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

   1: #include "../h/rt.h"
   2: 
   3: /*
   4:  * x ||| y - concatenate lists x and y.
   5:  */
   6: 
   7: lconcat(nargs, arg2, arg1, arg0)
   8: int nargs;
   9: struct descrip arg2, arg1, arg0;
  10:    {
  11:    register struct b_list *bp1, *bp2;
  12:    register struct b_lelem *lp1, *lp2;
  13:    int size1, size2;
  14: 
  15:    SetBound;
  16:    /*
  17:     * x and y must be lists.
  18:     */
  19:    DeRef(arg1)
  20:    DeRef(arg2)
  21:    if (QUAL(arg1) || TYPE(arg1) != T_LIST)
  22:       runerr(108, &arg1);
  23:    if (QUAL(arg2) || TYPE(arg2) != T_LIST)
  24:       runerr(108, &arg2);
  25: 
  26:    /*
  27:     * Get the size of both lists.
  28:     */
  29:    size1 = BLKLOC(arg1)->list.cursize;
  30:    size2 = BLKLOC(arg2)->list.cursize;
  31: 
  32:    /*
  33:     * Make a copy of both lists.
  34:     */
  35:    cplist(&arg1, &arg1, 1, size1 + 1);
  36:    cplist(&arg2, &arg2, 1, size2 + 1);
  37: 
  38:    /*
  39:     * Get a pointer to both lists.  bp1 points to the copy of x and is
  40:     *  the list that will be returned.
  41:     */
  42:    bp1 = (struct b_list *) BLKLOC(arg1);
  43:    bp2 = (struct b_list *) BLKLOC(arg2);
  44: 
  45:    /*
  46:     * Perform the concatenation by hooking the lists together so
  47:     *  that the next list of x is y and the previous list of y is x.
  48:     */
  49:    lp1 = (struct b_lelem *) BLKLOC(bp1->listtail);
  50:    lp2 = (struct b_lelem *) BLKLOC(bp2->listhead);
  51: 
  52:    lp1->listnext.type = D_LELEM;
  53:    BLKLOC(lp1->listnext) = (union block *) lp2;
  54: 
  55:    lp2->listprev.type = D_LELEM;
  56:    BLKLOC(lp2->listprev) = (union block *) lp1;
  57: 
  58:    /*
  59:     * Adjust the size field to reflect the length of the concatenated lists.
  60:     */
  61:    bp1->cursize = size1 + size2;
  62:    BLKLOC(bp1->listtail) = BLKLOC(bp2->listtail);
  63: 
  64:    arg0 = arg1;
  65:    ClearBound;
  66:    }
  67: 
  68: Opblock(lconcat,2,"|||")

Defined functions