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Annotation of 43BSD/contrib/icon/operators/lconcat.c, revision 1.1.1.1

1.1       root        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,"|||")

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