Add entries_for method to indexer (#2500)

lib/ruby_indexer/lib/ruby_indexer/index.rb

@@ -616,6 +616,17 @@ def existing_or_new_singleton_class(name)
       singleton
     end
 
+    sig do
+      type_parameters(:T).params(
+        path: String,
+        type: T::Class[T.all(T.type_parameter(:T), Entry)],
+      ).returns(T.nilable(T::Array[T.type_parameter(:T)]))
+    end
+    def entries_for(path, type)
+      entries = @files_to_entries[path]
+      entries&.grep(type)
+    end
+
     private
 
     # Runs the registered included hooks

lib/ruby_indexer/test/index_test.rb

@@ -1842,5 +1842,26 @@ class Foo
       candidates = @index.method_completion_candidates("=", "Foo")
       assert_equal(["==", "==="], candidates.map(&:name))
     end
+
+    def test_entries_for
+      index(<<~RUBY)
+        class Foo; end
+
+        module Bar
+          def my_def; end
+          def self.my_singleton_def; end
+        end
+      RUBY
+
+      entries = @index.entries_for("/fake/path/foo.rb", Entry)
+      assert_equal(["Foo", "Bar", "my_def", "Bar::<Class:Bar>", "my_singleton_def"], entries.map(&:name))
+
+      entries = @index.entries_for("/fake/path/foo.rb", RubyIndexer::Entry::Namespace)
+      assert_equal(["Foo", "Bar", "Bar::<Class:Bar>"], entries.map(&:name))
+    end
+
+    def test_entries_for_returns_nil_if_no_matches
+      assert_nil(@index.entries_for("non_existing_file.rb", Entry::Namespace))
+    end
   end
 end