Perl__invlist_union_maybe_complement_2nd(pTHX_ SV* const a, SV* const b,
const bool complement_b, SV** output)
{
- /* Take the union of two inversion lists and point 'output. to it. *output
- * SHOULD BE DEFINED upon input, and if it points to one of the two lists,
- * the reference count to that list will be decremented if not already a
- * temporary (mortal); otherwise just its contents will be modified to be
- * the union. The first list, 'a., may be NULL, in which case a copy of
- * the second list is returned. If 'complement_b. is TRUE, the union is
- * taken of the complement (inversion) of 'b. instead of b itself.
+ /* Take the union of two inversion lists and point '*output' to it. On
+ * input, '*output' MUST POINT TO NULL OR TO AN SV* INVERSION LIST (possibly
+ * even 'a' or 'b'). If to an inversion list, the contents of the original
+ * list will be replaced by the union. The first list, 'a', may be
+ * NULL, in which case a copy of the second list is placed in '*output'.
+ * If 'complement_b' is TRUE, the union is taken of the complement
+ * (inversion) of 'b' instead of b itself.
*
* The basis for this comes from "Unicode Demystified" Chapter 13 by
* Richard Gillam, published by Addison-Wesley, and explained at some
PERL_ARGS_ASSERT__INVLIST_UNION_MAYBE_COMPLEMENT_2ND;
assert(a != b);
+ assert(*output == NULL || SvTYPE(*output) == SVt_INVLIST);
len_b = _invlist_len(b);
if (len_b == 0) {
if (*output == NULL) { /* If the output didn't exist, just point it
at the new list */
*output = everything;
- return;
+ }
+ else { /* Otherwise, replace its contents with the new list */
+ invlist_replace_list_destroys_src(*output, everything);
+ SvREFCNT_dec_NN(everything);
}
- /* Otherwise, replace its contents with the new list */
- invlist_replace_list_destroys_src(*output, everything);
- SvREFCNT_dec_NN(everything);
return;
}
* the union will come entirely from 'a'. If 'a' is NULL or empty, the
* output will be empty */
- if (a == NULL) {
- *output = _new_invlist(0);
+ if (a == NULL || _invlist_len(a) == 0) {
+ if (*output == NULL) {
+ *output = _new_invlist(0);
+ }
+ else {
+ invlist_clear(*output);
+ }
return;
}
- if (_invlist_len(a) == 0) {
- invlist_clear(*output);
+ /* Here, 'a' is not empty, but 'b' is, so 'a' entirely determines the
+ * union. We can just return a copy of 'a' if '*output' doesn't point
+ * to an existing list */
+ if (*output == NULL) {
+ *output = invlist_clone(a);
return;
}
- /* Here, 'a' is not empty, and entirely determines the union. If the
- * output is not to overwrite 'b', we can just return 'a'. */
- if (*output != b) {
-
- /* If the output is to overwrite 'a', we have a no-op, as it's
- * already in 'a' */
- if (*output == a) {
- return;
- }
-
- /* But otherwise we have to copy 'a' to the output */
- *output = invlist_clone(a);
+ /* If the output is to overwrite 'a', we have a no-op, as it's
+ * already in 'a' */
+ if (*output == a) {
return;
}
- /* Here, 'b' is to be overwritten by the output, which will be 'a' */
+ /* Here, '*output' is to be overwritten by 'a' */
u = invlist_clone(a);
invlist_replace_list_destroys_src(*output, u);
SvREFCNT_dec_NN(u);
if (a == NULL || ((len_a = _invlist_len(a)) == 0)) {
/* Here, 'a' is empty (and b is not). That means the union will come
- * entirely from 'b'. If the output is not to overwrite 'a', we can
- * just return what's in 'b'. */
- if (*output != a) {
-
- /* If the output is to overwrite 'b', it's already in 'b', but
- * otherwise we have to copy 'b' to the output */
- if (*output != b) {
- *output = invlist_clone(b);
- }
-
- /* And if the output is to be the inversion of 'b', do that */
- if (complement_b) {
- _invlist_invert(*output);
- }
+ * entirely from 'b'. If '*output' is NULL, we can directly return a
+ * clone of 'b'. Otherwise, we replace the contents of '*output' with
+ * the clone */
- return;
+ SV ** dest = (*output == NULL) ? output : &u;
+ *dest = invlist_clone(b);
+ if (complement_b) {
+ _invlist_invert(*dest);
}
- /* Here, 'a', which is empty or even NULL, is to be overwritten by the
- * output, which will either be 'b' or the complement of 'b' */
-
- if (a == NULL) {
- *output = invlist_clone(b);
- }
- else {
- u = invlist_clone(b);
+ if (dest == &u) {
invlist_replace_list_destroys_src(*output, u);
SvREFCNT_dec_NN(u);
- }
-
- if (complement_b) {
- _invlist_invert(*output);
}
return;
array_u = invlist_array(u);
}
- /* If the output is not to overwrite either of the inputs, just return the
- * calculated union */
- if (a != *output && b != *output) {
+ if (*output == NULL) { /* Simply return the new inversion list */
*output = u;
}
else {
- /* Here, the output is to be the same as one of the input scalars,
- * hence replacing it. The simple thing to do is to free the input
- * scalar, making it instead be the output one. But experience has
- * shown [perl #127392] that if the input is a mortal, we can get a
- * huge build-up of these during regex compilation before they get
- * freed. So for that case, replace just the input's interior with
- * the union's, and then free the union */
-
- assert(! invlist_is_iterating(*output));
-
- if (! SvTEMP(*output)) {
- SvREFCNT_dec_NN(*output);
- *output = u;
- }
- else {
- invlist_replace_list_destroys_src(*output, u);
- SvREFCNT_dec_NN(u);
- }
+ /* Otherwise, overwrite the inversion list that was in '*output'. We
+ * could instead free '*output', and then set it to 'u', but experience
+ * has shown [perl #127392] that if the input is a mortal, we can get a
+ * huge build-up of these during regex compilation before they get
+ * freed. */
+ invlist_replace_list_destroys_src(*output, u);
+ SvREFCNT_dec_NN(u);
}
return;
Perl__invlist_intersection_maybe_complement_2nd(pTHX_ SV* const a, SV* const b,
const bool complement_b, SV** i)
{
- /* Take the intersection of two inversion lists and point 'i' to it. *i
- * SHOULD BE DEFINED upon input, and if it points to one of the two lists,
- * the reference count to that list will be decremented if not already a
- * temporary (mortal); otherwise just its contents will be modified to be
- * the intersection. The first list, 'a', may be NULL, in which case an
- * empty list is returned. If 'complement_b' is TRUE, the result will be
- * the intersection of 'a' and the complement (or inversion) of 'b' instead
- * of 'b' directly.
+ /* Take the intersection of two inversion lists and point '*i' to it. On
+ * input, '*i' MUST POINT TO NULL OR TO AN SV* INVERSION LIST (possibly
+ * even 'a' or 'b'). If to an inversion list, the contents of the original
+ * list will be replaced by the intersection. The first list, 'a', may be
+ * NULL, in which case '*i' will be an empty list. If 'complement_b' is
+ * TRUE, the result will be the intersection of 'a' and the complement (or
+ * inversion) of 'b' instead of 'b' directly.
*
* The basis for this comes from "Unicode Demystified" Chapter 13 by
* Richard Gillam, published by Addison-Wesley, and explained at some
PERL_ARGS_ASSERT__INVLIST_INTERSECTION_MAYBE_COMPLEMENT_2ND;
assert(a != b);
+ assert(*i == NULL || SvTYPE(*i) == SVt_INVLIST);
/* Special case if either one is empty */
len_a = (a == NULL) ? 0 : _invlist_len(a);
return;
}
- /* If not overwriting either input, just make a copy of 'a' */
- if (*i != b) {
+ if (*i == NULL) {
*i = invlist_clone(a);
return;
}
- /* Here we are overwriting 'b' with 'a's contents */
r = invlist_clone(a);
invlist_replace_list_destroys_src(*i, r);
SvREFCNT_dec_NN(r);
array_r = invlist_array(r);
}
- /* Finish outputting any remaining */
- if (count >= 2) { /* At most one will have a non-zero copy count */
- IV copy_count;
- if ((copy_count = len_a - i_a) > 0) {
- Copy(array_a + i_a, array_r + i_r, copy_count, UV);
- }
- else if ((copy_count = len_b - i_b) > 0) {
- Copy(array_b + i_b, array_r + i_r, copy_count, UV);
- }
- }
-
- /* If the output is not to overwrite either of the inputs, just return the
- * calculated intersection */
- if (a != *i && b != *i) {
+ if (*i == NULL) { /* Simply return the calculated intersection */
*i = r;
}
- else {
- /* Here, the output is to be the same as one of the input scalars,
- * hence replacing it. The simple thing to do is to free the input
- * scalar, making it instead be the output one. But experience has
- * shown [perl #127392] that if the input is a mortal, we can get a
- * huge build-up of these during regex compilation before they get
- * freed. So for that case, replace just the input's interior with
- * the output's, and then free the output. A short-cut in this case
- * is if the output is empty, we can just set the input to be empty */
-
- assert(! invlist_is_iterating(*i));
-
- if (! SvTEMP(*i)) {
- SvREFCNT_dec_NN(*i);
- *i = r;
+ else { /* Otherwise, replace the existing inversion list in '*i'. We could
+ instead free '*i', and then set it to 'r', but experience has
+ shown [perl #127392] that if the input is a mortal, we can get a
+ huge build-up of these during regex compilation before they get
+ freed. */
+ if (len_r) {
+ invlist_replace_list_destroys_src(*i, r);
}
else {
- if (len_r) {
- invlist_replace_list_destroys_src(*i, r);
- }
- else {
- invlist_clear(*i);
- }
- SvREFCNT_dec_NN(r);
+ invlist_clear(*i);
}
+ SvREFCNT_dec_NN(r);
}
return;
{
SV* i = NULL;
SV* u = NULL;
- SV* element;
_invlist_union(lhs, rhs, &u);
_invlist_intersection(lhs, rhs, &i);
- /* _invlist_subtract will overwrite rhs
- without freeing what it already contains */
- element = rhs;
_invlist_subtract(u, i, &rhs);
SvREFCNT_dec_NN(i);
SvREFCNT_dec_NN(u);
- SvREFCNT_dec_NN(element);
break;
}
}
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