select2/select2.js

/*
Copyright 2012 Igor Vaynberg

Version: @@ver@@ Timestamp: @@timestamp@@

This software is licensed under the Apache License, Version 2.0 (the "Apache License") or the GNU
General Public License version 2 (the "GPL License"). You may choose either license to govern your
use of this software only upon the condition that you accept all of the terms of either the Apache
License or the GPL License.

You may obtain a copy of the Apache License and the GPL License at:

    http://www.apache.org/licenses/LICENSE-2.0
    http://www.gnu.org/licenses/gpl-2.0.html

Unless required by applicable law or agreed to in writing, software distributed under the
Apache License or the GPL License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied. See the Apache License and the GPL License for
the specific language governing permissions and limitations under the Apache License and the GPL License.
*/
(function ($) {
    if(typeof $.fn.each2 == "undefined") {
        $.extend($.fn, {
            /*
            * 4-10 times faster .each replacement
            * use it carefully, as it overrides jQuery context of element on each iteration
            */
            each2 : function (c) {
                var j = $([0]), i = -1, l = this.length;
                while (
                    ++i < l
                    && (j.context = j[0] = this[i])
                    && c.call(j[0], i, j) !== false //"this"=DOM, i=index, j=jQuery object
                );
                return this;
            }
        });
    }
})(jQuery);

(function ($, undefined) {
    "use strict";
    /*global document, window, jQuery, console */

    if (window.Select2 !== undefined) {
        return;
    }

    var KEY, AbstractSelect2, SingleSelect2, MultiSelect2, nextUid, sizer,
        lastMousePosition={x:0,y:0}, $document, scrollBarDimensions,

    KEY = {
        TAB: 9,
        ENTER: 13,
        ESC: 27,
        SPACE: 32,
        LEFT: 37,
        UP: 38,
        RIGHT: 39,
        DOWN: 40,
        SHIFT: 16,
        CTRL: 17,
        ALT: 18,
        PAGE_UP: 33,
        PAGE_DOWN: 34,
        HOME: 36,
        END: 35,
        BACKSPACE: 8,
        DELETE: 46,
        isArrow: function (k) {
            k = k.which ? k.which : k;
            switch (k) {
            case KEY.LEFT:
            case KEY.RIGHT:
            case KEY.UP:
            case KEY.DOWN:
                return true;
            }
            return false;
        },
        isControl: function (e) {
            var k = e.which;
            switch (k) {
            case KEY.SHIFT:
            case KEY.CTRL:
            case KEY.ALT:
                return true;
            }

            if (e.metaKey) return true;

            return false;
        },
        isFunctionKey: function (k) {
            k = k.which ? k.which : k;
            return k >= 112 && k <= 123;
        }
    },
    MEASURE_SCROLLBAR_TEMPLATE = "<div class='select2-measure-scrollbar'></div>",

    DIACRITICS = {"\u24B6":"A","\uFF21":"A","\u00C0":"A","\u00C1":"A","\u00C2":"A","\u1EA6":"A","\u1EA4":"A","\u1EAA":"A","\u1EA8":"A","\u00C3":"A","\u0100":"A","\u0102":"A","\u1EB0":"A","\u1EAE":"A","\u1EB4":"A","\u1EB2":"A","\u0226":"A","\u01E0":"A","\u00C4":"A","\u01DE":"A","\u1EA2":"A","\u00C5":"A","\u01FA":"A","\u01CD":"A","\u0200":"A","\u0202":"A","\u1EA0":"A","\u1EAC":"A","\u1EB6":"A","\u1E00":"A","\u0104":"A","\u023A":"A","\u2C6F":"A","\uA732":"AA","\u00C6":"AE","\u01FC":"AE","\u01E2":"AE","\uA734":"AO","\uA736":"AU","\uA738":"AV","\uA73A":"AV","\uA73C":"AY","\u24B7":"B","\uFF22":"B","\u1E02":"B","\u1E04":"B","\u1E06":"B","\u0243":"B","\u0182":"B","\u0181":"B","\u24B8":"C","\uFF23":"C","\u0106":"C","\u0108":"C","\u010A":"C","\u010C":"C","\u00C7":"C","\u1E08":"C","\u0187":"C","\u023B":"C","\uA73E":"C","\u24B9":"D","\uFF24":"D","\u1E0A":"D","\u010E":"D","\u1E0C":"D","\u1E10":"D","\u1E12":"D","\u1E0E":"D","\u0110":"D","\u018B":"D","\u018A":"D","\u0189":"D","\uA779":"D","\u01F1":"DZ","\u01C4":"DZ","\u01F2":"Dz","\u01C5":"Dz","\u24BA":"E","\uFF25":"E","\u00C8":"E","\u00C9":"E","\u00CA":"E","\u1EC0":"E","\u1EBE":"E","\u1EC4":"E","\u1EC2":"E","\u1EBC":"E","\u0112":"E","\u1E14":"E","\u1E16":"E","\u0114":"E","\u0116":"E","\u00CB":"E","\u1EBA":"E","\u011A":"E","\u0204":"E","\u0206":"E","\u1EB8":"E","\u1EC6":"E","\u0228":"E","\u1E1C":"E","\u0118":"E","\u1E18":"E","\u1E1A":"E","\u0190":"E","\u018E":"E","\u24BB":"F","\uFF26":"F","\u1E1E":"F","\u0191":"F","\uA77B":"F","\u24BC":"G","\uFF27":"G","\u01F4":"G","\u011C":"G","\u1E20":"G","\u011E":"G","\u0120":"G","\u01E6":"G","\u0122":"G","\u01E4":"G","\u0193":"G","\uA7A0":"G","\uA77D":"G","\uA77E":"G","\u24BD":"H","\uFF28":"H","\u0124":"H","\u1E22":"H","\u1E26":"H","\u021E":"H","\u1E24":"H","\u1E28":"H","\u1E2A":"H","\u0126":"H","\u2C67":"H","\u2C75":"H","\uA78D":"H","\u24BE":"I","\uFF29":"I","\u00CC":"I","\u00CD":"I","\u00CE":"I","\u0128":"I","\u012A":"I","\u012C":"I","\u0130":"I","\u00CF":"I","\u1E2E":"I","\u1EC8":"I","\u01CF":"I","\u0208":"I","\u020A":"I","\u1ECA":"I","\u012E":"I","\u1E2C":"I","\u0197":"I","\u24BF":"J","\uFF2A":"J","\u0134":"J","\u0248":"J","\u24C0":"K","\uFF2B":"K","\u1E30":"K","\u01E8":"K","\u1E32":"K","\u0136":"K","\u1E34":"K","\u0198":"K","\u2C69":"K","\uA740":"K","\uA742":"K","\uA744":"K","\uA7A2":"K","\u24C1":"L","\uFF2C":"L","\u013F":"L","\u0139":"L","\u013D":"L","\u1E36":"L","\u1E38":"L","\u013B":"L","\u1E3C":"L","\u1E3A":"L","\u0141":"L","\u023D":"L","\u2C62":"L","\u2C60":"L","\uA748":"L","\uA746":"L","\uA780":"L","\u01C7":"LJ","\u01C8":"Lj","\u24C2":"M","\uFF2D":"M","\u1E3E":"M","\u1E40":"M","\u1E42":"M","\u2C6E":"M","\u019C":"M","\u24C3":"N","\uFF2E":"N","\u01F8":"N","\u0143":"N","\u00D1":"N","\u1E44":"N","\u0147":"N","\u1E46":"N","\u0145":"N","\u1E4A":"N","\u1E48":"N","\u0220":"N","\u019D":"N","\uA790":"N","\uA7A4":"N","\u01CA":"NJ","\u01CB":"Nj","\u24C4":"O","\uFF2F":"O","\u00D2":"O","\u00D3":"O","\u00D4":"O","\u1ED2":"O","\u1ED0":"O","\u1ED6":"O","\u1ED4":"O","\u00D5":"O","\u1E4C":"O","\u022C":"O","\u1E4E":"O","\u014C":"O","\u1E50":"O","\u1E52":"O","\u014E":"O","\u022E":"O","\u0230":"O","\u00D6":"O","\u022A":"O","\u1ECE":"O","\u0150":"O","\u01D1":"O","\u020C":"O","\u020E":"O","\u01A0":"O","\u1EDC":"O","\u1EDA":"O","\u1EE0":"O","\u1EDE":"O","\u1EE2":"O","\u1ECC":"O","\u1ED8":"O","\u01EA":"O","\u01EC":"O","\u00D8":"O","\u01FE":"O","\u0186":"O","\u019F":"O","\uA74A":"O","\uA74C":"O","\u01A2":"OI","\uA74E":"OO","\u0222":"OU","\u24C5":"P","\uFF30":"P","\u1E54":"P","\u1E56":"P","\u01A4":"P","\u2C63":"P","\uA750":"P","\uA752":"P","\uA754":"P","\u24C6":"Q","\uFF31":"Q","\uA756":"Q","\uA758":"Q","\u024A":"Q","\u24C7":"R","\uFF32":"R","\u0154":"R","\u1E58":"R","\u0158":"R","\u0210":"R","\u0212":"R","\u1E5A":"R","\u1E5C":"R","\u0156":"R","\u1E5E":"R","\u024C":"R","\u2C64":"R","\uA75A":"R","\uA7A6":"R","\uA782":"R","\u24C8":"S","\uFF33":"S","\u1E9E":"S","\u015A":"S","\u1E64":"S","\u015C":"S","\u1E60":"S","\u0160":"S","\u1E66":"S","\u1E62":"S","\u1E68":"S","\u0218":"S","\u015E":"S","\u2C7E":"S","\uA7A8":"S","\uA784":"S","\u24C9":"T","\uFF34":"T","\u1E6A":"T","\u0164":"T","\u1E6C":"T","\u021A":"T","\u0162":"T","\u1E70":"T","\u1E6E":"T","\u0166":"T","\u01AC":"T","\u01AE":"T","\u023E":"T","\uA786":"T","\uA728":"TZ","\u24CA":"U","\uFF35":"U","\u00D9":"U","\u00DA":"U","\u00DB":"U","\u0168":"U","\u1E78":"U","\u016A":"U","\u1E7A":"U","\u016C":"U","\u00DC":"U","\u01DB":"U","\u01D7":"U","\u01D5":"U","\u01D9":"U","\u1EE6":"U","\u016E":"U","\u0170":"U","\u01D3":"U","\u0214":"U","\u0216":"U","\u01AF":"U","\u1EEA":"U","\u1EE8":"U","\u1EEE":"U","\u1EEC":"U","\u1EF0":"U","\u1EE4":"U","\u1E72":"U","\u0172":"U","\u1E76":"U","\u1E74":"U","\u0244":"U","\u24CB":"V","\uFF36":"V","\u1E7C":"V","\u1E7E":"V","\u01B2":"V","\uA75E":"V","\u0245":"V","\uA760":"VY","\u24CC":"W","\uFF37":"W","\u1E80":"W","\u1E82":"W","\u0174":"W","\u1E86":"W","\u1E84":"W","\u1E88":"W","\u2C72":"W","\u24CD":"X","\uFF38":"X","\u1E8A":"X","\u1E8C":"X","\u24CE":"Y","\uFF39":"Y","\u1EF2":"Y","\u00DD":"Y","\u0176":"Y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    $document = $(document);

    nextUid=(function() { var counter=1; return function() { return counter++; }; }());


    function reinsertElement(element) {
        var placeholder = $(document.createTextNode(''));

        element.before(placeholder);
        placeholder.before(element);
        placeholder.remove();
    }

    function stripDiacritics(str) {
        var ret, i, l, c;

        if (!str || str.length < 1) return str;

        ret = "";
        for (i = 0, l = str.length; i < l; i++) {
            c = str.charAt(i);
            ret += DIACRITICS[c] || c;
        }
        return ret;
    }

    function indexOf(value, array) {
        var i = 0, l = array.length;
        for (; i < l; i = i + 1) {
            if (equal(value, array[i])) return i;
        }
        return -1;
    }

    function measureScrollbar () {
        var $template = $( MEASURE_SCROLLBAR_TEMPLATE );
        $template.appendTo('body');

        var dim = {
            width: $template.width() - $template[0].clientWidth,
            height: $template.height() - $template[0].clientHeight
        };
        $template.remove();

        return dim;
    }

    /**
     * Compares equality of a and b
     * @param a
     * @param b
     */
    function equal(a, b) {
        if (a === b) return true;
        if (a === undefined || b === undefined) return false;
        if (a === null || b === null) return false;
        // Check whether 'a' or 'b' is a string (primitive or object).
        // The concatenation of an empty string (+'') converts its argument to a string's primitive.
        if (a.constructor === String) return a+'' === b+''; // a+'' - in case 'a' is a String object
        if (b.constructor === String) return b+'' === a+''; // b+'' - in case 'b' is a String object
        return false;
    }

    /**
     * Splits the string into an array of values, trimming each value. An empty array is returned for nulls or empty
     * strings
     * @param string
     * @param separator
     */
    function splitVal(string, separator) {
        var val, i, l;
        if (string === null || string.length < 1) return [];
        val = string.split(separator);
        for (i = 0, l = val.length; i < l; i = i + 1) val[i] = $.trim(val[i]);
        return val;
    }

    function getSideBorderPadding(element) {
        return element.outerWidth(false) - element.width();
    }

    function installKeyUpChangeEvent(element) {
        var key="keyup-change-value";
        element.on("keydown", function () {
            if ($.data(element, key) === undefined) {
                $.data(element, key, element.val());
            }
        });
        element.on("keyup", function () {
            var val= $.data(element, key);
            if (val !== undefined && element.val() !== val) {
                $.removeData(element, key);
                element.trigger("keyup-change");
            }
        });
    }

    $document.on("mousemove", function (e) {
        lastMousePosition.x = e.pageX;
        lastMousePosition.y = e.pageY;
    });

    /**
     * filters mouse events so an event is fired only if the mouse moved.
     *
     * filters out mouse events that occur when mouse is stationary but
     * the elements under the pointer are scrolled.
     */
    function installFilteredMouseMove(element) {
        element.on("mousemove", function (e) {
            var lastpos = lastMousePosition;
            if (lastpos === undefined || lastpos.x !== e.pageX || lastpos.y !== e.pageY) {
                $(e.target).trigger("mousemove-filtered", e);
            }
        });
    }

    /**
     * Debounces a function. Returns a function that calls the original fn function only if no invocations have been made
     * within the last quietMillis milliseconds.
     *
     * @param quietMillis number of milliseconds to wait before invoking fn
     * @param fn function to be debounced
     * @param ctx object to be used as this reference within fn
     * @return debounced version of fn
     */
    function debounce(quietMillis, fn, ctx) {
        ctx = ctx || undefined;
        var timeout;
        return function () {
            var args = arguments;
            window.clearTimeout(timeout);
            timeout = window.setTimeout(function() {
                fn.apply(ctx, args);
            }, quietMillis);
        };
    }

    /**
     * A simple implementation of a thunk
     * @param formula function used to lazily initialize the thunk
     * @return {Function}
     */
    function thunk(formula) {
        var evaluated = false,
            value;
        return function() {
            if (evaluated === false) { value = formula(); evaluated = true; }
            return value;
        };
    };

    function installDebouncedScroll(threshold, element) {
        var notify = debounce(threshold, function (e) { element.trigger("scroll-debounced", e);});
        element.on("scroll", function (e) {
            if (indexOf(e.target, element.get()) >= 0) notify(e);
        });
    }

    function focus($el) {
        if ($el[0] === document.activeElement) return;

        /* set the focus in a 0 timeout - that way the focus is set after the processing
            of the current event has finished - which seems like the only reliable way
            to set focus */
        window.setTimeout(function() {
            var el=$el[0], pos=$el.val().length, range;

            $el.focus();

            /* make sure el received focus so we do not error out when trying to manipulate the caret.
                sometimes modals or others listeners may steal it after its set */
            var isVisible = (el.offsetWidth > 0 || el.offsetHeight > 0);
            if (isVisible && el === document.activeElement) {

                /* after the focus is set move the caret to the end, necessary when we val()
                    just before setting focus */
                if(el.setSelectionRange)
                {
                    el.setSelectionRange(pos, pos);
                }
                else if (el.createTextRange) {
                    range = el.createTextRange();
                    range.collapse(false);
                    range.select();
                }
            }
        }, 0);
    }

    function getCursorInfo(el) {
        el = $(el)[0];
        var offset = 0;
        var length = 0;
        if ('selectionStart' in el) {
            offset = el.selectionStart;
            length = el.selectionEnd - offset;
        } else if ('selection' in document) {
            el.focus();
            var sel = document.selection.createRange();
            length = document.selection.createRange().text.length;
            sel.moveStart('character', -el.value.length);
            offset = sel.text.length - length;
        }
        return { offset: offset, length: length };
    }

    function killEvent(event) {
        event.preventDefault();
        event.stopPropagation();
    }
    function killEventImmediately(event) {
        event.preventDefault();
        event.stopImmediatePropagation();
    }

    function measureTextWidth(e) {
        if (!sizer){
            var style = e[0].currentStyle || window.getComputedStyle(e[0], null);
            sizer = $(document.createElement("div")).css({
                position: "absolute",
                left: "-10000px",
                top: "-10000px",
                display: "none",
                fontSize: style.fontSize,
                fontFamily: style.fontFamily,
                fontStyle: style.fontStyle,
                fontWeight: style.fontWeight,
                letterSpacing: style.letterSpacing,
                textTransform: style.textTransform,
                whiteSpace: "nowrap"
            });
            sizer.attr("class","select2-sizer");
            $("body").append(sizer);
        }
        sizer.text(e.val());
        return sizer.width();
    }

    function syncCssClasses(dest, src, adapter) {
        var classes, replacements = [], adapted;

        classes = dest.attr("class");
        if (classes) {
            classes = '' + classes; // for IE which returns object
            $(classes.split(" ")).each2(function() {
                if (this.indexOf("select2-") === 0) {
                    replacements.push(this);
                }
            });
        }
        classes = src.attr("class");
        if (classes) {
            classes = '' + classes; // for IE which returns object
            $(classes.split(" ")).each2(function() {
                if (this.indexOf("select2-") !== 0) {
                    adapted = adapter(this);
                    if (adapted) {
                        replacements.push(adapted);
                    }
                }
            });
        }
        dest.attr("class", replacements.join(" "));
    }


    function markMatch(text, term, markup, escapeMarkup) {
        var match=stripDiacritics(text.toUpperCase()).indexOf(stripDiacritics(term.toUpperCase())),
            tl=term.length;

        if (match<0) {
            markup.push(escapeMarkup(text));
            return;
        }

        markup.push(escapeMarkup(text.substring(0, match)));
        markup.push("<span class='select2-match'>");
        markup.push(escapeMarkup(text.substring(match, match + tl)));
        markup.push("</span>");
        markup.push(escapeMarkup(text.substring(match + tl, text.length)));
    }

    function defaultEscapeMarkup(markup) {
        var replace_map = {
            '\\': '&#92;',
            '&': '&amp;',
            '<': '&lt;',
            '>': '&gt;',
            '"': '&quot;',
            "'": '&#39;',
            "/": '&#47;'
        };

        return String(markup).replace(/[&<>"'\/\\]/g, function (match) {
            return replace_map[match];
        });
    }

    /**
     * Produces an ajax-based query function
     *
     * @param options object containing configuration parameters
     * @param options.params parameter map for the transport ajax call, can contain such options as cache, jsonpCallback, etc. see $.ajax
     * @param options.transport function that will be used to execute the ajax request. must be compatible with parameters supported by $.ajax
     * @param options.url url for the data
     * @param options.data a function(searchTerm, pageNumber, context) that should return an object containing query string parameters for the above url.
     * @param options.dataType request data type: ajax, jsonp, other datatypes supported by jQuery's $.ajax function or the transport function if specified
     * @param options.quietMillis (optional) milliseconds to wait before making the ajaxRequest, helps debounce the ajax function if invoked too often
     * @param options.results a function(remoteData, pageNumber) that converts data returned form the remote request to the format expected by Select2.
     *      The expected format is an object containing the following keys:
     *      results array of objects that will be used as choices
     *      more (optional) boolean indicating whether there are more results available
     *      Example: {results:[{id:1, text:'Red'},{id:2, text:'Blue'}], more:true}
     */
    function ajax(options) {
        var timeout, // current scheduled but not yet executed request
            handler = null,
            quietMillis = options.quietMillis || 100,
            ajaxUrl = options.url,
            self = this;

        return function (query) {
            window.clearTimeout(timeout);
            timeout = window.setTimeout(function () {
                var data = options.data, // ajax data function
                    url = ajaxUrl, // ajax url string or function
                    transport = options.transport || $.fn.select2.ajaxDefaults.transport,
                    // deprecated - to be removed in 4.0  - use params instead
                    deprecated = {
                        type: options.type || 'GET', // set type of request (GET or POST)
                        cache: options.cache || false,
                        jsonpCallback: options.jsonpCallback||undefined,
                        dataType: options.dataType||"json"
                    },
                    params = $.extend({}, $.fn.select2.ajaxDefaults.params, deprecated);

                data = data ? data.call(self, query.term, query.page, query.context) : null;
                url = (typeof url === 'function') ? url.call(self, query.term, query.page, query.context) : url;

                if (handler && typeof handler.abort === "function") { handler.abort(); }

                if (options.params) {
                    if ($.isFunction(options.params)) {
                        $.extend(params, options.params.call(self));
                    } else {
                        $.extend(params, options.params);
                    }
                }

                $.extend(params, {
                    url: url,
                    dataType: options.dataType,
                    data: data,
                    success: function (data) {
                        // TODO - replace query.page with query so users have access to term, page, etc.
                        var results = options.results(data, query.page);
                        query.callback(results);
                    }
                });
                handler = transport.call(self, params);
            }, quietMillis);
        };
    }

    /**
     * Produces a query function that works with a local array
     *
     * @param options object containing configuration parameters. The options parameter can either be an array or an
     * object.
     *
     * If the array form is used it is assumed that it contains objects with 'id' and 'text' keys.
     *
     * If the object form is used ti is assumed that it contains 'data' and 'text' keys. The 'data' key should contain
     * an array of objects that will be used as choices. These objects must contain at least an 'id' key. The 'text'
     * key can either be a String in which case it is expected that each element in the 'data' array has a key with the
     * value of 'text' which will be used to match choices. Alternatively, text can be a function(item) that can extract
     * the text.
     */
    function local(options) {
        var data = options, // data elements
            dataText,
            tmp,
            text = function (item) { return ""+item.text; }; // function used to retrieve the text portion of a data item that is matched against the search

         if ($.isArray(data)) {
            tmp = data;
            data = { results: tmp };
        }

         if ($.isFunction(data) === false) {
            tmp = data;
            data = function() { return tmp; };
        }

        var dataItem = data();
        if (dataItem.text) {
            text = dataItem.text;
            // if text is not a function we assume it to be a key name
            if (!$.isFunction(text)) {
                dataText = dataItem.text; // we need to store this in a separate variable because in the next step data gets reset and data.text is no longer available
                text = function (item) { return item[dataText]; };
            }
        }

        return function (query) {
            var t = query.term, filtered = { results: [] }, process;
            if (t === "") {
                query.callback(data());
                return;
            }

            process = function(datum, collection) {
                var group, attr;
                datum = datum[0];
                if (datum.children) {
                    group = {};
                    for (attr in datum) {
                        if (datum.hasOwnProperty(attr)) group[attr]=datum[attr];
                    }
                    group.children=[];
                    $(datum.children).each2(function(i, childDatum) { process(childDatum, group.children); });
                    if (group.children.length || query.matcher(t, text(group), datum)) {
                        collection.push(group);
                    }
                } else {
                    if (query.matcher(t, text(datum), datum)) {
                        collection.push(datum);
                    }
                }
            };

            $(data().results).each2(function(i, datum) { process(datum, filtered.results); });
            query.callback(filtered);
        };
    }

    // TODO javadoc
    function tags(data) {
        var isFunc = $.isFunction(data);
        return function (query) {
            var t = query.term, filtered = {results: []};
            $(isFunc ? data() : data).each(function () {
                var isObject = this.text !== undefined,
                    text = isObject ? this.text : this;
                if (t === "" || query.matcher(t, text)) {
                    filtered.results.push(isObject ? this : {id: this, text: this});
                }
            });
            query.callback(filtered);
        };
    }

    /**
     * Checks if the formatter function should be used.
     *
     * Throws an error if it is not a function. Returns true if it should be used,
     * false if no formatting should be performed.
     *
     * @param formatter
     */
    function checkFormatter(formatter, formatterName) {
        if ($.isFunction(formatter)) return true;
        if (!formatter) return false;
        throw new Error(formatterName +" must be a function or a falsy value");
    }

    function evaluate(val) {
        return $.isFunction(val) ? val() : val;
    }

    function countResults(results) {
        var count = 0;
        $.each(results, function(i, item) {
            if (item.children) {
                count += countResults(item.children);
            } else {
                count++;
            }
        });
        return count;
    }

    /**
     * Default tokenizer. This function uses breaks the input on substring match of any string from the
     * opts.tokenSeparators array and uses opts.createSearchChoice to create the choice object. Both of those
     * two options have to be defined in order for the tokenizer to work.
     *
     * @param input text user has typed so far or pasted into the search field
     * @param selection currently selected choices
     * @param selectCallback function(choice) callback tho add the choice to selection
     * @param opts select2's opts
     * @return undefined/null to leave the current input unchanged, or a string to change the input to the returned value
     */
    function defaultTokenizer(input, selection, selectCallback, opts) {
        var original = input, // store the original so we can compare and know if we need to tell the search to update its text
            dupe = false, // check for whether a token we extracted represents a duplicate selected choice
            token, // token
            index, // position at which the separator was found
            i, l, // looping variables
            separator; // the matched separator

        if (!opts.createSearchChoice || !opts.tokenSeparators || opts.tokenSeparators.length < 1) return undefined;

        while (true) {
            index = -1;

            for (i = 0, l = opts.tokenSeparators.length; i < l; i++) {
                separator = opts.tokenSeparators[i];
                index = input.indexOf(separator);
                if (index >= 0) break;
            }

            if (index < 0) break; // did not find any token separator in the input string, bail

            token = input.substring(0, index);
            input = input.substring(index + separator.length);

            if (token.length > 0) {
                token = opts.createSearchChoice.call(this, token, selection);
                if (token !== undefined && token !== null && opts.id(token) !== undefined && opts.id(token) !== null) {
                    dupe = false;
                    for (i = 0, l = selection.length; i < l; i++) {
                        if (equal(opts.id(token), opts.id(selection[i]))) {
                            dupe = true; break;
                        }
                    }

                    if (!dupe) selectCallback(token);
                }
            }
        }

        if (original!==input) return input;
    }

    /**
     * Creates a new class
     *
     * @param superClass
     * @param methods
     */
    function clazz(SuperClass, methods) {
        var constructor = function () {};
        constructor.prototype = new SuperClass;
        constructor.prototype.constructor = constructor;
        constructor.prototype.parent = SuperClass.prototype;
        constructor.prototype = $.extend(constructor.prototype, methods);
        return constructor;
    }

    AbstractSelect2 = clazz(Object, {

        // abstract
        bind: function (func) {
            var self = this;
            return function () {
                func.apply(self, arguments);
            };
        },

        // abstract
        init: function (opts) {
            var results, search, resultsSelector = ".select2-results";

            // prepare options
            this.opts = opts = this.prepareOpts(opts);

            this.id=opts.id;

            // destroy if called on an existing component
            if (opts.element.data("select2") !== undefined &&
                opts.element.data("select2") !== null) {
                opts.element.data("select2").destroy();
            }

            this.container = this.createContainer();

            this.liveRegion = $("<span>", {
                    role: "status",
                    "aria-live": "polite"
                })
                .addClass("select2-hidden-accessible")
                .appendTo(document.body);

            this.containerId="s2id_"+(opts.element.attr("id") || "autogen"+nextUid()).replace(/([;&,\-\.\+\*\~':"\!\^#$%@\[\]\(\)=>\|])/g, '\\$1');
            this.containerSelector="#"+this.containerId;
            this.container.attr("id", this.containerId);

            // cache the body so future lookups are cheap
            this.body = thunk(function() { return opts.element.closest("body"); });

            syncCssClasses(this.container, this.opts.element, this.opts.adaptContainerCssClass);

            this.container.attr("style", opts.element.attr("style"));
            this.container.css(evaluate(opts.containerCss));
            this.container.addClass(evaluate(opts.containerCssClass));

            this.elementTabIndex = this.opts.element.attr("tabindex");

            // swap container for the element
            this.opts.element
                .data("select2", this)
                .attr("tabindex", "-1")
                .before(this.container)
                .on("click.select2", killEvent); // do not leak click events

            this.container.data("select2", this);

            this.dropdown = this.container.find(".select2-drop");

            syncCssClasses(this.dropdown, this.opts.element, this.opts.adaptDropdownCssClass);

            this.dropdown.addClass(evaluate(opts.dropdownCssClass));
            this.dropdown.data("select2", this);
            this.dropdown.on("click", killEvent);

            this.results = results = this.container.find(resultsSelector);
            this.search = search = this.container.find("input.select2-input");

            this.queryCount = 0;
            this.resultsPage = 0;
            this.context = null;

            // initialize the container
            this.initContainer();

            this.container.on("click", killEvent);

            installFilteredMouseMove(this.results);
            this.dropdown.on("mousemove-filtered touchstart touchmove touchend", resultsSelector, this.bind(this.highlightUnderEvent));

            installDebouncedScroll(80, this.results);
            this.dropdown.on("scroll-debounced", resultsSelector, this.bind(this.loadMoreIfNeeded));

            // do not propagate change event from the search field out of the component
            $(this.container).on("change", ".select2-input", function(e) {e.stopPropagation();});
            $(this.dropdown).on("change", ".select2-input", function(e) {e.stopPropagation();});

            // if jquery.mousewheel plugin is installed we can prevent out-of-bounds scrolling of results via mousewheel
            if ($.fn.mousewheel) {
                results.mousewheel(function (e, delta, deltaX, deltaY) {
                    var top = results.scrollTop();
                    if (deltaY > 0 && top - deltaY <= 0) {
                        results.scrollTop(0);
                        killEvent(e);
                    } else if (deltaY < 0 && results.get(0).scrollHeight - results.scrollTop() + deltaY <= results.height()) {
                        results.scrollTop(results.get(0).scrollHeight - results.height());
                        killEvent(e);
                    }
                });
            }

            installKeyUpChangeEvent(search);
            search.on("keyup-change input paste", this.bind(this.updateResults));
            search.on("focus", function () { search.addClass("select2-focused"); });
            search.on("blur", function () { search.removeClass("select2-focused");});

            this.dropdown.on("mouseup", resultsSelector, this.bind(function (e) {
                if ($(e.target).closest(".select2-result-selectable").length > 0) {
                    this.highlightUnderEvent(e);
                    this.selectHighlighted(e);
                }
            }));

            // trap all mouse events from leaving the dropdown. sometimes there may be a modal that is listening
            // for mouse events outside of itself so it can close itself. since the dropdown is now outside the select2's
            // dom it will trigger the popup close, which is not what we want
            this.dropdown.on("click mouseup mousedown", function (e) { e.stopPropagation(); });

            this.nextSearchTerm = undefined;

            if ($.isFunction(this.opts.initSelection)) {
                // initialize selection based on the current value of the source element
                this.initSelection();

                // if the user has provided a function that can set selection based on the value of the source element
                // we monitor the change event on the element and trigger it, allowing for two way synchronization
                this.monitorSource();
            }

            if (opts.maximumInputLength !== null) {
                this.search.attr("maxlength", opts.maximumInputLength);
            }

            var disabled = opts.element.prop("disabled");
            if (disabled === undefined) disabled = false;
            this.enable(!disabled);

            var readonly = opts.element.prop("readonly");
            if (readonly === undefined) readonly = false;
            this.readonly(readonly);

            // Calculate size of scrollbar
            scrollBarDimensions = scrollBarDimensions || measureScrollbar();

            this.autofocus = opts.element.prop("autofocus");
            opts.element.prop("autofocus", false);
            if (this.autofocus) this.focus();

            this.search.attr("placeholder", opts.searchInputPlaceholder);
        },

        // abstract
        destroy: function () {
            var element=this.opts.element, select2 = element.data("select2");

            this.close();

            if (this.propertyObserver) { delete this.propertyObserver; this.propertyObserver = null; }

            if (select2 !== undefined) {
                select2.container.remove();
                select2.liveRegion.remove();
                select2.dropdown.remove();
                element
                    .removeClass("select2-offscreen")
                    .removeData("select2")
                    .off(".select2")
                    .prop("autofocus", this.autofocus || false);
                if (this.elementTabIndex) {
                    element.attr({tabindex: this.elementTabIndex});
                } else {
                    element.removeAttr("tabindex");
                }
                element.show();
            }
        },

        // abstract
        optionToData: function(element) {
            if (element.is("option")) {
                return {
                    id:element.prop("value"),
                    text:element.text(),
                    element: element.get(),
                    css: element.attr("class"),
                    disabled: element.prop("disabled"),
                    locked: equal(element.attr("locked"), "locked") || equal(element.data("locked"), true)
                };
            } else if (element.is("optgroup")) {
                return {
                    text:element.attr("label"),
                    children:[],
                    element: element.get(),
                    css: element.attr("class")
                };
            }
        },

        // abstract
        prepareOpts: function (opts) {
            var element, select, idKey, ajaxUrl, self = this;

            element = opts.element;

            if (element.get(0).tagName.toLowerCase() === "select") {
                this.select = select = opts.element;
            }

            if (select) {
                // these options are not allowed when attached to a select because they are picked up off the element itself
                $.each(["id", "multiple", "ajax", "query", "createSearchChoice", "initSelection", "data", "tags"], function () {
                    if (this in opts) {
                        throw new Error("Option '" + this + "' is not allowed for Select2 when attached to a <select> element.");
                    }
                });
            }

            opts = $.extend({}, {
                populateResults: function(container, results, query) {
                    var populate, id=this.opts.id, liveRegion=this.liveRegion;

                    populate=function(results, container, depth) {

                        var i, l, result, selectable, disabled, compound, node, label, innerContainer, formatted;

                        results = opts.sortResults(results, container, query);

                        for (i = 0, l = results.length; i < l; i = i + 1) {

                            result=results[i];

                            disabled = (result.disabled === true);
                            selectable = (!disabled) && (id(result) !== undefined);

                            compound=result.children && result.children.length > 0;

                            node=$("<li></li>");
                            node.addClass("select2-results-dept-"+depth);
                            node.addClass("select2-result");
                            node.addClass(selectable ? "select2-result-selectable" : "select2-result-unselectable");
                            if (disabled) { node.addClass("select2-disabled"); }
                            if (compound) { node.addClass("select2-result-with-children"); }
                            node.addClass(self.opts.formatResultCssClass(result));
                            node.attr("role", "presentation");

                            label=$(document.createElement("div"));
                            label.addClass("select2-result-label");
                            label.attr("id", "select2-result-label-" + nextUid());
                            label.attr("role", "option");

                            formatted=opts.formatResult(result, label, query, self.opts.escapeMarkup);
                            if (formatted!==undefined) {
                                label.html(formatted);
                                node.append(label);
                            }


                            if (compound) {

                                innerContainer=$("<ul></ul>");
                                innerContainer.addClass("select2-result-sub");
                                populate(result.children, innerContainer, depth+1);
                                node.append(innerContainer);
                            }

                            node.data("select2-data", result);
                            container.append(node);
                        }

                        liveRegion.text(opts.formatMatches(results.length));
                    };

                    populate(results, container, 0);
                }
            }, $.fn.select2.defaults, opts);

            if (typeof(opts.id) !== "function") {
                idKey = opts.id;
                opts.id = function (e) { return e[idKey]; };
            }

            if ($.isArray(opts.element.data("select2Tags"))) {
                if ("tags" in opts) {
                    throw "tags specified as both an attribute 'data-select2-tags' and in options of Select2 " + opts.element.attr("id");
                }
                opts.tags=opts.element.data("select2Tags");
            }

            if (select) {
                opts.query = this.bind(function (query) {
                    var data = { results: [], more: false },
                        term = query.term,
                        children, placeholderOption, process;

                    process=function(element, collection) {
                        var group;
                        if (element.is("option")) {
                            if (query.matcher(term, element.text(), element)) {
                                collection.push(self.optionToData(element));
                            }
                        } else if (element.is("optgroup")) {
                            group=self.optionToData(element);
                            element.children().each2(function(i, elm) { process(elm, group.children); });
                            if (group.children.length>0) {
                                collection.push(group);
                            }
                        }
                    };

                    children=element.children();

                    // ignore the placeholder option if there is one
                    if (this.getPlaceholder() !== undefined && children.length > 0) {
                        placeholderOption = this.getPlaceholderOption();
                        if (placeholderOption) {
                            children=children.not(placeholderOption);
                        }
                    }

                    children.each2(function(i, elm) { process(elm, data.results); });

                    query.callback(data);
                });
                // this is needed because inside val() we construct choices from options and there id is hardcoded
                opts.id=function(e) { return e.id; };
            } else {
                if (!("query" in opts)) {

                    if ("ajax" in opts) {
                        ajaxUrl = opts.element.data("ajax-url");
                        if (ajaxUrl && ajaxUrl.length > 0) {
                            opts.ajax.url = ajaxUrl;
                        }
                        opts.query = ajax.call(opts.element, opts.ajax);
                    } else if ("data" in opts) {
                        opts.query = local(opts.data);
                    } else if ("tags" in opts) {
                        opts.query = tags(opts.tags);
                        if (opts.createSearchChoice === undefined) {
                            opts.createSearchChoice = function (term) { return {id: $.trim(term), text: $.trim(term)}; };
                        }
                        if (opts.initSelection === undefined) {
                            opts.initSelection = function (element, callback) {
                                var data = [];
                                $(splitVal(element.val(), opts.separator)).each(function () {
                                    var obj = { id: this, text: this },
                                        tags = opts.tags;
                                    if ($.isFunction(tags)) tags=tags();
                                    $(tags).each(function() { if (equal(this.id, obj.id)) { obj = this; return false; } });
                                    data.push(obj);
                                });

                                callback(data);
                            };
                        }
                    }
                }
            }
            if (typeof(opts.query) !== "function") {
                throw "query function not defined for Select2 " + opts.element.attr("id");
            }

            if (opts.createSearchChoicePosition === 'top') {
                opts.createSearchChoicePosition = function(list, item) { list.unshift(item); };
            }
            else if (opts.createSearchChoicePosition === 'bottom') {
                opts.createSearchChoicePosition = function(list, item) { list.push(item); };
            }
            else if (typeof(opts.createSearchChoicePosition) !== "function")  {
                throw "invalid createSearchChoicePosition option must be 'top', 'bottom' or a custom function";
            }

            return opts;
        },

        /**
         * Monitor the original element for changes and update select2 accordingly
         */
        // abstract
        monitorSource: function () {
            var el = this.opts.element, sync, observer;

            el.on("change.select2", this.bind(function (e) {
                if (this.opts.element.data("select2-change-triggered") !== true) {
                    this.initSelection();
                }
            }));

            sync = this.bind(function () {

                // sync enabled state
                var disabled = el.prop("disabled");
                if (disabled === undefined) disabled = false;
                this.enable(!disabled);

                var readonly = el.prop("readonly");
                if (readonly === undefined) readonly = false;
                this.readonly(readonly);

                syncCssClasses(this.container, this.opts.element, this.opts.adaptContainerCssClass);
                this.container.addClass(evaluate(this.opts.containerCssClass));

                syncCssClasses(this.dropdown, this.opts.element, this.opts.adaptDropdownCssClass);
                this.dropdown.addClass(evaluate(this.opts.dropdownCssClass));

            });

            // IE8-10
            el.on("propertychange.select2", sync);

            // hold onto a reference of the callback to work around a chromium bug
            if (this.mutationCallback === undefined) {
                this.mutationCallback = function (mutations) {
                    mutations.forEach(sync);
                }
            }

            // safari, chrome, firefox, IE11
            observer = window.MutationObserver || window.WebKitMutationObserver|| window.MozMutationObserver;
            if (observer !== undefined) {
                if (this.propertyObserver) { delete this.propertyObserver; this.propertyObserver = null; }
                this.propertyObserver = new observer(this.mutationCallback);
                this.propertyObserver.observe(el.get(0), { attributes:true, subtree:false });
            }
        },

        // abstract
        triggerSelect: function(data) {
            var evt = $.Event("select2-selecting", { val: this.id(data), object: data });
            this.opts.element.trigger(evt);
            return !evt.isDefaultPrevented();
        },

        /**
         * Triggers the change event on the source element
         */
        // abstract
        triggerChange: function (details) {

            details = details || {};
            details= $.extend({}, details, { type: "change", val: this.val() });
            // prevents recursive triggering
            this.opts.element.data("select2-change-triggered", true);
            this.opts.element.trigger(details);
            this.opts.element.data("select2-change-triggered", false);

            // some validation frameworks ignore the change event and listen instead to keyup, click for selects
            // so here we trigger the click event manually
            this.opts.element.click();

            // ValidationEngine ignores the change event and listens instead to blur
            // so here we trigger the blur event manually if so desired
            if (this.opts.blurOnChange)
                this.opts.element.blur();
        },

        //abstract
        isInterfaceEnabled: function()
        {
            return this.enabledInterface === true;
        },

        // abstract
        enableInterface: function() {
            var enabled = this._enabled && !this._readonly,
                disabled = !enabled;

            if (enabled === this.enabledInterface) return false;

            this.container.toggleClass("select2-container-disabled", disabled);
            this.close();
            this.enabledInterface = enabled;

            return true;
        },

        // abstract
        enable: function(enabled) {
            if (enabled === undefined) enabled = true;
            if (this._enabled === enabled) return;
            this._enabled = enabled;

            this.opts.element.prop("disabled", !enabled);
            this.enableInterface();
        },

        // abstract
        disable: function() {
            this.enable(false);
        },

        // abstract
        readonly: function(enabled) {
            if (enabled === undefined) enabled = false;
            if (this._readonly === enabled) return false;
            this._readonly = enabled;

            this.opts.element.prop("readonly", enabled);
            this.enableInterface();
            return true;
        },

        // abstract
        opened: function () {
            return this.container.hasClass("select2-dropdown-open");
        },

        // abstract
        positionDropdown: function() {
            var $dropdown = this.dropdown,
                offset = this.container.offset(),
                height = this.container.outerHeight(false),
                width = this.container.outerWidth(false),
                dropHeight = $dropdown.outerHeight(false),
                $window = $(window),
                windowWidth = $window.width(),
                windowHeight = $window.height(),
                viewPortRight = $window.scrollLeft() + windowWidth,
                viewportBottom = $window.scrollTop() + windowHeight,
                dropTop = offset.top + height,
                dropLeft = offset.left,
                enoughRoomBelow = dropTop + dropHeight <= viewportBottom,
                enoughRoomAbove = (offset.top - dropHeight) >= this.body().scrollTop(),
                dropWidth = $dropdown.outerWidth(false),
                enoughRoomOnRight = dropLeft + dropWidth <= viewPortRight,
                aboveNow = $dropdown.hasClass("select2-drop-above"),
                bodyOffset,
                above,
                changeDirection,
                css,
                resultsListNode;

            // always prefer the current above/below alignment, unless there is not enough room
            if (aboveNow) {
                above = true;
                if (!enoughRoomAbove && enoughRoomBelow) {
                    changeDirection = true;
                    above = false;
                }
            } else {
                above = false;
                if (!enoughRoomBelow && enoughRoomAbove) {
                    changeDirection = true;
                    above = true;
                }
            }

            //if we are changing direction we need to get positions when dropdown is hidden;
            if (changeDirection) {
                $dropdown.hide();
                offset = this.container.offset();
                height = this.container.outerHeight(false);
                width = this.container.outerWidth(false);
                dropHeight = $dropdown.outerHeight(false);
                viewPortRight = $window.scrollLeft() + windowWidth;
                viewportBottom = $window.scrollTop() + windowHeight;
                dropTop = offset.top + height;
                dropLeft = offset.left;
                dropWidth = $dropdown.outerWidth(false);
                enoughRoomOnRight = dropLeft + dropWidth <= viewPortRight;
                $dropdown.show();
            }

            if (this.opts.dropdownAutoWidth) {
                resultsListNode = $('.select2-results', $dropdown)[0];
                $dropdown.addClass('select2-drop-auto-width');
                $dropdown.css('width', '');
                // Add scrollbar width to dropdown if vertical scrollbar is present
                dropWidth = $dropdown.outerWidth(false) + (resultsListNode.scrollHeight === resultsListNode.clientHeight ? 0 : scrollBarDimensions.width);
                dropWidth > width ? width = dropWidth : dropWidth = width;
                enoughRoomOnRight = dropLeft + dropWidth <= viewPortRight;
            }
            else {
                this.container.removeClass('select2-drop-auto-width');
            }

            //console.log("below/ droptop:", dropTop, "dropHeight", dropHeight, "sum", (dropTop+dropHeight)+" viewport bottom", viewportBottom, "enough?", enoughRoomBelow);
            //console.log("above/ offset.top", offset.top, "dropHeight", dropHeight, "top", (offset.top-dropHeight), "scrollTop", this.body().scrollTop(), "enough?", enoughRoomAbove);

            // fix positioning when body has an offset and is not position: static
            if (this.body().css('position') !== 'static') {
                bodyOffset = this.body().offset();
                dropTop -= bodyOffset.top;
                dropLeft -= bodyOffset.left;
            }

            if (!enoughRoomOnRight) {
                dropLeft = offset.left + this.container.outerWidth(false) - dropWidth;
            }

            css =  {
                left: dropLeft,
                width: width
            };

            if (above) {
                css.top = offset.top - dropHeight;
                css.bottom = 'auto';
                this.container.addClass("select2-drop-above");
                $dropdown.addClass("select2-drop-above");
            }
            else {
                css.top = dropTop;
                css.bottom = 'auto';
                this.container.removeClass("select2-drop-above");
                $dropdown.removeClass("select2-drop-above");
            }
            css = $.extend(css, evaluate(this.opts.dropdownCss));

            $dropdown.css(css);
        },

        // abstract
        shouldOpen: function() {
            var event;

            if (this.opened()) return false;

            if (this._enabled === false || this._readonly === true) return false;

            event = $.Event("select2-opening");
            this.opts.element.trigger(event);
            return !event.isDefaultPrevented();
        },

        // abstract
        clearDropdownAlignmentPreference: function() {
            // clear the classes used to figure out the preference of where the dropdown should be opened
            this.container.removeClass("select2-drop-above");
            this.dropdown.removeClass("select2-drop-above");
        },

        /**
         * Opens the dropdown
         *
         * @return {Boolean} whether or not dropdown was opened. This method will return false if, for example,
         * the dropdown is already open, or if the 'open' event listener on the element called preventDefault().
         */
        // abstract
        open: function () {

            if (!this.shouldOpen()) return false;

            this.opening();

            return true;
        },

        /**
         * Performs the opening of the dropdown
         */
        // abstract
        opening: function() {
            var cid = this.containerId,
                scroll = "scroll." + cid,
                resize = "resize."+cid,
                orient = "orientationchange."+cid,
                mask;

            this.container.addClass("select2-dropdown-open").addClass("select2-container-active");

            this.clearDropdownAlignmentPreference();

            if(this.dropdown[0] !== this.body().children().last()[0]) {
                this.dropdown.detach().appendTo(this.body());
            }

            // create the dropdown mask if doesn't already exist
            mask = $("#select2-drop-mask");
            if (mask.length == 0) {
                mask = $(document.createElement("div"));
                mask.attr("id","select2-drop-mask").attr("class","select2-drop-mask");
                mask.hide();
                mask.appendTo(this.body());
                mask.on("mousedown touchstart click", function (e) {
                    // Prevent IE from generating a click event on the body
                    reinsertElement(mask);

                    var dropdown = $("#select2-drop"), self;
                    if (dropdown.length > 0) {
                        self=dropdown.data("select2");
                        if (self.opts.selectOnBlur) {
                            self.selectHighlighted({noFocus: true});
                        }
                        self.close({focus:true});
                        e.preventDefault();
                        e.stopPropagation();
                    }
                });
            }

            // ensure the mask is always right before the dropdown
            if (this.dropdown.prev()[0] !== mask[0]) {
                this.dropdown.before(mask);
            }

            // move the global id to the correct dropdown
            $("#select2-drop").removeAttr("id");
            this.dropdown.attr("id", "select2-drop");

            // show the elements
            mask.show();

            this.positionDropdown();
            this.dropdown.show();
            this.positionDropdown();

            this.dropdown.addClass("select2-drop-active");

            // attach listeners to events that can change the position of the container and thus require
            // the position of the dropdown to be updated as well so it does not come unglued from the container
            var that = this;
            this.container.parents().add(window).each(function () {
                $(this).on(resize+" "+scroll+" "+orient, function (e) {
                    that.positionDropdown();
                });
            });


        },

        // abstract
        close: function () {
            if (!this.opened()) return;

            var cid = this.containerId,
                scroll = "scroll." + cid,
                resize = "resize."+cid,
                orient = "orientationchange."+cid;

            // unbind event listeners
            this.container.parents().add(window).each(function () { $(this).off(scroll).off(resize).off(orient); });

            this.clearDropdownAlignmentPreference();

            $("#select2-drop-mask").hide();
            this.dropdown.removeAttr("id"); // only the active dropdown has the select2-drop id
            this.dropdown.hide();
            this.container.removeClass("select2-dropdown-open").removeClass("select2-container-active");
            this.results.empty();


            this.clearSearch();
            this.search.removeClass("select2-active");
            this.opts.element.trigger($.Event("select2-close"));
        },

        /**
         * Opens control, sets input value, and updates results.
         */
        // abstract
        externalSearch: function (term) {
            this.open();
            this.search.val(term);
            this.updateResults(false);
        },

        // abstract
        clearSearch: function () {

        },

        //abstract
        getMaximumSelectionSize: function() {
            return evaluate(this.opts.maximumSelectionSize);
        },

        // abstract
        ensureHighlightVisible: function () {
            var results = this.results, children, index, child, hb, rb, y, more;

            index = this.highlight();

            if (index < 0) return;

            if (index == 0) {

                // if the first element is highlighted scroll all the way to the top,
                // that way any unselectable headers above it will also be scrolled
                // into view

                results.scrollTop(0);
                return;
            }

            children = this.findHighlightableChoices().find('.select2-result-label');

            child = $(children[index]);

            hb = child.offset().top + child.outerHeight(true);

            // if this is the last child lets also make sure select2-more-results is visible
            if (index === children.length - 1) {
                more = results.find("li.select2-more-results");
                if (more.length > 0) {
                    hb = more.offset().top + more.outerHeight(true);
                }
            }

            rb = results.offset().top + results.outerHeight(true);
            if (hb > rb) {
                results.scrollTop(results.scrollTop() + (hb - rb));
            }
            y = child.offset().top - results.offset().top;

            // make sure the top of the element is visible
            if (y < 0 && child.css('display') != 'none' ) {
                results.scrollTop(results.scrollTop() + y); // y is negative
            }
        },

        // abstract
        findHighlightableChoices: function() {
            return this.results.find(".select2-result-selectable:not(.select2-disabled):not(.select2-selected)");
        },

        // abstract
        moveHighlight: function (delta) {
            var choices = this.findHighlightableChoices(),
                index = this.highlight();

            while (index > -1 && index < choices.length) {
                index += delta;
                var choice = $(choices[index]);
                if (choice.hasClass("select2-result-selectable") && !choice.hasClass("select2-disabled") && !choice.hasClass("select2-selected")) {
                    this.highlight(index);
                    break;
                }
            }
        },

        // abstract
        highlight: function (index) {
            var choices = this.findHighlightableChoices(),
                choice,
                data;

            if (arguments.length === 0) {
                return indexOf(choices.filter(".select2-highlighted")[0], choices.get());
            }

            if (index >= choices.length) index = choices.length - 1;
            if (index < 0) index = 0;

            this.removeHighlight();

            choice = $(choices[index]);
            choice.addClass("select2-highlighted");

            // ensure assistive technology can determine the active choice
            this.search.attr("aria-activedescendant", choice.find(".select2-result-label").attr("id"));

            this.ensureHighlightVisible();

            this.liveRegion.text(choice.text());

            data = choice.data("select2-data");
            if (data) {
                this.opts.element.trigger({ type: "select2-highlight", val: this.id(data), choice: data });
            }
        },

        removeHighlight: function() {
            this.results.find(".select2-highlighted").removeClass("select2-highlighted");
        },

        // abstract
        countSelectableResults: function() {
            return this.findHighlightableChoices().length;
        },

        // abstract
        highlightUnderEvent: function (event) {
            var el = $(event.target).closest(".select2-result-selectable");
            if (el.length > 0 && !el.is(".select2-highlighted")) {
                var choices = this.findHighlightableChoices();
                this.highlight(choices.index(el));
            } else if (el.length == 0) {
                // if we are over an unselectable item remove all highlights
                this.removeHighlight();
            }
        },

        // abstract
        loadMoreIfNeeded: function () {
            var results = this.results,
                more = results.find("li.select2-more-results"),
                below, // pixels the element is below the scroll fold, below==0 is when the element is starting to be visible
                page = this.resultsPage + 1,
                self=this,
                term=this.search.val(),
                context=this.context;

            if (more.length === 0) return;
            below = more.offset().top - results.offset().top - results.height();

            if (below <= this.opts.loadMorePadding) {
                more.addClass("select2-active");
                this.opts.query({
                        element: this.opts.element,
                        term: term,
                        page: page,
                        context: context,
                        matcher: this.opts.matcher,
                        callback: this.bind(function (data) {

                    // ignore a response if the select2 has been closed before it was received
                    if (!self.opened()) return;


                    self.opts.populateResults.call(this, results, data.results, {term: term, page: page, context:context});
                    self.postprocessResults(data, false, false);

                    if (data.more===true) {
                        more.detach().appendTo(results).text(self.opts.formatLoadMore(page+1));
                        window.setTimeout(function() { self.loadMoreIfNeeded(); }, 10);
                    } else {
                        more.remove();
                    }
                    self.positionDropdown();
                    self.resultsPage = page;
                    self.context = data.context;
                    this.opts.element.trigger({ type: "select2-loaded", items: data });
                })});
            }
        },

        /**
         * Default tokenizer function which does nothing
         */
        tokenize: function() {

        },

        /**
         * @param initial whether or not this is the call to this method right after the dropdown has been opened
         */
        // abstract
        updateResults: function (initial) {
            var search = this.search,
                results = this.results,
                opts = this.opts,
                data,
                self = this,
                input,
                term = search.val(),
                lastTerm = $.data(this.container, "select2-last-term"),
                // sequence number used to drop out-of-order responses
                queryNumber;

            // prevent duplicate queries against the same term
            if (initial !== true && lastTerm && equal(term, lastTerm)) return;

            $.data(this.container, "select2-last-term", term);

            // if the search is currently hidden we do not alter the results
            if (initial !== true && (this.showSearchInput === false || !this.opened())) {
                return;
            }

            function postRender() {
                search.removeClass("select2-active");
                self.positionDropdown();
                if (results.find('.select2-no-results,.select2-selection-limit,.select2-searching').length) {
                    self.liveRegion.text(results.text());
                }
                else {
                    self.liveRegion.text(self.opts.formatMatches(results.find('.select2-result-selectable').length));
                }
            }

            function render(html) {
                results.html(html);
                postRender();
            }

            queryNumber = ++this.queryCount;

            var maxSelSize = this.getMaximumSelectionSize();
            if (maxSelSize >=1) {
                data = this.data();
                if ($.isArray(data) && data.length >= maxSelSize && checkFormatter(opts.formatSelectionTooBig, "formatSelectionTooBig")) {
                    render("<li class='select2-selection-limit'>" + opts.formatSelectionTooBig(maxSelSize) + "</li>");
                    return;
                }
            }

            if (search.val().length < opts.minimumInputLength) {
                if (checkFormatter(opts.formatInputTooShort, "formatInputTooShort")) {
                    render("<li class='select2-no-results'>" + opts.formatInputTooShort(search.val(), opts.minimumInputLength) + "</li>");
                } else {
                    render("");
                }
                if (initial && this.showSearch) this.showSearch(true);
                return;
            }

            if (opts.maximumInputLength && search.val().length > opts.maximumInputLength) {
                if (checkFormatter(opts.formatInputTooLong, "formatInputTooLong")) {
                    render("<li class='select2-no-results'>" + opts.formatInputTooLong(search.val(), opts.maximumInputLength) + "</li>");
                } else {
                    render("");
                }
                return;
            }

            if (opts.formatSearching && this.findHighlightableChoices().length === 0) {
                render("<li class='select2-searching'>" + opts.formatSearching() + "</li>");
            }

            search.addClass("select2-active");

            this.removeHighlight();

            // give the tokenizer a chance to pre-process the input
            input = this.tokenize();
            if (input != undefined && input != null) {
                search.val(input);
            }

            this.resultsPage = 1;

            opts.query({
                element: opts.element,
                    term: search.val(),
                    page: this.resultsPage,
                    context: null,
                    matcher: opts.matcher,
                    callback: this.bind(function (data) {
                var def; // default choice

                // ignore old responses
                if (queryNumber != this.queryCount) {
                  return;
                }

                // ignore a response if the select2 has been closed before it was received
                if (!this.opened()) {
                    this.search.removeClass("select2-active");
                    return;
                }

                // save context, if any
                this.context = (data.context===undefined) ? null : data.context;
                // create a default choice and prepend it to the list
                if (this.opts.createSearchChoice && search.val() !== "") {
                    def = this.opts.createSearchChoice.call(self, search.val(), data.results);
                    if (def !== undefined && def !== null && self.id(def) !== undefined && self.id(def) !== null) {
                        if ($(data.results).filter(
                            function () {
                                return equal(self.id(this), self.id(def));
                            }).length === 0) {
                            this.opts.createSearchChoicePosition(data.results, def);
                        }
                    }
                }

                if (data.results.length === 0 && checkFormatter(opts.formatNoMatches, "formatNoMatches")) {
                    render("<li class='select2-no-results'>" + opts.formatNoMatches(search.val()) + "</li>");
                    return;
                }

                results.empty();
                self.opts.populateResults.call(this, results, data.results, {term: search.val(), page: this.resultsPage, context:null});

                if (data.more === true && checkFormatter(opts.formatLoadMore, "formatLoadMore")) {
                    results.append("<li class='select2-more-results'>" + self.opts.escapeMarkup(opts.formatLoadMore(this.resultsPage)) + "</li>");
                    window.setTimeout(function() { self.loadMoreIfNeeded(); }, 10);
                }

                this.postprocessResults(data, initial);

                postRender();

                this.opts.element.trigger({ type: "select2-loaded", items: data });
            })});
        },

        // abstract
        cancel: function () {
            this.close();
        },

        // abstract
        blur: function () {
            // if selectOnBlur == true, select the currently highlighted option
            if (this.opts.selectOnBlur)
                this.selectHighlighted({noFocus: true});

            this.close();
            this.container.removeClass("select2-container-active");
            // synonymous to .is(':focus'), which is available in jquery >= 1.6
            if (this.search[0] === document.activeElement) { this.search.blur(); }
            this.clearSearch();
            this.selection.find(".select2-search-choice-focus").removeClass("select2-search-choice-focus");
        },

        // abstract
        focusSearch: function () {
            focus(this.search);
        },

        // abstract
        selectHighlighted: function (options) {
            var index=this.highlight(),
                highlighted=this.results.find(".select2-highlighted"),
                data = highlighted.closest('.select2-result').data("select2-data");

            if (data) {
                this.highlight(index);
                this.onSelect(data, options);
            } else if (options && options.noFocus) {
                this.close();
            }
        },

        // abstract
        getPlaceholder: function () {
            var placeholderOption;
            return this.opts.element.attr("placeholder") ||
                this.opts.element.attr("data-placeholder") || // jquery 1.4 compat
                this.opts.element.data("placeholder") ||
                this.opts.placeholder ||
                ((placeholderOption = this.getPlaceholderOption()) !== undefined ? placeholderOption.text() : undefined);
        },

        // abstract
        getPlaceholderOption: function() {
            if (this.select) {
                var firstOption = this.select.children('option').first();
                if (this.opts.placeholderOption !== undefined ) {
                    //Determine the placeholder option based on the specified placeholderOption setting
                    return (this.opts.placeholderOption === "first" && firstOption) ||
                           (typeof this.opts.placeholderOption === "function" && this.opts.placeholderOption(this.select));
                } else if (firstOption.text() === "" && firstOption.val() === "") {
                    //No explicit placeholder option specified, use the first if it's blank
                    return firstOption;
                }
            }
        },

        /**
         * Get the desired width for the container element.  This is
         * derived first from option `width` passed to select2, then
         * the inline 'style' on the original element, and finally
         * falls back to the jQuery calculated element width.
         */
        // abstract
        initContainerWidth: function () {
            function resolveContainerWidth() {
                var style, attrs, matches, i, l, attr;

                if (this.opts.width === "off") {
                    return null;
                } else if (this.opts.width === "element"){
                    return this.opts.element.outerWidth(false) === 0 ? 'auto' : this.opts.element.outerWidth(false) + 'px';
                } else if (this.opts.width === "copy" || this.opts.width === "resolve") {
                    // check if there is inline style on the element that contains width
                    style = this.opts.element.attr('style');
                    if (style !== undefined) {
                        attrs = style.split(';');
                        for (i = 0, l = attrs.length; i < l; i = i + 1) {
                            attr = attrs[i].replace(/\s/g, '');
                            matches = attr.match(/^width:(([-+]?([0-9]*\.)?[0-9]+)(px|em|ex|%|in|cm|mm|pt|pc))/i);
                            if (matches !== null && matches.length >= 1)
                                return matches[1];
                        }
                    }

                    if (this.opts.width === "resolve") {
                        // next check if css('width') can resolve a width that is percent based, this is sometimes possible
                        // when attached to input type=hidden or elements hidden via css
                        style = this.opts.element.css('width');
                        if (style.indexOf("%") > 0) return style;

                        // finally, fallback on the calculated width of the element
                        return (this.opts.element.outerWidth(false) === 0 ? 'auto' : this.opts.element.outerWidth(false) + 'px');
                    }

                    return null;
                } else if ($.isFunction(this.opts.width)) {
                    return this.opts.width();
                } else {
                    return this.opts.width;
               }
            };

            var width = resolveContainerWidth.call(this);
            if (width !== null) {
                this.container.css("width", width);
            }
        }
    });

    SingleSelect2 = clazz(AbstractSelect2, {

        // single

        createContainer: function () {
            var container = $(document.createElement("div")).attr({
                "class": "select2-container"
            }).html([
                "<a href='javascript:void(0)' onclick='return false;' class='select2-choice' tabindex='-1'>",
                "   <span class='select2-chosen'>&nbsp;</span><abbr class='select2-search-choice-close'></abbr>",
                "   <span class='select2-arrow' role='presentation'><b role='presentation'></b></span>",
                "</a>",
                "<label for='' class='select2-offscreen'></label>",
                "<input class='select2-focusser select2-offscreen' type='text' aria-haspopup='true' role='button' />",
                "<div class='select2-drop select2-display-none'>",
                "   <div class='select2-search'>",
                "       <label for='' class='select2-offscreen'></label>",
                "       <input type='text' autocomplete='off' autocorrect='off' autocapitalize='off' spellcheck='false' class='select2-input' role='combobox' aria-expanded='true'",
                "       aria-autocomplete='list' />",
                "   </div>",
                "   <ul class='select2-results' role='listbox'>",
                "   </ul>",
                "</div>"].join(""));
            return container;
        },

        // single
        enableInterface: function() {
            if (this.parent.enableInterface.apply(this, arguments)) {
                this.focusser.prop("disabled", !this.isInterfaceEnabled());
            }
        },

        // single
        opening: function () {
            var el, range, len;

            if (this.opts.minimumResultsForSearch >= 0) {
                this.showSearch(true);
            }

            this.parent.opening.apply(this, arguments);

            if (this.showSearchInput !== false) {
                // IE appends focusser.val() at the end of field :/ so we manually insert it at the beginning using a range
                // all other browsers handle this just fine

                this.search.val(this.focusser.val());
            }
            this.search.focus();
            // move the cursor to the end after focussing, otherwise it will be at the beginning and
            // new text will appear *before* focusser.val()
            el = this.search.get(0);
            if (el.createTextRange) {
                range = el.createTextRange();
                range.collapse(false);
                range.select();
            } else if (el.setSelectionRange) {
                len = this.search.val().length;
                el.setSelectionRange(len, len);
            }

            // initializes search's value with nextSearchTerm (if defined by user)
            // ignore nextSearchTerm if the dropdown is opened by the user pressing a letter
            if(this.search.val() === "") {
                if(this.nextSearchTerm != undefined){
                    this.search.val(this.nextSearchTerm);
                    this.search.select();
                }
            }

            this.focusser.prop("disabled", true).val("");
            this.updateResults(true);
            this.opts.element.trigger($.Event("select2-open"));
        },

        // single
        close: function (params) {
            if (!this.opened()) return;
            this.parent.close.apply(this, arguments);

            params = params || {focus: true};
            this.focusser.prop("disabled", false);

            if (params.focus) {
                this.focusser.focus();
            }
        },

        // single
        focus: function () {
            if (this.opened()) {
                this.close();
            } else {
                this.focusser.prop("disabled", false);
                this.focusser.focus();
            }
        },

        // single
        isFocused: function () {
            return this.container.hasClass("select2-container-active");
        },

        // single
        cancel: function () {
            this.parent.cancel.apply(this, arguments);
            this.focusser.prop("disabled", false);
            this.focusser.focus();
        },

        // single
        destroy: function() {
            $("label[for='" + this.focusser.attr('id') + "']")
                .attr('for', this.opts.element.attr("id"));
            this.parent.destroy.apply(this, arguments);
        },

        // single
        initContainer: function () {

            var selection,
                container = this.container,
                dropdown = this.dropdown,
                idSuffix = nextUid(),
                elementLabel;

            if (this.opts.minimumResultsForSearch < 0) {
                this.showSearch(false);
            } else {
                this.showSearch(true);
            }

            this.selection = selection = container.find(".select2-choice");

            this.focusser = container.find(".select2-focusser");

            // add aria associations
            selection.find(".select2-chosen").attr("id", "select2-chosen-"+idSuffix);
            this.focusser.attr("aria-labelledby", "select2-chosen-"+idSuffix);
            this.results.attr("id", "select2-results-"+idSuffix);
            this.search.attr("aria-owns", "select2-results-"+idSuffix);

            // rewrite labels from original element to focusser
            this.focusser.attr("id", "s2id_autogen"+idSuffix);

            elementLabel = $("label[for='" + this.opts.element.attr("id") + "']");

            this.focusser.prev()
                .text(elementLabel.text())
                .attr('for', this.focusser.attr('id'));

            // Ensure the original element retains an accessible name
            var originalTitle = this.opts.element.attr("title");
            this.opts.element.attr("title", (originalTitle || elementLabel.text()));

            this.focusser.attr("tabindex", this.elementTabIndex);

            // write label for search field using the label from the focusser element
            this.search.attr("id", this.focusser.attr('id') + '_search');

            this.search.prev()
                .text($("label[for='" + this.focusser.attr('id') + "']").text())
                .attr('for', this.search.attr('id'));

            this.search.on("keydown", this.bind(function (e) {
                if (!this.isInterfaceEnabled()) return;

                if (e.which === KEY.PAGE_UP || e.which === KEY.PAGE_DOWN) {
                    // prevent the page from scrolling
                    killEvent(e);
                    return;
                }

                switch (e.which) {
                    case KEY.UP:
                    case KEY.DOWN:
                        this.moveHighlight((e.which === KEY.UP) ? -1 : 1);
                        killEvent(e);
                        return;
                    case KEY.ENTER:
                        this.selectHighlighted();
                        killEvent(e);
                        return;
                    case KEY.TAB:
                        this.selectHighlighted({noFocus: true});
                        return;
                    case KEY.ESC:
                        this.cancel(e);
                        killEvent(e);
                        return;
                }
            }));

            this.search.on("blur", this.bind(function(e) {
                // a workaround for chrome to keep the search field focussed when the scroll bar is used to scroll the dropdown.
                // without this the search field loses focus which is annoying
                if (document.activeElement === this.body().get(0)) {
                    window.setTimeout(this.bind(function() {
                        if (this.opened()) {
                            this.search.focus();
                        }
                    }), 0);
                }
            }));

            this.focusser.on("keydown", this.bind(function (e) {
                if (!this.isInterfaceEnabled()) return;

                if (e.which === KEY.TAB || KEY.isControl(e) || KEY.isFunctionKey(e) || e.which === KEY.ESC) {
                    return;
                }

                if (this.opts.openOnEnter === false && e.which === KEY.ENTER) {
                    killEvent(e);
                    return;
                }

                if (e.which == KEY.DOWN || e.which == KEY.UP
                    || (e.which == KEY.ENTER && this.opts.openOnEnter)) {

                    if (e.altKey || e.ctrlKey || e.shiftKey || e.metaKey) return;

                    this.open();
                    killEvent(e);
                    return;
                }

                if (e.which == KEY.DELETE || e.which == KEY.BACKSPACE) {
                    if (this.opts.allowClear) {
                        this.clear();
                    }
                    killEvent(e);
                    return;
                }
            }));


            installKeyUpChangeEvent(this.focusser);
            this.focusser.on("keyup-change input", this.bind(function(e) {
                if (this.opts.minimumResultsForSearch >= 0) {
                    e.stopPropagation();
                    if (this.opened()) return;
                    this.open();
                }
            }));

            selection.on("mousedown touchstart", "abbr", this.bind(function (e) {
                if (!this.isInterfaceEnabled()) return;
                this.clear();
                killEventImmediately(e);
                this.close();
                this.selection.focus();
            }));

            selection.on("mousedown touchstart", this.bind(function (e) {
                // Prevent IE from generating a click event on the body
                reinsertElement(selection);

                if (!this.container.hasClass("select2-container-active")) {
                    this.opts.element.trigger($.Event("select2-focus"));
                }

                if (this.opened()) {
                    this.close();
                } else if (this.isInterfaceEnabled()) {
                    this.open();
                }

                killEvent(e);
            }));

            dropdown.on("mousedown touchstart", this.bind(function() { this.search.focus(); }));

            selection.on("focus", this.bind(function(e) {
                killEvent(e);
            }));

            this.focusser.on("focus", this.bind(function(){
                if (!this.container.hasClass("select2-container-active")) {
                    this.opts.element.trigger($.Event("select2-focus"));
                }
                this.container.addClass("select2-container-active");
            })).on("blur", this.bind(function() {
                if (!this.opened()) {
                    this.container.removeClass("select2-container-active");
                    this.opts.element.trigger($.Event("select2-blur"));
                }
            }));
            this.search.on("focus", this.bind(function(){
                if (!this.container.hasClass("select2-container-active")) {
                    this.opts.element.trigger($.Event("select2-focus"));
                }
                this.container.addClass("select2-container-active");
            }));

            this.initContainerWidth();
            this.opts.element.addClass("select2-offscreen");
            this.setPlaceholder();

        },

        // single
        clear: function(triggerChange) {
            var data=this.selection.data("select2-data");
            if (data) { // guard against queued quick consecutive clicks
                var evt = $.Event("select2-clearing");
                this.opts.element.trigger(evt);
                if (evt.isDefaultPrevented()) {
                    return;
                }
                var placeholderOption = this.getPlaceholderOption();
                this.opts.element.val(placeholderOption ? placeholderOption.val() : "");
                this.selection.find(".select2-chosen").empty();
                this.selection.removeData("select2-data");
                this.setPlaceholder();

                if (triggerChange !== false){
                    this.opts.element.trigger({ type: "select2-removed", val: this.id(data), choice: data });
                    this.triggerChange({removed:data});
                }
            }
        },

        /**
         * Sets selection based on source element's value
         */
        // single
        initSelection: function () {
            var selected;
            if (this.isPlaceholderOptionSelected()) {
                this.updateSelection(null);
                this.close();
                this.setPlaceholder();
            } else {
                var self = this;
                this.opts.initSelection.call(null, this.opts.element, function(selected){
                    if (selected !== undefined && selected !== null) {
                        self.updateSelection(selected);
                        self.close();
                        self.setPlaceholder();
                        self.nextSearchTerm = self.opts.nextSearchTerm(selected, self.search.val());
                    }
                });
            }
        },

        isPlaceholderOptionSelected: function() {
            var placeholderOption;
            if (!this.getPlaceholder()) return false; // no placeholder specified so no option should be considered
            return ((placeholderOption = this.getPlaceholderOption()) !== undefined && placeholderOption.prop("selected"))
                || (this.opts.element.val() === "")
                || (this.opts.element.val() === undefined)
                || (this.opts.element.val() === null);
        },

        // single
        prepareOpts: function () {
            var opts = this.parent.prepareOpts.apply(this, arguments),
                self=this;

            if (opts.element.get(0).tagName.toLowerCase() === "select") {
                // install the selection initializer
                opts.initSelection = function (element, callback) {
                    var selected = element.find("option").filter(function() { return this.selected });
                    // a single select box always has a value, no need to null check 'selected'
                    callback(self.optionToData(selected));
                };
            } else if ("data" in opts) {
                // install default initSelection when applied to hidden input and data is local
                opts.initSelection = opts.initSelection || function (element, callback) {
                    var id = element.val();
                    //search in data by id, storing the actual matching item
                    var match = null;
                    opts.query({
                        matcher: function(term, text, el){
                            var is_match = equal(id, opts.id(el));
                            if (is_match) {
                                match = el;
                            }
                            return is_match;
                        },
                        callback: !$.isFunction(callback) ? $.noop : function() {
                            callback(match);
                        }
                    });
                };
            }

            return opts;
        },

        // single
        getPlaceholder: function() {
            // if a placeholder is specified on a single select without a valid placeholder option ignore it
            if (this.select) {
                if (this.getPlaceholderOption() === undefined) {
                    return undefined;
                }
            }

            return this.parent.getPlaceholder.apply(this, arguments);
        },

        // single
        setPlaceholder: function () {
            var placeholder = this.getPlaceholder();

            if (this.isPlaceholderOptionSelected() && placeholder !== undefined) {

                // check for a placeholder option if attached to a select
                if (this.select && this.getPlaceholderOption() === undefined) return;

                this.selection.find(".select2-chosen").html(this.opts.escapeMarkup(placeholder));

                this.selection.addClass("select2-default");

                this.container.removeClass("select2-allowclear");
            }
        },

        // single
        postprocessResults: function (data, initial, noHighlightUpdate) {
            var selected = 0, selectedElm = null, self = this, showSearchInput = true;

            // find the selected element in the result list

            this.findHighlightableChoices().each2(function (i, elm) {
                if (equal(self.id(elm.data("select2-data")), self.opts.element.val())) {
                    selected = i;
                    selectedElm = elm;
                    return false;
                }
            });

            // and highlight it
            if (noHighlightUpdate !== false) {
                if (initial === true && selected >= 0) {
                    // By default, the selected item is displayed inside the result list from a single select
                    // User can provide an implementation for 'hideSelectionFromResult' and hide it
                    if(selectedElm !== null) {
                        if(this.opts.hideSelectionFromResult(selectedElm))
                            selectedElm.addClass("select2-selected");
                    }
                    else
                        this.highlight(selected);
                } else {
                    this.highlight(0);
                }
            }

            // hide the search box if this is the first we got the results and there are enough of them for search

            if (initial === true) {
                var min = this.opts.minimumResultsForSearch;
                if (min >= 0) {
                    this.showSearch(countResults(data.results) >= min);
                }
            }
        },

        // single
        showSearch: function(showSearchInput) {
            if (this.showSearchInput === showSearchInput) return;

            this.showSearchInput = showSearchInput;

            this.dropdown.find(".select2-search").toggleClass("select2-search-hidden", !showSearchInput);
            this.dropdown.find(".select2-search").toggleClass("select2-offscreen", !showSearchInput);
            //add "select2-with-searchbox" to the container if search box is shown
            $(this.dropdown, this.container).toggleClass("select2-with-searchbox", showSearchInput);
        },

        // single
        onSelect: function (data, options) {

            if (!this.triggerSelect(data)) { return; }

            var old = this.opts.element.val(),
                oldData = this.data();

            this.opts.element.val(this.id(data));
            this.updateSelection(data);

            this.opts.element.trigger({ type: "select2-selected", val: this.id(data), choice: data });

            this.nextSearchTerm = this.opts.nextSearchTerm(data, this.search.val());
            this.close();

            if (!options || !options.noFocus)
                this.focusser.focus();

            if (!equal(old, this.id(data))) { this.triggerChange({added:data,removed:oldData}); }
        },

        // single
        updateSelection: function (data) {

            var container=this.selection.find(".select2-chosen"), formatted, cssClass;

            this.selection.data("select2-data", data);

            container.empty();
            if (data !== null) {
                formatted=this.opts.formatSelection(data, container, this.opts.escapeMarkup);
            }
            if (formatted !== undefined) {
                container.append(formatted);
            }
            cssClass=this.opts.formatSelectionCssClass(data, container);
            if (cssClass !== undefined) {
                container.addClass(cssClass);
            }

            this.selection.removeClass("select2-default");

            if (this.opts.allowClear && this.getPlaceholder() !== undefined) {
                this.container.addClass("select2-allowclear");
            }
        },

        // single
        val: function () {
            var val,
                triggerChange = false,
                data = null,
                self = this,
                oldData = this.data();

            if (arguments.length === 0) {
                return this.opts.element.val();
            }

            val = arguments[0];

            if (arguments.length > 1) {
                triggerChange = arguments[1];
            }

            if (this.select) {
                this.select
                    .val(val)
                    .find("option").filter(function() { return this.selected }).each2(function (i, elm) {
                        data = self.optionToData(elm);
                        return false;
                    });
                this.updateSelection(data);
                this.setPlaceholder();
                if (triggerChange) {
                    this.triggerChange({added: data, removed:oldData});
                }
            } else {
                // val is an id. !val is true for [undefined,null,'',0] - 0 is legal
                if (!val && val !== 0) {
                    this.clear(triggerChange);
                    return;
                }
                if (this.opts.initSelection === undefined) {
                    throw new Error("cannot call val() if initSelection() is not defined");
                }
                this.opts.element.val(val);
                this.opts.initSelection(this.opts.element, function(data){
                    self.opts.element.val(!data ? "" : self.id(data));
                    self.updateSelection(data);
                    self.setPlaceholder();
                    if (triggerChange) {
                        self.triggerChange({added: data, removed:oldData});
                    }
                });
            }
        },

        // single
        clearSearch: function () {
            this.search.val("");
            this.focusser.val("");
        },

        // single
        data: function(value) {
            var data,
                triggerChange = false;

            if (arguments.length === 0) {
                data = this.selection.data("select2-data");
                if (data == undefined) data = null;
                return data;
            } else {
                if (arguments.length > 1) {
                    triggerChange = arguments[1];
                }
                if (!value) {
                    this.clear(triggerChange);
                } else {
                    data = this.data();
                    this.opts.element.val(!value ? "" : this.id(value));
                    this.updateSelection(value);
                    if (triggerChange) {
                        this.triggerChange({added: value, removed:data});
                    }
                }
            }
        }
    });

    MultiSelect2 = clazz(AbstractSelect2, {

        // multi
        createContainer: function () {
            var container = $(document.createElement("div")).attr({
                "class": "select2-container select2-container-multi"
            }).html([
                "<ul class='select2-choices'>",
                "  <li class='select2-search-field'>",
                "    <label for='' class='select2-offscreen'></label>",
                "    <input type='text' autocomplete='off' autocorrect='off' autocapitalize='off' spellcheck='false' class='select2-input'>",
                "  </li>",
                "</ul>",
                "<div class='select2-drop select2-drop-multi select2-display-none'>",
                "   <ul class='select2-results'>",
                "   </ul>",
                "</div>"].join(""));
            return container;
        },

        // multi
        prepareOpts: function () {
            var opts = this.parent.prepareOpts.apply(this, arguments),
                self=this;

            // TODO validate placeholder is a string if specified

            if (opts.element.get(0).tagName.toLowerCase() === "select") {
                // install the selection initializer
                opts.initSelection = function (element, callback) {

                    var data = [];

                    element.find("option").filter(function() { return this.selected }).each2(function (i, elm) {
                        data.push(self.optionToData(elm));
                    });
                    callback(data);
                };
            } else if ("data" in opts) {
                // install default initSelection when applied to hidden input and data is local
                opts.initSelection = opts.initSelection || function (element, callback) {
                    var ids = splitVal(element.val(), opts.separator);
                    //search in data by array of ids, storing matching items in a list
                    var matches = [];
                    opts.query({
                        matcher: function(term, text, el){
                            var is_match = $.grep(ids, function(id) {
                                return equal(id, opts.id(el));
                            }).length;
                            if (is_match) {
                                matches.push(el);
                            }
                            return is_match;
                        },
                        callback: !$.isFunction(callback) ? $.noop : function() {
                            // reorder matches based on the order they appear in the ids array because right now
                            // they are in the order in which they appear in data array
                            var ordered = [];
                            for (var i = 0; i < ids.length; i++) {
                                var id = ids[i];
                                for (var j = 0; j < matches.length; j++) {
                                    var match = matches[j];
                                    if (equal(id, opts.id(match))) {
                                        ordered.push(match);
                                        matches.splice(j, 1);
                                        break;
                                    }
                                }
                            }
                            callback(ordered);
                        }
                    });
                };
            }

            return opts;
        },

        // multi
        selectChoice: function (choice) {

            var selected = this.container.find(".select2-search-choice-focus");
            if (selected.length && choice && choice[0] == selected[0]) {

            } else {
                if (selected.length) {
                    this.opts.element.trigger("choice-deselected", selected);
                }
                selected.removeClass("select2-search-choice-focus");
                if (choice && choice.length) {
                    this.close();
                    choice.addClass("select2-search-choice-focus");
                    this.opts.element.trigger("choice-selected", choice);
                }
            }
        },

        // multi
        destroy: function() {
            $("label[for='" + this.search.attr('id') + "']")
                .attr('for', this.opts.element.attr("id"));
            this.parent.destroy.apply(this, arguments);
        },

        // multi
        initContainer: function () {

            var selector = ".select2-choices", selection;

            this.searchContainer = this.container.find(".select2-search-field");
            this.selection = selection = this.container.find(selector);

            var _this = this;
            this.selection.on("click", ".select2-search-choice:not(.select2-locked)", function (e) {
                //killEvent(e);
                _this.search[0].focus();
                _this.selectChoice($(this));
            });

            // rewrite labels from original element to focusser
            this.search.attr("id", "s2id_autogen"+nextUid());

            this.search.prev()
                .text($("label[for='" + this.opts.element.attr("id") + "']").text())
                .attr('for', this.search.attr('id'));

            this.search.on("input paste", this.bind(function() {
                if (!this.isInterfaceEnabled()) return;
                if (!this.opened()) {
                    this.open();
                }
            }));

            this.search.attr("tabindex", this.elementTabIndex);

            this.keydowns = 0;
            this.search.on("keydown", this.bind(function (e) {
                if (!this.isInterfaceEnabled()) return;

                ++this.keydowns;
                var selected = selection.find(".select2-search-choice-focus");
                var prev = selected.prev(".select2-search-choice:not(.select2-locked)");
                var next = selected.next(".select2-search-choice:not(.select2-locked)");
                var pos = getCursorInfo(this.search);

                if (selected.length &&
                    (e.which == KEY.LEFT || e.which == KEY.RIGHT || e.which == KEY.BACKSPACE || e.which == KEY.DELETE || e.which == KEY.ENTER)) {
                    var selectedChoice = selected;
                    if (e.which == KEY.LEFT && prev.length) {
                        selectedChoice = prev;
                    }
                    else if (e.which == KEY.RIGHT) {
                        selectedChoice = next.length ? next : null;
                    }
                    else if (e.which === KEY.BACKSPACE) {
                        this.unselect(selected.first());
                        this.search.width(10);
                        selectedChoice = prev.length ? prev : next;
                    } else if (e.which == KEY.DELETE) {
                        this.unselect(selected.first());
                        this.search.width(10);
                        selectedChoice = next.length ? next : null;
                    } else if (e.which == KEY.ENTER) {
                        selectedChoice = null;
                    }

                    this.selectChoice(selectedChoice);
                    killEvent(e);
                    if (!selectedChoice || !selectedChoice.length) {
                        this.open();
                    }
                    return;
                } else if (((e.which === KEY.BACKSPACE && this.keydowns == 1)
                    || e.which == KEY.LEFT) && (pos.offset == 0 && !pos.length)) {

                    this.selectChoice(selection.find(".select2-search-choice:not(.select2-locked)").last());
                    killEvent(e);
                    return;
                } else {
                    this.selectChoice(null);
                }

                if (this.opened()) {
                    switch (e.which) {
                    case KEY.UP:
                    case KEY.DOWN:
                        this.moveHighlight((e.which === KEY.UP) ? -1 : 1);
                        killEvent(e);
                        return;
                    case KEY.ENTER:
                        this.selectHighlighted();
                        killEvent(e);
                        return;
                    case KEY.TAB:
                        this.selectHighlighted({noFocus:true});
                        this.close();
                        return;
                    case KEY.ESC:
                        this.cancel(e);
                        killEvent(e);
                        return;
                    }
                }

                if (e.which === KEY.TAB || KEY.isControl(e) || KEY.isFunctionKey(e)
                 || e.which === KEY.BACKSPACE || e.which === KEY.ESC) {
                    return;
                }

                if (e.which === KEY.ENTER) {
                    if (this.opts.openOnEnter === false) {
                        return;
                    } else if (e.altKey || e.ctrlKey || e.shiftKey || e.metaKey) {
                        return;
                    }
                }

                this.open();

                if (e.which === KEY.PAGE_UP || e.which === KEY.PAGE_DOWN) {
                    // prevent the page from scrolling
                    killEvent(e);
                }

                if (e.which === KEY.ENTER) {
                    // prevent form from being submitted
                    killEvent(e);
                }

            }));

            this.search.on("keyup", this.bind(function (e) {
                this.keydowns = 0;
                this.resizeSearch();
            })
            );

            this.search.on("blur", this.bind(function(e) {
                this.container.removeClass("select2-container-active");
                this.search.removeClass("select2-focused");
                this.selectChoice(null);
                if (!this.opened()) this.clearSearch();
                e.stopImmediatePropagation();
                this.opts.element.trigger($.Event("select2-blur"));
            }));

            this.container.on("click", selector, this.bind(function (e) {
                if (!this.isInterfaceEnabled()) return;
                if ($(e.target).closest(".select2-search-choice").length > 0) {
                    // clicked inside a select2 search choice, do not open
                    return;
                }
                this.selectChoice(null);
                this.clearPlaceholder();
                if (!this.container.hasClass("select2-container-active")) {
                    this.opts.element.trigger($.Event("select2-focus"));
                }
                this.open();
                this.focusSearch();
                e.preventDefault();
            }));

            this.container.on("focus", selector, this.bind(function () {
                if (!this.isInterfaceEnabled()) return;
                if (!this.container.hasClass("select2-container-active")) {
                    this.opts.element.trigger($.Event("select2-focus"));
                }
                this.container.addClass("select2-container-active");
                this.dropdown.addClass("select2-drop-active");
                this.clearPlaceholder();
            }));

            this.initContainerWidth();
            this.opts.element.addClass("select2-offscreen");

            // set the placeholder if necessary
            this.clearSearch();
        },

        // multi
        enableInterface: function() {
            if (this.parent.enableInterface.apply(this, arguments)) {
                this.search.prop("disabled", !this.isInterfaceEnabled());
            }
        },

        // multi
        initSelection: function () {
            var data;
            if (this.opts.element.val() === "" && this.opts.element.text() === "") {
                this.updateSelection([]);
                this.close();
                // set the placeholder if necessary
                this.clearSearch();
            }
            if (this.select || this.opts.element.val() !== "") {
                var self = this;
                this.opts.initSelection.call(null, this.opts.element, function(data){
                    if (data !== undefined && data !== null) {
                        self.updateSelection(data);
                        self.close();
                        // set the placeholder if necessary
                        self.clearSearch();
                    }
                });
            }
        },

        // multi
        clearSearch: function () {
            var placeholder = this.getPlaceholder(),
                maxWidth = this.getMaxSearchWidth();

            if (placeholder !== undefined  && this.getVal().length === 0 && this.search.hasClass("select2-focused") === false) {
                this.search.val(placeholder).addClass("select2-default");
                // stretch the search box to full width of the container so as much of the placeholder is visible as possible
                // we could call this.resizeSearch(), but we do not because that requires a sizer and we do not want to create one so early because of a firefox bug, see #944
                this.search.width(maxWidth > 0 ? maxWidth : this.container.css("width"));
            } else {
                this.search.val("").width(10);
            }
        },

        // multi
        clearPlaceholder: function () {
            if (this.search.hasClass("select2-default")) {
                this.search.val("").removeClass("select2-default");
            }
        },

        // multi
        opening: function () {
            this.clearPlaceholder(); // should be done before super so placeholder is not used to search
            this.resizeSearch();

            this.parent.opening.apply(this, arguments);

            this.focusSearch();

            // initializes search's value with nextSearchTerm (if defined by user)
            // ignore nextSearchTerm if the dropdown is opened by the user pressing a letter
            if(this.search.val() === "") {
                if(this.nextSearchTerm != undefined){
                    this.search.val(this.nextSearchTerm);
                    this.search.select();
                }
            }

            this.updateResults(true);
            this.search.focus();
            this.opts.element.trigger($.Event("select2-open"));
        },

        // multi
        close: function () {
            if (!this.opened()) return;
            this.parent.close.apply(this, arguments);
        },

        // multi
        focus: function () {
            this.close();
            this.search.focus();
        },

        // multi
        isFocused: function () {
            return this.search.hasClass("select2-focused");
        },

        // multi
        updateSelection: function (data) {
            var ids = [], filtered = [], self = this;

            // filter out duplicates
            $(data).each(function () {
                if (indexOf(self.id(this), ids) < 0) {
                    ids.push(self.id(this));
                    filtered.push(this);
                }
            });
            data = filtered;

            this.selection.find(".select2-search-choice").remove();
            $(data).each(function () {
                self.addSelectedChoice(this);
            });
            self.postprocessResults();
        },

        // multi
        tokenize: function() {
            var input = this.search.val();
            input = this.opts.tokenizer.call(this, input, this.data(), this.bind(this.onSelect), this.opts);
            if (input != null && input != undefined) {
                this.search.val(input);
                if (input.length > 0) {
                    this.open();
                }
            }

        },

        // multi
        onSelect: function (data, options) {

            if (!this.triggerSelect(data)) { return; }

            this.addSelectedChoice(data);

            this.opts.element.trigger({ type: "selected", val: this.id(data), choice: data });

            // keep track of the search's value before it gets cleared
            this.nextSearchTerm = this.opts.nextSearchTerm(data, this.search.val());

            this.clearSearch();
            this.updateResults();

            if (this.select || !this.opts.closeOnSelect) this.postprocessResults(data, false, this.opts.closeOnSelect===true);

            if (this.opts.closeOnSelect) {
                this.close();
                this.search.width(10);
            } else {
                if (this.countSelectableResults()>0) {
                    this.search.width(10);
                    this.resizeSearch();
                    if (this.getMaximumSelectionSize() > 0 && this.val().length >= this.getMaximumSelectionSize()) {
                        // if we reached max selection size repaint the results so choices
                        // are replaced with the max selection reached message
                        this.updateResults(true);
                    } else {
                        // initializes search's value with nextSearchTerm and update search result
                        if(this.nextSearchTerm != undefined){
                            this.search.val(this.nextSearchTerm);
                            this.updateResults();
                            this.search.select();
                        }
                    }
                    this.positionDropdown();
                } else {
                    // if nothing left to select close
                    this.close();
                    this.search.width(10);
                }
            }

            // since its not possible to select an element that has already been
            // added we do not need to check if this is a new element before firing change
            this.triggerChange({ added: data });

            if (!options || !options.noFocus)
                this.focusSearch();
        },

        // multi
        cancel: function () {
            this.close();
            this.focusSearch();
        },

        addSelectedChoice: function (data) {
            var enableChoice = !data.locked,
                enabledItem = $(
                    "<li class='select2-search-choice'>" +
                    "    <div></div>" +
                    "    <a href='#' onclick='return false;' class='select2-search-choice-close' tabindex='-1'></a>" +
                    "</li>"),
                disabledItem = $(
                    "<li class='select2-search-choice select2-locked'>" +
                    "<div></div>" +
                    "</li>");
            var choice = enableChoice ? enabledItem : disabledItem,
                id = this.id(data),
                val = this.getVal(),
                formatted,
                cssClass;

            formatted=this.opts.formatSelection(data, choice.find("div"), this.opts.escapeMarkup);
            if (formatted != undefined) {
                choice.find("div").replaceWith("<div>"+formatted+"</div>");
            }
            cssClass=this.opts.formatSelectionCssClass(data, choice.find("div"));
            if (cssClass != undefined) {
                choice.addClass(cssClass);
            }

            if(enableChoice){
              choice.find(".select2-search-choice-close")
                  .on("mousedown", killEvent)
                  .on("click dblclick", this.bind(function (e) {
                  if (!this.isInterfaceEnabled()) return;

                  $(e.target).closest(".select2-search-choice").fadeOut('fast', this.bind(function(){
                      this.unselect($(e.target));
                      this.selection.find(".select2-search-choice-focus").removeClass("select2-search-choice-focus");
                      this.close();
                      this.focusSearch();
                  })).dequeue();
                  killEvent(e);
              })).on("focus", this.bind(function () {
                  if (!this.isInterfaceEnabled()) return;
                  this.container.addClass("select2-container-active");
                  this.dropdown.addClass("select2-drop-active");
              }));
            }

            choice.data("select2-data", data);
            choice.insertBefore(this.searchContainer);

            val.push(id);
            this.setVal(val);
        },

        // multi
        unselect: function (selected) {
            var val = this.getVal(),
                data,
                index;
            selected = selected.closest(".select2-search-choice");

            if (selected.length === 0) {
                throw "Invalid argument: " + selected + ". Must be .select2-search-choice";
            }

            data = selected.data("select2-data");

            if (!data) {
                // prevent a race condition when the 'x' is clicked really fast repeatedly the event can be queued
                // and invoked on an element already removed
                return;
            }

            while((index = indexOf(this.id(data), val)) >= 0) {
                val.splice(index, 1);
                this.setVal(val);
                if (this.select) this.postprocessResults();
            }

            var evt = $.Event("select2-removing");
            evt.val = this.id(data);
            evt.choice = data;
            this.opts.element.trigger(evt);

            if (evt.isDefaultPrevented()) {
                return;
            }

            selected.remove();

            this.opts.element.trigger({ type: "select2-removed", val: this.id(data), choice: data });
            this.triggerChange({ removed: data });
        },

        // multi
        postprocessResults: function (data, initial, noHighlightUpdate) {
            var val = this.getVal(),
                choices = this.results.find(".select2-result"),
                compound = this.results.find(".select2-result-with-children"),
                self = this;

            choices.each2(function (i, choice) {
                var id = self.id(choice.data("select2-data"));
                if (indexOf(id, val) >= 0) {
                    // By default, the selected item is hidden from the result list inside a multi select
                    // User can provide an implementation for 'hideSelectionFromResult' and allow the same
                    // element to be selected multiple times.
                    if(self.opts.hideSelectionFromResult(choice) === undefined || self.opts.hideSelectionFromResult(choice)) {
                        choice.addClass("select2-selected");
                        // mark all children of the selected parent as selected
                        choice.find(".select2-result-selectable").addClass("select2-selected");
                    }
                }
            });

            compound.each2(function(i, choice) {
                // hide an optgroup if it doesn't have any selectable children
                if (!choice.is('.select2-result-selectable')
                    && choice.find(".select2-result-selectable:not(.select2-selected)").length === 0) {
                    choice.addClass("select2-selected");
                }
            });

            if (this.highlight() == -1 && noHighlightUpdate !== false){
                self.highlight(0);
            }

            //If all results are chosen render formatNoMatches
            if(!this.opts.createSearchChoice && !choices.filter('.select2-result:not(.select2-selected)').length > 0){
                if(!data || data && !data.more && this.results.find(".select2-no-results").length === 0) {
                    if (checkFormatter(self.opts.formatNoMatches, "formatNoMatches")) {
                        this.results.append("<li class='select2-no-results'>" + self.opts.formatNoMatches(self.search.val()) + "</li>");
                    }
                }
            }

        },

        // multi
        getMaxSearchWidth: function() {
            return this.selection.width() - getSideBorderPadding(this.search);
        },

        // multi
        resizeSearch: function () {
            var minimumWidth, left, maxWidth, containerLeft, searchWidth,
                sideBorderPadding = getSideBorderPadding(this.search);

            minimumWidth = measureTextWidth(this.search) + 10;

            left = this.search.offset().left;

            maxWidth = this.selection.width();
            containerLeft = this.selection.offset().left;

            searchWidth = maxWidth - (left - containerLeft) - sideBorderPadding;

            if (searchWidth < minimumWidth) {
                searchWidth = maxWidth - sideBorderPadding;
            }

            if (searchWidth < 40) {
                searchWidth = maxWidth - sideBorderPadding;
            }

            if (searchWidth <= 0) {
              searchWidth = minimumWidth;
            }

            this.search.width(Math.floor(searchWidth));
        },

        // multi
        getVal: function () {
            var val;
            if (this.select) {
                val = this.select.val();
                return val === null ? [] : val;
            } else {
                val = this.opts.element.val();
                return splitVal(val, this.opts.separator);
            }
        },

        // multi
        setVal: function (val) {
            var unique;
            if (this.select) {
                this.select.val(val);
            } else {
                unique = [];
                // filter out duplicates
                $(val).each(function () {
                    if (indexOf(this, unique) < 0) unique.push(this);
                });
                this.opts.element.val(unique.length === 0 ? "" : unique.join(this.opts.separator));
            }
        },

        // multi
        buildChangeDetails: function (old, current) {
            var current = current.slice(0),
                old = old.slice(0);

            // remove intersection from each array
            for (var i = 0; i < current.length; i++) {
                for (var j = 0; j < old.length; j++) {
                    if (equal(this.opts.id(current[i]), this.opts.id(old[j]))) {
                        current.splice(i, 1);
                        if(i>0){
                        	i--;
                        }
                        old.splice(j, 1);
                        j--;
                    }
                }
            }

            return {added: current, removed: old};
        },


        // multi
        val: function (val, triggerChange) {
            var oldData, self=this;

            if (arguments.length === 0) {
                return this.getVal();
            }

            oldData=this.data();
            if (!oldData.length) oldData=[];

            // val is an id. !val is true for [undefined,null,'',0] - 0 is legal
            if (!val && val !== 0) {
                this.opts.element.val("");
                this.updateSelection([]);
                this.clearSearch();
                if (triggerChange) {
                    this.triggerChange({added: this.data(), removed: oldData});
                }
                return;
            }

            // val is a list of ids
            this.setVal(val);

            if (this.select) {
                this.opts.initSelection(this.select, this.bind(this.updateSelection));
                if (triggerChange) {
                    this.triggerChange(this.buildChangeDetails(oldData, this.data()));
                }
            } else {
                if (this.opts.initSelection === undefined) {
                    throw new Error("val() cannot be called if initSelection() is not defined");
                }

                this.opts.initSelection(this.opts.element, function(data){
                    var ids=$.map(data, self.id);
                    self.setVal(ids);
                    self.updateSelection(data);
                    self.clearSearch();
                    if (triggerChange) {
                        self.triggerChange(self.buildChangeDetails(oldData, self.data()));
                    }
                });
            }
            this.clearSearch();
        },

        // multi
        onSortStart: function() {
            if (this.select) {
                throw new Error("Sorting of elements is not supported when attached to <select>. Attach to <input type='hidden'/> instead.");
            }

            // collapse search field into 0 width so its container can be collapsed as well
            this.search.width(0);
            // hide the container
            this.searchContainer.hide();
        },

        // multi
        onSortEnd:function() {

            var val=[], self=this;

            // show search and move it to the end of the list
            this.searchContainer.show();
            // make sure the search container is the last item in the list
            this.searchContainer.appendTo(this.searchContainer.parent());
            // since we collapsed the width in dragStarted, we resize it here
            this.resizeSearch();

            // update selection
            this.selection.find(".select2-search-choice").each(function() {
                val.push(self.opts.id($(this).data("select2-data")));
            });
            this.setVal(val);
            this.triggerChange();
        },

        // multi
        data: function(values, triggerChange) {
            var self=this, ids, old;
            if (arguments.length === 0) {
                 return this.selection
                     .children(".select2-search-choice")
                     .map(function() { return $(this).data("select2-data"); })
                     .get();
            } else {
                old = this.data();
                if (!values) { values = []; }
                ids = $.map(values, function(e) { return self.opts.id(e); });
                this.setVal(ids);
                this.updateSelection(values);
                this.clearSearch();
                if (triggerChange) {
                    this.triggerChange(this.buildChangeDetails(old, this.data()));
                }
            }
        }
    });

    $.fn.select2 = function () {

        var args = Array.prototype.slice.call(arguments, 0),
            opts,
            select2,
            method, value, multiple,
            allowedMethods = ["val", "destroy", "opened", "open", "close", "focus", "isFocused", "container", "dropdown", "onSortStart", "onSortEnd", "enable", "disable", "readonly", "positionDropdown", "data", "search"],
            valueMethods = ["opened", "isFocused", "container", "dropdown"],
            propertyMethods = ["val", "data"],
            methodsMap = { search: "externalSearch" };

        this.each(function () {
            if (args.length === 0 || typeof(args[0]) === "object") {
                opts = args.length === 0 ? {} : $.extend({}, args[0]);
                opts.element = $(this);

                if (opts.element.get(0).tagName.toLowerCase() === "select") {
                    multiple = opts.element.prop("multiple");
                } else {
                    multiple = opts.multiple || false;
                    if ("tags" in opts) {opts.multiple = multiple = true;}
                }

                select2 = multiple ? new window.Select2["class"].multi() : new window.Select2["class"].single();
                select2.init(opts);
            } else if (typeof(args[0]) === "string") {

                if (indexOf(args[0], allowedMethods) < 0) {
                    throw "Unknown method: " + args[0];
                }

                value = undefined;
                select2 = $(this).data("select2");
                if (select2 === undefined) return;

                method=args[0];

                if (method === "container") {
                    value = select2.container;
                } else if (method === "dropdown") {
                    value = select2.dropdown;
                } else {
                    if (methodsMap[method]) method = methodsMap[method];

                    value = select2[method].apply(select2, args.slice(1));
                }
                if (indexOf(args[0], valueMethods) >= 0
                    || (indexOf(args[0], propertyMethods) && args.length == 1)) {
                    return false; // abort the iteration, ready to return first matched value
                }
            } else {
                throw "Invalid arguments to select2 plugin: " + args;
            }
        });
        return (value === undefined) ? this : value;
    };

    // plugin defaults, accessible to users
    $.fn.select2.defaults = {
        width: "copy",
        loadMorePadding: 0,
        closeOnSelect: true,
        openOnEnter: true,
        containerCss: {},
        dropdownCss: {},
        containerCssClass: "",
        dropdownCssClass: "",
        formatResult: function(result, container, query, escapeMarkup) {
            var markup=[];
            markMatch(result.text, query.term, markup, escapeMarkup);
            return markup.join("");
        },
        formatSelection: function (data, container, escapeMarkup) {
            return data ? escapeMarkup(data.text) : undefined;
        },
        sortResults: function (results, container, query) {
            return results;
        },
        formatResultCssClass: function(data) {return data.css;},
        formatSelectionCssClass: function(data, container) {return undefined;},
        formatMatches: function (matches) { return matches + " results are available, use up and down arrow keys to navigate."; },
        formatNoMatches: function () { return "No matches found"; },
        formatInputTooShort: function (input, min) { var n = min - input.length; return "Please enter " + n + " or more character" + (n == 1? "" : "s"); },
        formatInputTooLong: function (input, max) { var n = input.length - max; return "Please delete " + n + " character" + (n == 1? "" : "s"); },
        formatSelectionTooBig: function (limit) { return "You can only select " + limit + " item" + (limit == 1 ? "" : "s"); },
        formatLoadMore: function (pageNumber) { return "Loading more results…"; },
        formatSearching: function () { return "Searching…"; },
        minimumResultsForSearch: 0,
        minimumInputLength: 0,
        maximumInputLength: null,
        maximumSelectionSize: 0,
        id: function (e) { return e == undefined ? null : e.id; },
        matcher: function(term, text) {
            return stripDiacritics(''+text).toUpperCase().indexOf(stripDiacritics(''+term).toUpperCase()) >= 0;
        },
        separator: ",",
        tokenSeparators: [],
        tokenizer: defaultTokenizer,
        escapeMarkup: defaultEscapeMarkup,
        blurOnChange: false,
        selectOnBlur: false,
        adaptContainerCssClass: function(c) { return c; },
        adaptDropdownCssClass: function(c) { return null; },
        nextSearchTerm: function(selectedObject, currentSearchTerm) { return undefined; },
        hideSelectionFromResult: function(selectedObject) { return undefined; },
        searchInputPlaceholder: '',
        createSearchChoicePosition: 'top'
    };

    $.fn.select2.ajaxDefaults = {
        transport: $.ajax,
        params: {
            type: "GET",
            cache: false,
            dataType: "json"
        }
    };

    // exports
    window.Select2 = {
        query: {
            ajax: ajax,
            local: local,
            tags: tags
        }, util: {
            debounce: debounce,
            markMatch: markMatch,
            escapeMarkup: defaultEscapeMarkup,
            stripDiacritics: stripDiacritics
        }, "class": {
            "abstract": AbstractSelect2,
            "single": SingleSelect2,
            "multi": MultiSelect2
        }
    };

}(jQuery));