Cache expressions

R=arv BUG= Review URL: https://codereview.appspot.com/12815048
googlearchive · Aug 22, 2013 · d87b95b · d87b95b
1 parent ea5da4d
commit d87b95b
Showing 1 changed file with 9 additions and 3 deletions.
diff --git a/src/polymer-expressions.js b/src/polymer-expressions.js
@@ -125,11 +125,17 @@
     return binding;
   }
 
+  // TODO(rafaelw): Implement simple LRU.
+  var expressionParseCache = {};
+
   function getExpressionBinding(model, expressionText) {
     try {
-      // TODO(rafaelw): Cache expressions.
-      var delegate = new ASTDelegate();
-      esprima.parse(expressionText, delegate);
+      var delegate = expressionParseCache[expressionText];
+      if (!delegate) {
+        delegate = new ASTDelegate();
+        esprima.parse(expressionText, delegate);
+        expressionParseCache[expressionText] = delegate;
+      }
 
       if (!delegate.expression && !delegate.labeledStatements.length)
         return;