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

1.1       root        1: #include "../h/rt.h"
                      2: 
                      3: /*
                      4:  * x <- y - assign y to x.
                      5:  * Reverses assignment if resumed.
                      6:  */
                      7: 
                      8: rasgn(nargs, arg2, arg1, arg0)
                      9: int nargs;
                     10: struct descrip arg2, arg1, arg0;
                     11:    {
                     12:    DclSave
                     13:    SetBound;
                     14:    /*
                     15:     * x must be a variable.
                     16:     */
                     17:    if (QUAL(arg1) || !VAR(arg1))
                     18:       runerr(111, &arg1);
                     19:    /*
                     20:     * The return value is the variable x, so make a copy of it before
                     21:     *  it is dereferenced.
                     22:     */
                     23:    arg0 = arg1;
                     24:    DeRef(arg1)
                     25:    DeRef(arg2)
                     26:    /*
                     27:     * Assign y to x and suspend.
                     28:     */
                     29:    doasgn(&arg0, &arg2);
                     30:    suspend();
                     31:    /*
                     32:     * <- has been resumed, reverse the assignment by assigning the old value
                     33:     *  of x (present as arg1) back into x and fail.
                     34:     */
                     35:    doasgn(&arg0, &arg1);
                     36:    fail();
                     37:    }
                     38: 
                     39: Opblock(rasgn,2,"<-")

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