4.3BSD - /usr/src/new/icon/operators/nonnull.c

   1: #include "../h/rt.h"
   2: 
   3: /*
   4:  * \x - test x for non-null value.
   5:  */
   6: 
   7: nonnull(nargs, arg1, arg0)
   8: int nargs;
   9: struct descrip arg1, arg0;
  10:    {
  11: 
  12:    DclSave
  13:    SetBound;
  14: 
  15:    /*
  16:     * If x is not null, it is returned, otherwise, the function fails.
  17:     *  Because the pre-dereference value of x is the return value (if
  18:     *  any), x is copied into arg0.
  19:     */
  20:    arg0 = arg1;
  21:    DeRef(arg1)
  22:    if (NULLDESC(arg1))
  23:       fail();
  24:    ClearBound;
  25:    }
  26: 
  27: Opblock(nonnull,1,"\\")

Defined functions