Lady’s Gitweb - Pisces/blob - function.js

   1 // ♓🌟 Piscēs ∷ function.js
   2 // ====================================================================
   3 //
   4 // Copyright © 2022 Lady [@ Lady’s Computer].
   5 //
   6 // This Source Code Form is subject to the terms of the Mozilla Public
   7 // License, v. 2.0. If a copy of the MPL was not distributed with this
   8 // file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
   9
  10 import { defineOwnProperty, isObject } from "./object.js";
  11
  12 /**
  13  * Creates a bound function from the provided function using the
  14  * provided this value and arguments list.
  15  *
  16  * ☡ As with call and construct, the arguments must be passed as an
  17  * array.
  18  */
  19 export const bind = (() => {
  20   const callBind = Function.prototype.call.bind(
  21     Function.prototype.bind,
  22   );
  23   const bind = ($, boundThis, boundArgs) =>
  24     callBind($, boundThis, ...boundArgs);
  25   return bind;
  26 })();
  27
  28 /**
  29  * Calls the provided function with the provided this value and
  30  * arguments list.
  31  *
  32  * ☡ This is an alias for Reflect.apply—the arguments must be passed
  33  * as an array.
  34  */
  35 export const call = Reflect.apply;
  36
  37 /**
  38  * Constructs the provided function with the provided arguments list
  39  * and new target.
  40  *
  41  * ☡ This is an alias for Reflect.construct—the arguments must be
  42  * passed as an array.
  43  */
  44 export const construct = Reflect.construct;
  45
  46 /** Returns whether the provided value is a constructor. */
  47 export const isConstructor = ($) => {
  48   if (!isObject($)) {
  49     // The provided value is not an object.
  50     return false;
  51   } else {
  52     // The provided value is an object.
  53     try {
  54       construct(
  55         function () {},
  56         [],
  57         $,
  58       ); // will throw if $ is not a constructor
  59       return true;
  60     } catch {
  61       return false;
  62     }
  63   }
  64 };
  65
  66 /**
  67  * Returns a new function which calls the provided function with its
  68  * first argument as the `this` value and the remaining arguments
  69  * passed through.
  70  *
  71  * ※ This is effectively an alias for Function.prototype.call.bind.
  72  */
  73 export const makeCallable = (() => {
  74         const functionCall = Function.prototype.call;
  75         const callable = ($) => defineOwnProperty(
  76                 bind(functionCall, $, []),
  77                 "length",
  78                 { value: $.length + 1 },
  79         );
  80         return callable;
  81 })();
  82
  83 /**
  84  * Returns whether the provided object inherits from the prototype of
  85  * the provided function.
  86  */
  87 export const ordinaryHasInstance = makeCallable(
  88         Function.prototype[Symbol.hasInstance],
  89 );