# Yahoo! UI Library

### loader 3.3.0

Yahoo! UI Library > loader > loader.js (source view)
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    /**
     * 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
     */

    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',
        INTL = 'intl',
        VERSION = Y.version,
        ROOT_LANG = '',
        YObject = Y.Object,
        oeach = YObject.each,
        YArray = Y.Array,
        _queue = GLOBAL_ENV._loaderQueue,
        META = GLOBAL_ENV[VERSION],
        SKIN_PREFIX = 'skin-',
        L = Y.Lang,
        ON_PAGE = GLOBAL_ENV.mods,
        modulekey,
        cache,
        _path = function(dir, file, type, nomin) {
                            var path = dir + '/' + file;
                            if (!nomin) {
                                path += '-min';
                            }
                            path += '.' + (type || CSS);

                            return path;
                        };

    /**
     * The component metadata is stored in Y.Env.meta.
     * Part of the loader module.
     * @property Env.meta
     * @for YUI
     */
    Y.Env.meta = META;

    /**
     * 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.
     *
     * @constructor
     * @class Loader
     * @param {object} 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:
     *  The number of milliseconds before a timeout occurs when dynamically
     *  loading nodes.  If 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>
     *  <li>groups:
     *  A list of group definitions.  Each group can contain specific definitions
     *  for base, comboBase, combine, and accepts a list of modules.  See above
     *  for the description of these properties.</li>
     *  <li>2in3: the version of the YUI 2 in 3 wrapper to use.  The intrinsic
     *  support for YUI 2 modules in YUI 3 relies on versions of the YUI 2
     *  components inside YUI 3 module wrappers.  These wrappers
     *  change over time to accomodate the issues that arise from running YUI 2
     *  in a YUI 3 sandbox.</li>
     *  <li>yui2: when using the 2in3 project, you can select the version of
     *  YUI 2 to use.  Valid values *  are 2.2.2, 2.3.1, 2.4.1, 2.5.2, 2.6.0,
     *  2.7.0, 2.8.0, and 2.8.1 [default] -- plus all versions of YUI 2
     *  going forward.</li>
     * </ul>
     */
    Y.Loader = function(o) {

        var defaults = META.modules,
            self = this;

        modulekey = META.md5;

        /**
         * 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:
         *
         * 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);

        /*
         * Map of conditional modules
         * @since 3.2.0
         */
        self.conditions = {};

        // map of modules with a hash of modules that meet the requirement
        // self.provides = {};

        self.config = o;
        self._internal = true;

        cache = GLOBAL_ENV._renderedMods;

        if (cache) {
            oeach(cache, function(v, k) {
                self.moduleInfo[k] = Y.merge(v);
            });

            cache = GLOBAL_ENV._conditions;

            oeach(cache, function(v, k) {
                self.conditions[k] = Y.merge(v);
            });

        } else {
            oeach(defaults, self.addModule, self);
        }

        if (!GLOBAL_ENV._renderedMods) {
            GLOBAL_ENV._renderedMods = Y.merge(self.moduleInfo);
            GLOBAL_ENV._conditions = Y.merge(self.conditions);
        }

        self._inspectPage();

        self._internal = false;

        self._config(o);

        /**
         * 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.
         * @property 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);

        self.tested = {};

        /*
         * Cached sorted calculate results
         * @property results
         * @since 3.2.0
         */
        //self.results = {};

    };

    Y.Loader.prototype = {

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

       _inspectPage: function() {
           oeach(ON_PAGE, function(v, k) {
               if (v.details) {
                   var m = this.moduleInfo[k],
                       req = v.details.requires,
                       mr = m && m.requires;
                   if (m) {
                       if (!m._inspected && req && mr.length != req.length) {
                           // console.log('deleting ' + m.name);
                           delete m.expanded;
                       }
                   } else {
                       m = this.addModule(v.details, k);
                   }
                   m._inspected = true;
               }
           }, this);
       },

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

            var i, rm, after_map, s,
                info = this.moduleInfo,
                m = info[mod1],
                other = info[mod2];
                // key = mod1 + mod2;

            // if (this.tested[key]) {
                // return this.tested[key];
            // }

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

            rm = m.expanded_map;
            after_map = m.after_map;

            // check if this module should be sorted after the other
            // do this first to short circut circular deps
            if (after_map && (mod2 in after_map)) {
                return true;
            }

            after_map = other.after_map;

            // and vis-versa
            if (after_map && (mod1 in after_map)) {
                return false;
            }

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

            s = info[mod1] && info[mod1].supersedes;
            if (s) {
                for (i = 0; i < s.length; i++) {
                    if (this._requires(mod2, s[i])) {
                        return false;
                    }
                }
            }

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

        _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
                            oeach(val, self.addModule, self);
                        } else if (i == 'gallery') {
                            this.groups.gallery.update(val);
                        } else if (i == 'yui2' || i == '2in3') {
                            this.groups.yui2.update(o['2in3'], o.yui2);
                        } 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 {string} skin the name of the skin.
         * @param {string} mod optional: the name of a module to skin.
         * @return {string} the full skin module name.
         */
        formatSkin: function(skin, mod) {
            var s = SKIN_PREFIX + skin;
            if (mod) {
                s = s + '-' + mod;
            }

            return s;
        },

        /**
         * Adds the skin def to the module info
         * @method _addSkin
         * @param {string} skin the name of the skin.
         * @param {string} mod the name of the module.
         * @param {string} parent 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,
                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;
                    this.addModule({
                        name: name,
                        group: mdef.group,
                        type: 'css',
                        after: sinf.after,
                        path: (parent || pkg) + '/' + sinf.base + skin +
                              '/' + mod + '.css',
                        ext: ext
                    });

                    // Y.log('adding skin ' + name + ', '
                    // + parent + ', ' + pkg + ', ' + info[name].path);
                }
            }

            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 {object} o An object containing the module data.
         * @param {string} name the group name.
         */
        addGroup: function(o, name) {
            var mods = o.modules,
                self = this;
            name = name || o.name;
            o.name = name;
            self.groups[name] = o;

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

            if (mods) {
                oeach(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>after_map:</dt>  <dd>faster alternative to 'after' -- supply
         *     a hash instead of an array</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>group:</dt>      <dd>The group the module belongs to -- this
         *     is set automatically when it is added as part of a group
         *     configuration.</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>
         *     <dt>condition:</dt>
         *       <dd>Specifies that the module should be loaded automatically if
         *           a condition is met.  This is an object with up to three fields:
         *           [trigger] - the name of a module that can trigger the auto-load
         *           [test] - a function that returns true when the module is to be
         *           loaded.
         *           [when] - specifies the load order of the conditional module
         *           with regard to the position of the trigger module.
         *           This should be one of three values: 'before', 'after', or
         *           'instead'.  The default is 'after'.
         *       </dd>
         * </dl>
         * @method addModule
         * @param {object} o An object containing the module data.
         * @param {string} name the module name (optional), required if not
         * in the module data.
         * @return {object} 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.supersedes = o.supersedes || o.use;

            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, when,
                conditions = this.conditions, trigger;
                // , existing = this.moduleInfo[name], newr;

            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];

                        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

                                // default packages
                                packName = this.getLangPackName(ROOT_LANG, name);
                                supName = this.getLangPackName(ROOT_LANG, i);

                                smod = this.moduleInfo[packName];

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

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

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

                    }
                }
            }

            if (o.condition) {
                trigger = o.condition.trigger;
                when = o.condition.when;
                conditions[trigger] = conditions[trigger] || {};
                conditions[trigger][name] = o.condition;
                // the 'when' attribute can be 'before', 'after', or 'instead'
                // the default is after.
                if (when && when != 'after') {
                    if (when == 'instead') { // replace the trigger
                        o.supersedes = o.supersedes || [];
                        o.supersedes.push(trigger);
                    } else { // before the trigger
                        // the trigger requires the conditional mod,
                        // so it should appear before the conditional
                        // mod if we do not intersede.
                    }
                } else { // after the trigger
                    o.after = o.after || [];
                    o.after.push(trigger);
                }
            }

            if (o.after) {
                o.after_map = YArray.hash(o.after);
            }

            // 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 {string[] | string*} what 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 {object}  mod The module definition from moduleInfo.
         * @return {array} the expanded requirement list.
         */
        getRequires: function(mod) {

            if (!mod || mod._parsed) {
                // Y.log('returning no reqs for ' + mod.name);
                return NO_REQUIREMENTS;
            }

            var i, m, j, add, packName, lang,
                name = mod.name, cond, go,
                adddef = ON_PAGE[name] && ON_PAGE[name].details,
                d,
                r, old_mod,
                o, skinmod, skindef,
                intl = mod.lang || mod.intl,
                info = this.moduleInfo,
                hash;

            // pattern match leaves module stub that needs to be filled out
            if (mod.temp && adddef) {
                old_mod = mod;
                mod = this.addModule(adddef, name);
                mod.group = old_mod.group;
                mod.pkg = old_mod.pkg;
                delete mod.expanded;
            }

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

            d = [];
            hash = {};

            r = mod.requires;
            o = mod.optional;

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

            mod._parsed = true;

            for (i = 0; i < r.length; i++) {
                // Y.log(name + ' requiring ' + r[i]);
                if (!hash[r[i]]) {
                    d.push(r[i]);
                    hash[r[i]] = true;
                    m = this.getModule(r[i]);
                    if (m) {
                        add = this.getRequires(m);
                        intl = intl || (m.expanded_map &&
                            (INTL in m.expanded_map));
                        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]]) {
                        // if this module has submodules, the requirements list is
                        // expanded to include the submodules.  This is so we can
                        // prevent dups when a submodule is already loaded and the
                        // parent is requested.
                        if (mod.submodules) {
                            d.push(r[i]);
                        }

                        hash[r[i]] = true;
                        m = this.getModule(r[i]);

                        if (m) {
                            add = this.getRequires(m);
                            intl = intl || (m.expanded_map &&
                                (INTL in m.expanded_map));
                            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;
                        m = info[o[i]];
                        if (m) {
                            add = this.getRequires(m);
                            intl = intl || (m.expanded_map &&
                                (INTL in m.expanded_map));
                            for (j = 0; j < add.length; j++) {
                                d.push(add[j]);
                            }
                        }
                    }
                }
            }

            cond = this.conditions[name];

            if (cond) {
                oeach(cond, function(def, condmod) {

                    if (!hash[condmod]) {
                        go = def && ((def.ua && Y.UA[def.ua]) ||
                                     (def.test && def.test(Y, r)));
                        if (go) {
                            hash[condmod] = true;
                            d.push(condmod);
                            m = this.getModule(condmod);
                            // Y.log('conditional', m);
                            if (m) {
                                add = this.getRequires(m);
                                for (j = 0; j < add.length; j++) {
                                    d.push(add[j]);
                                }
                            }
                        }
                    }
                }, this);
            }

            // Create skin modules
            if (mod.skinnable) {
                skindef = this.skin.overrides;
                if (skindef && skindef[name]) {
                    for (i = 0; i < skindef[name].length; i++) {
                        skinmod = this._addSkin(skindef[name][i], name);
                        d.push(skinmod);
                    }
                } else {
                    skinmod = this._addSkin(this.skin.defaultSkin, name);
                    d.push(skinmod);
                }
            }

            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, name);
                    if (packName) {
                        d.unshift(packName);
                    }
                }

                d.unshift(INTL);
            }

            mod.expanded_map = YArray.hash(d);

            mod.expanded = YObject.keys(mod.expanded_map);

            return mod.expanded;
        },

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

            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 {object} o optional options object.
         * @param {string} type optional argument to prune modules.
         */
        calculate: function(o, type) {
            if (o || type || this.dirty) {

                if (o) {
                    this._config(o);
                }

                if (!this._init) {
                    this._setup();
                }

                this._explode();

                if (this.allowRollup) {
                    this._rollup();
                }
                this._reduce();
                this._sort();
            }
        },

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

            if (!existing) {

                packPath = _path((m.pkg || name), packName, JS, true);

                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, l,
                packName;

            for (name in info) {
                if (info.hasOwnProperty(name)) {
                    m = info[name];
                    if (m) {

                        // remove dups
                        m.requires = YObject.keys(YArray.hash(m.requires));

                        // Create lang pack modules
                        if (m.lang && m.lang.length) {
                            // 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);
            l = {};

            // 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++) {
                    if (this.force[i] in l) {
                        delete l[this.force[i]];
                    }
                }
            }

            Y.mix(this.loaded, l);

            this._init = true;
        },

        /**
         * Builds a module name for a language pack
         * @method getLangPackName
         * @param {string} lang the language code.
         * @param {string} mname the module to build it for.
         * @return {string} the language pack module name.
         */
        getLangPackName: 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, done = {},
                self = this;

            // the setup phase is over, all modules have been created
            self.dirty = false;

            oeach(r, function(v, name) {
                if (!done[name]) {
                    done[name] = true;
                    m = self.getModule(name);
                    if (m) {
                        var expound = m.expound;

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

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

            // 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, 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];

                        // 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);
                        m.temp = true;
                    }
                }
            }

            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
         * @return {object} the reduced dependency hash.
         * @private
         */
        _reduce: function(r) {

            r = r || this.required;

            var i, j, s, m, type = this.loadType;
            for (i in r) {
                if (r.hasOwnProperty(i)) {
                    m = this.getModule(i);
                    // remove if already loaded
                    if (((this.loaded[i] || ON_PAGE[i]) &&
                            !this.forceMap[i] && !this.ignoreRegistered) ||
                            (type && m && m.type != type)) {
                        delete r[i];
                    }
                    // remove anything this module supersedes
                    s = m && m.supersedes;
                    if (s) {
                        for (j = 0; j < s.length; j++) {
                            if (s[j] in r) {
                                delete r[s[j]];
                            }
                        }
                    }
                }
            }
            // Y.log('required now: ' + YObject.keys(r));

            return 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,
                    success: success
                });
            }
            this._continue();
        },

        _onSuccess: function() {
            var self = this, skipped = Y.merge(self.skipped), fn,
                failed = [], rreg = self.requireRegistration,
                success, msg;

            oeach(skipped, function(k) {
                delete self.inserted[k];
            });

            self.skipped = {};

            oeach(self.inserted, function(v, k) {
                var mod = self.getModule(k);
                if (mod && rreg && mod.type == JS && !(k in YUI.Env.mods)) {
                    failed.push(k);
                } else {
                    Y.mix(self.loaded, self.getProvides(k));
                }
            });

            fn = self.onSuccess;
            msg = (failed.length) ? 'notregistered' : 'success';
            success = !(failed.length);
            if (fn) {
                fn.call(self.context, {
                    msg: msg,
                    data: self.data,
                    success: success,
                    failed: failed,
                    skipped: skipped
                });
            }
            self._finish(msg, success);
        },
        _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),
                // loaded = this.loaded,
                done = {},
                p = 0, l, a, b, j, k, moved, doneKey;

            // 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++) {

                    // 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++) {
                        doneKey = a + s[k];

                        if (!done[doneKey] && this._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++;
                    }
                }

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

            }

            this.sorted = s;

        },

        partial: function(partial, o, type) {
            this.sorted = partial;
            this.insert(o, type, true);
        },

        _insert: function(source, o, type, skipcalc) {

    // 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
            // don't include type so we can process CSS and script in
            // one pass when the type is not specified.
            if (!skipcalc) {
                this.calculate(o);
            }

            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);
                };

                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 {object} o optional options object.
         * @param {string} type the type of dependency to insert.
         */
        insert: function(o, type, skipsort) {
            // Y.log('public insert() ' + (type || '') + ', ' +
            //  Y.Object.keys(this.required), "info", "loader");
            var self = this, copy = Y.merge(this);
            delete copy.require;
            delete copy.dirty;
            _queue.add(function() {
                self._insert(copy, o, type, skipsort);
            });
            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 {string} mname 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,
                self = this,
                type = self.loadType,
                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.inserted[combining[i]] = true;
                    }

                    handleSuccess(o);
                };

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

                combining = [];

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

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

                url = comboBase;
                urls = [];

                comboSources = {};

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

                        group = self.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 = self.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 || self.root) + m.path;

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

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

                                combining.push(m.name);
                            }

                        }

                        if (combining.length && (url != j)) {
                            urls.push(self._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 = self.cssAttributes;
                    } else {
                        fn = Y.Get.script;
                        attr = self.jsAttributes;
                    }

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

                    return;

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

            if (mname) {

                // if the module that was just loaded isn't what we were expecting,
                // continue to wait
                if (mname !== self._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
                self.inserted[mname] = true;
                // self.loaded[mname] = true;

                // provided = self.getProvides(mname);
                // Y.mix(self.loaded, provided);
                // Y.mix(self.inserted, provided);

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

            s = self.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 self.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] === self._loading) {
                    Y.log('still loading ' + s[i] + ', waiting', 'info', 'loader');
                    return;
                }

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

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

                }

                group = (m.group && self.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) {
                    self._loading = s[i];
    Y.log('attempting to load ' + s[i] + ', ' + self.base, 'info', 'loader');

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

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

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

                    return;
                }
            }

            // we are finished
            self._loading = null;

            fn = self._internalCallback;

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

        /**
         * Apply filter defined for this instance to a url/path
         * method _filter
         * @param {string} u the string to filter.
         * @param {string} name 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 {string} path 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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