support parse return

lib/emolang/ast/ast.rb

@@ -7,20 +7,11 @@
 module Emolang
   module AST
     class Statement < Node
+      attr_accessor :token
+
       def statement_name
         raise NotImplementedError
       end
-    end
-
-    class LetStatement < Statement
-      attr_accessor :token, :name
-
-      sig { params(token: Token).void }
-      def initialize(token)
-        super()
-        @token = token
-        @name = T.let(nil, T.nilable(AST::Identifier))
-      end
 
       sig { returns(String) }
       def token_literal

lib/emolang/ast/statement.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+# typed: true
+
+module Emolang
+  module AST
+    class LetStatement < Statement
+      attr_accessor :token, :name
+
+      sig { params(token: Token).void }
+      def initialize(token)
+        super()
+        @token = token
+        @name = T.let(nil, T.nilable(AST::Identifier))
+      end
+    end
+
+    class ReturnStatement < Statement
+      attr_accessor :token, :return_value
+
+      sig { params(token: Token).void }
+      def initialize(token)
+        super()
+        @token = token
+        @name = T.let(nil, T.nilable(AST::Identifier))
+      end
+    end
+  end
+end

lib/emolang/parser.rb

@@ -63,10 +63,24 @@ def parse_statement
 
       when TokenTypeEnum::LET
         parse_let_statement
+      when TokenTypeEnum::RETURN
+        parse_return_statement
       end
     end
 
-    sig { returns(T.nilable(AST::Statement)) }
+    sig { returns(T.nilable(AST::ReturnStatement)) }
+    def parse_return_statement
+      stmt = AST::ReturnStatement.new(@cur_token)
+      next_token
+      loop do
+        break if @cur_token.type == TokenTypeEnum::SEMICOLON
+
+        next_token
+      end
+      stmt
+    end
+
+    sig { returns(T.nilable(AST::LetStatement)) }
     def parse_let_statement
       stmt = AST::LetStatement.new(@cur_token)
 

test/test_emolang.rb

@@ -26,4 +26,12 @@ def test_next_token
       assert_equal(test[1], token.literal)
     end
   end
+
+  def test_parse_let
+    input = 'let a = 1;'
+    lexer = Emolang::Lexer.new(input)
+    parser = Emolang::EParser.new(lexer)
+    parser.parse_program
+    assert_equal(parser.errors, [])
+  end
 end