separate (Compilation_Unit.Produce_Metrics)
procedure Label (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

    --================================================
    -- Label ::= { "<<" <IDENTIFIER> ">>" }
    --================================================

    Current_Token : Token_Package.Token;

begin
    -- Label

    Process_Labels:
        while Token_Package.Value_Of (Peek (From => Current_Compilation_Unit)) =
                 Token_Package.Left_Label_Bracket_Token loop

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

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

            if "/=" (Token_Package.Class_Of (Current_Token),
                     Token_Package.Identifier) then
                raise Syntax_Error;
            end if;

            -- increment Halstead operand count
            Halstead.Store_Operand (Halstead_Operand.Definition
                                       (Token_Package.Value_Of
                                           (This_Token => Current_Token)));

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

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

            -- increment Halstead LABEL operator count
            Halstead.Store_Operator ((Kind =>
                                         Halstead_Operator.Label_Halstead));

        end loop Process_Labels;

end Label;