shed biking: it's always extmarks, never marks extended

src/nvim/extmark_defs.h

@@ -0,0 +1,37 @@
+#ifndef NVIM_EXTMARK_DEFS_H
+#define NVIM_EXTMARK_DEFS_H
+
+#include "nvim/pos.h"  // for colnr_T
+#include "nvim/lib/kvec.h"
+
+typedef struct {
+  char *text;
+  int hl_id;
+} VirtTextChunk;
+
+typedef kvec_t(VirtTextChunk) VirtText;
+#define VIRTTEXT_EMPTY ((VirtText)KV_INITIAL_VALUE)
+
+typedef struct
+{
+  uint64_t ns_id;
+  uint64_t mark_id;
+  int hl_id;  // highlight group
+  // TODO(bfredl): virt_text is pretty larger than the rest,
+  // pointer indirection?
+  VirtText virt_text;
+} ExtmarkItem;
+
+typedef struct undo_object ExtmarkUndoObject;
+typedef kvec_t(ExtmarkUndoObject) extmark_undo_vec_t;
+
+// Undo/redo extmarks
+
+typedef enum {
+  kExtmarkNOOP,        // Extmarks shouldn't be moved
+  kExtmarkUndo,        // Operation should be reversable/undoable
+  kExtmarkNoUndo,      // Operation should not be reversable
+  kExtmarkUndoNoRedo,  // Operation should be undoable, but not redoable
+} ExtmarkOp;
+
+#endif  // NVIM_EXTMARK_DEFS_H