1 files changed, 39 insertions, 3 deletions

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 8d82d22040..2890d89bc0 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -1400,6 +1400,13 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id,
 ///                   callbacks. The mark will only be used for the current
 ///                   redraw cycle, and not be permantently stored in the
 ///                   buffer.
+///               - right_gravity : boolean that indicates the direction
+///                   the extmark will be shifted in when new text is inserted
+///                   (true for right, false for left).  defaults to true.
+///               - end_right_gravity : boolean that indicates the direction
+///                   the extmark end position (if it exists) will be shifted
+///                   in when new text is inserted (true for right, false
+///                   for left). Defaults to false.
 /// @param[out]  err   Error details, if any
 /// @return Id of the created/updated extmark
 Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id,
@@ -1440,6 +1447,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id,
   DecorPriority priority = DECOR_PRIORITY_BASE;
   colnr_T col2 = 0;
   VirtText virt_text = KV_INITIAL_VALUE;
+  bool right_gravity = true;
+  bool end_right_gravity = false;
+  bool end_gravity_set = false;
+
   for (size_t i = 0; i < opts.size; i++) {
     String k = opts.items[i].key;
     Object *v = &opts.items[i].value;
@@ -1522,12 +1533,35 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id,
         goto error;
       }
       priority = (DecorPriority)v->data.integer;
+    } else if (strequal("right_gravity", k.data)) {
+      if (v->type != kObjectTypeBoolean) {
+        api_set_error(err, kErrorTypeValidation,
+                      "right_gravity must be a boolean");
+        goto error;
+      }
+      right_gravity = v->data.boolean;
+    } else if (strequal("end_right_gravity", k.data)) {
+      if (v->type != kObjectTypeBoolean) {
+        api_set_error(err, kErrorTypeValidation,
+                      "end_right_gravity must be a boolean");
+        goto error;
+      }
+      end_right_gravity = v->data.boolean;
+      end_gravity_set = true;
     } else {
       api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
       goto error;
     }
   }
 
+  // Only error out if they try to set end_right_gravity without
+  // setting end_col or end_line
+  if (line2 == -1 && col2 == 0 && end_gravity_set) {
+    api_set_error(err, kErrorTypeValidation,
+                  "cannot set end_right_gravity "
+                  "without setting end_line or end_col");
+  }
+
   if (col2 >= 0) {
     if (line2 >= 0 && line2 < buf->b_ml.ml_line_count) {
       len = STRLEN(ml_get_buf(buf, (linenr_T)line2 + 1, false));
@@ -1572,7 +1606,8 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id,
     }
 
     id = extmark_set(buf, (uint64_t)ns_id, id, (int)line, (colnr_T)col,
-                     line2, col2, decor, kExtmarkNoUndo);
+                     line2, col2, decor, right_gravity,
+                     end_right_gravity, kExtmarkNoUndo);
   }
 
   return (Integer)id;
@@ -1687,7 +1722,7 @@ Integer nvim_buf_add_highlight(Buffer buffer,
   extmark_set(buf, ns_id, 0,
               (int)line, (colnr_T)col_start,
               end_line, (colnr_T)col_end,
-              decor_hl(hl_id), kExtmarkNoUndo);
+              decor_hl(hl_id), true, false, kExtmarkNoUndo);
   return src_id;
 }
 
@@ -1796,7 +1831,8 @@ Integer nvim_buf_set_virtual_text(Buffer buffer,
   Decoration *decor = xcalloc(1, sizeof(*decor));
   decor->virt_text = virt_text;
 
-  extmark_set(buf, ns_id, 0, (int)line, 0, -1, -1, decor, kExtmarkNoUndo);
+  extmark_set(buf, ns_id, 0, (int)line, 0, -1, -1, decor, true,
+              false, kExtmarkNoUndo);
   return src_id;
 }