1  'use strict';
 2  
 3  var GetIntrinsic = require('get-intrinsic');
 4  var callBound = require('call-bound');
 5  var inspect = require('object-inspect');
 6  
 7  var $TypeError = require('es-errors/type');
 8  var $Map = GetIntrinsic('%Map%', true);
 9  
10  /** @type {<K, V>(thisArg: Map<K, V>, key: K) => V} */
11  var $mapGet = callBound('Map.prototype.get', true);
12  /** @type {<K, V>(thisArg: Map<K, V>, key: K, value: V) => void} */
13  var $mapSet = callBound('Map.prototype.set', true);
14  /** @type {<K, V>(thisArg: Map<K, V>, key: K) => boolean} */
15  var $mapHas = callBound('Map.prototype.has', true);
16  /** @type {<K, V>(thisArg: Map<K, V>, key: K) => boolean} */
17  var $mapDelete = callBound('Map.prototype.delete', true);
18  /** @type {<K, V>(thisArg: Map<K, V>) => number} */
19  var $mapSize = callBound('Map.prototype.size', true);
20  
21  /** @type {import('.')} */
22  module.exports = !!$Map && /** @type {Exclude<import('.'), false>} */ function getSideChannelMap() {
23  	/** @typedef {ReturnType<typeof getSideChannelMap>} Channel */
24  	/** @typedef {Parameters<Channel['get']>[0]} K */
25  	/** @typedef {Parameters<Channel['set']>[1]} V */
26  
27  	/** @type {Map<K, V> | undefined} */ var $m;
28  
29  	/** @type {Channel} */
30  	var channel = {
31  		assert: function (key) {
32  			if (!channel.has(key)) {
33  				throw new $TypeError('Side channel does not contain ' + inspect(key));
34  			}
35  		},
36  		'delete': function (key) {
37  			if ($m) {
38  				var result = $mapDelete($m, key);
39  				if ($mapSize($m) === 0) {
40  					$m = void undefined;
41  				}
42  				return result;
43  			}
44  			return false;
45  		},
46  		get: function (key) { // eslint-disable-line consistent-return
47  			if ($m) {
48  				return $mapGet($m, key);
49  			}
50  		},
51  		has: function (key) {
52  			if ($m) {
53  				return $mapHas($m, key);
54  			}
55  			return false;
56  		},
57  		set: function (key, value) {
58  			if (!$m) {
59  				// @ts-expect-error TS can't handle narrowing a variable inside a closure
60  				$m = new $Map();
61  			}
62  			$mapSet($m, key, value);
63  		}
64  	};
65  
66  	// @ts-expect-error TODO: figure out why TS is erroring here
67  	return channel;
68  };