BLI_utildefines: re-ordering array delete macro

1 files changed, 39 insertions, 10 deletions

diff --git a/source/blender/blenlib/BLI_utildefines.h b/source/blender/blenlib/BLI_utildefines.h
index 65dcbf04913..5af97ebb411 100644
--- a/source/blender/blenlib/BLI_utildefines.h
+++ b/source/blender/blenlib/BLI_utildefines.h
@@ -373,19 +373,48 @@ extern "C" {
 #define UNPACK4_EX(pre, a, post)  UNPACK3_EX(pre, a, post), (pre((a)[3])post)
 
 /* array helpers */
-#define ARRAY_LAST_ITEM(arr_start, arr_dtype, tot) \
-	(arr_dtype *)((char *)(arr_start) + (sizeof(*((arr_dtype *)NULL)) * (size_t)(tot - 1)))
+#define ARRAY_LAST_ITEM(arr_start, arr_dtype, arr_len) \
+	(arr_dtype *)((char *)(arr_start) + (sizeof(*((arr_dtype *)NULL)) * (size_t)(arr_len - 1)))
 
-#define ARRAY_HAS_ITEM(arr_item, arr_start, tot)  ( \
+#define ARRAY_HAS_ITEM(arr_item, arr_start, arr_len)  ( \
 	CHECK_TYPE_PAIR_INLINE(arr_start, arr_item), \
-	((unsigned int)((arr_item) - (arr_start)) < (unsigned int)(tot)))
+	((unsigned int)((arr_item) - (arr_start)) < (unsigned int)(arr_len)))
+
+/**
+ * \note use faster #ARRAY_DELETE_REORDER_LAST when we can re-order.
+ */
+#define ARRAY_DELETE(arr, index, delete_len, arr_len) \
+	{ \
+		BLI_assert(((index) >= 0) && ((index) + delete_len <= arr_len));  \
+		memmove(&(arr)[index], \
+		        &(arr)[(index) + (delete_len)], \
+		         (((arr_len) - (index)) - (delete_len)) * sizeof(*(arr))); \
+	} ((void)0)
+
+/**
+ * Re-ordering array removal.
+ *
+ * When removing single items this compiles down to:
+ * `if (index + 1 != arr_len) { arr[index] = arr[arr_len - 1]; }` (typical reordering removal),
+ * with removing multiple items, overlap is detected to avoid memcpy errors.
+ */
+#define ARRAY_DELETE_REORDER_LAST(arr, index, delete_len, arr_len) \
+	{ \
+		BLI_assert(((index) >= 0) && ((index) + delete_len <= arr_len));  \
+		if ((index) + (delete_len) != (arr_len)) { \
+			if (((delete_len) == 1) || ((delete_len) <= ((arr_len) - ((index) + (delete_len))))) { \
+				memcpy(&(arr)[index], \
+				       &(arr)[(arr_len) - (delete_len)], \
+				       (delete_len) * sizeof(*(arr))); \
+			} \
+			else { \
+				memcpy(&(arr)[index], \
+				       &(arr)[(arr_len) - ((arr_len) - ((index) + (delete_len)))], \
+				       ((arr_len) - ((index) + (delete_len))) * sizeof(*(arr))); \
+			} \
+		} \
+	} ((void)0)
 
-#define ARRAY_DELETE(arr, index, tot_delete, tot)  { \
-		BLI_assert(index + tot_delete <= tot);  \
-		memmove(&(arr)[(index)], \
-		        &(arr)[(index) + (tot_delete)], \
-		         (((tot) - (index)) - (tot_delete)) * sizeof(*(arr))); \
-	} (void)0
 
 /* assuming a static array */
 #if defined(__GNUC__) && !defined(__cplusplus) && !defined(__clang__) && !defined(__INTEL_COMPILER)