/* Compute the intersection of src_1 and src_2 and write the result to
* dst. It is allowed for dst to be equal to src_1. We assume that dst is a
* valid container. */
void array_run_container_intersection(const array_container_t *src_1,
const run_container_t *src_2,
array_container_t *dst) {
if (dst->capacity < src_1->cardinality)
array_container_grow(dst, src_1->cardinality, INT32_MAX, false);
if (src_2->n_runs == 0) {
return;
}
int32_t rlepos = 0;
int32_t arraypos = 0;
rle16_t rle = src_2->runs[rlepos];
int32_t newcard = 0;
while (arraypos < src_1->cardinality) {
const uint16_t arrayval = src_1->array[arraypos];
while (rle.value + rle.length <
arrayval) { // this will frequently be false
++rlepos;
if (rlepos == src_2->n_runs) {
dst->cardinality = newcard;
return; // we are done
}
rle = src_2->runs[rlepos];
}
if (rle.value > arrayval) {
arraypos = advanceUntil(src_1->array, arraypos, src_1->cardinality,
rle.value);
} else {
dst->array[newcard] = arrayval;
newcard++;
arraypos++;
}
}
dst->cardinality = newcard;
}
static int run_array_array_subtract(const run_container_t *r,
const array_container_t *a_in,
array_container_t *a_out) {
int out_card = 0;
int32_t in_array_pos =
-1; // since advanceUntil always assumes we start the search AFTER this
for (int rlepos = 0; rlepos < r->n_runs; rlepos++) {
int32_t start = r->runs[rlepos].value;
int32_t end = start + r->runs[rlepos].length + 1;
in_array_pos = advanceUntil(a_in->array, in_array_pos,
a_in->cardinality, (uint16_t)start);
if (in_array_pos >= a_in->cardinality) { // run has no items subtracted
for (int32_t i = start; i < end; ++i)
a_out->array[out_card++] = (uint16_t)i;
} else {
uint16_t next_nonincluded = a_in->array[in_array_pos];
if (next_nonincluded >= end) {
// another case when run goes unaltered
for (int32_t i = start; i < end; ++i)
a_out->array[out_card++] = (uint16_t)i;
in_array_pos--; // ensure we see this item again if necessary
} else {
for (int32_t i = start; i < end; ++i)
if (i != next_nonincluded)
a_out->array[out_card++] = (uint16_t)i;
else // 0 should ensure we don't match
next_nonincluded =
(in_array_pos + 1 >= a_in->cardinality)
? 0
: a_in->array[++in_array_pos];
in_array_pos--; // see again
}
}
}
return out_card;
}
