minor 20% optimization to lookup

Author: mkruskal-google

src/namespace.js

@@ -404,26 +404,36 @@ Namespace.prototype.lookup = function lookup(path, filterTypes, parentAlreadyChe
     // Start at root if path is absolute
     if (path[0] === "")
         return this.root.lookup(path.slice(1), filterTypes);
+    var flatPath = path.join(".");
 
-    var found = this._lookupImpl(path);
+    var found = this._lookupImpl(path, flatPath);
     if (found && (!filterTypes || filterTypes.indexOf(found.constructor) > -1)) {
         return found;
     }
 
-    // If there hasn't been a match, try again at the parent
-    if (this.parent === null || parentAlreadyChecked)
+    // If there hasn't been a match, walk up the tree
+    if (parentAlreadyChecked)
         return null;
-    return this.parent.lookup(path, filterTypes);
+
+    var current = this;
+    while (current.parent) {
+        found = current.parent._lookupImpl(path, flatPath);
+        if (found && (!filterTypes || filterTypes.indexOf(found.constructor) > -1)) {
+            return found;
+        }
+        current = current.parent;
+    }
+    return null;
 };
 
 /**
  * Internal helper for lookup that handles searching just at this namespace and below along with caching.
  * @param {string[]} path Path to look up
+ * @param {string} flatPath Flattened version of the path to use as a cache key
  * @returns {ReflectionObject|null} Looked up object or `null` if none could be found
  * @private
  */
-Namespace.prototype._lookupImpl = function lookup(path) {
-    var flatPath = path.join(".");
+Namespace.prototype._lookupImpl = function lookup(path, flatPath) {
     if(Object.prototype.hasOwnProperty.call(this._lookupCache, flatPath)) {
         return this._lookupCache[flatPath];
     }
@@ -434,13 +444,15 @@ Namespace.prototype._lookupImpl = function lookup(path) {
     if (found) {
         if (path.length === 1) {
             exact = found;
-        } else if (found instanceof Namespace && (found = found._lookupImpl(path.slice(1))))
-            exact = found;
+        } else if (found instanceof Namespace) {
+            path = path.slice(1);
+            exact = found._lookupImpl(path, path.join("."));
+        }
 
     // Otherwise try each nested namespace
     } else {
         for (var i = 0; i < this.nestedArray.length; ++i)
-            if (this._nestedArray[i] instanceof Namespace && (found = this._nestedArray[i]._lookupImpl(path)))
+            if (this._nestedArray[i] instanceof Namespace && (found = this._nestedArray[i]._lookupImpl(path, flatPath)))
                 exact = found;
     }