Issue 5735 - Use JS Map instead of Object for Filter.knownFilters

lib/filterClasses.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 61 matching lines @@
   },
 
   toString()
   {
     return this.text;
   }
 };
 
 /**
  * Cache for known filters, maps string representation to filter objects.
- * @type {Object}

[Wladimir Palant, 2017/09/20 11:00:27]

Actually, this needs to be adjusted - type should be Map.<string,Filter>

[sergei, 2017/09/20 11:31:27]

Done.

+ * @type {Map.<string,Filter>}
  */
 Filter.knownFilters = new Map();
 
 /**
  * Regular expression that element hiding filters should match
  * @type {RegExp}
  */
 Filter.elemhideRegExp = /^([^/*|@"!]*?)#([@?])?#(.+)$/;
 /**
  * Regular expression that RegExp filters specified as RegExps should match
  * @type {RegExp}
  */
 Filter.regexpRegExp = /^(@@)?\/.*\/(?:\$~?[\w-]+(?:=[^,\s]+)?(?:,~?[\w-]+(?:=[^,\s]+)?)*)?$/;
 /**
  * Regular expression that options on a RegExp filter should match
  * @type {RegExp}
  */
 Filter.optionsRegExp = /\$(~?[\w-]+(?:=[^,\s]+)?(?:,~?[\w-]+(?:=[^,\s]+)?)*)$/;
 
 /**
  * Creates a filter of correct type from its text representation - does the
  * basic parsing and calls the right constructor then.
  *
  * @param {string} text   as in Filter()
  * @return {Filter}
  */
 Filter.fromText = function(text)
 {
   let ret = Filter.knownFilters.get(text);

[Wladimir Palant, 2017/09/20 10:04:13]

Nit: maybe a more meaningful name for this variable, such as existingFilter?

[sergei, 2017/09/20 10:27:33]

I think it's not for this change because `ret` is used here and in the method
`Filter.fromObject` below, looks already like a pattern and it would be better
to rename them at the same time, for example to `filter`. In addition later this
variable is re-used for a new filter and one variable is actually sufficient
here.

Is it worth creation of the Noissue review with the renaming to `filter`?

[Wladimir Palant, 2017/09/20 10:58:00]

I see.

[kzar, 2017/09/20 12:30:24]

Yea I think so, if you don't want to just give it a better name now.

[sergei, 2017/09/20 13:12:45]

Done in https://codereview.adblockplus.org/29550667/

   if (ret)

[kzar, 2017/09/20 12:30:24]

Just an observation since I don't think it matters, but this behaviour is
slightly different. If we cached a falsey value for a filter previously we would
have returned it but now we won't.

     return ret;
 
   let match = (text.includes("#") ? Filter.elemhideRegExp.exec(text) : null);
   if (match)
   {
     let propsMatch;
     if (!match[2] &&
         (propsMatch = /\[-abp-properties=(["'])([^"']+)\1\]/.exec(match[3])))
     {
       // This is legacy CSS properties syntax, convert to current syntax
@@ skipping 897 matching lines @@
  */
 function ElemHideEmulationFilter(text, domains, selector)
 {
   ElemHideBase.call(this, text, domains, selector);
 }
 exports.ElemHideEmulationFilter = ElemHideEmulationFilter;
 
 ElemHideEmulationFilter.prototype = extend(ElemHideBase, {
   type: "elemhideemulation"
 });