separate (Compilation_Unit.Produce_Metrics)
procedure Case_Statement
             (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

    --=====================================================================
    -- CASE_Statement ::=
    --   "CASE" Expression "IS"
    --   Case_Statement_Alternative { Case_Statement_Alternative }
    --   "END" "CASE" ";"
    --=====================================================================

    Current_Token : Token_Package.Token;
    No_More_Case_Alternatives : Boolean := False;

begin
    -- CASE_Statement

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

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

    -- until "IS" is found
    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.Is_Token));

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

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

    Process_Case_Statement_Alternatives:
        -- repeat for every alternative
        loop

            Case_Statement_Alternative
               (Current_Compilation_Unit => Current_Compilation_Unit,
                Program_Unit => Program_Unit,
                Halstead => Halstead,
                Loc => Loc,
                Mccabe => Mccabe);

            if "/=" (Token_Package.Value_Of
                        (Peek (From => Current_Compilation_Unit)),
                     Token_Package.When_Token) then

                No_More_Case_Alternatives := True;
            end if;

            exit Process_Case_Statement_Alternatives when
               No_More_Case_Alternatives;

        end loop Process_Case_Statement_Alternatives;

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

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

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

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

    -- increment Halstead CASE_IS_END_CASE operator count
    Halstead.Store_Operator ((Kind =>
                                 Halstead_Operator.Case_Is_End_Case_Halstead));

    -- decrease McCabe PI
    Mccabe.Change_Pi (The_Amount_To_Change => -1);

    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 Case_Statement;