Issue 6538, 6781 - Implement script compilation 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 111 matching lines @@
 
         if (character == ";" && call.length > 0)
         {
           tree.push(call);
           call = [];
         }
       }
     }
 
     return tree;
+  },
+
+  /**
+   * Compiles a script against a given list of libraries into executable code
+   * @param {string} script
+   * @param {string[]} libraries
+   * @return {string}
+   */
+  compileScript(script, libraries)
+  {
+    return `
+      "use strict";
+      {
+        const libraries = ${JSON.stringify(libraries)};
+
+        const script = ${JSON.stringify(Snippets.parseScript(script))};
+
+        let imports = Object.create(null);
+        for (let library of libraries)
+          new Function("exports", library)(imports);
+
+        for (let [name, ...args] of script)
+        {
+          if (Object.prototype.hasOwnProperty.call(imports, name))
+          {
+            let value = imports[name];
+            if (typeof value == "function")
+              value(...args);
+          }
+        }
+      }
+    `;
   }
 };
 
 exports.Snippets = Snippets;