separate (Compilation_Unit.Produce_Metrics)
procedure Length_Clause (Current_Compilation_Unit : in out Ada_Compilation_Unit;
                         Program_Unit : in Program_Unit_State_Machine;
                         Halstead : in Halstead_State_Machine;
                         Loc : in Loc_State_Machine;
                         Mccabe : in Mccabe_State_Machine) is

    --==============================================
    -- Length_Clause ::= "USE" Expression ";"
    --==============================================

    Current_Token : Token_Package.Token;

begin
    -- Length_Clause

    Get_Next_Token (Out_Token => Current_Token,
                    From => Current_Compilation_Unit,
                    Current_Loc => Loc);

    if "/=" (Token_Package.Value_Of (Current_Token),
             Token_Package.Use_Token) then
        raise Syntax_Error;
    end if;

    -- increment Halstead FOR_USE operator count
    Halstead.Store_Operator ((Kind => Halstead_Operator.For_Use_Halstead));

    Expression
       (Current_Compilation_Unit => Current_Compilation_Unit,
        Program_Unit => Program_Unit,
        Halstead => Halstead,
        Loc => Loc,
        Mccabe => Mccabe,
        Terminate_Tokens => Set_Of_Tokens'(1 => Token_Package.Semicolon_Token));

    Get_Next_Token (Out_Token => Current_Token,
                    From => Current_Compilation_Unit,
                    Current_Loc => Loc);

    if "/=" (Token_Package.Value_Of (Current_Token),
             Token_Package.Semicolon_Token) then
        raise Syntax_Error;
    end if;

    -- increment Halstead SEMICOLON operator count
    Halstead.Store_Operator ((Kind => Halstead_Operator.Semicolon_Halstead));

end Length_Clause;