X-Git-Url: https://git.ladys.computer/Pisces/blobdiff_plain/1f05716e1051f4f92528a755f1ec4cc8e8a62f78..fb3e0d562e2dbe9e3ea911a80bfdabc8851f92b2:/object.js diff --git a/object.js b/object.js index d08f43a..f68909e 100644 --- a/object.js +++ b/object.js @@ -7,119 +7,791 @@ // License, v. 2.0. If a copy of the MPL was not distributed with this // file, You can obtain one at . -/** 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; - } - } -}; - -/** Returns whether the provided value is an object. */ -export const isObject = ($) => { - return $ !== null && - (typeof $ == "function" || typeof $ == "object"); -}; - -/** - * Returns whether the provided object inherits from the prototype of - * the provided function. - */ -export const ordinaryHasInstance = Function.prototype.call.bind( - Function.prototype[Symbol.hasInstance], -); +import { bind, call } from "./function.js"; +import { toPrimitive, type } from "./value.js"; /** - * Returns the primitive value of the provided object per its - * `toString` and `valueOf` methods. + * 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. * - * If the provided hint is "string", then `toString` takes precedence; - * otherwise, `valueOf` does. + * 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. * - * Throws an error if both of these methods are not callable or do not - * return a primitive. + * Methods will be called with the resulting object as their this + * value. + * + * LazyLoader objects have the same prototype as the passed methods + * object. */ -export const ordinaryToPrimitive = (O, hint) => { - for ( - const name of hint == "string" - ? ["toString", "valueOf"] - : ["valueOf", "toString"] - ) { - const method = O[name]; - if (typeof method == "function") { - // Method is callable. - const result = method.call(O); - if (!isObject(result)) { - // Method returns a primitive. - return result; - } else { - // Method returns an object. - continue; - } - } else { - // Method is not callable. - continue; +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: $, + writable, + }) + : void {}, + }); } + return result; } - throw new TypeError("Piscēs: Unable to convert object to primitive"); -}; +} /** - * Returns the provided value converted to a primitive, or throws if - * no such conversion is possible. + * A property descriptor object. * - * The provided preferred type, if specified, should be "string", - * "number", or "default". If the provided input has a - * `Symbol.toPrimitive` method, this function will throw rather than - * calling that method with a preferred type other than one of the - * above. + * Actually constructing a property descriptor object using this class + * is only necessary if you need strict guarantees about the types of + * its properties; the resulting object is proxied to ensure the types + * match what one would expect from composing FromPropertyDescriptor + * and ToPropertyDescriptor in the Ecmascript specification. + * + * Otherwise, the instance properties and methods are generic. */ -export const toPrimitive = ($, preferredType) => { - if (isObject($)) { - // The provided value is an object. - const exoticToPrim = $[Symbol.toPrimitive] ?? undefined; - if (exoticToPrim !== undefined) { - // The provided value has an exotic primitive conversion method. - if (typeof exoticToPrim != "function") { - // The method is not callable. +export const { PropertyDescriptor } = (() => { + class PropertyDescriptor extends null { + /** + * Constructs a new property descriptor object from the provided + * object. + * + * The resulting object is proxied to enforce types (for example, + * its `enumerable` property, if defined, will always be a + * boolean). + */ + //deno-lint-ignore constructor-super + constructor(O) { + if (type(O) !== "object") { + // The provided value is not an object. throw new TypeError( - "Piscēs: Symbol.toPrimitive was neither nullish nor callable.", + "Piscēs: Cannot convert primitive to property descriptor.", ); } else { - // The method is callable. - const hint = `${preferredType ?? "default"}`; - if (!["default", "string", "number"].includes(hint)) { - // An invalid preferred type was specified. + // 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: Invalid preferred type: ${preferredType}.`, + "Piscēs: Property descriptors cannot specify both accessor and data attributes.", ); } else { - // The resulting hint is either default, string, or number. - return exoticToPrim.call($, hint); + // The property descriptor is valid. + return new Proxy(desc, propertyDescriptorProxyHandler); } } - } else { - // Use the ordinary primitive conversion function. - ordinaryToPrimitive($, hint); } + + /** + * 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 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, + + /** + * Returns whether the provided object is frozen. + * + * ※ This is an alias for Object.isFrozen. + */ + isFrozen, + + /** + * Returns whether the provided object is sealed. + * + * ※ This is an alias for Object.isSealed. + */ + isSealed, + + /** + * 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. + */ + frozenCopy, +} = (() => { + const { + iterator: iteratorSymbol, + species: speciesSymbol, + } = Symbol; + const { + next: generatorIteratorNext, + } = getPrototype(function* () {}.prototype); + const propertyDescriptorEntryIterablePrototype = { + [iteratorSymbol]() { + 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?.[speciesSymbol] ?? 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 */ + } + } + }, + }, + }, + ), + ), + ), + ); + } + }, + }; +})(); + +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 { - // The provided value is already a primitive. - return $; + return func; } }; +/** + * Returns the provided value converted to an object. + * + * Existing objects are returned with no modification. + * + * ☡ This function throws a TypeError if its argument is null or + * undefined. + */ +export const { toObject } = (() => { + const makeObject = Object; + return { + toObject: ($) => { + 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.