| 581 |
|
|
| 582 |
|
|
| 583 |
|
EPNODE * |
| 584 |
< |
getE1(void) /* E1 -> E1 ADDOP E2 */ |
| 584 |
> |
getE1(void) /* E1 -> E1 ADDOP E2 */ |
| 585 |
|
/* E2 */ |
| 586 |
|
{ |
| 587 |
|
register EPNODE *ep1, *ep2; |
| 603 |
|
|
| 604 |
|
|
| 605 |
|
EPNODE * |
| 606 |
< |
getE2(void) /* E2 -> E2 MULOP E3 */ |
| 606 |
> |
getE2(void) /* E2 -> E2 MULOP E3 */ |
| 607 |
|
/* E3 */ |
| 608 |
|
{ |
| 609 |
|
register EPNODE *ep1, *ep2; |
| 615 |
|
scan(); |
| 616 |
|
addekid(ep2, ep1); |
| 617 |
|
addekid(ep2, getE3()); |
| 618 |
< |
if (esupport&E_RCONST && |
| 619 |
< |
ep1->type == NUM && ep1->sibling->type == NUM) |
| 620 |
< |
ep2 = rconst(ep2); |
| 618 |
> |
if (esupport&E_RCONST) { |
| 619 |
> |
EPNODE *ep3 = ep1->sibling; |
| 620 |
> |
if (ep1->type == NUM && ep3->type == NUM) { |
| 621 |
> |
ep2 = rconst(ep2); |
| 622 |
> |
} else if (ep3->type == NUM && ep3->v.num == 0) { |
| 623 |
> |
if (ep2->type == '/') |
| 624 |
> |
syntax("divide by zero constant"); |
| 625 |
> |
ep1->sibling = NULL; /* (E2 * 0) */ |
| 626 |
> |
epfree(ep2); |
| 627 |
> |
ep2 = ep3; |
| 628 |
> |
} else if (ep1->type == NUM && ep1->v.num == 0) { |
| 629 |
> |
epfree(ep3); /* (0 * E3) or (0 / E3) */ |
| 630 |
> |
ep1->sibling = NULL; |
| 631 |
> |
efree((char *)ep2); |
| 632 |
> |
ep2 = ep1; |
| 633 |
> |
} |
| 634 |
> |
} |
| 635 |
|
ep1 = ep2; |
| 636 |
|
} |
| 637 |
|
return(ep1); |
| 639 |
|
|
| 640 |
|
|
| 641 |
|
EPNODE * |
| 642 |
< |
getE3(void) /* E3 -> E4 ^ E3 */ |
| 642 |
> |
getE3(void) /* E3 -> E4 ^ E3 */ |
| 643 |
|
/* E4 */ |
| 644 |
|
{ |
| 645 |
< |
register EPNODE *ep1, *ep2; |
| 645 |
> |
register EPNODE *ep1, *ep2; |
| 646 |
|
|
| 647 |
< |
ep1 = getE4(); |
| 648 |
< |
if (nextc == '^') { |
| 647 |
> |
ep1 = getE4(); |
| 648 |
> |
if (nextc != '^') |
| 649 |
> |
return(ep1); |
| 650 |
|
ep2 = newnode(); |
| 651 |
|
ep2->type = nextc; |
| 652 |
|
scan(); |
| 653 |
|
addekid(ep2, ep1); |
| 654 |
|
addekid(ep2, getE3()); |
| 655 |
< |
if (esupport&E_RCONST && |
| 656 |
< |
ep1->type == NUM && ep1->sibling->type == NUM) |
| 657 |
< |
ep2 = rconst(ep2); |
| 655 |
> |
if (esupport&E_RCONST) { |
| 656 |
> |
EPNODE *ep3 = ep1->sibling; |
| 657 |
> |
if (ep1->type == NUM && ep3->type == NUM) { |
| 658 |
> |
ep2 = rconst(ep2); |
| 659 |
> |
} else if (ep1->type == NUM && ep1->v.num == 0) { |
| 660 |
> |
epfree(ep3); /* (0 ^ E3) */ |
| 661 |
> |
ep1->sibling = NULL; |
| 662 |
> |
efree((char *)ep2); |
| 663 |
> |
ep2 = ep1; |
| 664 |
> |
} else if ((ep3->type == NUM && ep3->v.num == 0) || |
| 665 |
> |
(ep1->type == NUM && ep1->v.num == 1)) { |
| 666 |
> |
epfree(ep2); /* (E4 ^ 0) or (1 ^ E3) */ |
| 667 |
> |
ep2 = newnode(); |
| 668 |
> |
ep2->type = NUM; |
| 669 |
> |
ep2->v.num = 1; |
| 670 |
> |
} |
| 671 |
> |
} |
| 672 |
|
return(ep2); |
| 644 |
– |
} |
| 645 |
– |
return(ep1); |
| 673 |
|
} |
| 674 |
|
|
| 675 |
|
|
| 676 |
|
EPNODE * |
| 677 |
< |
getE4(void) /* E4 -> ADDOP E5 */ |
| 677 |
> |
getE4(void) /* E4 -> ADDOP E5 */ |
| 678 |
|
/* E5 */ |
| 679 |
|
{ |
| 680 |
|
register EPNODE *ep1, *ep2; |