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 117 matching lines @@
         tree.push(call);
         call = [];
       }
     }
   }
 
   return tree;
 }
 
 exports.parseScript = parseScript;
+
+/**
+ * Compiles a script against a given list of libraries into executable code
+ * @param {string} script
+ * @param {string[]} libraries
+ * @return {string}
+ */
+function compileScript(script, libraries)
+{
+  return `
+    "use strict";
+    {
+      const libraries = ${JSON.stringify(libraries)};
+
+      const script = ${JSON.stringify(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.compileScript = compileScript;