextDiff(chunks, start, isOrig) {
      for (var i = 0; i < chunks.length; i++) {
        var chunk = chunks[i];
        var from = (isOrig ? chunk.origFrom : chunk.editFrom);
        if (from > start) return from;
      }
    }
  
    function goNearbyDiff(cm, dir) {
      var found = null, views = cm.state.diffViews, line = cm.getCursor().line;
      if (views) for (var i = 0; i < views.length; i++) {
        var dv = views[i], isOrig = cm == dv.orig;
        ensureDiff(dv);
        var pos = dir < 0 ? findPrevDiff(dv.chunks, line, isOrig) : findNextDiff(dv.chunks, line, isOrig);
        if (pos != null && (found == null || (dir < 0 ? pos > found : pos < found)))
          found = pos;
      }
      if (found != null)
        cm.setCursor(found, 0);
      else
        return CodeMirror.Pass;
    }
  
    CodeMirror.commands.goNextDiff = function(cm) {
      return goNearbyDiff(cm, 1);
    };
    CodeMirror.commands.goPrevDiff = function(cm) {
      return goNearbyDiff(cm, -1);
    };
  });
  