* infinity, then the first element of that range will be in the inversion list
* at a position that is divisible by two, and is the final element in the
* list.)
+ * Taking the complement (inverting) an inversion list is quite simple, if the
+ * first element is 0, remove it; otherwise add a 0 element at the beginning.
+ * This implementation reserves an element at the beginning of each inversion list
+ * to contain 0 when the list contains 0, and contains 1 otherwise. The actual
+ * beginning of the list is either that element if 0, or the next one if 1.
+ *
* More about inversion lists can be found in "Unicode Demystified"
* Chapter 13 by Richard Gillam, published by Addison-Wesley.
* More will be coming when functionality is added later.
#define INVLIST_LEN_OFFSET 0 /* Number of elements in the inversion list */
#define INVLIST_ITER_OFFSET 1 /* Current iteration position */
-#define HEADER_LENGTH (INVLIST_ITER_OFFSET + 1)
+#define INVLIST_ZERO_OFFSET 2 /* 0 or 1; must be last element in header */
+/* The UV at position ZERO contains either 0 or 1. If 0, the inversion list
+ * contains the code point U+00000, and begins here. If 1, the inversion list
+ * doesn't contain U+0000, and it begins at the next UV in the array.
+ * Inverting an inversion list consists of adding or removing the 0 at the
+ * beginning of it. By reserving a space for that 0, inversion can be made
+ * very fast */
+
+#define HEADER_LENGTH (INVLIST_ZERO_OFFSET + 1)
/* Internally things are UVs */
#define TO_INTERNAL_SIZE(x) ((x + HEADER_LENGTH) * sizeof(UV))
#define INVLIST_INITIAL_LEN 10
PERL_STATIC_INLINE UV*
+S__invlist_array_init(pTHX_ SV* const invlist, const bool will_have_0)
+{
+ /* Returns a pointer to the first element in the inversion list's array.
+ * This is called upon initialization of an inversion list. Where the
+ * array begins depends on whether the list has the code point U+0000
+ * in it or not. The other parameter tells it whether the code that
+ * follows this call is about to put a 0 in the inversion list or not.
+ * The first element is either the element with 0, if 0, or the next one,
+ * if 1 */
+
+ UV* zero = get_invlist_zero_addr(invlist);
+
+ PERL_ARGS_ASSERT__INVLIST_ARRAY_INIT;
+
+ /* Must be empty */
+ assert(! *get_invlist_len_addr(invlist));
+
+ /* 1^1 = 0; 1^0 = 1 */
+ *zero = 1 ^ will_have_0;
+ return zero + *zero;
+}
+
+PERL_STATIC_INLINE UV*
S_invlist_array(pTHX_ SV* const invlist)
{
/* Returns the pointer to the inversion list's array. Every time the
PERL_ARGS_ASSERT_INVLIST_ARRAY;
- return (UV *) (SvPVX(invlist) + TO_INTERNAL_SIZE(0));
+ /* Must not be empty */
+ assert(*get_invlist_len_addr(invlist));
+ assert(*get_invlist_zero_addr(invlist) == 0
+ || *get_invlist_zero_addr(invlist) == 1);
+
+ /* The array begins either at the element reserved for zero if the
+ * list contains 0 (that element will be set to 0), or otherwise the next
+ * element (in which case the reserved element will be set to 1). */
+ return (UV *) (get_invlist_zero_addr(invlist)
+ + *get_invlist_zero_addr(invlist));
}
PERL_STATIC_INLINE UV*
PERL_ARGS_ASSERT_INVLIST_SET_LEN;
- SvCUR_set(invlist, TO_INTERNAL_SIZE(len));
*get_invlist_len_addr(invlist) = len;
+
+ SvCUR_set(invlist, TO_INTERNAL_SIZE(len));
+ /* If the list contains U+0000, that element is part of the header,
+ * and should not be counted as part of the array. It will contain
+ * 0 in that case, and 1 otherwise. So we could flop 0=>1, 1=>0 and
+ * subtract:
+ * SvCUR_set(invlist,
+ * TO_INTERNAL_SIZE(len
+ * - (*get_invlist_zero_addr(inv_list) ^ 1)));
+ * But, this is only valid if len is not 0. The consequences of not doing
+ * this is that the memory allocation code may think that the 1 more UV
+ * is being used than actually is, and so might do an unnecessary grow.
+ * That seems worth not bothering to make this the precise amount */
}
PERL_STATIC_INLINE UV
return FROM_INTERNAL_SIZE(SvLEN(invlist));
}
+PERL_STATIC_INLINE UV*
+S_get_invlist_zero_addr(pTHX_ SV* invlist)
+{
+ /* Return the address of the UV that is reserved to hold 0 if the inversion
+ * list contains 0. This has to be the last element of the heading, as the
+ * list proper starts with either it if 0, or the next element if not.
+ * (But we force it to contain either 0 or 1) */
+
+ PERL_ARGS_ASSERT_GET_INVLIST_ZERO_ADDR;
+
+ return (UV *) (SvPVX(invlist) + (INVLIST_ZERO_OFFSET * sizeof (UV)));
+}
#ifndef PERL_IN_XSUB_RE
SV*
/* Force iterinit() to be used to get iteration to work */
*get_invlist_iter_addr(new_list) = UV_MAX;
+ /* This should force a segfault if a method doesn't initialize this
+ * properly */
+ *get_invlist_zero_addr(new_list) = UV_MAX;
+
return new_list;
}
#endif
* the end of the inversion list. The range must be above any existing
* ones. */
- UV* array = invlist_array(invlist);
+ UV* array;
UV max = invlist_max(invlist);
UV len = invlist_len(invlist);
PERL_ARGS_ASSERT__APPEND_RANGE_TO_INVLIST;
- if (len > 0) {
-
+ if (len == 0) { /* Empty lists must be initialized */
+ array = _invlist_array_init(invlist, start == 0);
+ }
+ else {
/* Here, the existing list is non-empty. The current max entry in the
* list is generally the first value not in the set, except when the
* set extends to the end of permissible values, in which case it is
* append out-of-order */
UV final_element = len - 1;
+ array = invlist_array(invlist);
if (array[final_element] > start
|| ELEMENT_IN_INVLIST_SET(final_element))
{
* moved */
if (max < len) {
invlist_extend(invlist, len);
+ invlist_set_len(invlist, len); /* Have to set len here to avoid assert
+ failure in invlist_array() */
array = invlist_array(invlist);
}
-
- invlist_set_len(invlist, len);
+ else {
+ invlist_set_len(invlist, len);
+ }
/* The next item on the list starts the range, the one after that is
* one past the new range. */
* return the larger of the input lists, but then outside code might need
* to keep track of whether to free the input list or not */
- UV* array_a = invlist_array(a); /* a's array */
- UV* array_b = invlist_array(b);
- UV len_a = invlist_len(a); /* length of a's array */
- UV len_b = invlist_len(b);
+ UV* array_a; /* a's array */
+ UV* array_b;
+ UV len_a; /* length of a's array */
+ UV len_b;
SV* u; /* the resulting union */
UV* array_u;
PERL_ARGS_ASSERT_INVLIST_UNION;
+ /* If either one is empty, the union is the other one */
+ len_a = invlist_len(a);
+ if (len_a == 0) {
+ if (output == &a) {
+ SvREFCNT_dec(a);
+ }
+ else if (output != &b) {
+ *output = invlist_clone(b);
+ }
+ /* else *output already = b; */
+ return;
+ }
+ else if ((len_b = invlist_len(b)) == 0) {
+ if (output == &b) {
+ SvREFCNT_dec(b);
+ }
+ else if (output != &a) {
+ *output = invlist_clone(a);
+ }
+ /* else *output already = a; */
+ return;
+ }
+
+ /* Here both lists exist and are non-empty */
+ array_a = invlist_array(a);
+ array_b = invlist_array(b);
+
/* Size the union for the worst case: that the sets are completely
* disjoint */
u = _new_invlist(len_a + len_b);
- array_u = invlist_array(u);
+
+ /* Will contain U+0000 if either component does */
+ array_u = _invlist_array_init(u, (len_a > 0 && array_a[0] == 0)
+ || (len_b > 0 && array_b[0] == 0));
/* Go through each list item by item, stopping when exhausted one of
* them */
* union above
*/
- UV* array_a = invlist_array(a); /* a's array */
- UV* array_b = invlist_array(b);
- UV len_a = invlist_len(a); /* length of a's array */
- UV len_b = invlist_len(b);
+ UV* array_a; /* a's array */
+ UV* array_b;
+ UV len_a; /* length of a's array */
+ UV len_b;
SV* r; /* the resulting intersection */
UV* array_r;
PERL_ARGS_ASSERT_INVLIST_INTERSECTION;
+ /* If either one is empty, the intersection is null */
+ len_a = invlist_len(a);
+ if ((len_a == 0) || ((len_b = invlist_len(b)) == 0)) {
+ *i = _new_invlist(0);
+
+ /* If the result is the same as one of the inputs, the input is being
+ * overwritten */
+ if (i == &a) {
+ SvREFCNT_dec(a);
+ }
+ else if (i == &b) {
+ SvREFCNT_dec(b);
+ }
+ return;
+ }
+
+ /* Here both lists exist and are non-empty */
+ array_a = invlist_array(a);
+ array_b = invlist_array(b);
+
/* Size the intersection for the worst case: that the intersection ends up
* fragmenting everything to be completely disjoint */
r= _new_invlist(len_a + len_b);
- array_r = invlist_array(r);
+
+ /* Will contain U+0000 iff both components do */
+ array_r = _invlist_array_init(r, len_a > 0 && array_a[0] == 0
+ && len_b > 0 && array_b[0] == 0);
/* Go through each list item by item, stopping when exhausted one of
* them */
#undef INVLIST_INITIAL_LENGTH
#undef TO_INTERNAL_SIZE
#undef FROM_INTERNAL_SIZE
+#undef INVLIST_LEN_OFFSET
+#undef INVLIST_ZERO_OFFSET
#undef INVLIST_ITER_OFFSET
/* End of inversion list object */
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