Merge pull request #38 from ruby/it_parameter

Support it parameter

Author: tompng

lib/repl_type_completor.rb

@@ -101,6 +101,8 @@ def analyze_code(code, binding = Object::TOPLEVEL_BINDING)
         [op == '::' ? :call_or_const : :call, name, receiver_type, self_call]
       when Prism::LocalVariableReadNode, Prism::LocalVariableTargetNode
         [:lvar_or_method, target_node.name.to_s, calculate_scope.call]
+      when Prism::ItLocalVariableReadNode
+        [:lvar_or_method, 'it', calculate_scope.call]
       when Prism::ConstantPathNode, Prism::ConstantPathTargetNode
         name = target_node.name.to_s
         if target_node.parent # A::B
@@ -122,8 +124,8 @@ def analyze_code(code, binding = Object::TOPLEVEL_BINDING)
     end
 
     def find_target(node, position)
-      # Skip because NumberedParametersNode#location gives location of whole block
-      return if node.is_a? Prism::NumberedParametersNode
+      # Skip because location of these nodes gives location of whole block
+      return if node.is_a?(Prism::NumberedParametersNode) || node.is_a?(Prism::ItParametersNode)
 
       node.compact_child_nodes.each do |n|
         match = find_target(n, position)

lib/repl_type_completor/type_analyzer.rb

@@ -229,6 +229,11 @@ def evaluate_reference_read(node, scope)
     alias evaluate_class_variable_read_node evaluate_reference_read
     alias evaluate_instance_variable_read_node evaluate_reference_read
 
+    def evaluate_it_local_variable_read_node(_node, scope)
+      # `it` is not a normal local variable. It can be overridden like `tap{p it; it=1}`.
+      # Use the name `_1` instead of `it` to avoid conflict.
+      scope['_1'] || Types::NIL
+    end
 
     def evaluate_call_node(node, scope)
       receiver_type = node.receiver ? evaluate(node.receiver, scope) : scope.self_type
@@ -262,6 +267,8 @@ def evaluate_call_node(node, scope)
                 assign_numbered_parameters node.block.parameters.maximum, block_scope, block_args, {}
               when Prism::BlockParametersNode
                 assign_parameters node.block.parameters.parameters, block_scope, block_args, {}
+              when Prism::ItParametersNode
+                scope['_1'] = block_args.first || Types::NIL
               end
               result = node.block.body ? evaluate(node.block.body, block_scope) : Types::NIL
               block_scope.merge_jumps
@@ -425,9 +432,14 @@ def evaluate_constant_path_write_node(node, scope)
 
     def evaluate_lambda_node(node, scope)
       local_table = node.locals.to_h { [_1.to_s, Types::OBJECT] }
+
+      # `it` is not added to local_table because it is not a normal local variable.
+      # We need to explicitly add it to the scope.
+      local_table['_1'] = Types::OBJECT if node.parameters.is_a?(Prism::ItParametersNode)
+
       block_scope = Scope.new scope, { **local_table, Scope::BREAK_RESULT => nil, Scope::NEXT_RESULT => nil, Scope::RETURN_RESULT => nil }
       block_scope.conditional do |s|
-        assign_parameters node.parameters.parameters, s, [], {} if node.parameters&.parameters
+        assign_parameters node.parameters.parameters, s, [], {} if node.parameters.is_a?(Prism::ParametersNode) && node.parameters.parameters
         evaluate node.body, s if node.body
       end
       block_scope.merge_jumps

test/repl_type_completor/test_repl_type_completor.rb

@@ -92,6 +92,13 @@ def test_lvar
       assert_doc_namespace('lvar = ""; lvar.ascii_only?', 'String#ascii_only?', binding: bind)
     end
 
+    def test_confusing_lvar_method_it
+      bind = eval('item = 1; ins=1; random = 1; binding')
+      assert_completion('->{it', binding: bind, include: ['em', 'self'])
+      assert_completion('->{ins', binding: bind, include: 'pect')
+      assert_completion('->{rand', binding: bind, include: 'om')
+    end
+
     def test_const
       assert_completion('Ar', include: 'ray')
       assert_completion('::Ar', include: 'ray')

test/repl_type_completor/test_type_analyze.rb

@@ -552,6 +552,16 @@ def test_numbered_parameter
       assert_call('[:a].each_with_index{_2.', include: Integer, exclude: Symbol)
     end
 
+    def test_it_parameter
+      assert_call('->{it.', include: Object, exclude: NilClass)
+      assert_call('->{p it; it=:a; it.', include: Symbol, exclude: Object)
+      assert_call('1.tap{it.', include: Integer)
+      assert_call('1.tap{p it; it=:a; it.', include: Symbol, exclude: Integer)
+      assert_call('[1].tap{it.', include: Array)
+      assert_call('loop{it.', include: NilClass, exclude: Object)
+      assert_call('[:a].each_with_index{it.', include: Symbol, exclude: [Integer, Array])
+    end
+
     def test_if_unless
       assert_call('if cond; 1; end.', include: Integer)
       assert_call('unless true; 1; end.', include: Integer)