|
|
@@ -0,0 +1,49 @@
|
|
|
+{$mode objfpc}{$H+}
|
|
|
+type
|
|
|
+ ternary = (F, U, T);
|
|
|
+
|
|
|
+ operator and (const a,b:ternary):ternary;inline;
|
|
|
+ const lookupAnd:array[ternary,ternary] of ternary =
|
|
|
+ ((F,F,F),(F,U,U),(F,U,T));
|
|
|
+ begin
|
|
|
+ Result:= LookupAnd[a,b];
|
|
|
+ end;
|
|
|
+
|
|
|
+ operator or (const a,b:ternary):ternary;inline;
|
|
|
+ const lookupOr:array[ternary,ternary] of ternary =
|
|
|
+ ((F,U,T),(U,U,T),(T,T,T));
|
|
|
+ begin
|
|
|
+ Result := LookUpOr[a,b];
|
|
|
+ end;
|
|
|
+
|
|
|
+ operator not (const a:ternary):ternary;inline;
|
|
|
+ const LookupNot:array[ternary] of ternary =(T,U,F);
|
|
|
+ begin
|
|
|
+ Result:= LookUpNot[a];
|
|
|
+ end;
|
|
|
+
|
|
|
+
|
|
|
+begin
|
|
|
+ // works as expected
|
|
|
+ writeln('AND');write(F and F);write(F and U);
|
|
|
+ writeln(F and T);write(U and F);write(U and U);
|
|
|
+ writeln(U and T);write(T and F);write(T and U);
|
|
|
+ writeln(T and T);
|
|
|
+ writeln;
|
|
|
+ //works as expected
|
|
|
+ writeln('OR');write(F or F);write(F or U);
|
|
|
+ writeln(F or T);write(U or F);write(U or U);
|
|
|
+ writeln(U or T);write(T or F);write(T or U);
|
|
|
+ writeln(T or T);
|
|
|
+ writeln;
|
|
|
+ // this fails, but compiles and runs w/o error indication.
|
|
|
+ // and renders the wrong results
|
|
|
+ writeln('NOT');
|
|
|
+ writeln(not F);// prints -1 unstead of T, it does not pick the overload!
|
|
|
+ writeln(not U);// prints -2 instead of U, it does not pick the overload!
|
|
|
+ writeln(not T);// prints -3 instead of F, it does not pick the overload!
|
|
|
+ // which makes this next construct impossible while the compiler suggests it's legal.
|
|
|
+ {
|
|
|
+ writeln(T and not F);
|
|
|
+ }
|
|
|
+end.
|
florian