cesiumDemo/Source/DataSources/Property.js

import defaultValue from '../Core/defaultValue.js';
import defined from '../Core/defined.js';
import defineProperties from '../Core/defineProperties.js';
import DeveloperError from '../Core/DeveloperError.js';

    /**
     * The interface for all properties, which represent a value that can optionally vary over time.
     * This type defines an interface and cannot be instantiated directly.
     *
     * @alias Property
     * @constructor
     * @abstract
     *
     * @see CompositeProperty
     * @see ConstantProperty
     * @see SampledProperty
     * @see TimeIntervalCollectionProperty
     * @see MaterialProperty
     * @see PositionProperty
     * @see ReferenceProperty
     */
    function Property() {
        DeveloperError.throwInstantiationError();
    }

    defineProperties(Property.prototype, {
        /**
         * Gets a value indicating if this property is constant.  A property is considered
         * constant if getValue always returns the same result for the current definition.
         * @memberof Property.prototype
         *
         * @type {Boolean}
         * @readonly
         */
        isConstant : {
            get : DeveloperError.throwInstantiationError
        },
        /**
         * Gets the event that is raised whenever the definition of this property changes.
         * The definition is considered to have changed if a call to getValue would return
         * a different result for the same time.
         * @memberof Property.prototype
         *
         * @type {Event}
         * @readonly
         */
        definitionChanged : {
            get : DeveloperError.throwInstantiationError
        }
    });

    /**
     * Gets the value of the property at the provided time.
     * @function
     *
     * @param {JulianDate} time The time for which to retrieve the value.
     * @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
     * @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
     */
    Property.prototype.getValue = DeveloperError.throwInstantiationError;

    /**
     * Compares this property to the provided property and returns
     * <code>true</code> if they are equal, <code>false</code> otherwise.
     * @function
     *
     * @param {Property} [other] The other property.
     * @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
     */
    Property.prototype.equals = DeveloperError.throwInstantiationError;

    /**
     * @private
     */
    Property.equals = function(left, right) {
        return left === right || (defined(left) && left.equals(right));
    };

    /**
     * @private
     */
    Property.arrayEquals = function(left, right) {
        if (left === right) {
            return true;
        }
        if ((!defined(left) || !defined(right)) || (left.length !== right.length)) {
            return false;
        }
        var length = left.length;
        for (var i = 0; i < length; i++) {
            if (!Property.equals(left[i], right[i])) {
                return false;
            }
        }
        return true;
    };

    /**
     * @private
     */
    Property.isConstant = function(property) {
        return !defined(property) || property.isConstant;
    };

    /**
     * @private
     */
    Property.getValueOrUndefined = function(property, time, result) {
        return defined(property) ? property.getValue(time, result) : undefined;
    };

    /**
     * @private
     */
    Property.getValueOrDefault = function(property, time, valueDefault, result) {
        return defined(property) ? defaultValue(property.getValue(time, result), valueDefault) : valueDefault;
    };

    /**
     * @private
     */
    Property.getValueOrClonedDefault = function(property, time, valueDefault, result) {
        var value;
        if (defined(property)) {
            value = property.getValue(time, result);
        }
        if (!defined(value)) {
            value = valueDefault.clone(value);
        }
        return value;
    };
export default Property;