Adds Polymer.BasicElement

Provides minimal element starting point using PropertyAccessors to create properties using a properties object similar to Polymer.Element. No template or binding support is provided.

lib/elements/basic-element.html

@@ -0,0 +1,100 @@
+<!--
+@license
+Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+
+<link rel="import" href="../utils/boot.html">
+<link rel="import" href="../utils/mixin.html">
+<link rel="import" href="../mixins/property-accessors.html">
+
+<script>
+(function() {
+  'use strict';
+
+  /**
+   * Custom element base class that provides minimal starting point
+   * using PropertyAccessors to create properties.
+   *
+   * @customElement
+   * @polymer
+   * @memberof Polymer
+   * @constructor
+   * @implements {Polymer_PropertyAccessors}
+   * @extends HTMLElement
+   * @appliesMixin Polymer.PropertyAccessors
+   * @summary Custom element base class that provides minimal starting point
+   * using PropertyAccessors to create properties
+   */
+   class BasicElement extends Polymer.PropertyAccessors(HTMLElement) {
+
+    static _ensureFinalized(name) {
+      const proto = this.prototype;
+      if (!proto.hasOwnProperty('__finalized')) {
+        proto.__finalized = true;
+        this.finalize(name);
+      }
+    }
+
+    static get observedAttributes() {
+      const props = this.properties;
+      return props ? Object.keys(props) : [];
+    }
+
+    /**
+     * Finalizes an element definition. This includes ensuring property
+     * accessors exist on the element prototype and parsing the element
+     * template.
+     * @param {string} name Name of the element
+     */
+    static finalize(name) {
+      const props = this.properties;
+      if (props) {
+        this.prototype.__propertyInfo = props;
+        this.createProperties(Object.keys(props));
+      }
+    }
+
+    /**
+     * Overrides default behavior and adds a call to `finalize`.
+     * @override
+     */
+    _initializeProperties() {
+      this.constructor._ensureFinalized(this.localName);
+      super._initializeProperties();
+    }
+
+    _attributeToProperty(attribute, value, type) {
+      if (!type) {
+        const property = this._propertyNameForAttribute(attribute);
+        const props = this.__propertyInfo;
+        const info = props && props[property];
+        type = info && info.type || info ;
+      }
+      super._attributeToProperty(attribute, value, type);
+    }
+
+    connectedCallback() {
+      this._enableProperties();
+    }
+
+    /**
+     * Called when the element is removed from a document
+     */
+     disconnectedCallback() {}
+
+   }
+  /**
+   * @constructor
+   * @implements {Polymer_PropertyAccessors}
+   * @extends {HTMLElement}
+   */
+  Polymer.BasicElement = BasicElement;
+
+})();
+
+</script>

lib/mixins/property-accessors.html

@@ -157,6 +157,26 @@
         }
       }
 
+      /**
+       * Returns a property name that corresponds to the given attribute.
+       * By default, converts dash to camel case, e.g. `foo-bar` to `fooBar`.
+       * @param {string} attribute Attribute to convert
+       * @return {string} Property name corresponding to the given attribute.
+       */
+      _propertyNameForAttribute(attribute) {
+        return caseMap.dashToCamelCase(attribute);
+      }
+
+      /**
+       * Returns an attribute name that corresponds to the given property.
+       * By default, converts camel to dash case, e.g. `fooBar` to `foo-bar`.
+       * @param {string} property Property to convert
+       * @return {string} Attribute name corresponding to the given property.
+       */
+       _attributeNameForProperty(property) {
+        return caseMap.camelToDashCase(property);
+      }
+
       /**
        * Initializes the local storage for property accessors.
        *
@@ -245,7 +265,7 @@
       _attributeToProperty(attribute, value, type) {
         // Don't deserialize back to property if currently reflecting
         if (!this.__serializing) {
-          let property = caseMap.dashToCamelCase(attribute);
+          let property = this._propertyNameForAttribute(attribute);
           this[property] = this._deserializeValue(value, type);
         }
       }
@@ -261,7 +281,7 @@
         this.__serializing = true;
         value = (arguments.length < 3) ? this[property] : value;
         this._valueToNodeAttribute(this, value,
-          attribute || caseMap.camelToDashCase(property));
+          attribute || this._attributeNameForProperty(property));
         this.__serializing = false;
       }