@webex/common/dist/make-state-datatype.js

Common utilities for Cisco Webex

"use strict";

var _Object$defineProperty = require("@babel/runtime-corejs2/core-js/object/define-property");
_Object$defineProperty(exports, "__esModule", {
  value: true
});
exports.default = makeStateDataType;
/*!
 * Copyright (c) 2015-2020 Cisco Systems, Inc. See LICENSE file.
 */

// Reminder: any class using this function must have something like the
// following in its initialize method:
//
// // HACK to deal with the fact that AmpersandState#dataTypes#set is a pure
// // function.
// this._dataTypes = cloneDeep(this._dataTypes);
// Object.keys(this._dataTypes).forEach((key) => {
//   if (this._dataTypes[key].set) {
//     this._dataTypes[key].set = this._dataTypes[key].set.bind(this);
//   }
// });
// // END HACK

/**
 * Creates an ampersand state object that wires its event handlers like a an
 * ampersand child
 * @param {Function} Constructor
 * @param {string} name
 * @returns {Object}
 */
function makeStateDataType(Constructor, name) {
  if (!Constructor || !name) {
    throw new Error('missing parameter for makeStateDataType');
  }
  return {
    dataType: {
      set: function set(newVal) {
        // newVal.parent = this;
        if (newVal instanceof Constructor) {
          newVal.parent = this;
          return {
            val: newVal,
            type: name
          };
        }

        // We only want to construct the new instance if we have some set of
        // attributes (even an empty object) to base it on. This is to deal with
        // the unexpected side effect that AmpState#unset will create a new
        // instance.
        return {
          val: newVal ? new Constructor(newVal, {
            parent: this
          }) : undefined,
          type: name
        };
      },
      compare: function compare(currentValue, newVal) {
        return currentValue === newVal;
      },
      onChange: function onChange(newVal, previousVal, attributeName) {
        // Copied from ampersand-state.js
        // if this has changed we want to also handle
        // event propagation
        if (previousVal) {
          this.stopListening(previousVal, 'all', this._getCachedEventBubblingHandler(attributeName));
        }
        if (newVal) {
          this.listenTo(newVal, 'all', this._getCachedEventBubblingHandler(attributeName));
        }
      }
    },
    prop: {
      /**
       * This is a really unfortunate hack to deal with ampersand`s decision to
       * make the dateType#set function pure. The only function called with the
       * scope of the parent at set time seems to be test
       * @param {AmpersandState} newVal
       * @returns {boolean}
       */
      test: function test(newVal) {
        if (!newVal) {
          return false;
        }
        newVal.parent = this;
        return false;
      },
      type: name
    }
  };
}
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