Issue 6538, 6781 - Implement script parsing for snippets

lib/snippets.js

Index: lib/snippets.js
===================================================================
--- a/lib/snippets.js
+++ b/lib/snippets.js
@@ -18,16 +18,20 @@
 "use strict";
 
 /**
  * @fileOverview Snippets implementation.
  */
 
 const {Filter} = require("./filterClasses");
 
+const singleCharacterEscapes = new Map([
+  ["n", "\n"], ["r", "\r"], ["t", "\t"]
+]);
+
 let filters = new Set();
 
 /**
  * Container for snippet filters
  * @class
  */
 let Snippets = {
   /**
@@ -70,8 +74,82 @@
       if (filter.isActiveOnDomain(domain))
         result.push(filter.script);
     }
     return result;
   }
 };
 
 exports.Snippets = Snippets;
+
+/**
+ * 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 = [];
+
+  let escape = false;
+  let withinQuotes = false;
+
+  let unicodeEscape = null;
+
+  let call = [];
+  let argument = "";
+
+  for (let character of script.trim() + ";")
+  {
+    if (unicodeEscape != null)
+    {
+      unicodeEscape += character;
+
+      if (unicodeEscape.length == 4)
+      {
+        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;
+    }
+    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;