+ 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.
+ */
+ deleteOwnProperty,
+
+ /**
+ * 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.
+ */
+ setPropertyValue,
+} = (() => {
+ const { deleteProperty, set } = Reflect;
+
+ return {
+ deleteOwnProperty: (O, P) => {
+ if (!deleteProperty(O, P)) {
+ throw new TypeError(
+ `Piscēs: Tried to delete property from object but [[Delete]] returned false: ${P}`,
+ );
+ } else {
+ return O;
+ }
+ },
+ setPropertyValue: (O, P, V, Receiver = O) => {
+ 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 {
+ /**
+ * 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;
+
+/**
+ * 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.
+ *
+ * ※ This is effectively a nonconstructible version of the Object
+ * constructor.
+ */
+export const { toObject } = (() => {
+ const makeObject = Object;
+ return { toObject: ($) => makeObject($) };
+})();
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