diff -r 0f4d90a1ae23 -r 9b2b40a3c9f0 src/list.c --- a/src/list.c Tue Nov 04 14:31:31 2025 +0100 +++ b/src/list.c Tue Nov 04 14:38:42 2025 +0100 @@ -932,3 +932,64 @@ return 0; } + +int cxListIntersection(CxList *dst, + const CxList *src, const CxList *other, + cx_clone_func clone_func, const CxAllocator *clone_allocator, void *data) { + if (clone_allocator == NULL) clone_allocator = cxDefaultAllocator; + + // optimize for sorted collections + if (cxCollectionSorted(src) && cxCollectionSorted(other)) { + bool dst_was_empty = cxCollectionSize(dst) == 0; + + CxIterator src_iter = cxListIterator(src); + CxIterator other_iter = cxListIterator(other); + while (cxIteratorValid(src_iter) && cxIteratorValid(other_iter)) { + void *src_elem = cxIteratorCurrent(src_iter); + void *other_elem = cxIteratorCurrent(other_iter); + int d = src->collection.cmpfunc(src_elem, other_elem); + if (d == 0) { + // is contained, clone it + void **dst_mem = cxListEmplace(dst); + void *target = cxCollectionStoresPointers(dst) ? NULL : dst_mem; + void* dst_ptr = clone_func(target, src_elem, clone_allocator, data); + if (dst_ptr == NULL) { + cx_list_pop_uninitialized_elements(dst, 1); + return 1; + } + if (cxCollectionStoresPointers(dst)) { + *dst_mem = dst_ptr; + } + cxIteratorNext(src_iter); + } else if (d < 0) { + // the other element is larger, skip the source element + cxIteratorNext(src_iter); + } else { + // the source element is larger, try to find it in the other list + cxIteratorNext(other_iter); + } + } + + // if dst was empty, it is now guaranteed to be sorted + dst->collection.sorted = dst_was_empty; + } else { + CxIterator src_iter = cxListIterator(src); + cx_foreach(void *, elem, src_iter) { + if (!cxListContains(other, elem)) { + continue; + } + void **dst_mem = cxListEmplace(dst); + void *target = cxCollectionStoresPointers(dst) ? NULL : dst_mem; + void* dst_ptr = clone_func(target, elem, clone_allocator, data); + if (dst_ptr == NULL) { + cx_list_pop_uninitialized_elements(dst, 1); + return 1; + } + if (cxCollectionStoresPointers(dst)) { + *dst_mem = dst_ptr; + } + } + } + + return 0; +}