// ♓🌟 Piscēs ∷ object.js
// ====================================================================
//
-// Copyright © 2022 Lady [@ Lady’s Computer].
+// Copyright © 2022–2023 Lady [@ Lady’s Computer].
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
-/** Returns whether the provided value is a constructor. */
-export const isConstructor = ($) => {
- if (!isObject($)) {
- // The provided value is not an object.
- return false;
- } else {
- // The provided value is an object.
- try {
- Reflect.construct(
- function () {},
- [],
- $,
- ); // will throw if $ is not a constructor
- return true;
- } catch {
- return false;
+import { bind, call } from "./function.js";
+import { ITERATOR, SPECIES, 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.
+ *
+ * ☡ This function throws if the provided value is not an object.
+ */
+ constructor(loadMethods) {
+ if (type(loadMethods) !== "object") {
+ throw new TypeError(
+ `Piscēs: Cannot construct LazyLoader: Provided argument is not an object: ${loadMethods}.`,
+ );
+ } else {
+ const result = objectCreate(getPrototype(loadMethods));
+ const methodKeys = getOwnPropertyKeys(loadMethods);
+ for (let index = 0; index < methodKeys.length; ++index) {
+ const methodKey = methodKeys[index];
+ const { configurable, enumerable, writable } =
+ getOwnPropertyDescriptor(loadMethods, methodKey);
+ defineOwnProperty(result, methodKey, {
+ configurable: true,
+ enumerable,
+ get: () => {
+ const value = call(loadMethods[methodKey], result, []);
+ defineOwnProperty(result, methodKey, {
+ configurable,
+ enumerable,
+ value,
+ writable,
+ });
+ return value;
+ },
+ set: writable
+ ? ($) =>
+ defineOwnProperty(result, methodKey, {
+ configurable,
+ enumerable,
+ value: $,
+ writable,
+ })
+ : void {},
+ });
+ }
+ return result;
}
}
-};
+}
+
+/**
+ * A property descriptor object.
+ *
+ * Actually constructing a property descriptor object using this class
+ * is only necessary if you need strict guarantees about the types of
+ * its properties; the resulting object is proxied to ensure the types
+ * match what one would expect from composing FromPropertyDescriptor
+ * and ToPropertyDescriptor in the Ecmascript specification.
+ *
+ * Otherwise, the instance properties and methods are generic.
+ */
+export const { PropertyDescriptor } = (() => {
+ class PropertyDescriptor extends null {
+ /**
+ * Constructs a new property descriptor object from the provided
+ * object.
+ *
+ * The resulting object is proxied to enforce types (for example,
+ * its `.enumerable` property, if defined, will always be a
+ * boolean).
+ */
+ constructor(O) {
+ if (type(O) !== "object") {
+ // The provided value is not an object.
+ throw new TypeError(
+ `Piscēs: Cannot convert primitive to property descriptor: ${O}.`,
+ );
+ } else {
+ // The provided value is an object.
+ const desc = objectCreate(propertyDescriptorPrototype);
+ if ("enumerable" in O) {
+ // An enumerable property is specified.
+ desc.enumerable = !!O.enumerable;
+ } else {
+ // An enumerable property is not specified.
+ /* do nothing */
+ }
+ if ("configurable" in O) {
+ // A configurable property is specified.
+ desc.configurable = !!O.configurable;
+ } else {
+ // A configurable property is not specified.
+ /* do nothing */
+ }
+ if ("value" in O) {
+ // A value property is specified.
+ desc.value = O.value;
+ } else {
+ // A value property is not specified.
+ /* do nothing */
+ }
+ if ("writable" in O) {
+ // A writable property is specified.
+ desc.writable = !!O.writable;
+ } else {
+ // A writable property is not specified.
+ /* do nothing */
+ }
+ if ("get" in O) {
+ // A get property is specified.
+ const getter = O.get;
+ if (getter !== undefined && typeof getter !== "function") {
+ // The getter is not callable.
+ throw new TypeError("Piscēs: Getters must be callable.");
+ } else {
+ // The getter is callable.
+ desc.get = getter;
+ }
+ } else {
+ // A get property is not specified.
+ /* do nothing */
+ }
+ if ("set" in O) {
+ // A set property is specified.
+ const setter = O.set;
+ if (setter !== undefined && typeof setter !== "function") {
+ // The setter is not callable.
+ throw new TypeError("Piscēs: Setters must be callable.");
+ } else {
+ // The setter is callable.
+ desc.set = setter;
+ }
+ } else {
+ // A set property is not specified.
+ /* do nothing */
+ }
+ if (
+ ("get" in desc || "set" in desc) &&
+ ("value" in desc || "writable" in desc)
+ ) {
+ // Both accessor and data attributes have been defined.
+ throw new TypeError(
+ "Piscēs: Property descriptors cannot specify both accessor and data attributes.",
+ );
+ } else {
+ // The property descriptor is valid.
+ return new Proxy(desc, propertyDescriptorProxyHandler);
+ }
+ }
+ }
+
+ /**
+ * Completes this property descriptor by setting missing values to
+ * their defaults.
+ *
+ * This method modifies this object and returns undefined.
+ */
+ complete() {
+ if (this !== undefined && !("get" in this || "set" in this)) {
+ // This is a generic or data descriptor.
+ if (!("value" in this)) {
+ // `value` is not defined on this.
+ this.value = undefined;
+ } else {
+ // `value` is already defined on this.
+ /* do nothing */
+ }
+ if (!("writable" in this)) {
+ // `writable` is not defined on this.
+ this.writable = false;
+ } else {
+ // `writable` is already defined on this.
+ /* do nothing */
+ }
+ } else {
+ // This is not a generic or data descriptor.
+ if (!("get" in this)) {
+ // `get` is not defined on this.
+ this.get = undefined;
+ } else {
+ // `get` is already defined on this.
+ /* do nothing */
+ }
+ if (!("set" in this)) {
+ // `set` is not defined on this.
+ this.set = undefined;
+ } else {
+ // `set` is already defined on this.
+ /* do nothing */
+ }
+ }
+ if (!("enumerable" in this)) {
+ // `enumerable` is not defined on this.
+ this.enumerable = false;
+ } else {
+ // `enumerable` is already defined on this.
+ /* do nothing */
+ }
+ if (!("configurable" in this)) {
+ // `configurable` is not defined on this.
+ this.configurable = false;
+ } else {
+ // `configurable` is already defined on this.
+ /* do nothing */
+ }
+ }
+
+ /** Gets whether this is an accessor descrtiptor. */
+ get isAccessorDescriptor() {
+ return this !== undefined && ("get" in this || "set" in this);
+ }
+
+ /** Gets whether this is a data descrtiptor. */
+ get isDataDescriptor() {
+ return this !== undefined &&
+ ("value" in this || "writable" in this);
+ }
+
+ /** Gets whether this is a fully‐populated property descriptor. */
+ get isFullyPopulated() {
+ return this !== undefined &&
+ ("value" in this && "writable" in this ||
+ "get" in this && "set" in this) &&
+ "enumerable" in this && "configurable" in this;
+ }
+
+ /**
+ * Gets whether this is a generic (not accessor or data)
+ * descrtiptor.
+ */
+ get isGenericDescriptor() {
+ return this !== undefined &&
+ !("get" in this || "set" in this || "value" in this ||
+ "writable" in this);
+ }
+ }
+
+ const coercePropertyDescriptorValue = (P, V) => {
+ switch (P) {
+ case "configurable":
+ case "enumerable":
+ case "writable":
+ return !!V;
+ case "value":
+ return V;
+ case "get":
+ if (V !== undefined && typeof V !== "function") {
+ throw new TypeError(
+ "Piscēs: Getters must be callable.",
+ );
+ } else {
+ return V;
+ }
+ case "set":
+ if (V !== undefined && typeof V !== "function") {
+ throw new TypeError(
+ "Piscēs: Setters must be callable.",
+ );
+ } else {
+ return V;
+ }
+ default:
+ return V;
+ }
+ };
+
+ const {
+ prototype: propertyDescriptorPrototype,
+ } = PropertyDescriptor;
+
+ const propertyDescriptorProxyHandler = Object.assign(
+ Object.create(null),
+ {
+ defineProperty(O, P, Desc) {
+ if (
+ P === "configurable" || P === "enumerable" ||
+ P === "writable" || P === "value" ||
+ P === "get" || P === "set"
+ ) {
+ // P is a property descriptor attribute.
+ const desc = new PropertyDescriptor(Desc);
+ if ("get" in desc || "set" in desc) {
+ // Desc is an accessor property descriptor.
+ throw new TypeError(
+ "Piscēs: Property descriptor attributes must be data properties.",
+ );
+ } else if ("value" in desc || !(P in O)) {
+ // Desc has a value or P does not already exist on O.
+ desc.value = coercePropertyDescriptorValue(P, desc.value);
+ } else {
+ // Desc is not an accessor property descriptor and has no
+ // value.
+ /* do nothing */
+ }
+ const isAccessorDescriptor = "get" === P || "set" === P ||
+ "get" in O || "set" in O;
+ const isDataDescriptor = "value" === P || "writable" === P ||
+ "value" in O || "writable" in O;
+ if (isAccessorDescriptor && isDataDescriptor) {
+ // Both accessor and data attributes will be present on O
+ // after defining P.
+ throw new TypeError(
+ "Piscēs: Property descriptors cannot specify both accessor and data attributes.",
+ );
+ } else {
+ // P can be safely defined on O.
+ return defineOwnProperty(O, P, desc);
+ }
+ } else {
+ // P is not a property descriptor attribute.
+ return defineOwnProperty(O, P, Desc);
+ }
+ },
+ set(O, P, V, Receiver) {
+ if (
+ P === "configurable" || P === "enumerable" ||
+ P === "writable" || P === "value" ||
+ P === "get" || P === "set"
+ ) {
+ // P is a property descriptor attribute.
+ const newValue = coercePropertyDescriptorValue(P, V);
+ const isAccessorDescriptor = "get" === P || "set" === P ||
+ "get" in O || "set" in O;
+ const isDataDescriptor = "value" === P || "writable" === P ||
+ "value" in O || "writable" in O;
+ if (isAccessorDescriptor && isDataDescriptor) {
+ // Both accessor and data attributes will be present on O
+ // after defining P.
+ throw new TypeError(
+ "Piscēs: Property descriptors cannot specify both accessor and data attributes.",
+ );
+ } else {
+ // P can be safely defined on O.
+ //
+ // ☡ Receiver will be the *proxied* object, so passing it
+ // through to setPropertyValue here would produce an
+ // infinite loop.
+ //
+ // ☡ This has implications on objects with a proxied
+ // PropertyDescriptor in their prototype.
+ return setPropertyValue(O, P, newValue, O);
+ }
+ } else {
+ return setPropertyValue(O, P, V, Receiver);
+ }
+ },
+ setPrototypeOf(O, V) {
+ if (V !== propertyDescriptorPrototype) {
+ // V is not the property descriptor prototype.
+ return false;
+ } else {
+ // V is the property descriptor prototype.
+ return setPrototype(O, V);
+ }
+ },
+ },
+ );
+
+ return { PropertyDescriptor };
+})();
+
+export const {
+ /**
+ * Defines own properties on the provided object using the
+ * descriptors on the enumerable own properties of the provided
+ * additional objects.
+ *
+ * ※ This differs from `Object.defineProperties` in that it can take
+ * multiple source objects.
+ */
+ defineOwnProperties,
+} = (() => {
+ const { defineProperties } = Object;
+ const { forEach: arrayForEach } = Array.prototype;
+ return {
+ defineOwnProperties: (O, ...sources) => {
+ call(
+ arrayForEach,
+ sources,
+ [(source) => defineProperties(O, source)],
+ );
+ return O;
+ },
+ };
+})();
+
+export const {
+ /**
+ * Defines an own property on the provided object on the provided
+ * property key using the provided property descriptor.
+ *
+ * ※ This is an alias for `Object.defineProperty`.
+ */
+ defineProperty: defineOwnProperty,
+
+ /**
+ * Marks the provided object as non·extensible and marks all its
+ * properties as nonconfigurable and (if data properties)
+ * nonwritable, and returns the object.
+ *
+ * ※ This is an alias for `Object.freeze`.
+ */
+ freeze,
+
+ /**
+ * Returns the property descriptor for the own property with the
+ * provided property key on the provided object, or null if none
+ * exists.
+ *
+ * ※ This is an alias for `Object.getOwnPropertyDescriptor`.
+ */
+ getOwnPropertyDescriptor,
+
+ /**
+ * Returns the property descriptors for the own properties on the
+ * provided object.
+ *
+ * ※ This is an alias for `Object.getOwnPropertyDescriptors`.
+ */
+ getOwnPropertyDescriptors,
+
+ /**
+ * Returns an array of string‐valued own property keys on the
+ * provided object.
+ *
+ * ☡ This includes both enumerable and non·enumerable properties.
+ *
+ * ※ This is an alias for `Object.getOwnPropertyNames`.
+ */
+ getOwnPropertyNames: getOwnPropertyStrings,
-/** Returns whether the provided value is an object. */
-export const isObject = ($) => {
- return $ !== null &&
- (typeof $ == "function" || typeof $ == "object");
+ /**
+ * Returns an array of symbol‐valued own property keys on the
+ * provided object.
+ *
+ * ☡ This includes both enumerable and non·enumerable properties.
+ *
+ * ※ This is an alias for `Object.getOwnPropertySymbols`.
+ */
+ getOwnPropertySymbols,
+
+ /**
+ * Returns the prototype of the provided object.
+ *
+ * ※ This is an alias for `Object.getPrototypeOf`.
+ */
+ getPrototypeOf: getPrototype,
+
+ /**
+ * Returns whether the provided object has an own property with the
+ * provided property key.
+ *
+ * ※ This is an alias for `Object.hasOwn`.
+ */
+ hasOwn: hasOwnProperty,
+
+ /**
+ * Returns whether the provided object is extensible.
+ *
+ * ※ This is an alias for `Object.isExtensible`.
+ */
+ isExtensible: isExtensibleObject,
+
+ /**
+ * Returns whether the provided object is frozen.
+ *
+ * ※ This is an alias for `Object.isFrozen`.
+ */
+ isFrozen: isFrozenObject,
+
+ /**
+ * Returns whether the provided object is sealed.
+ *
+ * ※ This is an alias for `Object.isSealed`.
+ */
+ isSealed: isSealedObject,
+
+ /**
+ * Returns an array of key~value pairs for the enumerable,
+ * string‐valued property keys on the provided object.
+ *
+ * ※ This is an alias for `Object.entries`.
+ */
+ entries: namedEntries,
+
+ /**
+ * Returns an array of the enumerable, string‐valued property keys on
+ * the provided object.
+ *
+ * ※ This is an alias for `Object.keys`.
+ */
+ keys: namedKeys,
+
+ /**
+ * Returns an array of property values for the enumerable,
+ * string‐valued property keys on the provided object.
+ *
+ * ※ This is an alias for `Object.values`.
+ */
+ values: namedValues,
+
+ /**
+ * Returns a new object with the provided prototype and property
+ * descriptors.
+ *
+ * ※ This is an alias for `Object.create`.
+ */
+ create: objectCreate,
+
+ /**
+ * Returns a new object with the provided property keys and values.
+ *
+ * ※ This is an alias for `Object.fromEntries`.
+ */
+ fromEntries: objectFromEntries,
+
+ /**
+ * Marks the provided object as non·extensible, and returns the
+ * object.
+ *
+ * ※ This is an alias for `Object.preventExtensions`.
+ */
+ preventExtensions,
+
+ /**
+ * Marks the provided object as non·extensible and marks all its
+ * properties as nonconfigurable, and returns the object.
+ *
+ * ※ This is an alias for `Object.seal`.
+ */
+ seal,
+
+ /**
+ * Sets the values of the enumerable own properties of the provided
+ * additional objects on the provided object.
+ *
+ * ※ This is an alias for `Object.assign`.
+ */
+ assign: setPropertyValues,
+
+ /**
+ * Sets the prototype of the provided object to the provided value
+ * and returns the object.
+ *
+ * ※ This is an alias for `Object.setPrototypeOf`.
+ */
+ setPrototypeOf: setPrototype,
+} = Object;
+
+export const {
+ /**
+ * Removes the provided property key from the provided object and
+ * returns the object.
+ *
+ * ※ 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, get, has, ownKeys, set } = Reflect;
+
+ return {
+ deleteOwnProperty: (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}`,
+ );
+ } else {
+ 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 (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}`,
+ );
+ } else {
+ return O;
+ }
+ },
+ };
+})();
+
+export const {
+ /**
+ * Returns a new frozen shallow copy of the enumerable own properties
+ * of the provided object, according to the following rules :—
+ *
+ * - For data properties, create a nonconfigurable, nonwritable
+ * property with the same value.
+ *
+ * - For accessor properties, create a nonconfigurable accessor
+ * property with the same getter *and* setter.
+ *
+ * The prototype for the resulting object will be taken from the
+ * `.prototype` property of the provided constructor, or the
+ * `.prototype` of the `.constructor` of the provided object if the
+ * provided constructor is undefined. If the used constructor has a
+ * nonnullish `.[Symbol.species]`, that will be used instead. If the
+ * used constructor or species is nullish or does not have a
+ * `.prototype` property, the prototype is set to null.
+ *
+ * ※ The prototype of the provided object itself is ignored.
+ */
+ frozenCopy,
+} = (() => {
+ const {
+ next: generatorIteratorNext,
+ } = getPrototype(function* () {}.prototype);
+ const propertyDescriptorEntryIterablePrototype = {
+ [ITERATOR]() {
+ return {
+ next: bind(generatorIteratorNext, this.generator(), []),
+ };
+ },
+ };
+ return {
+ frozenCopy: (O, constructor = O?.constructor) => {
+ if (O == null) {
+ // O is null or undefined.
+ throw new TypeError(
+ "Piscēs: Cannot copy properties of null or undefined.",
+ );
+ } else {
+ // O is not null or undefined.
+ //
+ // (If not provided, the constructor will be the value of
+ // getting the `.constructor` property of O.)
+ const species = constructor?.[SPECIES] ?? constructor;
+ return preventExtensions(
+ objectCreate(
+ species == null || !("prototype" in species)
+ ? null
+ : species.prototype,
+ objectFromEntries(
+ objectCreate(
+ propertyDescriptorEntryIterablePrototype,
+ {
+ generator: {
+ value: function* () {
+ const ownPropertyKeys = getOwnPropertyKeys(O);
+ for (
+ let i = 0;
+ i < ownPropertyKeys.length;
+ ++i
+ ) {
+ const P = ownPropertyKeys[i];
+ const Desc = getOwnPropertyDescriptor(O, P);
+ if (Desc.enumerable) {
+ // P is an enumerable property.
+ yield [
+ P,
+ "get" in Desc || "set" in Desc
+ ? {
+ configurable: false,
+ enumerable: true,
+ get: Desc.get,
+ set: Desc.set,
+ }
+ : {
+ configurable: false,
+ enumerable: true,
+ value: Desc.value,
+ writable: false,
+ },
+ ];
+ } else {
+ // P is not an enumerable property.
+ /* do nothing */
+ }
+ }
+ },
+ },
+ },
+ ),
+ ),
+ ),
+ );
+ }
+ },
+ };
+})();
+
+/**
+ * Returns the function on the provided value at the provided property
+ * key.
+ *
+ * ☡ This function throws if the provided property key does not have an
+ * associated value which is callable.
+ */
+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: ${P}`);
+ } else {
+ return func;
+ }
};
/**
- * Returns whether the provided object inherits from the prototype of
- * the provided function.
+ * Returns the provided value converted to an object.
+ *
+ * Existing objects are returned with no modification.
+ *
+ * ☡ This function throws if its argument is null or undefined.
*/
-export const ordinaryHasInstance = Function.prototype.call.bind(
- Function.prototype[Symbol.hasInstance],
-);
+export const { toObject } = (() => {
+ const makeObject = Object;
+ return {
+ toObject: ($) => {
+ if ($ == null) {
+ throw new TypeError(
+ `Piscēs: Cannot convert ${$} into an object.`,
+ );
+ } else {
+ return makeObject($);
+ }
+ },
+ };
+})();
+
+/**
+ * Returns the property key (symbol or string) corresponding to the
+ * provided value.
+ */
+export const toPropertyKey = ($) => {
+ const key = toPrimitive($, "string");
+ return typeof key == "symbol" ? key : `${key}`;
+};
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