grammar Statement
  include Expression

  rule type
    (typ:("int" | "ref") space*) { capture(:typ).to_s }
  end

  rule typed_arg
    (type name_expression) {
      Ast::TypedName.new(capture(:type).value , capture(:name_expression).value.name)
    }
  end

  rule variable_definition
    (typed_arg ("=" space* value_expression)?) {
      type = capture(:typed_arg).value
      value = capture(:value_expression) ? capture(:value_expression).value : nil
      var = Ast::VariableDefinition.new(type.type , type.name ,  value)
    }
  end

  rule assignment
    (name_expression "=" space* value_expression){
    Ast::AssignmentExpression.new( capture(:name_expression).value.name , capture(:value_expression).value)
    }
  end

  rule conditional
    (keyword_if left_parenthesis value_expression right_parenthesis
    body
    keyword_end)  {
    Ast::IfExpression.new( capture(:value_expression).value  , capture(:body).value , nil)
    }
  end

  rule while
    keyword_while left_parenthesis value_expression right_parenthesis keyword_do
    body
    keyword_end
  end

  rule return
    keyword_return value_expression newline
  end

  rule body
    (statement+){
      captures(:statement).collect{|u| u.value }
    }
  end

  rule statement
    conditional | while | return | variable_definition | assignment
  end

  root statement

end