third_party/polymer/components/core-meta/core-meta.html

   1 <!--
   2 Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   3 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   4 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   5 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   6 Code distributed by Google as part of the polymer project is also
   7 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   8 -->
   9
  10 <!--
  11 `core-meta` provides a method of constructing a self-organizing database.
  12 It is useful to collate element meta-data for things like catalogs and for
  13 designer.
  14
  15 Example, an element folder has a `metadata.html` file in it, that contains a
  16 `core-meta`, something like this:
  17
  18     <core-meta id="my-element" label="My Element">
  19       <property name="color" value="blue"></property>
  20     </core-meta>
  21
  22 An application can import as many of these files as it wants, and then use
  23 `core-meta` again to access the collected data.
  24
  25     <script>
  26       var meta = document.createElement('core-meta');
  27       console.log(meta.list); // dump a list of all meta-data elements that have been created
  28     </script>
  29
  30 Use `byId(id)` to retrive a specific core-meta.
  31
  32     <script>
  33       var meta = document.createElement('core-meta');
  34       console.log(meta.byId('my-element'));
  35     </script>
  36
  37 By default all meta-data are stored in a single databse.  If your meta-data
  38 have different types and want them to be stored separately, use `type` to
  39 differentiate them.
  40
  41 Example:
  42
  43     <core-meta id="x-foo" type="xElt"></core-meta>
  44     <core-meta id="x-bar" type="xElt"></core-meta>
  45     <core-meta id="y-bar" type="yElt"></core-meta>
  46
  47     <script>
  48       var meta = document.createElement('core-meta');
  49       meta.type = 'xElt';
  50       console.log(meta.list);
  51     </script>
  52
  53 @group Polymer Core Elements
  54 @element core-meta
  55 @homepage github.io
  56 -->
  57
  58 <link rel="import" href="../polymer/polymer.html">
  59
  60 <polymer-element name="core-meta" attributes="label type" hidden>
  61 <script>
  62
  63   (function() {
  64
  65     var SKIP_ID = 'meta';
  66     var metaData = {}, metaArray = {};
  67
  68     Polymer('core-meta', {
  69
  70       /**
  71        * The type of meta-data.  All meta-data with the same type with be
  72        * stored together.
  73        *
  74        * @attribute type
  75        * @type string
  76        * @default 'default'
  77        */
  78       type: 'default',
  79
  80       alwaysPrepare: true,
  81
  82       ready: function() {
  83         this.register(this.id);
  84       },
  85
  86       get metaArray() {
  87         var t = this.type;
  88         if (!metaArray[t]) {
  89           metaArray[t] = [];
  90         }
  91         return metaArray[t];
  92       },
  93
  94       get metaData() {
  95         var t = this.type;
  96         if (!metaData[t]) {
  97           metaData[t] = {};
  98         }
  99         return metaData[t];
 100       },
 101
 102       register: function(id, old) {
 103         if (id && id !== SKIP_ID) {
 104           this.unregister(this, old);
 105           this.metaData[id] = this;
 106           this.metaArray.push(this);
 107         }
 108       },
 109
 110       unregister: function(meta, id) {
 111         delete this.metaData[id || meta.id];
 112         var i = this.metaArray.indexOf(meta);
 113         if (i >= 0) {
 114           this.metaArray.splice(i, 1);
 115         }
 116       },
 117
 118       /**
 119        * Returns a list of all meta-data elements with the same type.
 120        *
 121        * @property list
 122        * @type array
 123        * @default []
 124        */
 125       get list() {
 126         return this.metaArray;
 127       },
 128
 129       /**
 130        * Retrieves meta-data by ID.
 131        *
 132        * @method byId
 133        * @param {String} id The ID of the meta-data to be returned.
 134        * @returns Returns meta-data.
 135        */
 136       byId: function(id) {
 137         return this.metaData[id];
 138       }
 139
 140     });
 141
 142   })();
 143
 144 </script>
 145 </polymer-element>