Track rest, keyword rest and post parameters (#1228)

lib/ruby_indexer/lib/ruby_indexer/entry.rb

@@ -106,6 +106,16 @@ class KeywordParameter < Parameter
     class OptionalKeywordParameter < Parameter
     end
 
+    # A rest method parameter, e.g. `def foo(*a)`
+    class RestParameter < Parameter
+      DEFAULT_NAME = T.let(:"<anonymous splat>", Symbol)
+    end
+
+    # A keyword rest method parameter, e.g. `def foo(**a)`
+    class KeywordRestParameter < Parameter
+      DEFAULT_NAME = T.let(:"<anonymous keyword splat>", Symbol)
+    end
+
     class Member < Entry
       extend T::Sig
       extend T::Helpers
@@ -203,17 +213,47 @@ def list_params(parameters_node)
           end
         end
 
+        rest = parameters_node.rest
+
+        if rest
+          rest_name = rest.name || RestParameter::DEFAULT_NAME
+          parameters << RestParameter.new(name: rest_name)
+        end
+
+        keyword_rest = parameters_node.keyword_rest
+
+        if keyword_rest.is_a?(Prism::KeywordRestParameterNode)
+          keyword_rest_name = parameter_name(keyword_rest) || KeywordRestParameter::DEFAULT_NAME
+          parameters << KeywordRestParameter.new(name: keyword_rest_name)
+        end
+
+        parameters_node.posts.each do |post|
+          name = parameter_name(post)
+          next unless name
+
+          parameters << RequiredParameter.new(name: name)
+        end
+
         parameters
       end
 
-      sig { params(node: Prism::Node).returns(T.nilable(Symbol)) }
+      sig { params(node: T.nilable(Prism::Node)).returns(T.nilable(Symbol)) }
       def parameter_name(node)
         case node
         when Prism::RequiredParameterNode, Prism::OptionalParameterNode,
-          Prism::RequiredKeywordParameterNode, Prism::OptionalKeywordParameterNode
+          Prism::RequiredKeywordParameterNode, Prism::OptionalKeywordParameterNode,
+          Prism::RestParameterNode, Prism::KeywordRestParameterNode
           node.name
         when Prism::MultiTargetNode
-          names = [*node.lefts, *node.rest, *node.rights].map { |parameter_node| parameter_name(parameter_node) }
+          names = node.lefts.map { |parameter_node| parameter_name(parameter_node) }
+
+          rest = node.rest
+          if rest.is_a?(Prism::SplatNode)
+            name = rest.expression&.slice
+            names << (rest.operator == "*" ? "*#{name}".to_sym : name&.to_sym)
+          end
+
+          names.concat(node.rights.map { |parameter_node| parameter_name(parameter_node) })
 
           names_with_commas = names.join(", ")
           :"(#{names_with_commas})"

lib/ruby_indexer/test/method_test.rb

@@ -106,6 +106,118 @@ def bar(a:, b: 123)
       assert_instance_of(Entry::OptionalKeywordParameter, b)
     end
 
+    def test_method_with_rest_and_keyword_rest_parameters
+      index(<<~RUBY)
+        class Foo
+          def bar(*a, **b)
+          end
+        end
+      RUBY
+
+      assert_entry("bar", Entry::InstanceMethod, "/fake/path/foo.rb:1-2:2-5")
+      entry = T.must(@index["bar"].first)
+      assert_equal(2, entry.parameters.length)
+      a, b = entry.parameters
+
+      assert_equal(:a, a.name)
+      assert_instance_of(Entry::RestParameter, a)
+
+      assert_equal(:b, b.name)
+      assert_instance_of(Entry::KeywordRestParameter, b)
+    end
+
+    def test_method_with_post_parameters
+      index(<<~RUBY)
+        class Foo
+          def bar(*a, b)
+          end
+
+          def baz(**a, b)
+          end
+
+          def qux(*a, (b, c))
+        end
+      RUBY
+
+      assert_entry("bar", Entry::InstanceMethod, "/fake/path/foo.rb:1-2:2-5")
+      entry = T.must(@index["bar"].first)
+      assert_equal(2, entry.parameters.length)
+      a, b = entry.parameters
+
+      assert_equal(:a, a.name)
+      assert_instance_of(Entry::RestParameter, a)
+
+      assert_equal(:b, b.name)
+      assert_instance_of(Entry::RequiredParameter, b)
+
+      entry = T.must(@index["baz"].first)
+      assert_equal(2, entry.parameters.length)
+      a, b = entry.parameters
+
+      assert_equal(:a, a.name)
+      assert_instance_of(Entry::KeywordRestParameter, a)
+
+      assert_equal(:b, b.name)
+      assert_instance_of(Entry::RequiredParameter, b)
+
+      entry = T.must(@index["qux"].first)
+      assert_equal(2, entry.parameters.length)
+      _a, second = entry.parameters
+
+      assert_equal(:"(b, c)", second.name)
+      assert_instance_of(Entry::RequiredParameter, second)
+    end
+
+    def test_method_with_destructured_rest_parameters
+      index(<<~RUBY)
+        class Foo
+          def bar((a, *b))
+          end
+        end
+      RUBY
+
+      assert_entry("bar", Entry::InstanceMethod, "/fake/path/foo.rb:1-2:2-5")
+      entry = T.must(@index["bar"].first)
+      assert_equal(1, entry.parameters.length)
+      param = entry.parameters.first
+
+      assert_equal(:"(a, *b)", param.name)
+      assert_instance_of(Entry::RequiredParameter, param)
+    end
+
+    def test_method_with_anonymous_rest_parameters
+      index(<<~RUBY)
+        class Foo
+          def bar(*, **)
+          end
+        end
+      RUBY
+
+      assert_entry("bar", Entry::InstanceMethod, "/fake/path/foo.rb:1-2:2-5")
+      entry = T.must(@index["bar"].first)
+      assert_equal(2, entry.parameters.length)
+      first, second = entry.parameters
+
+      assert_equal(Entry::RestParameter::DEFAULT_NAME, first.name)
+      assert_instance_of(Entry::RestParameter, first)
+
+      assert_equal(Entry::KeywordRestParameter::DEFAULT_NAME, second.name)
+      assert_instance_of(Entry::KeywordRestParameter, second)
+    end
+
+    def test_method_with_forbidden_keyword_splat_parameter
+      index(<<~RUBY)
+        class Foo
+          def bar(**nil)
+          end
+        end
+      RUBY
+
+      assert_entry("bar", Entry::InstanceMethod, "/fake/path/foo.rb:1-2:2-5")
+      entry = T.must(@index["bar"].first)
+      assert_empty(entry.parameters)
+    end
+
     def test_keeps_track_of_method_owner
       index(<<~RUBY)
         class Foo