Support shadowing on highlight

lib/rucoa/handlers/text_document_document_highlight_handler.rb

@@ -427,7 +427,6 @@ def nodes
             ].compact
           end
 
-          # @todo Support shadowing.
           # @return [Enumerable<Rucoa::Nodes::LvarNode>]
           def reference_nodes
             return [] unless assignment_node
@@ -446,13 +445,30 @@ def reference_nodes
                 node,
                 *node.descendants
               ]
+            end.take_while do |node| # FIXME: flat_map and take_while are not correct solution for shadowing.
+              case node
+              when Nodes::ArgNode, Nodes::LvasgnNode
+                node.equal?(assignment_node) || node.name != assignment_node.name
+              else
+                true
+              end
             end.select do |node|
               case node
               when Nodes::LvarNode
                 node.name == @node.name
               end
             end
           end
+
+          class UnshadowedNodeVisitor
+            def initialize(
+              node:,
+              &block
+            )
+              @block = block
+              @node = node
+            end
+          end
         end
 
         class ModuleMapper < Base

spec/rucoa/handlers/text_document_document_highlight_handler_spec.rb

@@ -1335,5 +1335,71 @@ def a
         )
       end
     end
+
+    context 'when local variable is shadowed by local variable assignment' do
+      let(:content) do
+        <<~RUBY
+          a = 1
+          b = 2
+          a
+          a = 2
+          a
+        RUBY
+      end
+
+      let(:position) do
+        Rucoa::Position.new(
+          column: 0,
+          line: 1
+        )
+      end
+
+      it 'returns highlights' do
+        subject
+        expect(server.responses).to match(
+          [
+            hash_including(
+              'id' => 1,
+              'result' => Array.new(2) do
+                a_kind_of(Hash)
+              end
+            )
+          ]
+        )
+      end
+    end
+
+    context 'when local variable is shadowed by block argument' do
+      let(:content) do
+        <<~RUBY
+          a = 1
+          a
+          foo do |a|
+            a
+          end
+        RUBY
+      end
+
+      let(:position) do
+        Rucoa::Position.new(
+          column: 0,
+          line: 1
+        )
+      end
+
+      it 'returns highlights' do
+        subject
+        expect(server.responses).to match(
+          [
+            hash_including(
+              'id' => 1,
+              'result' => Array.new(2) do
+                a_kind_of(Hash)
+              end
+            )
+          ]
+        )
+      end
+    end
   end
 end