334 lines
8.1 KiB
HTML
334 lines
8.1 KiB
HTML
<!--
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@license
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Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
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This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
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The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
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The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
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Code distributed by Google as part of the polymer project is also
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subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
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-->
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<link rel="import" href="../polymer/polymer.html">
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<!--
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`iron-meta` is a generic element you can use for sharing information across the DOM tree.
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It uses [monostate pattern](http://c2.com/cgi/wiki?MonostatePattern) such that any
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instance of iron-meta has access to the shared
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information. You can use `iron-meta` to share whatever you want (or create an extension
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[like x-meta] for enhancements).
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The `iron-meta` instances containing your actual data can be loaded in an import,
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or constructed in any way you see fit. The only requirement is that you create them
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before you try to access them.
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Examples:
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If I create an instance like this:
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<iron-meta key="info" value="foo/bar"></iron-meta>
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Note that value="foo/bar" is the metadata I've defined. I could define more
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attributes or use child nodes to define additional metadata.
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Now I can access that element (and it's metadata) from any iron-meta instance
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via the byKey method, e.g.
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meta.byKey('info');
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Pure imperative form would be like:
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document.createElement('iron-meta').byKey('info');
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Or, in a Polymer element, you can include a meta in your template:
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<iron-meta id="meta"></iron-meta>
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...
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this.$.meta.byKey('info');
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@group Iron Elements
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@demo demo/index.html
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@hero hero.svg
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@element iron-meta
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-->
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<script>
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(function() {
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// monostate data
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var metaDatas = {};
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var metaArrays = {};
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var singleton = null;
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Polymer.IronMeta = Polymer({
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is: 'iron-meta',
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properties: {
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/**
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* The type of meta-data. All meta-data of the same type is stored
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* together.
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*/
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type: {
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type: String,
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value: 'default',
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observer: '_typeChanged'
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},
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/**
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* The key used to store `value` under the `type` namespace.
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*/
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key: {
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type: String,
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observer: '_keyChanged'
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},
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/**
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* The meta-data to store or retrieve.
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*/
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value: {
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type: Object,
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notify: true,
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observer: '_valueChanged'
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},
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/**
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* If true, `value` is set to the iron-meta instance itself.
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*/
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self: {
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type: Boolean,
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observer: '_selfChanged'
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},
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/**
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* Array of all meta-data values for the given type.
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*/
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list: {
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type: Array,
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notify: true
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}
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},
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hostAttributes: {
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hidden: true
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},
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/**
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* Only runs if someone invokes the factory/constructor directly
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* e.g. `new Polymer.IronMeta()`
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*
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* @param {{type: (string|undefined), key: (string|undefined), value}=} config
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*/
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factoryImpl: function(config) {
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if (config) {
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for (var n in config) {
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switch(n) {
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case 'type':
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case 'key':
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case 'value':
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this[n] = config[n];
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break;
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}
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}
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}
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},
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created: function() {
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// TODO(sjmiles): good for debugging?
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this._metaDatas = metaDatas;
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this._metaArrays = metaArrays;
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},
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_keyChanged: function(key, old) {
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this._resetRegistration(old);
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},
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_valueChanged: function(value) {
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this._resetRegistration(this.key);
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},
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_selfChanged: function(self) {
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if (self) {
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this.value = this;
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}
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},
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_typeChanged: function(type) {
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this._unregisterKey(this.key);
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if (!metaDatas[type]) {
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metaDatas[type] = {};
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}
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this._metaData = metaDatas[type];
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if (!metaArrays[type]) {
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metaArrays[type] = [];
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}
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this.list = metaArrays[type];
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this._registerKeyValue(this.key, this.value);
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},
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/**
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* Retrieves meta data value by key.
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*
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* @method byKey
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* @param {string} key The key of the meta-data to be returned.
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* @return {*}
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*/
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byKey: function(key) {
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return this._metaData && this._metaData[key];
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},
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_resetRegistration: function(oldKey) {
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this._unregisterKey(oldKey);
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this._registerKeyValue(this.key, this.value);
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},
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_unregisterKey: function(key) {
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this._unregister(key, this._metaData, this.list);
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},
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_registerKeyValue: function(key, value) {
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this._register(key, value, this._metaData, this.list);
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},
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_register: function(key, value, data, list) {
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if (key && data && value !== undefined) {
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data[key] = value;
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list.push(value);
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}
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},
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_unregister: function(key, data, list) {
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if (key && data) {
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if (key in data) {
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var value = data[key];
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delete data[key];
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this.arrayDelete(list, value);
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}
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}
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}
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});
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Polymer.IronMeta.getIronMeta = function getIronMeta() {
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if (singleton === null) {
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singleton = new Polymer.IronMeta();
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}
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return singleton;
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};
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/**
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`iron-meta-query` can be used to access infomation stored in `iron-meta`.
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Examples:
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If I create an instance like this:
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<iron-meta key="info" value="foo/bar"></iron-meta>
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|
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Note that value="foo/bar" is the metadata I've defined. I could define more
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attributes or use child nodes to define additional metadata.
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Now I can access that element (and it's metadata) from any `iron-meta-query` instance:
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var value = new Polymer.IronMetaQuery({key: 'info'}).value;
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@group Polymer Iron Elements
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@element iron-meta-query
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*/
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Polymer.IronMetaQuery = Polymer({
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is: 'iron-meta-query',
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properties: {
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/**
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* The type of meta-data. All meta-data of the same type is stored
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* together.
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*/
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type: {
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type: String,
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value: 'default',
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observer: '_typeChanged'
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},
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/**
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* Specifies a key to use for retrieving `value` from the `type`
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* namespace.
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*/
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key: {
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type: String,
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observer: '_keyChanged'
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},
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/**
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* The meta-data to store or retrieve.
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*/
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value: {
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type: Object,
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notify: true,
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readOnly: true
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},
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/**
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* Array of all meta-data values for the given type.
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*/
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list: {
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type: Array,
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notify: true
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}
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},
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/**
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* Actually a factory method, not a true constructor. Only runs if
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* someone invokes it directly (via `new Polymer.IronMeta()`);
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*
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* @param {{type: (string|undefined), key: (string|undefined)}=} config
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*/
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factoryImpl: function(config) {
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if (config) {
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for (var n in config) {
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switch(n) {
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case 'type':
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case 'key':
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this[n] = config[n];
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break;
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}
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}
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}
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},
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created: function() {
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// TODO(sjmiles): good for debugging?
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this._metaDatas = metaDatas;
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this._metaArrays = metaArrays;
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},
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_keyChanged: function(key) {
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this._setValue(this._metaData && this._metaData[key]);
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},
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_typeChanged: function(type) {
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this._metaData = metaDatas[type];
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this.list = metaArrays[type];
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if (this.key) {
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this._keyChanged(this.key);
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}
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},
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/**
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* Retrieves meta data value by key.
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* @param {string} key The key of the meta-data to be returned.
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* @return {*}
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*/
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byKey: function(key) {
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return this._metaData && this._metaData[key];
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}
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});
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})();
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</script>
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