Add latest changes from gitlab-org/gitlab@master

1 files changed, 55 insertions, 0 deletions

diff --git a/rubocop/cop/gitlab/keys-first-and-values-first.rb b/rubocop/cop/gitlab/keys-first-and-values-first.rb
new file mode 100644
index 00000000000..9b68957cba2
--- /dev/null
+++ b/rubocop/cop/gitlab/keys-first-and-values-first.rb
@@ -0,0 +1,55 @@
+module RuboCop
+  module Cop
+    module Gitlab
+      class KeysFirstAndValuesFirst < RuboCop::Cop::Cop
+        FIRST_PATTERN = /\Afirst\z/.freeze
+
+        def message(used_method)
+          <<~MSG
+          Don't use `.keys.first` and `.values.first`.
+          Instead use `.each_key.first` and `.each_value.first` (or `.first.first` and `first.second`)
+
+          This will reduce memory usage and execution time.
+          MSG
+        end
+
+        def on_send(node)
+          if find_on_keys_or_values?(node)
+            add_offense(node, location: :selector, message: message(node.method_name))
+          end
+        end
+
+        def autocorrect(node)
+          lambda do |corrector|
+            replace_with = if node.descendants.first.method_name == :values
+                             '.each_value'
+                           elsif node.descendants.first.method_name == :keys
+                             '.each_key'
+                           else
+                             throw("Expect '.values.first' or '.keys.first', but get #{node.descendants.first.method_name}.first")
+                           end
+
+            upto_including_keys_or_values = node.descendants.first.source_range
+            before_keys_or_values = node.descendants[1].source_range
+            range_to_replace = node.source_range
+                                  .with(begin_pos: before_keys_or_values.end_pos,
+                                        end_pos: upto_including_keys_or_values.end_pos)
+            corrector.replace(range_to_replace, replace_with)
+          end
+        end
+
+        def find_on_keys_or_values?(node)
+          chained_on_node = node.descendants.first
+          node.method_name.to_s =~ FIRST_PATTERN &&
+              chained_on_node.is_a?(RuboCop::AST::SendNode) &&
+              [:keys, :values].include?(chained_on_node.method_name) &&
+              node.descendants[1]
+        end
+
+        def method_name_for_node(node)
+          children[1].to_s
+        end
+      end
+    end
+  end
+end