Add existing to tracked

node_modules/@cesium/engine/Source/Scene/MetadataSchemaLoader.js

@@ -0,0 +1,126 @@
+import Frozen from "../Core/Frozen.js";
+import defined from "../Core/defined.js";
+import DeveloperError from "../Core/DeveloperError.js";
+import MetadataSchema from "./MetadataSchema.js";
+import ResourceLoader from "./ResourceLoader.js";
+import ResourceLoaderState from "./ResourceLoaderState.js";
+
+/**
+ * A {@link MetadataSchema} loader.
+ * <p>
+ * Implements the {@link ResourceLoader} interface.
+ * </p>
+ *
+ * @private
+ * @experimental This feature is using part of the 3D Tiles spec that is not final and is subject to change without Cesium's standard deprecation policy.
+ */
+class MetadataSchemaLoader extends ResourceLoader {
+  /**
+   * @param {object} options Object with the following properties:
+   * @param {object} [options.schema] An object that explicitly defines a schema JSON. Mutually exclusive with options.resource.
+   * @param {Resource} [options.resource] The {@link Resource} pointing to the schema JSON. Mutually exclusive with options.schema.
+   * @param {string} [options.cacheKey] The cache key of the resource.
+   *
+   * @exception {DeveloperError} One of options.schema and options.resource must be defined.
+   */
+  constructor(options) {
+    super();
+
+    options = options ?? Frozen.EMPTY_OBJECT;
+    const schema = options.schema;
+    const resource = options.resource;
+    const cacheKey = options.cacheKey;
+
+    //>>includeStart('debug', pragmas.debug);
+    if (defined(schema) === defined(resource)) {
+      throw new DeveloperError(
+        "One of options.schema and options.resource must be defined.",
+      );
+    }
+    //>>includeEnd('debug');
+
+    this._schema = defined(schema)
+      ? MetadataSchema.fromJson(schema)
+      : undefined;
+    this._resource = resource;
+    this._cacheKey = cacheKey;
+    this._state = ResourceLoaderState.UNLOADED;
+    this._promise = undefined;
+  }
+
+  /**
+   * The cache key of the resource.
+   *
+   *
+   * @type {string}
+   * @readonly
+   * @private
+   */
+  get cacheKey() {
+    return this._cacheKey;
+  }
+
+  /**
+   * The metadata schema object.
+   *
+   *
+   * @type {MetadataSchema}
+   * @readonly
+   * @private
+   */
+  get schema() {
+    return this._schema;
+  }
+
+  /**
+   * Loads the resource.
+   * @returns {Promise<MetadataSchemaLoader>} A promise which resolves to the loader when the resource loading is completed.
+   * @private
+   */
+  async load() {
+    if (defined(this._promise)) {
+      return this._promise;
+    }
+
+    if (defined(this._schema)) {
+      this._promise = Promise.resolve(this);
+      return this._promise;
+    }
+
+    this._promise = loadExternalSchema(this);
+    return this._promise;
+  }
+
+  /**
+   * Unloads the resource.
+   * @private
+   */
+  unload() {
+    this._schema = undefined;
+  }
+}
+
+async function loadExternalSchema(schemaLoader) {
+  const resource = schemaLoader._resource;
+  schemaLoader._state = ResourceLoaderState.LOADING;
+  try {
+    const json = await resource.fetchJson();
+    if (schemaLoader.isDestroyed()) {
+      return;
+    }
+
+    schemaLoader._schema = MetadataSchema.fromJson(json);
+    schemaLoader._state = ResourceLoaderState.READY;
+    return schemaLoader;
+  } catch (error) {
+    if (schemaLoader.isDestroyed()) {
+      return;
+    }
+
+    schemaLoader._state = ResourceLoaderState.FAILED;
+    const errorMessage = `Failed to load schema: ${resource.url}`;
+    throw schemaLoader.getError(errorMessage, error);
+  }
+}
+
+export default MetadataSchemaLoader;