[perf] Split try catch into separate function (#40)

Author: Tom Atkinson

index.js

@@ -322,17 +322,22 @@ function decodeString(str) {
 
   // look up json data
   if (str.charAt(++i)) {
-    try {
-      p.data = json.parse(str.substr(i));
-    } catch(e){
-      return error();
-    }
+    p = tryParse(p, str.substr(i));
   }
 
   debug('decoded %s as %j', str, p);
   return p;
 }
 
+function tryParse(p, str) {
+  try {
+    p.data = json.parse(str);
+  } catch(e){
+    return error();
+  }
+  return p; 
+};
+
 /**
  * Deallocates a parser's resources
  *