import { bind, call } from "./function.js";
import { toPrimitive, type } from "./value.js";
+/**
+ * An object whose properties are lazy‐loaded from the methods on the
+ * own properties of the provided object.
+ *
+ * This is useful when you are looking to reference properties on
+ * objects which, due to module dependency graphs, cannot be guaranteed
+ * to have been initialized yet.
+ *
+ * The resulting properties will have the same attributes (regarding
+ * configurability, enumerability, and writability) as the
+ * corresponding properties on the methods object. If a property is
+ * marked as writable, the method will never be called if it is set
+ * before it is gotten. By necessity, the resulting properties are all
+ * configurable before they are accessed for the first time.
+ *
+ * Methods will be called with the resulting object as their this
+ * value.
+ *
+ * LazyLoader objects have the same prototype as the passed methods
+ * object.
+ */
+export class LazyLoader extends null {
+ /** Constructs a new LazyLoader object. */
+ constructor(loadMethods) {
+ const result = objectCreate(getPrototype(loadMethods));
+ const methodKeys = getOwnPropertyKeys(loadMethods);
+ for (let index = 0; index < methodKeys.length; ++index) {
+ const methodKey = methodKeys[index];
+ const { configurable, enumerable, writable } =
+ getOwnPropertyDescriptor(loadMethods, methodKey);
+ defineOwnProperty(result, methodKey, {
+ configurable: true,
+ enumerable,
+ get: () => {
+ const value = call(loadMethods[methodKey], result, []);
+ defineOwnProperty(result, methodKey, {
+ configurable,
+ enumerable,
+ value,
+ writable,
+ });
+ return value;
+ },
+ set: writable
+ ? ($) =>
+ defineOwnProperty(result, methodKey, {
+ configurable,
+ enumerable,
+ value: $,
+ writable,
+ })
+ : void {},
+ });
+ }
+ return result;
+ }
+}
+
/**
* A property descriptor object.
*
* Removes the provided property key from the provided object and
* returns the object.
*
- * ☡ This function differs from Reflect.deleteProperty and the
+ * ※ This function differs from Reflect.deleteProperty and the
* `delete` operator in that it throws if the deletion is
* unsuccessful.
+ *
+ * ※ This function throws if the first argument is not an object.
*/
deleteOwnProperty,
+ /**
+ * Returns an array of property keys on the provided object.
+ *
+ * ※ This is effectively an alias for Reflect.ownKeys, except that
+ * it does not require that the argument be an object.
+ */
+ getOwnPropertyKeys,
+
+ /**
+ * Returns the value of the provided property key on the provided
+ * object.
+ *
+ * ※ This is effectively an alias for Reflect.get, except that it
+ * does not require that the argument be an object.
+ */
+ getPropertyValue,
+
+ /**
+ * Returns whether the provided property key exists on the provided
+ * object.
+ *
+ * ※ This is effectively an alias for Reflect.has, except that it
+ * does not require that the argument be an object.
+ *
+ * ※ This includes properties present on the prototype chain.
+ */
+ hasProperty,
+
/**
* Sets the provided property key to the provided value on the
* provided object and returns the object.
*
* ※ This function differs from Reflect.set in that it throws if the
* setting is unsuccessful.
+ *
+ * ※ This function throws if the first argument is not an object.
*/
setPropertyValue,
} = (() => {
- const { deleteProperty, set } = Reflect;
+ const { deleteProperty, get, has, ownKeys, set } = Reflect;
return {
deleteOwnProperty: (O, P) => {
- if (!deleteProperty(O, P)) {
+ if (type(O) !== "object") {
+ throw new TypeError(
+ `Piscēs: Tried to set property but provided value was not an object: ${V}`,
+ );
+ } else if (!deleteProperty(O, P)) {
throw new TypeError(
`Piscēs: Tried to delete property from object but [[Delete]] returned false: ${P}`,
);
return O;
}
},
+ getOwnPropertyKeys: (O) => ownKeys(toObject(O)),
+ getPropertyValue: (O, P, Receiver = O) =>
+ get(toObject(O), P, Receiver),
+ hasProperty: (O, P) => has(toObject(O), P),
setPropertyValue: (O, P, V, Receiver = O) => {
- if (!set(O, P, V, Receiver)) {
+ if (type(O) !== "object") {
+ throw new TypeError(
+ `Piscēs: Tried to set property but provided value was not an object: ${V}`,
+ );
+ } else if (!set(O, P, V, Receiver)) {
throw new TypeError(
`Piscēs: Tried to set property on object but [[Set]] returned false: ${P}`,
);
};
})();
-export const {
- /**
- * Returns an array of property keys on the provided object.
- *
- * ※ This is an alias for Reflect.ownKeys.
- */
- ownKeys: getOwnPropertyKeys,
-
- /**
- * Returns the value of the provided property key on the provided
- * object.
- *
- * ※ This is an alias for Reflect.get.
- */
- get: getPropertyValue,
-
- /**
- * Returns whether the provided property key exists on the provided
- * object.
- *
- * ※ This is an alias for Reflect.has.
- *
- * ※ This includes properties present on the prototype chain.
- */
- has: hasProperty,
-} = Reflect;
+export const getMethod = (V, P) => {
+ const func = getPropertyValue(V, P);
+ if (func == null) {
+ return undefined;
+ } else if (typeof func !== "function") {
+ throw new TypeError(`Piscēs: Method not callable: ${P}`);
+ } else {
+ return func;
+ }
+};
/**
* Returns the provided value converted to an object.
*
- * Null and undefined are converted to a new, empty object. Other
- * primitives are wrapped. Existing objects are returned with no
- * modification.
+ * Existing objects are returned with no modification.
*
- * ※ This is effectively a nonconstructible version of the Object
- * constructor.
+ * ☡ This function throws a TypeError if its argument is null or
+ * undefined.
*/
export const { toObject } = (() => {
const makeObject = Object;
- return { toObject: ($) => makeObject($) };
+ return {
+ toObject: ($) => {
+ if ($ == null) {
+ throw new TypeError(
+ `Piscēs: Cannot convert ${$} into an object.`,
+ );
+ } else {
+ return makeObject($);
+ }
+ },
+ };
})();
/**
Lady’s Gitweb / Pisces / blobdiff