'use strict';
var GetIntrinsic = require('get-intrinsic');
var callBound = require('call-bind/callBound');
var inspect = require('object-inspect');
var $TypeError = GetIntrinsic('%TypeError%');
var $WeakMap = GetIntrinsic('%WeakMap%', true);
var $Map = GetIntrinsic('%Map%', true);
var $weakMapGet = callBound('WeakMap.prototype.get', true);
var $weakMapSet = callBound('WeakMap.prototype.set', true);
var $weakMapHas = callBound('WeakMap.prototype.has', true);
var $mapGet = callBound('Map.prototype.get', true);
var $mapSet = callBound('Map.prototype.set', true);
var $mapHas = callBound('Map.prototype.has', true);
/*
* This function traverses the list returning the node corresponding to the
* given key.
*
* That node is also moved to the head of the list, so that if it's accessed
* again we don't need to traverse the whole list. By doing so, all the recently
* used nodes can be accessed relatively quickly.
*/
var listGetNode = function (list, key) { // eslint-disable-line consistent-return
for (var prev = list, curr; (curr = prev.next) !== null; prev = curr) {
if (curr.key === key) {
prev.next = curr.next;
curr.next = list.next;
list.next = curr; // eslint-disable-line no-param-reassign
return curr;
}
}
};
var listGet = function (objects, key) {
var node = listGetNode(objects, key);
return node && node.value;
};
var listSet = function (objects, key, value) {
var node = listGetNode(objects, key);
if (node) {
node.value = value;
} else {
// Prepend the new node to the beginning of the list
objects.next = { // eslint-disable-line no-param-reassign
key: key,
next: objects.next,
value: value
};
}
};
var listHas = function (objects, key) {
return !!listGetNode(objects, key);
};
module.exports = function getSideChannel() {
var $wm;
var $m;
var $o;
var channel = {
assert: function (key) {
if (!channel.has(key)) {
throw new $TypeError('Side channel does not contain ' + inspect(key));
}
},
get: function (key) { // eslint-disable-line consistent-return
if ($WeakMap && key && (typeof key === 'object' || typeof key === 'function')) {
if ($wm) {
return $weakMapGet($wm, key);
}
} else if ($Map) {
if ($m) {
return $mapGet($m, key);
}
} else {
if ($o) { // eslint-disable-line no-lonely-if
return listGet($o, key);
}
}
},
has: function (key) {
if ($WeakMap && key && (typeof key === 'object' || typeof key === 'function')) {
if ($wm) {
return $weakMapHas($wm, key);
}
} else if ($Map) {
if ($m) {
return $mapHas($m, key);
}
} else {
if ($o) { // eslint-disable-line no-lonely-if
return listHas($o, key);
}
}
return false;
},
set: function (key, value) {
if ($WeakMap && key && (typeof key === 'object' || typeof key === 'function')) {
if (!$wm) {
$wm = new $WeakMap();
}
$weakMapSet($wm, key, value);
} else if ($Map) {
if (!$m) {
$m = new $Map();
}
$mapSet($m, key, value);
} else {
if (!$o) {
/*
* Initialize the linked list as an empty node, so that we don't have
* to special-case handling of the first node: we can always refer to
* it as (previous node).next, instead of something like (list).head
*/
$o = { key: {}, next: null };
}
listSet($o, key, value);
}
}
};
return channel;
};