Issue 6538, 6781 - Implement script parsing for snippets

lib/snippets.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 71 matching lines @@
 
 /**
  * Parses a script and returns a list of all its commands and their arguments
  * @param {string} script
  * @return {Array.<string[]>}
  */
 function parseScript(script)
 {
   let tree = [];
 
-  // Whether the next character should be treated as an escape sequence.

[kzar, 2018/07/12 10:30:37]

I don't these new comments add much, and they are kind of patronising. I'd
prefer to remove them.

[Manish Jethani, 2018/07/12 10:57:49]

Well I'm glad you think so, because I don't like to repeat the logic in the
comments, it's harder to maintain (the comments need to be kept up to date).

Done.

   let escape = false;
-
-  // Whether we are within a quoted sequence.
   let withinQuotes = false;
 
-  // The Unicode code point following a "\u"
   let unicodeEscape = null;
 
   let call = [];
   let argument = "";
 
-  // The terminating semicolon for the last command is optional; we add one
-  // here to make our loop consistent.
   for (let character of script.trim() + ";")
   {
     if (unicodeEscape != null)
     {
       unicodeEscape += character;
 
       if (unicodeEscape.length == 4)
       {
-        // Consider the Unicode escape only if it parses as a valid code point.
         let codePoint = parseInt(unicodeEscape, 16);
         if (!isNaN(codePoint))
           argument += String.fromCodePoint(codePoint);
 
         unicodeEscape = null;
       }
     }
     else if (escape)
     {
       escape = false;
 
       if (character == "u")
         unicodeEscape = "";
       else
         argument += singleCharacterEscapes.get(character) || character;
     }
     else if (character == "\\")
     {
       escape = true;
     }
     else if (character == "'")
     {
       withinQuotes = !withinQuotes;

[kzar, 2018/07/12 10:30:37]

Nice, I think this variable name is an improvement.

     }
-    // Normally a semicolon or a whitespace character marks the end of an
-    // argument, but within quotes these characters are taken literally and
-    // included in the argument.
     else if (withinQuotes || character != ";" && !/\s/u.test(character))
     {
       argument += character;
     }
     else
     {
       if (argument)
       {
         call.push(argument);
         argument = "";
       }
 
       if (character == ";" && call.length > 0)
       {
         tree.push(call);
         call = [];
       }
     }
   }
 
   return tree;
 }
 
 exports.parseScript = parseScript;