Mercurial > hg > ucx / file diff

--- 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;
+}