overleaf/services/web/public/js/ace/multi_select.js

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define(function(require, exports, module) {

var RangeList = require("./range_list").RangeList;
var Range = require("./range").Range;
var Selection = require("./selection").Selection;
var onMouseDown = require("./mouse/multi_select_handler").onMouseDown;
var event = require("./lib/event");
var lang = require("./lib/lang");
var commands = require("./commands/multi_select_commands");
exports.commands = commands.defaultCommands.concat(commands.multiSelectCommands);

// Todo: session.find or editor.findVolatile that returns range
var Search = require("./search").Search;
var search = new Search();

function find(session, needle, dir) {
    search.$options.wrap = true;
    search.$options.needle = needle;
    search.$options.backwards = dir == -1;
    return search.find(session);
}

// extend EditSession
var EditSession = require("./edit_session").EditSession;
(function() {
    this.getSelectionMarkers = function() {
        return this.$selectionMarkers;
    };
}).call(EditSession.prototype);

// extend Selection
(function() {
    // list of ranges in reverse addition order
    this.ranges = null;

    // automatically sorted list of ranges
    this.rangeList = null;

    /** 
     * Adds a range to a selection by entering multiselect mode, if necessary.
     * @param {Range} range The new range to add
     * @param {Boolean} $blockChangeEvents Whether or not to block changing events
     * @method Selection.addRange
     **/
    this.addRange = function(range, $blockChangeEvents) {
        if (!range)
            return;

        if (!this.inMultiSelectMode && this.rangeCount == 0) {
            var oldRange = this.toOrientedRange();
            this.rangeList.add(oldRange);
            this.rangeList.add(range);
            if (this.rangeList.ranges.length != 2) {
                this.rangeList.removeAll();
                return $blockChangeEvents || this.fromOrientedRange(range);
            }
            this.rangeList.removeAll();
            this.rangeList.add(oldRange);
            this.$onAddRange(oldRange);
        }

        if (!range.cursor)
            range.cursor = range.end;

        var removed = this.rangeList.add(range);

        this.$onAddRange(range);

        if (removed.length)
            this.$onRemoveRange(removed);

        if (this.rangeCount > 1 && !this.inMultiSelectMode) {
            this._emit("multiSelect");
            this.inMultiSelectMode = true;
            this.session.$undoSelect = false;
            this.rangeList.attach(this.session);
        }

        return $blockChangeEvents || this.fromOrientedRange(range);
    };

    /**
     * @method Selection.toSingleRange
     **/

    this.toSingleRange = function(range) {
        range = range || this.ranges[0];
        var removed = this.rangeList.removeAll();
        if (removed.length)
            this.$onRemoveRange(removed);

        range && this.fromOrientedRange(range);
    };

    /**
     * Removes a Range containing pos (if it exists).
     * @param {Range} pos The position to remove, as a `{row, column}` object
     * @method Selection.substractPoint
     **/
    this.substractPoint = function(pos) {
        var removed = this.rangeList.substractPoint(pos);
        if (removed) {
            this.$onRemoveRange(removed);
            return removed[0];
        }
    };

    /**
     * Merges overlapping ranges ensuring consistency after changes
     * @method Selection.mergeOverlappingRanges
     **/
    this.mergeOverlappingRanges = function() {
        var removed = this.rangeList.merge();
        if (removed.length)
            this.$onRemoveRange(removed);
        else if(this.ranges[0])
            this.fromOrientedRange(this.ranges[0]);
    };

    this.$onAddRange = function(range) {
        this.rangeCount = this.rangeList.ranges.length;
        this.ranges.unshift(range);
        this._emit("addRange", {range: range});
    };

    this.$onRemoveRange = function(removed) {
        this.rangeCount = this.rangeList.ranges.length;
        if (this.rangeCount == 1 && this.inMultiSelectMode) {
            var lastRange = this.rangeList.ranges.pop();
            removed.push(lastRange);
            this.rangeCount = 0;
        }

        for (var i = removed.length; i--; ) {
            var index = this.ranges.indexOf(removed[i]);
            this.ranges.splice(index, 1);
        }

        this._emit("removeRange", {ranges: removed});

        if (this.rangeCount == 0 && this.inMultiSelectMode) {
            this.inMultiSelectMode = false;
            this._emit("singleSelect");
            this.session.$undoSelect = true;
            this.rangeList.detach(this.session);
        }

        lastRange = lastRange || this.ranges[0];
        if (lastRange && !lastRange.isEqual(this.getRange()))
            this.fromOrientedRange(lastRange);
    };

    // adds multicursor support to selection
    this.$initRangeList = function() {
        if (this.rangeList)
            return;

        this.rangeList = new RangeList();
        this.ranges = [];
        this.rangeCount = 0;
    };

    /**
     * Returns a concatenation of all the ranges.
     * @returns {Array}
     * @method Selection.getAllRanges
     **/
    this.getAllRanges = function() {
        return this.rangeCount ? this.rangeList.ranges.concat() : [this.getRange()];
    };

    /**
     * Splits all the ranges into lines.
     * @method Selection.splitIntoLines
     **/

    this.splitIntoLines = function () {
        if (this.rangeCount > 1) {
            var ranges = this.rangeList.ranges;
            var lastRange = ranges[ranges.length - 1];
            var range = Range.fromPoints(ranges[0].start, lastRange.end);

            this.toSingleRange();
            this.setSelectionRange(range, lastRange.cursor == lastRange.start);
        } else {
            var range = this.getRange();
            var isBackwards = this.isBackwards();
            var startRow = range.start.row;
            var endRow = range.end.row;
            if (startRow == endRow) {
                if (isBackwards)
                    var start = range.end, end = range.start;
                else
                    var start = range.start, end = range.end;
                
                this.addRange(Range.fromPoints(end, end));
                this.addRange(Range.fromPoints(start, start));
                return;
            }

            var rectSel = [];
            var r = this.getLineRange(startRow, true);
            r.start.column = range.start.column;
            rectSel.push(r);

            for (var i = startRow + 1; i < endRow; i++)
                rectSel.push(this.getLineRange(i, true));

            r = this.getLineRange(endRow, true);
            r.end.column = range.end.column;
            rectSel.push(r);

            rectSel.forEach(this.addRange, this);
        }
    };

    /**
     * @method Selection.toggleBlockSelection
     **/
    this.toggleBlockSelection = function () {
        if (this.rangeCount > 1) {
            var ranges = this.rangeList.ranges;
            var lastRange = ranges[ranges.length - 1];
            var range = Range.fromPoints(ranges[0].start, lastRange.end);

            this.toSingleRange();
            this.setSelectionRange(range, lastRange.cursor == lastRange.start);
        } else {
            var cursor = this.session.documentToScreenPosition(this.selectionLead);
            var anchor = this.session.documentToScreenPosition(this.selectionAnchor);

            var rectSel = this.rectangularRangeBlock(cursor, anchor);
            rectSel.forEach(this.addRange, this);
        }
    };

    /**
     * 
     * Gets list of ranges composing rectangular block on the screen
     * 
     * @param {Cursor} screenCursor The cursor to use
     * @param {Anchor} screenAnchor The anchor to use
     * @param {Boolean} includeEmptyLines If true, this includes ranges inside the block which are empty due to clipping
     * @returns {Range}
     * @method Selection.rectangularRangeBlock
     **/
    this.rectangularRangeBlock = function(screenCursor, screenAnchor, includeEmptyLines) {
        var rectSel = [];

        var xBackwards = screenCursor.column < screenAnchor.column;
        if (xBackwards) {
            var startColumn = screenCursor.column;
            var endColumn = screenAnchor.column;
        } else {
            var startColumn = screenAnchor.column;
            var endColumn = screenCursor.column;
        }

        var yBackwards = screenCursor.row < screenAnchor.row;
        if (yBackwards) {
            var startRow = screenCursor.row;
            var endRow = screenAnchor.row;
        } else {
            var startRow = screenAnchor.row;
            var endRow = screenCursor.row;
        }

        if (startColumn < 0)
            startColumn = 0;
        if (startRow < 0)
            startRow = 0;

        if (startRow == endRow)
            includeEmptyLines = true;

        for (var row = startRow; row <= endRow; row++) {
            var range = Range.fromPoints(
                this.session.screenToDocumentPosition(row, startColumn),
                this.session.screenToDocumentPosition(row, endColumn)
            );
            if (range.isEmpty()) {
                if (docEnd && isSamePoint(range.end, docEnd))
                    break;
                var docEnd = range.end;
            }
            range.cursor = xBackwards ? range.start : range.end;
            rectSel.push(range);
        }

        if (yBackwards)
            rectSel.reverse();

        if (!includeEmptyLines) {
            var end = rectSel.length - 1;
            while (rectSel[end].isEmpty() && end > 0)
                end--;
            if (end > 0) {
                var start = 0;
                while (rectSel[start].isEmpty())
                    start++;
            }
            for (var i = end; i >= start; i--) {
                if (rectSel[i].isEmpty())
                    rectSel.splice(i, 1);
            }
        }

        return rectSel;
    };
}).call(Selection.prototype);

// extend Editor
var Editor = require("./editor").Editor;
(function() {

    /** 
     * 
     * Updates the cursor and marker layers.
     * @method Editor.updateSelectionMarkers
     *
     **/
    this.updateSelectionMarkers = function() {
        this.renderer.updateCursor();
        this.renderer.updateBackMarkers();
    };

    /** 
     * Adds the selection and cursor.
     * @param {Range} orientedRange A range containing a cursor
     * @returns {Range}
     * @method Editor.addSelectionMarker
     **/
    this.addSelectionMarker = function(orientedRange) {
        if (!orientedRange.cursor)
            orientedRange.cursor = orientedRange.end;

        var style = this.getSelectionStyle();
        orientedRange.marker = this.session.addMarker(orientedRange, "ace_selection", style);

        this.session.$selectionMarkers.push(orientedRange);
        this.session.selectionMarkerCount = this.session.$selectionMarkers.length;
        return orientedRange;
    };

    /** 
     * Removes the selection marker.
     * @param {Range} range The selection range added with [[Editor.addSelectionMarker `addSelectionMarker()`]].
     * @method Editor.removeSelectionMarker
     **/
    this.removeSelectionMarker = function(range) {
        if (!range.marker)
            return;
        this.session.removeMarker(range.marker);
        var index = this.session.$selectionMarkers.indexOf(range);
        if (index != -1)
            this.session.$selectionMarkers.splice(index, 1);
        this.session.selectionMarkerCount = this.session.$selectionMarkers.length;
    };

    this.removeSelectionMarkers = function(ranges) {
        var markerList = this.session.$selectionMarkers;
        for (var i = ranges.length; i--; ) {
            var range = ranges[i];
            if (!range.marker)
                continue;
            this.session.removeMarker(range.marker);
            var index = markerList.indexOf(range);
            if (index != -1)
                markerList.splice(index, 1);
        }
        this.session.selectionMarkerCount = markerList.length;
    };

    this.$onAddRange = function(e) {
        this.addSelectionMarker(e.range);
        this.renderer.updateCursor();
        this.renderer.updateBackMarkers();
    };

    this.$onRemoveRange = function(e) {
        this.removeSelectionMarkers(e.ranges);
        this.renderer.updateCursor();
        this.renderer.updateBackMarkers();
    };

    this.$onMultiSelect = function(e) {
        if (this.inMultiSelectMode)
            return;
        this.inMultiSelectMode = true;

        this.setStyle("ace_multiselect");
        this.keyBinding.addKeyboardHandler(commands.keyboardHandler);
        this.commands.setDefaultHandler("exec", this.$onMultiSelectExec);

        this.renderer.updateCursor();
        this.renderer.updateBackMarkers();
    };

    this.$onSingleSelect = function(e) {
        if (this.session.multiSelect.inVirtualMode)
            return;
        this.inMultiSelectMode = false;

        this.unsetStyle("ace_multiselect");
        this.keyBinding.removeKeyboardHandler(commands.keyboardHandler);

        this.commands.removeDefaultHandler("exec", this.$onMultiSelectExec);
        this.renderer.updateCursor();
        this.renderer.updateBackMarkers();
    };

    this.$onMultiSelectExec = function(e) {
        var command = e.command;
        var editor = e.editor;
        if (!editor.multiSelect)
            return;
        if (!command.multiSelectAction) {
            var result = command.exec(editor, e.args || {});
            editor.multiSelect.addRange(editor.multiSelect.toOrientedRange());
            editor.multiSelect.mergeOverlappingRanges();
        } else if (command.multiSelectAction == "forEach") {
            result = editor.forEachSelection(command, e.args);
        } else if (command.multiSelectAction == "forEachLine") {
            result = editor.forEachSelection(command, e.args, true);
        } else if (command.multiSelectAction == "single") {
            editor.exitMultiSelectMode();
            result = command.exec(editor, e.args || {});
        } else {
            result = command.multiSelectAction(editor, e.args || {});
        }
        return result;
    };

    /** 
     * Executes a command for each selection range.
     * @param {String} cmd The command to execute
     * @param {String} args Any arguments for the command
     * @method Editor.forEachSelection
     **/ 
    this.forEachSelection = function(cmd, args, $byLines) {
        if (this.inVirtualSelectionMode)
            return;

        var session = this.session;
        var selection = this.selection;
        var rangeList = selection.rangeList;
        var result;
        
        var reg = selection._eventRegistry;
        selection._eventRegistry = {};

        var tmpSel = new Selection(session);
        this.inVirtualSelectionMode = true;
        for (var i = rangeList.ranges.length; i--;) {
            if ($byLines) {
                while (i > 0 && rangeList.ranges[i].start.row == rangeList.ranges[i - 1].end.row)
                    i--;
            }
            tmpSel.fromOrientedRange(rangeList.ranges[i]);
            this.selection = session.selection = tmpSel;
            var cmdResult = cmd.exec(this, args || {});
            if (!result == undefined)
                result = cmdResult;
            tmpSel.toOrientedRange(rangeList.ranges[i]);
        }
        tmpSel.detach();

        this.selection = session.selection = selection;
        this.inVirtualSelectionMode = false;
        selection._eventRegistry = reg;
        selection.mergeOverlappingRanges();
        
        var anim = this.renderer.$scrollAnimation;
        this.onCursorChange();
        this.onSelectionChange();
        if (anim && anim.from == anim.to)
            this.renderer.animateScrolling(anim.from);
        
        return result;
    };

    /** 
    * Removes all the selections except the last added one.
    * @method Editor.exitMultiSelectMode
    **/
    this.exitMultiSelectMode = function() {
        if (!this.inMultiSelectMode || this.inVirtualSelectionMode)
            return;
        this.multiSelect.toSingleRange();
    };

    this.getSelectedText = function() {
        var text = "";
        if (this.inMultiSelectMode && !this.inVirtualSelectionMode) {
            var ranges = this.multiSelect.rangeList.ranges;
            var buf = [];
            for (var i = 0; i < ranges.length; i++) {
                buf.push(this.session.getTextRange(ranges[i]));
            }
            var nl = this.session.getDocument().getNewLineCharacter();
            text = buf.join(nl);
            if (text.length == (buf.length - 1) * nl.length)
                text = "";
        } else if (!this.selection.isEmpty()) {
            text = this.session.getTextRange(this.getSelectionRange());
        }
        return text;
    };

    // todo this should change when paste becomes a command
    this.onPaste = function(text) {
        if (this.$readOnly)
            return;

        this._signal("paste", text);
        if (!this.inMultiSelectMode || this.inVirtualSelectionMode)
            return this.insert(text);

        var lines = text.split(/\r\n|\r|\n/);
        var ranges = this.selection.rangeList.ranges;

        if (lines.length > ranges.length || lines.length < 2 || !lines[1])
            return this.commands.exec("insertstring", this, text);

        for (var i = ranges.length; i--;) {
            var range = ranges[i];
            if (!range.isEmpty())
                this.session.remove(range);

            this.session.insert(range.start, lines[i]);
        }
    };

    /**
     * Finds and selects all the occurences of `needle`.
     * @param {String} The text to find
     * @param {Object} The search options
     * @param {Boolean} keeps
     *
     * @returns {Number} The cumulative count of all found matches 
     * @method Editor.findAll
     **/
    this.findAll = function(needle, options, additive) {
        options = options || {};
        options.needle = needle || options.needle;
        this.$search.set(options);

        var ranges = this.$search.findAll(this.session);
        if (!ranges.length)
            return 0;

        this.$blockScrolling += 1;
        var selection = this.multiSelect;

        if (!additive)
            selection.toSingleRange(ranges[0]);

        for (var i = ranges.length; i--; )
            selection.addRange(ranges[i], true);

        this.$blockScrolling -= 1;

        return ranges.length;
    };

    /**
     * Adds a cursor above or below the active cursor.
     * 
     * @param {Number} dir The direction of lines to select: -1 for up, 1 for down
     * @param {Boolean} skip If `true`, removes the active selection range
     *
     * @method Editor.selectMoreLines 
     */
    this.selectMoreLines = function(dir, skip) {
        var range = this.selection.toOrientedRange();
        var isBackwards = range.cursor == range.end;

        var screenLead = this.session.documentToScreenPosition(range.cursor);
        if (this.selection.$desiredColumn)
            screenLead.column = this.selection.$desiredColumn;

        var lead = this.session.screenToDocumentPosition(screenLead.row + dir, screenLead.column);

        if (!range.isEmpty()) {
            var screenAnchor = this.session.documentToScreenPosition(isBackwards ? range.end : range.start);
            var anchor = this.session.screenToDocumentPosition(screenAnchor.row + dir, screenAnchor.column);
        } else {
            var anchor = lead;
        }

        if (isBackwards) {
            var newRange = Range.fromPoints(lead, anchor);
            newRange.cursor = newRange.start;
        } else {
            var newRange = Range.fromPoints(anchor, lead);
            newRange.cursor = newRange.end;
        }

        newRange.desiredColumn = screenLead.column;
        if (!this.selection.inMultiSelectMode) {
            this.selection.addRange(range);
        } else {
            if (skip)
                var toRemove = range.cursor;
        }

        this.selection.addRange(newRange);
        if (toRemove)
            this.selection.substractPoint(toRemove);
    };

    /** 
     * Transposes the selected ranges.
     * @param {Number} dir The direction to rotate selections
     * @method Editor.transposeSelections
     **/
    this.transposeSelections = function(dir) {
        var session = this.session;
        var sel = session.multiSelect;
        var all = sel.ranges;

        for (var i = all.length; i--; ) {
            var range = all[i];
            if (range.isEmpty()) {
                var tmp = session.getWordRange(range.start.row, range.start.column);
                range.start.row = tmp.start.row;
                range.start.column = tmp.start.column;
                range.end.row = tmp.end.row;
                range.end.column = tmp.end.column;
            }
        }
        sel.mergeOverlappingRanges();

        var words = [];
        for (var i = all.length; i--; ) {
            var range = all[i];
            words.unshift(session.getTextRange(range));
        }

        if (dir < 0)
            words.unshift(words.pop());
        else
            words.push(words.shift());

        for (var i = all.length; i--; ) {
            var range = all[i];
            var tmp = range.clone();
            session.replace(range, words[i]);
            range.start.row = tmp.start.row;
            range.start.column = tmp.start.column;
        }
    };

    /** 
     * Finds the next occurence of text in an active selection and adds it to the selections.
     * @param {Number} dir The direction of lines to select: -1 for up, 1 for down
     * @param {Boolean} skip If `true`, removes the active selection range
     * @method Editor.selectMore
     **/
    this.selectMore = function(dir, skip) {
        var session = this.session;
        var sel = session.multiSelect;

        var range = sel.toOrientedRange();
        if (range.isEmpty()) {
            range = session.getWordRange(range.start.row, range.start.column);
            range.cursor = dir == -1 ? range.start : range.end;
            this.multiSelect.addRange(range);
            // todo add option for sublime like behavior
            // return;
        }
        var needle = session.getTextRange(range);

        var newRange = find(session, needle, dir);
        if (newRange) {
            newRange.cursor = dir == -1 ? newRange.start : newRange.end;
            this.$blockScrolling += 1;
            this.session.unfold(newRange);
            this.multiSelect.addRange(newRange);
            this.$blockScrolling -= 1;
            this.renderer.scrollCursorIntoView(null, 0.5);
        }
        if (skip)
            this.multiSelect.substractPoint(range.cursor);
    };

    /** 
     * Aligns the cursors or selected text.
     * @method Editor.alignCursors
     **/
    this.alignCursors = function() {
        var session = this.session;
        var sel = session.multiSelect;
        var ranges = sel.ranges;

        if (!ranges.length) {
            var range = this.selection.getRange();
            var fr = range.start.row, lr = range.end.row;
            var guessRange = fr == lr;
            if (guessRange) {
                var max = this.session.getLength();
                var line;
                do {
                    line = this.session.getLine(lr);
                } while (/[=:]/.test(line) && ++lr < max);
                do {
                    line = this.session.getLine(fr);
                } while (/[=:]/.test(line) && --fr > 0);
                
                if (fr < 0) fr = 0;
                if (lr >= max) lr = max - 1;
            }
            var lines = this.session.doc.removeLines(fr, lr);
            lines = this.$reAlignText(lines, guessRange);
            this.session.doc.insert({row: fr, column: 0}, lines.join("\n") + "\n");
            if (!guessRange) {
                range.start.column = 0;
                range.end.column = lines[lines.length - 1].length;
            }
            this.selection.setRange(range);
        } else {
            // filter out ranges on same row
            var row = -1;
            var sameRowRanges = ranges.filter(function(r) {
                if (r.cursor.row == row)
                    return true;
                row = r.cursor.row;
            });
            sel.$onRemoveRange(sameRowRanges);

            var maxCol = 0;
            var minSpace = Infinity;
            var spaceOffsets = ranges.map(function(r) {
                var p = r.cursor;
                var line = session.getLine(p.row);
                var spaceOffset = line.substr(p.column).search(/\S/g);
                if (spaceOffset == -1)
                    spaceOffset = 0;

                if (p.column > maxCol)
                    maxCol = p.column;
                if (spaceOffset < minSpace)
                    minSpace = spaceOffset;
                return spaceOffset;
            });
            ranges.forEach(function(r, i) {
                var p = r.cursor;
                var l = maxCol - p.column;
                var d = spaceOffsets[i] - minSpace;
                if (l > d)
                    session.insert(p, lang.stringRepeat(" ", l - d));
                else
                    session.remove(new Range(p.row, p.column, p.row, p.column - l + d));

                r.start.column = r.end.column = maxCol;
                r.start.row = r.end.row = p.row;
                r.cursor = r.end;
            });
            sel.fromOrientedRange(ranges[0]);
            this.renderer.updateCursor();
            this.renderer.updateBackMarkers();
        }
    };

    this.$reAlignText = function(lines, forceLeft) {
        var isLeftAligned = true, isRightAligned = true;
        var startW, textW, endW;

        return lines.map(function(line) {
            var m = line.match(/(\s*)(.*?)(\s*)([=:].*)/);
            if (!m)
                return [line];

            if (startW == null) {
                startW = m[1].length;
                textW = m[2].length;
                endW = m[3].length;
                return m;
            }

            if (startW + textW + endW != m[1].length + m[2].length + m[3].length)
                isRightAligned = false;
            if (startW != m[1].length)
                isLeftAligned = false;

            if (startW > m[1].length)
                startW = m[1].length;
            if (textW < m[2].length)
                textW = m[2].length;
            if (endW > m[3].length)
                endW = m[3].length;

            return m;
        }).map(forceLeft ? alignLeft :
            isLeftAligned ? isRightAligned ? alignRight : alignLeft : unAlign);

        function spaces(n) {
            return lang.stringRepeat(" ", n);
        }

        function alignLeft(m) {
            return !m[2] ? m[0] : spaces(startW) + m[2]
                + spaces(textW - m[2].length + endW)
                + m[4].replace(/^([=:])\s+/, "$1 ")
        }
        function alignRight(m) {
            return !m[2] ? m[0] : spaces(startW + textW - m[2].length) + m[2]
                + spaces(endW, " ")
                + m[4].replace(/^([=:])\s+/, "$1 ")
        }
        function unAlign(m) {
            return !m[2] ? m[0] : spaces(startW) + m[2]
                + spaces(endW)
                + m[4].replace(/^([=:])\s+/, "$1 ")
        }
    }
}).call(Editor.prototype);


function isSamePoint(p1, p2) {
    return p1.row == p2.row && p1.column == p2.column;
}

// patch
// adds multicursor support to a session
exports.onSessionChange = function(e) {
    var session = e.session;
    if (!session.multiSelect) {
        session.$selectionMarkers = [];
        session.selection.$initRangeList();
        session.multiSelect = session.selection;
    }
    this.multiSelect = session.multiSelect;

    var oldSession = e.oldSession;
    if (oldSession) {
        oldSession.multiSelect.removeEventListener("addRange", this.$onAddRange);
        oldSession.multiSelect.removeEventListener("removeRange", this.$onRemoveRange);
        oldSession.multiSelect.removeEventListener("multiSelect", this.$onMultiSelect);
        oldSession.multiSelect.removeEventListener("singleSelect", this.$onSingleSelect);
    }

    session.multiSelect.on("addRange", this.$onAddRange);
    session.multiSelect.on("removeRange", this.$onRemoveRange);
    session.multiSelect.on("multiSelect", this.$onMultiSelect);
    session.multiSelect.on("singleSelect", this.$onSingleSelect);

    // this.$onSelectionChange = this.onSelectionChange.bind(this);

    if (this.inMultiSelectMode != session.selection.inMultiSelectMode) {
        if (session.selection.inMultiSelectMode)
            this.$onMultiSelect();
        else
            this.$onSingleSelect();
    }
};

// MultiSelect(editor)
// adds multiple selection support to the editor
// (note: should be called only once for each editor instance)
function MultiSelect(editor) {
    if (editor.$multiselectOnSessionChange)
        return;
    editor.$onAddRange = editor.$onAddRange.bind(editor);
    editor.$onRemoveRange = editor.$onRemoveRange.bind(editor);
    editor.$onMultiSelect = editor.$onMultiSelect.bind(editor);
    editor.$onSingleSelect = editor.$onSingleSelect.bind(editor);
    editor.$multiselectOnSessionChange = exports.onSessionChange.bind(editor);

    editor.$multiselectOnSessionChange(editor);
    editor.on("changeSession", editor.$multiselectOnSessionChange);

    editor.on("mousedown", onMouseDown);
    editor.commands.addCommands(commands.defaultCommands);

    addAltCursorListeners(editor);
}

function addAltCursorListeners(editor){
    var el = editor.textInput.getElement();
    var altCursor = false;
    event.addListener(el, "keydown", function(e) {
        if (e.keyCode == 18 && !(e.ctrlKey || e.shiftKey || e.metaKey)) {
            if (!altCursor) {
                editor.renderer.setMouseCursor("crosshair");
                altCursor = true;
            }
        } else if (altCursor) {
            reset();
        }
    });

    event.addListener(el, "keyup", reset);
    event.addListener(el, "blur", reset);
    function reset(e) {
        if (altCursor) {
            editor.renderer.setMouseCursor("");
            altCursor = false;
            // TODO disable menu poping up
            // e && e.preventDefault()
        }
    }
}

exports.MultiSelect = MultiSelect;


require("./config").defineOptions(Editor.prototype, "editor", {
    enableMultiselect: {
        set: function(val) {
            MultiSelect(this);
            if (val) {
                this.on("changeSession", this.$multiselectOnSessionChange);
                this.on("mousedown", onMouseDown);
            } else {
                this.off("changeSession", this.$multiselectOnSessionChange);
                this.off("mousedown", onMouseDown);
            }
        },
        value: true
    }
})



});