Power-Programmierung/CD1.mdf/oberon/oephone.mod

Text File | 1991-02-24 | 2KB | 86 lines

(* Phone number recording
   (Oberon Example) (c) Copyright E. R. Videki 1991 *)
MODULE OEPhone ;
    IMPORT OETree , OEIO ;


(* this module is structured much like OENames.Mod, which has more comments
about what is going on *)


CONST MaxPhone * = 20 ;

      PrtPhone * = 1 ;    (* command we will handle in our record nodes *)


TYPE    PhoneData * = ARRAY MaxPhone OF CHAR ;
    PhonePtr * = POINTER TO Phone ;
    Phone * =
        RECORD(OETree.Apple)
            phone *  : PhoneData
        END ;


VAR PhoneTree *  : PhonePtr ;
    refnode : PhonePtr ;


PROCEDURE * Handler ( p : OETree.ApplePtr ;  cmd : INTEGER );
BEGIN
    IF cmd = PrtPhone THEN
        OEIO.WriteString(   p(PhonePtr).phone  )
    END
END Handler;



PROCEDURE * PhoneSearch(p,ref:OETree.ApplePtr;  VAR result:INTEGER);
VAR i:INTEGER;
BEGIN
    IF p IS PhonePtr THEN
        WITH p : PhonePtr DO
            WITH ref : PhonePtr DO
                i := 0 ;
                WHILE (i < MaxPhone) & (p.phone[i] # 0X) &
                    (p.phone[i] = ref.phone[i]) DO INC(i) END;
                result := ORD(ref.phone[i]) - ORD(p.phone[i])
            END
        END
    ELSE result := -1
    END
END PhoneSearch ;



PROCEDURE NewPhone * ( p : PhonePtr ;  VAR result : INTEGER) ;
BEGIN
    p.method := Handler ;
    OETree.AddNew( PhoneTree, p , result, PhoneSearch)
END NewPhone;


PROCEDURE FindPhone * (VAR ph : PhoneData ;  VAR result:INTEGER;  VAR p : PhonePtr );
VAR p1 : OETree.ApplePtr ;
BEGIN
    refnode.phone := ph ;
    OETree.Search( PhoneTree, refnode, p1, result, PhoneSearch);
    IF result = 0 THEN p := p1(PhonePtr)
        (* expand scope for caller, from that of OETree's result *)
    ELSE p := NIL
    END
END FindPhone;


PROCEDURE Init;
VAR result : INTEGER;
BEGIN
    NEW(refnode);  refnode.phone[0] := 0X ;
    NEW(PhoneTree); PhoneTree.phone[0] := 0X;
    PhoneTree.refptr := NIL;   PhoneTree.method := Handler ;
    OETree.AddNew(NIL,PhoneTree,result,PhoneSearch)    (*set links in OETree's private flds*)
END Init;

BEGIN Init
END OEPhone.