# Yahoo! UI Library

### loader 3.1.1

Yahoo! UI Library > loader > loader.js (source view)
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    (function() {
    /**
     * Loader dynamically loads script and css files.  It includes the dependency
     * info for the version of the library in use, and will automatically pull in
     * dependencies for the modules requested.  It supports rollup files and will
     * automatically use these when appropriate in order to minimize the number of
     * http connections required to load all of the dependencies.  It can load the
     * files from the Yahoo! CDN, and it can utilize the combo service provided on
     * this network to reduce the number of http connections required to download
     * YUI files.
     *
     * @module loader
     * @submodule loader-base
     */

    /**
     * Loader dynamically loads script and css files.  It includes the dependency
     * info for the version of the library in use, and will automatically pull in
     * dependencies for the modules requested.  It supports rollup files and will
     * automatically use these when appropriate in order to minimize the number of
     * http connections required to load all of the dependencies.  It can load the
     * files from the Yahoo! CDN, and it can utilize the combo service provided on
     * this network to reduce the number of http connections required to download
     * YUI files.
     *
     * While the loader can be instantiated by the end user, it normally is not.
     * @see YUI.use for the normal use case.  The use function automatically will
     * pull in missing dependencies.
     *
     * @class Loader
     * @constructor
     * @param o an optional set of configuration options.  Valid options:
     * <ul>
     *  <li>base:
     *  The base dir</li>
     *  <li>comboBase:
     *  The YUI combo service base dir. Ex: http://yui.yahooapis.com/combo?</li>
     *  <li>root:
     *  The root path to prepend to module names for the combo service. Ex: 2.5.2/build/</li>
     *  <li>filter:
     *
     * A filter to apply to result urls.  This filter will modify the default
     * path for all modules.  The default path for the YUI library is the
     * minified version of the files (e.g., event-min.js).  The filter property
     * can be a predefined filter or a custom filter.  The valid predefined
     * filters are:
     * <dl>
     *  <dt>DEBUG</dt>
     *  <dd>Selects the debug versions of the library (e.g., event-debug.js).
     *      This option will automatically include the Logger widget</dd>
     *  <dt>RAW</dt>
     *  <dd>Selects the non-minified version of the library (e.g., event.js).</dd>
     * </dl>
     * You can also define a custom filter, which must be an object literal
     * containing a search expression and a replace string:
     * <pre>
     *  myFilter: &#123;
     *      'searchExp': "-min\\.js",
     *      'replaceStr': "-debug.js"
     *  &#125;
     * </pre>
     *
     *  </li>
     *  <li>filters: per-component filter specification.  If specified for a given component, this overrides the filter config</li>
     *  <li>combine:
     *  Use the YUI combo service to reduce the number of http connections required to load your dependencies</li>
     *  <li>ignore:
     *  A list of modules that should never be dynamically loaded</li>
     *  <li>force:
     *  A list of modules that should always be loaded when required, even if already present on the page</li>
     *  <li>insertBefore:
     *  Node or id for a node that should be used as the insertion point for new nodes</li>
     *  <li>charset:
     *  charset for dynamic nodes (deprecated, use jsAttributes or cssAttributes)</li>
     *  <li>jsAttributes: object literal containing attributes to add to script nodes</li>
     *  <li>cssAttributes: object literal containing attributes to add to link nodes</li>
     *  <li>timeout:
     *  number of milliseconds before a timeout occurs when dynamically loading nodes.  in not set, there is no timeout</li>
     *  <li>context:
     *  execution context for all callbacks</li>
     *  <li>onSuccess:
     *  callback for the 'success' event</li>
     *  <li>onFailure: callback for the 'failure' event</li>
     *  <li>onCSS: callback for the 'CSSComplete' event.  When loading YUI components with CSS
     *  the CSS is loaded first, then the script.  This provides a moment you can tie into to improve
     *  the presentation of the page while the script is loading.</li>
     *  <li>onTimeout:
     *  callback for the 'timeout' event</li>
     *  <li>onProgress:
     *  callback executed each time a script or css file is loaded</li>
     *  <li>modules:
     *  A list of module definitions.  See Loader.addModule for the supported module metadata</li>
     * </ul>
     */

    var NOT_FOUND       = {},
        NO_REQUIREMENTS = [],
        MAX_URL_LENGTH  = (Y.UA.ie) ? 2048 : 8192,
        GLOBAL_ENV      = YUI.Env,
        GLOBAL_LOADED   = GLOBAL_ENV._loaded,
        CSS             = 'css',
        JS              = 'js',
        VERSION         = Y.version,
        ROOT_LANG       = "",
        YObject         = Y.Object,
        YArray          = Y.Array,
        _queue          = YUI.Env._loaderQueue,
        META            = GLOBAL_ENV[VERSION],
        L               = Y.Lang,
        _path           = Y.cached(function(dir, file, type, nomin) {
                            var path = dir + '/' + file;
                            if (!nomin) {
                                path += '-min';
                            }
                            path += '.' + (type || CSS);

                            return path;
                        });

    Y.Env.meta = META;

    Y.Loader = function(o) {

        var defaults = Y.Env.meta.modules, i, onPage = GLOBAL_ENV.mods,
            self = this;

        /**
         * Internal callback to handle multiple internal insert() calls
         * so that css is inserted prior to js
         * @property _internalCallback
         * @private
         */
        // self._internalCallback = null;

        /**
         * Callback that will be executed when the loader is finished
         * with an insert
         * @method onSuccess
         * @type function
         */
        // self.onSuccess = null;

        /**
         * Callback that will be executed if there is a failure
         * @method onFailure
         * @type function
         */
        // self.onFailure = null;

        /**
         * Callback for the 'CSSComplete' event.  When loading YUI components with CSS
         * the CSS is loaded first, then the script.  This provides a moment you can tie into to improve
         * the presentation of the page while the script is loading.
         * @method onCSS
         * @type function
         */
        // self.onCSS = null;

        /**
         * Callback executed each time a script or css file is loaded
         * @method onProgress
         * @type function
         */
        // self.onProgress = null;

        /**
         * Callback that will be executed if a timeout occurs
         * @method onTimeout
         * @type function
         */
        // self.onTimeout = null;

        /**
         * The execution context for all callbacks
         * @property context
         * @default {YUI} the YUI instance
         */
        self.context = Y;

        /**
         * Data that is passed to all callbacks
         * @property data
         */
        // self.data = null;

        /**
         * Node reference or id where new nodes should be inserted before
         * @property insertBefore
         * @type string|HTMLElement
         */
        // self.insertBefore = null;

        /**
         * The charset attribute for inserted nodes
         * @property charset
         * @type string
         * @deprecated, use cssAttributes or jsAttributes
         */
        // self.charset = null;

        /**
         * An object literal containing attributes to add to link nodes
         * @property cssAttributes
         * @type object
         */
        // self.cssAttributes = null;

        /**
         * An object literal containing attributes to add to script nodes
         * @property jsAttributes
         * @type object
         */
        // self.jsAttributes = null;

        /**
         * The base directory.
         * @property base
         * @type string
         * @default http://yui.yahooapis.com/[YUI VERSION]/build/
         */
        self.base = Y.Env.meta.base;

        /**
         * Base path for the combo service
         * @property comboBase
         * @type string
         * @default http://yui.yahooapis.com/combo?
         */
        self.comboBase = Y.Env.meta.comboBase;

        /*
         * Base path for language packs.
         */
        // self.langBase = Y.Env.meta.langBase;
        // self.lang = "";

        /**
         * If configured, the loader will attempt to use the combo
         * service for YUI resources and configured external resources.
         * @property combine
         * @type boolean
         * @default true if a base dir isn't in the config
         */
        self.combine = o.base && (o.base.indexOf( self.comboBase.substr(0, 20)) > -1);

        /**
         * Max url length for combo urls.  The default is 2048 for
         * internet explorer, and 8192 otherwise.  This is the URL
         * limit for the Yahoo! hosted combo servers.  If consuming
         * a different combo service that has a different URL limit
         * it is possible to override this default by supplying
         * the maxURLLength config option.  The config option will
         * only take effect if lower than the default.
         *
         * Browsers:
         *    IE: 2048
         *    Other A-Grade Browsers: Higher that what is typically supported
         *    'capable' mobile browsers: @TODO
         *
         * Servers:
         *    Apache: 8192
         *
         * @property maxURLLength
         * @type int
         */
        self.maxURLLength = MAX_URL_LENGTH;

        /**
         * Ignore modules registered on the YUI global
         * @property ignoreRegistered
         * @default false
         */
        // self.ignoreRegistered = false;

        /**
         * Root path to prepend to module path for the combo
         * service
         * @property root
         * @type string
         * @default [YUI VERSION]/build/
         */
        self.root = Y.Env.meta.root;

        /**
         * Timeout value in milliseconds.  If set, self value will be used by
         * the get utility.  the timeout event will fire if
         * a timeout occurs.
         * @property timeout
         * @type int
         */
        self.timeout = 0;

        /**
         * A list of modules that should not be loaded, even if
         * they turn up in the dependency tree
         * @property ignore
         * @type string[]
         */
        // self.ignore = null;

        /**
         * A list of modules that should always be loaded, even
         * if they have already been inserted into the page.
         * @property force
         * @type string[]
         */
        // self.force = null;

        self.forceMap = {};

        /**
         * Should we allow rollups
         * @property allowRollup
         * @type boolean
         * @default true
         */
        self.allowRollup = true;

        /**
         * A filter to apply to result urls.  This filter will modify the default
         * path for all modules.  The default path for the YUI library is the
         * minified version of the files (e.g., event-min.js).  The filter property
         * can be a predefined filter or a custom filter.  The valid predefined
         * filters are:
         * <dl>
         *  <dt>DEBUG</dt>
         *  <dd>Selects the debug versions of the library (e.g., event-debug.js).
         *      This option will automatically include the Logger widget</dd>
         *  <dt>RAW</dt>
         *  <dd>Selects the non-minified version of the library (e.g., event.js).</dd>
         * </dl>
         * You can also define a custom filter, which must be an object literal
         * containing a search expression and a replace string:
         * <pre>
         *  myFilter: &#123;
         *      'searchExp': "-min\\.js",
         *      'replaceStr': "-debug.js"
         *  &#125;
         * </pre>
         * @property filter
         * @type string|{searchExp: string, replaceStr: string}
         */
        // self.filter = null;

        /**
         * per-component filter specification.  If specified for a given component, this
         * overrides the filter config.
         * @property filters
         * @type object
         */
        self.filters = {};

        /**
         * The list of requested modules
         * @property required
         * @type {string: boolean}
         */
        self.required = {};

        /**
         * If a module name is predefined when requested, it is checked againsts
         * the patterns provided in this property.  If there is a match, the
         * module is added with the default configuration.
         *
         * At the moment only supporting module prefixes, but anticipate supporting
         * at least regular expressions.
         * @property patterns
         * @type Object
         */
        // self.patterns = Y.merge(Y.Env.meta.patterns);
        self.patterns = {};

        /**
         * The library metadata
         * @property moduleInfo
         */
        // self.moduleInfo = Y.merge(Y.Env.meta.moduleInfo);
        self.moduleInfo = {};

        self.groups = Y.merge(Y.Env.meta.groups);

        /**
         * Provides the information used to skin the skinnable components.
         * The following skin definition would result in 'skin1' and 'skin2'
         * being loaded for calendar (if calendar was requested), and
         * 'sam' for all other skinnable components:
         *
         *   <code>
         *   skin: {
         *
         *      // The default skin, which is automatically applied if not
         *      // overriden by a component-specific skin definition.
         *      // Change this in to apply a different skin globally
         *      defaultSkin: 'sam',
         *
         *      // This is combined with the loader base property to get
         *      // the default root directory for a skin. ex:
         *      // http://yui.yahooapis.com/2.3.0/build/assets/skins/sam/
         *      base: 'assets/skins/',
         *
         *      // Any component-specific overrides can be specified here,
         *      // making it possible to load different skins for different
         *      // components.  It is possible to load more than one skin
         *      // for a given component as well.
         *      overrides: {
         *          calendar: ['skin1', 'skin2']
         *      }
         *   }
         *   </code>
         *   @property skin
         */
        self.skin = Y.merge(Y.Env.meta.skin);

        self.config = o;
        self._config(o);

        self._internal = true;

        // YObject.each(defaults, function(k, v) {
        //     self.addModule(v, k);
        // });

        for (i in defaults) {
            if (defaults.hasOwnProperty(i)) {
                self.addModule(defaults[i], i);
            }
        }

        for (i in onPage) {
            if ((!(i in self.moduleInfo)) && onPage[i].details) {
                self.addModule(onPage[i].details, i);
            }
        }

        self._internal = false;

        /**
         * List of rollup files found in the library metadata
         * @property rollups
         */
        // self.rollups = null;

        /**
         * Whether or not to load optional dependencies for
         * the requested modules
         * @property loadOptional
         * @type boolean
         * @default false
         */
        // self.loadOptional = false;

        /**
         * All of the derived dependencies in sorted order, which
         * will be populated when either calculate() or insert()
         * is called
         * @property sorted
         * @type string[]
         */
        self.sorted = [];

        /**
         * Set when beginning to compute the dependency tree.
         * Composed of what YUI reports to be loaded combined
         * with what has been loaded by any instance on the page
         * with the version number specified in the metadata.
         * @propery loaded
         * @type {string: boolean}
         */
        self.loaded = GLOBAL_LOADED[VERSION];

        /**
         * A list of modules to attach to the YUI instance when complete.
         * If not supplied, the sorted list of dependencies are applied.
         * @property attaching
         */
        // self.attaching = null;

        /**
         * Flag to indicate the dependency tree needs to be recomputed
         * if insert is called again.
         * @property dirty
         * @type boolean
         * @default true
         */
        self.dirty = true;

        /**
         * List of modules inserted by the utility
         * @property inserted
         * @type {string: boolean}
         */
        self.inserted = {};

        /**
         * List of skipped modules during insert() because the module
         * was not defined
         * @property skipped
         */
        self.skipped = {};

        // Y.on('yui:load', self.loadNext, self);

    };

    Y.Loader.prototype = {

        FILTER_DEFS: {
            RAW: {
                'searchExp': "-min\\.js",
                'replaceStr': ".js"
            },
            DEBUG: {
                'searchExp': "-min\\.js",
                'replaceStr': "-debug.js"
            }
        },

        SKIN_PREFIX: "skin-",

        _config: function(o) {
            var i, j, val, f, group, groupName, self = this;
            // apply config values
            if (o) {
                for (i in o) {
                    if (o.hasOwnProperty(i)) {
                        val = o[i];
                        if (i == 'require') {
                            self.require(val);
                        } else if (i == 'skin') {
                            Y.mix(self.skin, o[i], true);
                        } else if (i == 'groups') {
                            for (j in val) {
                                if (val.hasOwnProperty(j)) {
                                    // Y.log('group: ' + j);
                                    groupName = j;
                                    group = val[j];
                                    self.addGroup(group, groupName);
                                }
                            }

                        } else if (i == 'modules') {
                            // add a hash of module definitions
                            YObject.each(val, self.addModule, self);
                        } else if (i == 'maxURLLength') {
                            self[i] = Math.min(MAX_URL_LENGTH, val);
                        } else {
                            self[i] = val;
                        }
                    }
                }
            }

            // fix filter
            f = self.filter;

            if (L.isString(f)) {
                f = f.toUpperCase();
                self.filterName = f;
                self.filter = self.FILTER_DEFS[f];
                if (f == 'DEBUG') {
                    self.require('yui-log', 'dump');
                }
            }

        },

        /**
         * Returns the skin module name for the specified skin name.  If a
         * module name is supplied, the returned skin module name is
         * specific to the module passed in.
         * @method formatSkin
         * @param skin {string} the name of the skin
         * @param mod {string} optional: the name of a module to skin
         * @return {string} the full skin module name
         */
        formatSkin: function(skin, mod) {
            var s = this.SKIN_PREFIX + skin;
            if (mod) {
                s = s + "-" + mod;
            }

            return s;
        },

        /**
         * Adds the skin def to the module info
         * @method _addSkin
         * @param skin {string} the name of the skin
         * @param mod {string} the name of the module
         * @param parent {string} parent module if this is a skin of a
         * submodule or plugin
         * @return {string} the module name for the skin
         * @private
         */
        _addSkin: function(skin, mod, parent) {
            var mdef, pkg,
                name = this.formatSkin(skin),
                info = this.moduleInfo,
                sinf = this.skin,
                ext  = info[mod] && info[mod].ext;

            // Add a module definition for the module-specific skin css
            if (mod) {
                name = this.formatSkin(skin, mod);
                if (!info[name]) {
                    mdef = info[mod];
                    pkg = mdef.pkg || mod;
                    // Y.log('adding skin ' + name);
                    this.addModule({
                        name:  name,
                        group: mdef.group,
                        type:  'css',
                        after: sinf.after,
                        path:  (parent || pkg) + '/' + sinf.base + skin + '/' + mod + '.css',
                        ext:   ext
                    });
                }
            }

            return name;
        },

        /** Add a new module group
         * <dl>
         *   <dt>name:</dt>      <dd>required, the group name</dd>
         *   <dt>base:</dt>      <dd>The base dir for this module group</dd>
         *   <dt>root:</dt>      <dd>The root path to add to each combo resource path</dd>
         *   <dt>combine:</dt>   <dd>combo handle</dd>
         *   <dt>comboBase:</dt> <dd>combo service base path</dd>
         *   <dt>modules:</dt>   <dd>the group of modules</dd>
         * </dl>
         * @method addGroup
         * @param o An object containing the module data
         * @param name the module name (optional), required if not in the module data
         * @return {boolean} true if the module was added, false if
         * the object passed in did not provide all required attributes
         */
        addGroup: function(o, name) {
            var mods = o.modules,
                self = this;
            name   = name || o.name;
            o.name = name;
            self.groups[name] = o;

            if (o.patterns) {
                YObject.each(o.patterns, function(v, k) {
                    v.group = name;
                    self.patterns[k] = v;
                });
            }

            if (mods) {
                YObject.each(mods, function(v, k) {
                    v.group = name;
                    self.addModule(v, k);
                }, self);
            }
        },

        /** Add a new module to the component metadata.
         * <dl>
         *     <dt>name:</dt>       <dd>required, the component name</dd>
         *     <dt>type:</dt>       <dd>required, the component type (js or css)</dd>
         *     <dt>path:</dt>       <dd>required, the path to the script from "base"</dd>
         *     <dt>requires:</dt>   <dd>array of modules required by this component</dd>
         *     <dt>optional:</dt>   <dd>array of optional modules for this component</dd>
         *     <dt>supersedes:</dt> <dd>array of the modules this component replaces</dd>
         *     <dt>after:</dt>      <dd>array of modules the components which, if present, should be sorted above this one</dd>
         *     <dt>rollup:</dt>     <dd>the number of superseded modules required for automatic rollup</dd>
         *     <dt>fullpath:</dt>   <dd>If fullpath is specified, this is used instead of the configured base + path</dd>
         *     <dt>skinnable:</dt>  <dd>flag to determine if skin assets should automatically be pulled in</dd>
         *     <dt>submodules:</dt> <dd>a hash of submodules</dd>
         *     <dt>lang:</dt>       <dd>array of BCP 47 language tags of
         *                              languages for which this module has localized resource bundles,
         *                              e.g., ["en-GB","zh-Hans-CN"]</dd>
         * </dl>
         * @method addModule
         * @param o An object containing the module data
         * @param name the module name (optional), required if not in the module data
         * @return the module definition or null if
         * the object passed in did not provide all required attributes
         */
        addModule: function(o, name) {

            name = name || o.name;
            o.name = name;

            if (!o || !o.name) {
                return null;
            }

            if (!o.type) {
                o.type = JS;
            }

            if (!o.path && !o.fullpath) {
                o.path = _path(name, name, o.type);
            }

            o.ext = ('ext' in o) ? o.ext : (this._internal) ? false : true;
            o.requires = o.requires || [];

            // Handle submodule logic
            var subs = o.submodules, i, l, sup, s, smod, plugins, plug,
                j, langs, packName, supName, flatSup, flatLang, lang, ret,
                overrides, skinname;
                // , existing = this.moduleInfo[name], newr;

            // Adding a module again merges requirements to pick up new
            // requirements when the module arrives.  We allow this only
            // once to prevent redundant checks when an application calls
            // use() many times.
            // if (existing && !existing.reparsed) {
            //     for (i=0; i<o.requires.length; i++) {
            //         newr = o.requires[i];
            //         if (YArray.indexOf(existing.requires, newr) == -1) {
            //             existing.requires.push(newr);
            //             delete existing.expanded;
            //         }
            //     }
            //     existing.reparsed = true;
            //     return existing;
            // }

            this.moduleInfo[name] = o;

            if (!o.langPack && o.lang) {
                langs = YArray(o.lang);
                for (j=0; j < langs.length; j++) {
                    lang = langs[j];
                    packName = this.getLangPackName(lang, name);
                    smod = this.moduleInfo[packName];
                    if (!smod) {
                        smod = this._addLangPack(lang, o, packName);
                    }
                }
            }

            if (subs) {
                sup = o.supersedes || [];
                l   = 0;

                for (i in subs) {
                    if (subs.hasOwnProperty(i)) {
                        s = subs[i];

                        // console.log('submodule: ' + i);

                        s.path = s.path || _path(name, i, o.type);
                        s.pkg = name;
                        s.group = o.group;

                        if (s.supersedes) {
                            sup = sup.concat(s.supersedes);
                        }

                        smod = this.addModule(s, i);
                        sup.push(i);

                        if (smod.skinnable) {
                            o.skinnable = true;
                            overrides = this.skin.overrides;
                            if (overrides && overrides[i]) {
                                for (j=0; j<overrides[i].length; j++) {
                                    skinname = this._addSkin(overrides[i][j], i, name);
                                    sup.push(skinname);
                                }
                            }
                            skinname = this._addSkin(this.skin.defaultSkin, i, name);
                            sup.push(skinname);
                        }

                        // looks like we are expected to work out the metadata
                        // for the parent module language packs from what is
                        // specified in the child modules.
                        if (s.lang && s.lang.length) {

                            langs = YArray(s.lang);
                            for (j=0; j < langs.length; j++) {
                                lang = langs[j];
                                packName = this.getLangPackName(lang, name);
                                supName = this.getLangPackName(lang, i);
                                smod = this.moduleInfo[packName];

                                if (!smod) {
                                    smod = this._addLangPack(lang, o, packName);
                                }

                                flatSup = flatSup || YArray.hash(smod.supersedes);

                                if (!(supName in flatSup)) {
                                    smod.supersedes.push(supName);
                                }

                                o.lang = o.lang || [];

                                flatLang = flatLang || YArray.hash(o.lang);

                                if (!(lang in flatLang)) {
                                    o.lang.push(lang);
                                }

                                // Y.log('pack ' + packName + ' should supersede ' + supName);
                                // Add rollup file, need to add to supersedes list too
                            }
                        }

                        l++;
                    }
                }
                o.supersedes = YObject.keys(YArray.hash(sup));
                o.rollup = (l<4) ? l : Math.min(l-1, 4);
            }

            plugins = o.plugins;
            if (plugins) {
                for (i in plugins) {
                    if (plugins.hasOwnProperty(i)) {
                        plug = plugins[i];
                        plug.path = plug.path || _path(name, i, o.type);
                        plug.requires = plug.requires || [];
                        plug.group = o.group;
                        // plug.requires.push(name);
                        this.addModule(plug, i);
                        if (o.skinnable) {
                            this._addSkin(this.skin.defaultSkin, i, name);
                        }
                    }
                }
            }

            this.dirty = true;

            if (o.configFn) {
                ret = o.configFn(o);
                if (ret === false) {
                    delete this.moduleInfo[name];
                    o = null;
                }
            }

            return o;
        },

        /**
         * Add a requirement for one or more module
         * @method require
         * @param what {string[] | string*} the modules to load
         */
        require: function(what) {
            var a = (typeof what === "string") ? arguments : what;
            this.dirty = true;
            Y.mix(this.required, YArray.hash(a));
        },

        /**
         * Returns an object containing properties for all modules required
         * in order to load the requested module
         * @method getRequires
         * @param mod The module definition from moduleInfo
         */
        getRequires: function(mod) {
            if (!mod || mod._parsed) {
                return NO_REQUIREMENTS;
            }

            if (!this.dirty && mod.expanded && (!mod.langCache || mod.langCache == this.lang)) {
                // Y.log('already expanded ' + mod.name);
                return mod.expanded;
            }

            // Y.log("getRequires: " + mod.name + " (dirty:" + this.dirty + ", expanded:" + mod.expanded + ")");

            mod._parsed = true;

            var i, m, j, add, packName, lang,
                d    = [],
                r    = mod.requires,
                o    = mod.optional,
                intl = mod.lang || mod.intl,
                info = this.moduleInfo,
                hash = {};

            for (i=0; i<r.length; i++) {
                // Y.log(mod.name + ' requiring ' + r[i]);
                if (!hash[r[i]]) {
                    d.push(r[i]);
                    hash[r[i]] = true;
                    m = this.getModule(r[i]);
                    add = this.getRequires(m);
                    intl = intl || YArray.indexOf(add, 'intl') > -1;
                    for (j=0; j<add.length; j++) {
                        d.push(add[j]);
                    }
                }
            }

            // get the requirements from superseded modules, if any
            r=mod.supersedes;
            if (r) {
                for (i=0; i<r.length; i++) {
                    if (!hash[r[i]]) {
                        d.push(r[i]);
                        hash[r[i]] = true;
                        m = this.getModule(r[i]);
                        add = this.getRequires(m);
                        intl = intl || YArray.indexOf(add, 'intl') > -1;
                        for (j=0; j<add.length; j++) {
                            d.push(add[j]);
                        }
                    }
                }
            }

            if (o && this.loadOptional) {
                for (i=0; i<o.length; i++) {
                    if (!hash[o[i]]) {
                        d.push(o[i]);
                        hash[o[i]] = true;
                        add = this.getRequires(info[o[i]]);
                        intl = intl || YArray.indexOf(add, 'intl') > -1;
                        for (j=0; j<add.length; j++) {
                            d.push(add[j]);
                        }
                    }
                }
            }

            mod._parsed = false;

            if (intl) {

                if (mod.lang && !mod.langPack && Y.Intl) {
                    lang = Y.Intl.lookupBestLang(this.lang || ROOT_LANG, mod.lang);
    // Y.log('Best lang: ' + lang + ', this.lang: ' + this.lang + ', mod.lang: ' + mod.lang);
                    mod.langCache = this.lang;
                    packName = this.getLangPackName(lang, mod.name);
                    if (packName) {
                        d.unshift(packName);
                    }
                }

                d.unshift('intl');
            }

            mod.expanded = YObject.keys(YArray.hash(d));
            return mod.expanded;
        },

        /**
         * Returns a hash of module names the supplied module satisfies.
         * @method getProvides
         * @param name {string} The name of the module
         * @return what this module provides
         */
        getProvides: function(name) {
            var m = this.getModule(name), o, s;

            if (!m) {
                return NOT_FOUND;
            }

            if (m && !m.provides) {
                o = {};
                s = m.supersedes;

                if (s) {
                    YArray.each(s, function(v) {
                        Y.mix(o, this.getProvides(v));
                    }, this);
                }

                o[name] = true;
                m.provides = o;
            }

            return m.provides;
        },

        /**
         * Calculates the dependency tree, the result is stored in the sorted
         * property
         * @method calculate
         * @param o optional options object
         * @param type optional argument to prune modules
         */
        calculate: function(o, type) {
            if (o || type || this.dirty) {
                this._config(o);
                this._setup();
                this._explode();
                if (this.allowRollup) {
                    this._rollup();
                }
                this._reduce();
                this._sort();
                // this.dirty = false;
            }
        },

        _addLangPack: function(lang, m, packName) {
            var name = m.name,
                packPath = _path((m.pkg || name), packName, JS, true),
                existing = this.moduleInfo[packName];

            if (existing) {
                return existing;
            }

            this.addModule({
                path: packPath,
                intl: true,
                langPack: true,
                ext: m.ext,
                group: m.group,
                supersedes: []
            }, packName, true);

            if (lang) {
                Y.Env.lang = Y.Env.lang || {};
                Y.Env.lang[lang] = Y.Env.lang[lang] || {};
                Y.Env.lang[lang][name] = true;
            }

            return this.moduleInfo[packName];
        },

        /**
         * Investigates the current YUI configuration on the page.  By default,
         * modules already detected will not be loaded again unless a force
         * option is encountered.  Called by calculate()
         * @method _setup
         * @private
         */
        _setup: function() {
            var info = this.moduleInfo, name, i, j, m, o, l, smod,
                packName;
            for (name in info) {
                if (info.hasOwnProperty(name)) {
                    m = info[name];

                    // Create skin modules
                    if (m && m.skinnable) {
                        o = this.skin.overrides;
                        if (o && o[name]) {
                            for (i=0; i<o[name].length; i=i+1) {
                                smod = this._addSkin(o[name][i], name);
                                if (YArray.indexOf(m.requires, smod) == -1) {
                                    m.requires.push(smod);
                                }
                            }
                        } else {

                            smod = this._addSkin(this.skin.defaultSkin, name);
                            if (YArray.indexOf(m.requires, smod) == -1) {
                                m.requires.push(smod);
                            }
                        }

                    }

                    // Create lang pack modules
                    if (m && m.lang && m.lang.length) {
                        // langs = YArray(m.lang);
                        // for (i=0; i<langs.length; i=i+1) {
                        //     lang = langs[i];
                        //     packName = this.getLangPackName(lang, name);
                        //     this._addLangPack(lang, m, packName);
                        // }

                        // Setup root package if the module has lang defined,
                        // it needs to provide a root language pack
                        packName = this.getLangPackName(ROOT_LANG, name);
                        this._addLangPack(null, m, packName);
                    }
                }
            }

            l = Y.merge(this.inserted);

            // available modules
            if (!this.ignoreRegistered) {
                Y.mix(l, GLOBAL_ENV.mods);
            }

            // add the ignore list to the list of loaded packages
            if (this.ignore) {
                Y.mix(l, YArray.hash(this.ignore));
            }

            // expand the list to include superseded modules
            for (j in l) {
                if (l.hasOwnProperty(j)) {
                    Y.mix(l, this.getProvides(j));
                }
            }

            // remove modules on the force list from the loaded list
            if (this.force) {
                for (i=0; i<this.force.length; i=i+1) {
                    if (this.force[i] in l) {
                        delete l[this.force[i]];
                    }
                }
            }

            Y.mix(this.loaded, l);
        },

        /**
         * Builds a module name for a language pack
         * @function getLangPackName
         * @param lang {string} the language code
         * @param mname {string} the module to build it for
         * @return {string} the language pack module name
         */
        getLangPackName: Y.cached(function(lang, mname) {
            return ('lang/' + mname + ((lang) ? '_' + lang : ''));
        }),

        /**
         * Inspects the required modules list looking for additional
         * dependencies.  Expands the required list to include all
         * required modules.  Called by calculate()
         * @method _explode
         * @private
         */
        _explode: function() {
            var r = this.required, m, reqs;
            // the setup phase is over, all modules have been created
            this.dirty = false;

            YObject.each(r, function(v, name) {
                m = this.getModule(name);
                if (m) {
                    var expound = m.expound;

                    if (expound) {
                        r[expound] = this.getModule(expound);
                        reqs = this.getRequires(r[expound]);
                        Y.mix(r, YArray.hash(reqs));
                    }

                    reqs = this.getRequires(m);
                    Y.mix(r, YArray.hash(reqs));
                }
            }, this);

            // Y.log('After explode: ' + YObject.keys(r));
        },

        getModule: function(mname) {
            //TODO: Remove name check - it's a quick hack to fix pattern WIP
            if (!mname) {
                return null;
            }

            var p, type, found, pname,
                m = this.moduleInfo[mname],
                patterns = this.patterns;

            // check the patterns library to see if we should automatically add
            // the module with defaults
            if (!m) {
               // Y.log('testing patterns ' + YObject.keys(patterns));
                for (pname in patterns) {
                    if (patterns.hasOwnProperty(pname)) {
                        // Y.log('testing pattern ' + i);
                        p = patterns[pname];
                        type = p.type;

                        // use the metadata supplied for the pattern
                        // as the module definition.
                        if (mname.indexOf(pname) > -1) {
                            found = p;
                            break;
                        }
                    }
                }

                if (found) {
                    if (p.action) {
                        // Y.log('executing pattern action: ' + pname);
                        p.action.call(this, mname, pname);
                    } else {
    Y.log('Undefined module: ' + mname + ', matched a pattern: ' + pname, 'info', 'loader');
                        // ext true or false?
                        m = this.addModule(Y.merge(found), mname);
                    }
                }
            }

            return m;
        },

        // impl in rollup submodule
        _rollup: function() { },

        /**
         * Remove superceded modules and loaded modules.  Called by
         * calculate() after we have the mega list of all dependencies
         * @method _reduce
         * @private
         */
        _reduce: function() {
            var i, j, s, m, r=this.required, type = this.loadType;
            for (i in r) {
                if (r.hasOwnProperty(i)) {
                    m = this.getModule(i);
                    // remove if already loaded
                    if ((this.loaded[i] && (!this.forceMap[i]) && !this.ignoreRegistered) || (type && m && m.type != type)) {
                        delete r[i];
                    // remove anything this module supersedes
                    } else {
                        s = m && m.supersedes;
                        if (s) {
                            for (j=0; j<s.length; j=j+1) {
                                if (s[j] in r) {
                                    delete r[s[j]];
                                }
                            }
                        }
                    }
                }
            }
            // Y.log('required now: ' + YObject.keys(r));
        },

        _finish: function(msg, success) {
            Y.log('loader finishing: ' + msg + ', ' + Y.id + ', ' + this.data, "info", "loader");

            _queue.running = false;

            var onEnd = this.onEnd;
            if (onEnd) {
                onEnd.call(this.context, {
                    msg: msg,
                    data: this.data,
                    // data: this.sorted,
                    success: success
                });
            }
            this._continue();
        },

        _onSuccess: function() {
            // Y.log('loader _onSuccess, skipping: ' + Y.Object.keys(this.skipped), "info", "loader");
            var skipped = Y.merge(this.skipped), fn;
            YObject.each(skipped, function(k) {
                delete this.inserted[k];
            }, this);
            this.skipped = {};
            // Y.mix(this.loaded, this.inserted);
            fn = this.onSuccess;
            if (fn) {
                fn.call(this.context, {
                    msg: 'success',
                    data: this.data,
                    success: true,
                    skipped: skipped
                });
            }
            this._finish('success', true);
        },

        _onFailure: function(o) {
            Y.log('load error: ' + o.msg + ', ' + Y.id, "error", "loader");
            var f = this.onFailure, msg = 'failure: ' + o.msg;
            if (f) {
                f.call(this.context, {
                    msg: msg,
                    data: this.data,
                    success: false
                });
            }
            this._finish(msg, false);
        },

        _onTimeout: function() {
            Y.log('loader timeout: ' + Y.id, "error", "loader");
            var f = this.onTimeout;
            if (f) {
                f.call(this.context, {
                    msg: 'timeout',
                    data: this.data,
                    success: false
                });
            }
            this._finish('timeout', false);
        },

        /**
         * Sorts the dependency tree.  The last step of calculate()
         * @method _sort
         * @private
         */
        _sort: function() {

            // create an indexed list
            var s = YObject.keys(this.required),
                info = this.moduleInfo,
                // loaded = this.loaded,
                done = {},
                p=0, l, a, b, j, k, moved, doneKey,

            // returns true if b is not loaded, and is required
            // directly or by means of modules it supersedes.
                requires = Y.cached(function(mod1, mod2) {

                    var m = info[mod1], i, r, after, other = info[mod2], s;

                    // if (loaded[mod2] || !m || !other) {
                    if (!m || !other) {
                        return false;
                    }

                    r     = m.expanded;
                    after = m.after;

                    // check if this module requires the other directly
                    if (r && YArray.indexOf(r, mod2) > -1) {
                        return true;
                    }

                    // check if this module should be sorted after the other
                    if (after && YArray.indexOf(after, mod2) > -1) {
                        return true;
                    }

                    // check if this module requires one the other supersedes
                    s = info[mod2] && info[mod2].supersedes;
                    if (s) {
                        for (i=0; i<s.length; i=i+1) {
                            if (requires(mod1, s[i])) {
                                return true;
                            }
                        }
                    }

                    // external css files should be sorted below yui css
                    if (m.ext && m.type == CSS && !other.ext && other.type == CSS) {
                        return true;
                    }

                    return false;
                });

            // keep going until we make a pass without moving anything
            for (;;) {

                l     = s.length;
                moved = false;

                // start the loop after items that are already sorted
                for (j=p; j<l; j=j+1) {

                    // check the next module on the list to see if its
                    // dependencies have been met
                    a = s[j];

                    // check everything below current item and move if we
                    // find a requirement for the current item
                    for (k=j+1; k<l; k=k+1) {
                        doneKey = a + s[k];

                        if (!done[doneKey] && requires(a, s[k])) {

                            // extract the dependency so we can move it up
                            b = s.splice(k, 1);

                            // insert the dependency above the item that
                            // requires it
                            s.splice(j, 0, b[0]);

                            // only swap two dependencies once to short circut
                            // circular dependencies
                            done[doneKey] = true;

                            // keep working
                            moved = true;

                            break;
                        }
                    }

                    // jump out of loop if we moved something
                    if (moved) {
                        break;
                    // this item is sorted, move our pointer and keep going
                    } else {
                        p = p + 1;
                    }
                }

                // when we make it here and moved is false, we are
                // finished sorting
                if (!moved) {
                    break;
                }

            }

            this.sorted = s;
        },

        _insert: function(source, o, type) {

            // Y.log('private _insert() ' + (type || '') + ', ' + Y.id, "info", "loader");

            // restore the state at the time of the request
            if (source) {
                this._config(source);
            }

            // build the dependency list
            this.calculate(o); // don't include type so we can process CSS and script in
                               // one pass when the type is not specified.
            this.loadType = type;

            if (!type) {

                var self = this;

                // Y.log("trying to load css first");
                this._internalCallback = function() {

                    var f = self.onCSS, n, p, sib;

                    // IE hack for style overrides that are not being applied
                    if (this.insertBefore && Y.UA.ie) {
                        n = Y.config.doc.getElementById(this.insertBefore);
                        p = n.parentNode;
                        sib = n.nextSibling;
                        p.removeChild(n);
                        if (sib) {
                            p.insertBefore(n, sib);
                        } else {
                            p.appendChild(n);
                        }
                    }

                    if (f) {
                        f.call(self.context, Y);
                    }
                    self._internalCallback = null;

                    self._insert(null, null, JS);
                };

                // _queue.running = false;
                this._insert(null, null, CSS);

                return;
            }

            // set a flag to indicate the load has started
            this._loading = true;

            // flag to indicate we are done with the combo service
            // and any additional files will need to be loaded
            // individually
            this._combineComplete = {};

            // start the load
            this.loadNext();

        },

        // Once a loader operation is completely finished, process
        // any additional queued items.
        _continue: function() {
            if (!(_queue.running) && _queue.size() > 0) {
                _queue.running = true;
                _queue.next()();
            }
        },

        /**
         * inserts the requested modules and their dependencies.
         * <code>type</code> can be "js" or "css".  Both script and
         * css are inserted if type is not provided.
         * @method insert
         * @param o optional options object
         * @param type {string} the type of dependency to insert
         */
        insert: function(o, type) {
            // Y.log('public insert() ' + (type || '') + ', ' + Y.Object.keys(this.required), "info", "loader");
            var self = this, copy = Y.merge(this, true);
            delete copy.require;
            delete copy.dirty;
            _queue.add(function() {
                self._insert(copy, o, type);
            });
            this._continue();
        },

        /**
         * Executed every time a module is loaded, and if we are in a load
         * cycle, we attempt to load the next script.  Public so that it
         * is possible to call this if using a method other than
         * Y.register to determine when scripts are fully loaded
         * @method loadNext
         * @param mname {string} optional the name of the module that has
         * been loaded (which is usually why it is time to load the next
         * one)
         */
        loadNext: function(mname) {
            // It is possible that this function is executed due to something
            // else one the page loading a YUI module.  Only react when we
            // are actively loading something
            if (!this._loading) {
                return;
            }

            var s, len, i, m, url, fn, msg, attr, group, groupName, j, frag,
                comboSource, comboSources, mods, combining, urls, comboBase,
                type          = this.loadType,
                self          = this,
                handleSuccess = function(o) {
                                    self.loadNext(o.data);
                                },
                handleCombo   = function(o) {
                                    self._combineComplete[type] = true;
                                    var i, len = combining.length;

                                    for (i=0; i<len; i++) {
                                        self.loaded[combining[i]]   = true;
                                        self.inserted[combining[i]] = true;
                                    }

                                    handleSuccess(o);
                                };

            if (this.combine && (!this._combineComplete[type])) {

                combining = [];

                this._combining = combining;
                s = this.sorted;
                len = s.length;

                // the default combo base
                comboBase = this.comboBase;

                url = comboBase;
                urls = [];

                comboSources = {};

                for (i=0; i<len; i++) {
                    comboSource = comboBase;
                    m = this.getModule(s[i]);
                    groupName = m && m.group;
                    if (groupName) {

                        group = this.groups[groupName];

                        if (!group.combine) {
                            m.combine = false;
                            continue;
                        }
                        m.combine = true;
                        if (group.comboBase) {
                            comboSource = group.comboBase;
                        }

                        if (group.root) {
                            m.root = group.root;
                        }

                    }

                    comboSources[comboSource] = comboSources[comboSource] || [];
                    comboSources[comboSource].push(m);
                }

                for (j in comboSources) {
                    if (comboSources.hasOwnProperty(j)) {
                        url = j;
                        mods = comboSources[j];
                        len = mods.length;

                        for (i=0; i<len; i++) {
                            // m = this.getModule(s[i]);
                            m = mods[i];

                            // Do not try to combine non-yui JS unless combo def is found
                            if (m && (m.type === type) && (m.combine || !m.ext)) {

                                frag = (m.root || this.root) + m.path;

                                if ((url !== j) && (i < (len - 1)) && ((frag.length + url.length) > this.maxURLLength)) {
                                    urls.push(this._filter(url));
                                    url = j;
                                }

                                url += frag;
                                if (i < (len - 1)) {
                                    url += '&';
                                }

                                combining.push(m.name);
                            }

                        }

                        if (combining.length && (url != j)) {
                            urls.push(this._filter(url));
                        }
                    }
                }

                if (combining.length) {

    Y.log('Attempting to use combo: ' + combining, "info", "loader");

                    // if (m.type === CSS) {
                    if (type === CSS) {
                        fn = Y.Get.css;
                        attr = this.cssAttributes;
                    } else {
                        fn = Y.Get.script;
                        attr = this.jsAttributes;
                    }

                    fn(urls, {
                        data:         this._loading,
                        onSuccess:    handleCombo,
                        onFailure:    this._onFailure,
                        onTimeout:    this._onTimeout,
                        insertBefore: this.insertBefore,
                        charset:      this.charset,
                        attributes:   attr,
                        timeout:      this.timeout,
                        autopurge:    false,
                        context:      this
                    });

                    return;

                } else {
                    this._combineComplete[type] = true;
                }
            }

            if (mname) {

                // if the module that was just loaded isn't what we were expecting,
                // continue to wait
                if (mname !== this._loading) {
                    return;
                }

    // Y.log("loadNext executing, just loaded " + mname + ", " + Y.id, "info", "loader");

                // The global handler that is called when each module is loaded
                // will pass that module name to this function.  Storing this
                // data to avoid loading the same module multiple times
                // centralize this in the callback
                this.inserted[mname] = true;
                this.loaded[mname] = true;

                if (this.onProgress) {
                    this.onProgress.call(this.context, {
                            name: mname,
                            data: this.data
                        });
                }
            }

            s   = this.sorted;
            len = s.length;

            for (i=0; i<len; i=i+1) {
                // this.inserted keeps track of what the loader has loaded.
                // move on if this item is done.
                if (s[i] in this.inserted) {
                    continue;
                }

                // Because rollups will cause multiple load notifications
                // from Y, loadNext may be called multiple times for
                // the same module when loading a rollup.  We can safely
                // skip the subsequent requests
                if (s[i] === this._loading) {
                    Y.log("still loading " + s[i] + ", waiting", "info", "loader");
                    return;
                }

                // log("inserting " + s[i]);
                m = this.getModule(s[i]);

                if (!m) {
                    msg = "Undefined module " + s[i] + " skipped";
                    Y.log(msg, 'warn', 'loader');
                    this.inserted[s[i]] = true;
                    this.skipped[s[i]]  = true;
                    continue;

                }

                group = (m.group && this.groups[m.group]) || NOT_FOUND;

                // The load type is stored to offer the possibility to load
                // the css separately from the script.
                if (!type || type === m.type) {
                    this._loading = s[i];
                    Y.log("attempting to load " + s[i] + ", " + this.base, "info", "loader");

                    if (m.type === CSS) {
                        fn = Y.Get.css;
                        attr = this.cssAttributes;
                    } else {
                        fn = Y.Get.script;
                        attr = this.jsAttributes;
                    }

                    url = (m.fullpath) ? this._filter(m.fullpath, s[i]) : this._url(m.path, s[i], group.base || m.base);

                    fn(url, {
                        data:         s[i],
                        onSuccess:    handleSuccess,
                        insertBefore: this.insertBefore,
                        charset:      this.charset,
                        attributes:   attr,
                        onFailure:    this._onFailure,
                        onTimeout:    this._onTimeout,
                        timeout:      this.timeout,
                        autopurge:    false,
                        context:      self
                    });

                    return;
                }
            }

            // we are finished
            this._loading = null;

            fn = this._internalCallback;

            // internal callback for loading css first
            if (fn) {
                // Y.log('loader internal');
                this._internalCallback = null;
                fn.call(this);
            } else {
                // Y.log('loader complete');
                this._onSuccess();
            }
        },

        /**
         * Apply filter defined for this instance to a url/path
         * method _filter
         * @param u {string} the string to filter
         * @param name {string} the name of the module, if we are processing
         * a single module as opposed to a combined url
         * @return {string} the filtered string
         * @private
         */
        _filter: function(u, name) {
            var f = this.filter,
                hasFilter = name && (name in this.filters),
                modFilter = hasFilter && this.filters[name];

            if (u) {
                if (hasFilter) {
                    f = (L.isString(modFilter)) ? this.FILTER_DEFS[modFilter.toUpperCase()] || null : modFilter;
                }
                if (f) {
                    u = u.replace(new RegExp(f.searchExp, 'g'), f.replaceStr);
                }
            }

            return u;
        },

        /**
         * Generates the full url for a module
         * method _url
         * @param path {string} the path fragment
         * @return {string} the full url
         * @private
         */
        _url: function(path, name, base) {
            return this._filter((base || this.base || "") + path, name);
        }
    };

    })();

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