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 Licesnse 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"){
 		$.fn.extend({
 			/*
			* 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, $document;

    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;
        }
    };

    $document = $(document);

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

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

    /**
     * Compares equality of a and b
     * @param a
     * @param b
     */
    function equal(a, b) {
        return a===b;
    }

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

    $document.bind("mousemove", function (e) {
        lastMousePosition = {x: e.pageX, 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.bind("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.bind("scroll", function (e) {
            if (indexOf(e.target, element.get()) >= 0) notify(e);
        });
    }

    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 markMatch(text, term, markup, escapeMarkup) {
        var match=text.toUpperCase().indexOf(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)));
    }

    /**
     * Produces an ajax-based query function
     *
     * @param options object containing configuration paramters
     * @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 datatatypes supported by jQuery's $.ajax function or the transport function if specified
     * @param options.traditional a boolean flag that should be true if you wish to use the traditional style of param serialization for the ajax request
     * @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
            requestSequence = 0, // sequence used to drop out-of-order responses
            handler = null,
            quietMillis = options.quietMillis || 100;

        return function (query) {
            window.clearTimeout(timeout);
            timeout = window.setTimeout(function () {
                requestSequence += 1; // increment the sequence
                var requestNumber = requestSequence, // this request's sequence number
                    data = options.data, // ajax data function
                    url = options.url, // ajax url string or function
                    transport = options.transport || $.ajax,
                    traditional = options.traditional || false,
                    type = options.type || 'GET'; // set type of request (GET or POST)

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

                if( null !== handler) { handler.abort(); }

                handler = transport.call(null, {
                    url: url,
                    dataType: options.dataType,
                    data: data,
                    type: type,
                    cache: false,
                    traditional: traditional,
                    success: function (data) {
                        if (requestNumber < requestSequence) {
                            return;
                        }
                        // TODO 3.0 - replace query.page with query so users have access to term, page, etc.
                        var results = options.results(data, query.page);
                        query.callback(results);
                    }
                });
            }, 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,
            text = function (item) { return ""+item.text; }; // function used to retrieve the text portion of a data item that is matched against the search

        if (!$.isArray(data)) {
            text = data.text;
            // if text is not a function we assume it to be a key name
            if (!$.isFunction(text)) {
              dataText = data.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]; };
            }
            data = data.results;
        }

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

            // 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) {
                this.destroy();
            }

            this.enabled=true;
            this.container = this.createContainer();

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

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

            // create the dropdown mask if doesnt 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.bind("mousedown touchstart", function (e) {
                    var dropdown = $("#select2-drop"), self;
                    if (dropdown.length > 0) {
                        self=dropdown.data("select2");
                        if (self.opts.selectOnBlur) {
                            self.selectHighlighted({noFocus: true});
                        }
                        self.close();
                    }
                });
            }

            if (opts.element.attr("class") !== undefined) {
                this.container.addClass(opts.element.attr("class").replace(/validate\[[\S ]+] ?/, ''));
            }

            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)
                .addClass("select2-offscreen")
                .bind("focus.select2", function() { $(this).select2("focus"); })
                .attr("tabIndex", "-1")
                .before(this.container);
            this.container.data("select2", this);

            this.dropdown = this.container.find(".select2-drop");
            this.dropdown.addClass(evaluate(opts.dropdownCssClass));
            this.dropdown.data("select2", this);

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

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

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

            // initialize the container
            this.initContainer();
            this.initContainerWidth();

            installFilteredMouseMove(this.results);
            this.dropdown.delegate(resultsSelector, "mousemove-filtered", this.bind(this.highlightUnderEvent));

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

            // 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(), height;
                    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.bind("keyup-change", this.bind(this.updateResults));
            search.bind("focus", function () { search.addClass("select2-focused"); if (search.val() === " ") search.val(""); });
            search.bind("blur", function () { search.removeClass("select2-focused");});

            this.dropdown.delegate(resultsSelector, "mouseup", this.bind(function (e) {
                if ($(e.target).closest(".select2-result-selectable").length > 0) {
                    this.highlightUnderEvent(e);
                    this.selectHighlighted(e);
                } else {
                    this.focusSearch();
                }
                killEvent(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.bind("click mouseup mousedown", function (e) { e.stopPropagation(); });

            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.element.is(":disabled") || opts.element.is("[readonly='readonly']")) this.disable();
        },

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

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

            if (select2 !== undefined) {

                select2.container.remove();
                select2.dropdown.remove();
                select2.opts.element
                    .removeData("select2")
                    .unbind(".select2")
                    .attr({"tabIndex": this.elementTabIndex})
                    .show();
            }
        },

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

            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,  data, result, children, id=this.opts.id, self=this;

                    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));

                            label=$(document.createElement("div"));
                            label.addClass("select2-result-label");

                            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);
                        }
                    };

                    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.attr("data-select2-tags");
            }

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

                    process=function(element, collection) {
                        var group;
                        if (element.is("option")) {
                            if (query.matcher(term, element.text(), element)) {
                                collection.push({id:element.attr("value"), text:element.text(), element: element.get(), css: element.attr("class"), disabled: equal(element.attr("disabled"), "disabled") });
                            }
                        } else if (element.is("optgroup")) {
                            group={text:element.attr("label"), children:[], element: element.get(), css: element.attr("class")};
                            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) {
                        firstChild = children[0];
                        if ($(firstChild).text() === "") {
                            children=children.not(firstChild);
                        }
                    }

                    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; };
                opts.formatResultCssClass = function(data) { return data.css; };
            } 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(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: term, text: term}; };
                        }
                        if (opts.initSelection === undefined) {
                            opts.initSelection = function (element, callback) {
                                var data = [];
                                $(splitVal(element.val(), opts.separator)).each(function () {
                                    var id = this, text = this, tags=opts.tags;
                                    if ($.isFunction(tags)) tags=tags();
                                    $(tags).each(function() { if (equal(this.id, id)) { text = this.text; return false; } });
                                    data.push({id: id, text: text});
                                });

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

            return opts;
        },

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

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

            sync = this.bind(function () {
                var enabled = this.opts.element.attr("disabled") !== "disabled";
                var readonly = this.opts.element.attr("readonly") === "readonly";

                enabled = enabled && !readonly;

                if (this.enabled !== enabled) {
                    if (enabled) {
                        this.enable();
                    } else {
                        this.disable();
                    }
                }
            });

            // mozilla and IE
            el.bind("propertychange.select2 DOMAttrModified.select2", sync);
            // safari and chrome
            if (typeof WebKitMutationObserver !== "undefined") {
                if (this.propertyObserver) { delete this.propertyObserver; this.propertyObserver = null; }
                this.propertyObserver = new WebKitMutationObserver(function (mutations) {
                    mutations.forEach(sync);
                });
                this.propertyObserver.observe(el.get(0), { attributes:true, subtree:false });
            }
        },

        /**
         * 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 ignorea 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
        enable: function() {
            if (this.enabled) return;

            this.enabled=true;
            this.container.removeClass("select2-container-disabled");
            this.opts.element.removeAttr("disabled");
        },

        // abstract
        disable: function() {
            if (!this.enabled) return;

            this.close();

            this.enabled=false;
            this.container.addClass("select2-container-disabled");
            this.opts.element.attr("disabled", "disabled");
        },

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

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

            // 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;
            }

            // always prefer the current above/below alignment, unless there is not enough room

            if (aboveNow) {
                above = true;
                if (!enoughRoomAbove && enoughRoomBelow) above = false;
            } else {
                above = false;
                if (!enoughRoomBelow && enoughRoomAbove) above = true;
            }

	    if (!enoughRoomOnRight) {
		   dropLeft = offset.left + width - dropWidth;
	    }

            if (above) {
                dropTop = offset.top - dropHeight;
                this.container.addClass("select2-drop-above");
                this.dropdown.addClass("select2-drop-above");
            }
            else {
                this.container.removeClass("select2-drop-above");
                this.dropdown.removeClass("select2-drop-above");
            }

            css = $.extend({
                top: dropTop,
                left: dropLeft,
                width: width
            }, evaluate(this.opts.dropdownCss));

            this.dropdown.css(css);
        },

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

            if (this.opened()) return false;

            event = $.Event("open");
            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;

            window.setTimeout(this.bind(this.opening), 1);

            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.clearDropdownAlignmentPreference();

            if (this.search.val() === " ") { this.search.val(""); }

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


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

            this.updateResults(true);

            mask = $("#select2-drop-mask");

            // 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.css({
                width: document.documentElement.scrollWidth,
                height: document.documentElement.scrollHeight});
            mask.show();
            this.dropdown.show();
            this.positionDropdown();

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

            // 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
            this.container.parents().add(window).each(function () {
                $(this).bind(resize+" "+scroll+" "+orient, function (e) {
                    $("#select2-drop-mask").css({
                        width:document.documentElement.scrollWidth,
                        height:document.documentElement.scrollHeight});
                    $("#select2-drop").data("select2").positionDropdown();
                });
            });

            this.focusSearch();
        },

        // 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).unbind(scroll).unbind(resize).unbind(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.opts.element.trigger($.Event("close"));
        },

        // abstract
        clearSearch: function () {

        },

        // 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();

            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() {
            var h=this.results.find(".select2-result-selectable:not(.select2-selected):not(.select2-disabled)");
            return this.results.find(".select2-result-selectable:not(.select2-selected):not(.select2-disabled)");
        },

        // 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();

            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.results.find(".select2-highlighted").removeClass("select2-highlighted");

            $(choices[index]).addClass("select2-highlighted");
            this.ensureHighlightVisible();
        },

        // 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 al highlights
                this.results.find(".select2-highlighted").removeClass("select2-highlighted");
            }
        },

        // 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
                offset = -1, // index of first element without data
                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({
                        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});

                    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;
                })});
            }
        },

        /**
         * 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;

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

            search.addClass("select2-active");

            function postRender() {
                results.scrollTop(0);
                search.removeClass("select2-active");
                self.positionDropdown();
            }

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

            var maxSelSize = $.isFunction(opts.maximumSelectionSize) ? opts.maximumSelectionSize() : opts.maximumSelectionSize;
            if (maxSelSize >=1) {
                data = this.data();
                if ($.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("");
                }
                return;
            }
            else if (opts.formatSearching() && initial===true) {
                render("<li class='select2-searching'>" + opts.formatSearching() + "</li>");
            }

            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;
            }

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

                // ignore a response if the select2 has been closed before it was received
                if (!this.opened()) 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(null, 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) {
                            data.results.unshift(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();
            })});
        },

        // 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");
            this.dropdown.removeClass("select2-drop-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");
            this.opts.element.triggerHandler("blur");
        },

        // abstract
        focusSearch: function () {
            // need to do it here as well as in timeout so it works in IE
            this.search.show();
            this.search.focus();

            /* we do this in a timeout so that current event processing can complete before this code is executed.
             this makes sure the search field is focussed even if the current event would blur it */
            window.setTimeout(this.bind(function () {
                // reset the value so IE places the cursor at the end of the input box
                this.search.show();
                this.search.focus();
                this.search.val(this.search.val());
            }), 10);
        },

        // 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);
            }
        },

        // abstract
        getPlaceholder: function () {

            // if a placeholder is specified on a select without the first empty option ignore it
            if (this.select) {
               if (this.select.find("option").first().text() !== "") {
                   return undefined;
               }
            }

            return this.opts.element.attr("placeholder") ||
                this.opts.element.attr("data-placeholder") || // jquery 1.4 compat
                this.opts.element.data("placeholder") ||
                this.opts.placeholder;
        },

        /**
         * 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;

                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) {
                            matches = attrs[i].replace(/\s/g, '')
                                .match(/width:(([-+]?([0-9]*\.)?[0-9]+)(px|em|ex|%|in|cm|mm|pt|pc))/);
                            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.attr("style", "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'>",
                "   <span></span><abbr class='select2-search-choice-close' style='display:none;'></abbr>",
                "   <div><b></b></div>" ,
                "</a>",
                "    <div class='select2-drop select2-offscreen'>" ,
                "   <div class='select2-search'>" ,
                "       <input type='text' autocomplete='off' class='select2-input'/>" ,
                "   </div>" ,
                "   <ul class='select2-results'>" ,
                "   </ul>" ,
                "</div>"].join(""));
            return container;
        },

        // single
        disable: function() {
            if (!this.enabled) return;

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

            this.selection.attr("tabIndex", "-1");
            this.search.attr("tabIndex", "-1");
        },

        // single
        enable: function() {
            if (this.enabled) return;

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

            if (this.elementTabIndex) {
                this.selection.attr("tabIndex", this.elementTabIndex);
            } else {
                this.selection.removeAttr("tabIndex");
            }

            this.search.removeAttr("tabIndex");
        },

        // single
        opening: function () {
            this.search.show();
            this.parent.opening.apply(this, arguments);
            this.dropdown.removeClass("select2-offscreen");
        },

        // single
        close: function () {
            if (!this.opened()) return;
            this.parent.close.apply(this, arguments);
            this.dropdown.removeAttr("style").addClass("select2-offscreen").insertAfter(this.selection).show();
        },

        // single
        focus: function () {
            this.close();
            this.selection.focus();
            this.opts.element.triggerHandler("focus");
        },

        // single
        isFocused: function () {
            return this.selection[0] === document.activeElement;
        },

        // single
        cancel: function () {
            this.parent.cancel.apply(this, arguments);
            this.selection.focus();
        },

        // single
        initContainer: function () {

            var selection,
                container = this.container,
                dropdown = this.dropdown,
                clickingInside = false;

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

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

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

                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.TAB:
                        case KEY.ENTER:
                            this.selectHighlighted();
                            killEvent(e);
                            return;
                        case KEY.ESC:
                            this.cancel(e);
                            killEvent(e);
                            return;
                    }
                } else {

                    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) {
                        return;
                    }

                    this.open();

                    if (e.which === KEY.ENTER) {
                        // do not propagate the event otherwise we open, and propagate enter which closes
                        return;
                    }
                }
            }));

            this.search.bind("focus", this.bind(function() {
                this.selection.attr("tabIndex", "-1");
            }));
            this.search.bind("blur", this.bind(function() {
                if (!this.opened()) this.container.removeClass("select2-container-active");
                window.setTimeout(this.bind(function() {
                    // restore original tab index
                    var ti=this.elementTabIndex || 0;
                    if (ti) {
                        this.selection.attr("tabIndex", ti);
                    } else {
                        this.selection.removeAttr("tabIndex");
                    }
                }), 10);
            }));

            selection.delegate("abbr", "mousedown", this.bind(function (e) {
                if (!this.enabled) return;
                this.clear();
                killEventImmediately(e);
                this.close();
                this.triggerChange();
                this.selection.focus();
            }));

            selection.bind("mousedown", this.bind(function (e) {
                clickingInside = true;

                if (this.opened()) {
                    this.close();
                    this.selection.focus();
                } else if (this.enabled) {
                    this.open();
                }

                clickingInside = false;
            }));

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

            selection.bind("focus", this.bind(function() {
                if (!this.enabled) return;

                this.container.addClass("select2-container-active");
                // hide the search so the tab key does not focus on it
                this.search.attr("tabIndex", "-1");
            }));

            selection.bind("blur", this.bind(function() {
                if (!this.opened()) {
                    this.container.removeClass("select2-container-active");
                }
                window.setTimeout(this.bind(function() { this.search.attr("tabIndex", this.elementTabIndex || 0); }), 10);
            }));

            selection.bind("keydown", this.bind(function(e) {
                if (!this.enabled) return;

                if (e.which == KEY.DOWN || e.which == KEY.UP
                    || (e.which == KEY.ENTER && this.opts.openOnEnter)) {
                    this.open();
                    killEvent(e);
                    return;
                }

                if (e.which == KEY.DELETE || e.which == KEY.BACKSPACE) {
                    if (this.opts.allowClear) {
                        this.clear();
                    }
                    killEvent(e);
                    return;
                }
            }));
            selection.bind("keypress", this.bind(function(e) {
		if (e.which == KEY.DELETE || e.which == KEY.BACKSPACE || e.which == KEY.TAB || e.which == KEY.ENTER || e.which == 0) {
			return;
		}
                var key = String.fromCharCode(e.which);
                this.search.val(key);
                this.open();
            }));

            this.setPlaceholder();

            this.search.bind("focus", this.bind(function() {
                this.container.addClass("select2-container-active");
            }));
        },

        // single
        clear: function() {
            this.opts.element.val("");
            this.selection.find("span").empty();
            this.selection.removeData("select2-data");
            this.setPlaceholder();
        },

        /**
         * Sets selection based on source element's value
         */
        // single
        initSelection: function () {
            var selected;
            if (this.opts.element.val() === "" && this.opts.element.text() === "") {
                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();
                    }
                });
            }
        },

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

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

            return opts;
        },

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

            if (this.opts.element.val() === "" && placeholder !== undefined) {

                // check for a first blank option if attached to a select
                if (this.select && this.select.find("option:first").text() !== "") return;

                this.selection.find("span").html(this.opts.escapeMarkup(placeholder));

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

                this.selection.find("abbr").hide();
            }
        },

        // single
        postprocessResults: function (data, initial) {
            var selected = 0, 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;
                    return false;
                }
            });

            // and highlight it

            this.highlight(selected);

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

            if (initial === true) {
                showSearchInput = this.showSearchInput = countResults(data.results) >= this.opts.minimumResultsForSearch;
                this.dropdown.find(".select2-search")[showSearchInput ? "removeClass" : "addClass"]("select2-search-hidden");

                //add "select2-with-searchbox" to the container if search box is shown
                $(this.dropdown, this.container)[showSearchInput ? "addClass" : "removeClass"]("select2-with-searchbox");
            }

        },

        // single
        onSelect: function (data, options) {
            var old = this.opts.element.val();

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

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

            if (!equal(old, this.id(data))) { this.triggerChange(); }
        },

        // single
        updateSelection: function (data) {

            var container=this.selection.find("span"), formatted;

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

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

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

            if (this.opts.allowClear && this.getPlaceholder() !== undefined) {
                this.selection.find("abbr").show();
            }
        },

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

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

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

        // single
        data: function(value) {
            var data;

            if (arguments.length === 0) {
                data = this.selection.data("select2-data");
                if (data == undefined) data = null;
                return data;
            } else {
                if (!value || value === "") {
                    this.clear();
                } else {
                    this.opts.element.val(!value ? "" : this.id(value));
                    this.updateSelection(value);
                }
            }
        }
    });

    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-choice'><span>California</span><a href="javascript:void(0)" class="select2-search-choice-close"></a></li>" ,
                "  <li class='select2-search-field'>" ,
                "    <input type='text' autocomplete='off' class='select2-input'>" ,
                "  </li>" ,
                "</ul>" ,
                "<div class='select2-drop select2-drop-multi' style='display:none;'>" ,
                "   <ul class='select2-results'>" ,
                "   </ul>" ,
                "</div>"].join(""));
			return container;
        },

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

            // TODO validate placeholder is a string if specified

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

                    var data = [];
                    element.find(":selected").each2(function (i, elm) {
                        data.push({id: elm.attr("value"), text: elm.text(), element: elm});
                    });

                    if ($.isFunction(callback))
                        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
                    opts.query({
                        matcher: function(term, text, el){
                            return $.grep(ids, function(id) {
                                return equal(id, opts.id(el));
                            }).length;
                        },
                        callback: !$.isFunction(callback) ? $.noop : function(filtered) {
                            callback(filtered.results);
                        }
                    });
                };
            }

            return opts;
        },

        // multi
        initContainer: function () {

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

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

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

                if (e.which === KEY.BACKSPACE && this.search.val() === "") {
                    this.close();

                    var choices,
                        selected = selection.find(".select2-search-choice-focus");
                    if (selected.length > 0) {
                        this.unselect(selected.first());
                        this.search.width(10);
                        killEvent(e);
                        return;
                    }

                    choices = selection.find(".select2-search-choice:not(.select2-locked)");
                    if (choices.length > 0) {
                        choices.last().addClass("select2-search-choice-focus");
                    }
                } else {
                    selection.find(".select2-search-choice-focus").removeClass("select2-search-choice-focus");
                }

                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:
                    case KEY.TAB:
                        this.selectHighlighted();
                        killEvent(e);
                        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 (this.opts.openOnEnter === false && e.which === KEY.ENTER) {
                    return;
                }

                this.open();

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

            this.search.bind("keyup", this.bind(this.resizeSearch));

            this.search.bind("blur", this.bind(function(e) {
                this.container.removeClass("select2-container-active");
                this.search.removeClass("select2-focused");
                if (!this.opened()) this.clearSearch();
                e.stopImmediatePropagation();
            }));

            this.container.delegate(selector, "mousedown", this.bind(function (e) {
                if (!this.enabled) return;
                if ($(e.target).closest(".select2-search-choice").length > 0) {
                    // clicked inside a select2 search choice, do not open
                    return;
                }
                this.clearPlaceholder();
                this.open();
                this.focusSearch();
                e.preventDefault();
            }));

            this.container.delegate(selector, "focus", this.bind(function () {
                if (!this.enabled) return;
                this.container.addClass("select2-container-active");
                this.dropdown.addClass("select2-drop-active");
                this.clearPlaceholder();
            }));

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

        // multi
        enable: function() {
            if (this.enabled) return;

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

            this.search.removeAttr("disabled");
        },

        // multi
        disable: function() {
            if (!this.enabled) return;

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

            this.search.attr("disabled", true);
        },

        // 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();

            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
                this.resizeSearch();
            } else {
                // we set this to " " instead of "" and later clear it on focus() because there is a firefox bug
                // that does not properly render the caret when the field starts out blank
                this.search.val(" ").width(10);
            }
        },

        // multi
        clearPlaceholder: function () {
            if (this.search.hasClass("select2-default")) {
                this.search.val("").removeClass("select2-default");
            } else {
                // work around for the space character we set to avoid firefox caret bug
                if (this.search.val() === " ") this.search.val("");
            }
        },

        // multi
        opening: function () {
            this.parent.opening.apply(this, arguments);

            this.clearPlaceholder();
			this.resizeSearch();
            this.focusSearch();
        },

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

        // multi
        focus: function () {
            this.close();
            this.search.focus();
            this.opts.element.triggerHandler("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();
        },

        tokenize: function() {
            var input = this.search.val();
            input = this.opts.tokenizer(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) {
            this.addSelectedChoice(data);
            if (this.select || !this.opts.closeOnSelect) this.postprocessResults();

            if (this.opts.closeOnSelect) {
                this.close();
                this.search.width(10);
            } else {
                if (this.countSelectableResults()>0) {
                    this.search.width(10);
                    this.resizeSearch();
                    this.positionDropdown();
                } else {
                    // if nothing left to select close
                    this.close();
                }
            }

            // 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;

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

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

            index = indexOf(this.id(data), val);

            if (index >= 0) {
                val.splice(index, 1);
                this.setVal(val);
                if (this.select) this.postprocessResults();
            }
            selected.remove();
            this.triggerChange({ removed: data });
        },

        // multi
        postprocessResults: function () {
            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) {
                    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 doesnt 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){
                self.highlight(0);
            }

        },

        // 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(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
        val: function () {
            var val, triggerChange = false, data = [], self=this;

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

            val = arguments[0];

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

            // 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();
                }
                return;
            }

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

            if (this.select) {
                this.select.find(":selected").each(function () {
                    data.push({id: $(this).attr("value"), text: $(this).text()});
                });
                this.updateSelection(data);
                if (triggerChange) {
                    this.triggerChange();
                }
            } 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=$(data).map(self.id);
                    self.setVal(ids);
                    self.updateSelection(data);
                    self.clearSearch();
                    if (triggerChange) {
                        self.triggerChange();
                    }
                });
            }
            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) {
            var self=this, ids;
            if (arguments.length === 0) {
                 return this.selection
                     .find(".select2-search-choice")
                     .map(function() { return $(this).data("select2-data"); })
                     .get();
            } else {
                if (!values) { values = []; }
                ids = $.map(values, function(e) { return self.opts.id(e); });
                this.setVal(ids);
                this.updateSelection(values);
                this.clearSearch();
            }
        }
    });

    $.fn.select2 = function () {

        var args = Array.prototype.slice.call(arguments, 0),
            opts,
            select2,
            value, multiple, allowedMethods = ["val", "destroy", "opened", "open", "close", "focus", "isFocused", "container", "onSortStart", "onSortEnd", "enable", "disable", "positionDropdown", "data"];

        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.attr("multiple");
                } else {
                    multiple = opts.multiple || false;
                    if ("tags" in opts) {opts.multiple = multiple = true;}
                }

                select2 = multiple ? new MultiSelect2() : new SingleSelect2();
                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;
                if (args[0] === "container") {
                    value=select2.container;
                } else {
                    value = select2[args[0]].apply(select2, args.slice(1));
                }
                if (value !== undefined) {return false;}
            } 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) {
            return data ? data.text : undefined;
        },
        sortResults: function (results, container, query) {
            return results;
        },
        formatResultCssClass: function(data) {return undefined;},
        formatNoMatches: function () { return "No matches found"; },
        formatInputTooShort: function (input, min) { var n = min - input.length; return "Please enter " + n + " more character" + (n == 1? "" : "s"); },
        formatInputTooLong: function (input, max) { var n = input.length - max; return "Please enter " + n + " less 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.id; },
        matcher: function(term, text) {
            return text.toUpperCase().indexOf(term.toUpperCase()) >= 0;
        },
        separator: ",",
        tokenSeparators: [],
        tokenizer: defaultTokenizer,
        escapeMarkup: function (markup) {
            var replace_map = {
                '\\': '&#92;',
                '&': '&amp;',
                '<': '&lt;',
                '>': '&gt;',
                '"': '&quot;',
                "'": '&apos;',
                "/": '&#47;'
            };

            return String(markup).replace(/[&<>"'/\\]/g, function (match) {
                    return replace_map[match[0]];
            });
        },
        blurOnChange: false,
        selectOnBlur: false
    };

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

}(jQuery));