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117 lines
3.3 KiB
JavaScript
117 lines
3.3 KiB
JavaScript
import defined from "../Core/defined.js";
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import Event from "../Core/Event.js";
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/**
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* A {@link Property} whose value does not change with respect to simulation time.
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*
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* @alias ConstantProperty
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* @constructor
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*
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* @param {*} [value] The property value.
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*
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* @see ConstantPositionProperty
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*/
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function ConstantProperty(value) {
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this._value = undefined;
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this._hasClone = false;
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this._hasEquals = false;
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this._definitionChanged = new Event();
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this.setValue(value);
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}
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Object.defineProperties(ConstantProperty.prototype, {
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/**
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* Gets a value indicating if this property is constant.
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* This property always returns <code>true</code>.
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* @memberof ConstantProperty.prototype
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*
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* @type {Boolean}
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* @readonly
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*/
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isConstant: {
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value: true,
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},
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/**
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* Gets the event that is raised whenever the definition of this property changes.
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* The definition is changed whenever setValue is called with data different
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* than the current value.
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* @memberof ConstantProperty.prototype
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*
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* @type {Event}
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* @readonly
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*/
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definitionChanged: {
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get: function () {
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return this._definitionChanged;
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},
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},
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});
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/**
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* Gets the value of the property.
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*
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* @param {JulianDate} [time] The time for which to retrieve the value. This parameter is unused since the value does not change with respect to time.
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* @param {Object} [result] The object to store the value into, if omitted, a new instance is created and returned.
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* @returns {Object} The modified result parameter or a new instance if the result parameter was not supplied.
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*/
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ConstantProperty.prototype.getValue = function (time, result) {
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return this._hasClone ? this._value.clone(result) : this._value;
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};
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/**
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* Sets the value of the property.
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*
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* @param {*} value The property value.
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*/
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ConstantProperty.prototype.setValue = function (value) {
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var oldValue = this._value;
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if (oldValue !== value) {
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var isDefined = defined(value);
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var hasClone = isDefined && typeof value.clone === "function";
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var hasEquals = isDefined && typeof value.equals === "function";
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var changed = !hasEquals || !value.equals(oldValue);
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if (changed) {
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this._hasClone = hasClone;
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this._hasEquals = hasEquals;
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this._value = !hasClone ? value : value.clone(this._value);
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this._definitionChanged.raiseEvent(this);
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}
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}
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};
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/**
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* Compares this property to the provided property and returns
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* <code>true</code> if they are equal, <code>false</code> otherwise.
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*
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* @param {Property} [other] The other property.
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* @returns {Boolean} <code>true</code> if left and right are equal, <code>false</code> otherwise.
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*/
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ConstantProperty.prototype.equals = function (other) {
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return (
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this === other || //
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(other instanceof ConstantProperty && //
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((!this._hasEquals && this._value === other._value) || //
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(this._hasEquals && this._value.equals(other._value))))
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);
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};
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/**
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* Gets this property's value.
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*
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* @returns {*} This property's value.
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*/
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ConstantProperty.prototype.valueOf = function () {
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return this._value;
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};
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/**
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* Creates a string representing this property's value.
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*
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* @returns {String} A string representing the property's value.
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*/
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ConstantProperty.prototype.toString = function () {
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return String(this._value);
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};
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export default ConstantProperty;
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