Speedup and reduce Array creation when constantizing a non-namespaced string

1 files changed, 29 insertions, 25 deletions

diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index 18f3f53879..d33c79d60e 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -269,32 +269,36 @@ module ActiveSupport
     # NameError is raised when the name is not in CamelCase or the constant is
     # unknown.
     def constantize(camel_cased_word)
-      names = camel_cased_word.split("::")
-
-      # Trigger a built-in NameError exception including the ill-formed constant in the message.
-      Object.const_get(camel_cased_word) if names.empty?
-
-      # Remove the first blank element in case of '::ClassName' notation.
-      names.shift if names.size > 1 && names.first.empty?
-
-      names.inject(Object) do |constant, name|
-        if constant == Object
-          constant.const_get(name)
-        else
-          candidate = constant.const_get(name)
-          next candidate if constant.const_defined?(name, false)
-          next candidate unless Object.const_defined?(name)
-
-          # Go down the ancestors to check if it is owned directly. The check
-          # stops when we reach Object or the end of ancestors tree.
-          constant = constant.ancestors.inject(constant) do |const, ancestor|
-            break const    if ancestor == Object
-            break ancestor if ancestor.const_defined?(name, false)
-            const
+      if camel_cased_word.blank? || !camel_cased_word.include?('::')
+        Object.const_get(camel_cased_word)
+      else
+        names = camel_cased_word.split("::")
+
+        # Trigger a built-in NameError exception including the ill-formed constant in the message.
+        Object.const_get(camel_cased_word) if names.empty?
+
+        # Remove the first blank element in case of '::ClassName' notation.
+        names.shift if names.size > 1 && names.first.empty?
+
+        names.inject(Object) do |constant, name|
+          if constant == Object
+            constant.const_get(name)
+          else
+            candidate = constant.const_get(name)
+            next candidate if constant.const_defined?(name, false)
+            next candidate unless Object.const_defined?(name)
+
+            # Go down the ancestors to check if it is owned directly. The check
+            # stops when we reach Object or the end of ancestors tree.
+            constant = constant.ancestors.inject(constant) do |const, ancestor|
+              break const    if ancestor == Object
+              break ancestor if ancestor.const_defined?(name, false)
+              const
+            end
+
+            # owner is in Object, so raise
+            constant.const_get(name, false)
           end
-
-          # owner is in Object, so raise
-          constant.const_get(name, false)
         end
       end
     end