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