feat(decorations): allow more than one stacked highlight in a virt_text

3 files changed, 44 insertions, 14 deletions

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 78e36e5ef0..47216996b4 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -1433,8 +1433,14 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id,
 ///               - hl_group : name of the highlight group used to highlight
 ///                   this mark.
 ///               - virt_text : virtual text to link to this mark.
-///               - virt_text_pos : positioning of virtual text. Possible
-///                                 values:
+///                   A list of [text, highlight] tuples, each representing a
+///                   text chunk with specified highlight. `highlight` element
+///                   can either be a a single highlight group, or an array of
+///                   multiple highlight groups that will be stacked
+///                   (highest priority last). A highlight group can be supplied
+///                   either as a string or as an integer, the latter which
+///                   can be obtained using |nvim_get_hl_id_by_name|.
+///               - virt_text_pos : position of virtual text. Possible values:
 ///                 - "eol": right after eol character (default)
 ///                 - "overlay": display over the specified column, without
 ///                              shifting the underlying text.
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 9f2e94f31e..e78bd2ea9a 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -1603,22 +1603,38 @@ VirtText parse_virt_text(Array chunks, Error *err)
     Array chunk = chunks.items[i].data.array;
     if (chunk.size == 0 || chunk.size > 2
         || chunk.items[0].type != kObjectTypeString
-        || (chunk.size == 2 && chunk.items[1].type != kObjectTypeString)) {
+        || chunk.size > 2) {
       api_set_error(err, kErrorTypeValidation,
                     "Chunk is not an array with one or two strings");
       goto free_exit;
     }
 
     String str = chunk.items[0].data.string;
-    char *text = transstr(str.size > 0 ? str.data : "");  // allocates
 
     int hl_id = 0;
     if (chunk.size == 2) {
-      String hl = chunk.items[1].data.string;
-      if (hl.size > 0) {
-        hl_id = syn_check_group((char_u *)hl.data, (int)hl.size);
+      Object hl = chunk.items[1];
+      if (hl.type == kObjectTypeArray) {
+        Array arr = hl.data.array;
+        for (size_t j = 0; j < arr.size; j++) {
+          hl_id = object_to_hl_id(arr.items[j], "virt_text highlight", err);
+          if (ERROR_SET(err)) {
+            goto free_exit;
+          }
+          if (j < arr.size-1) {
+            kv_push(virt_text, ((VirtTextChunk){ .text = NULL,
+                                                 .hl_id = hl_id }));
+          }
+        }
+      } else {
+        hl_id = object_to_hl_id(hl, "virt_text highlight", err);
+        if (ERROR_SET(err)) {
+          goto free_exit;
+        }
       }
     }
+
+    char *text = transstr(str.size > 0 ? str.data : "");  // allocates
     kv_push(virt_text, ((VirtTextChunk){ .text = text, .hl_id = hl_id }));
   }
 
@@ -1656,7 +1672,7 @@ int object_to_hl_id(Object obj, const char *what, Error *err)
     String str = obj.data.string;
     return str.size ? syn_check_group((char_u *)str.data, (int)str.size) : 0;
   } else if (obj.type == kObjectTypeInteger) {
-    return (int)obj.data.integer;
+    return MAX((int)obj.data.integer, 0);
   } else {
     api_set_error(err, kErrorTypeValidation,
                   "%s is not a valid highlight", what);
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index ae785132bb..586aeff1e2 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -4021,6 +4021,7 @@ static int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow,
 
         while (wp->w_p_rl ? col >= 0 : col < grid->Columns) {
           int cells = -1;
+          // TODO: integrate this whith the other virt_text impl already
           if (do_virttext && !delay_virttext) {
             if (*s.p == NUL) {
               if (virt_pos < virt_text.size) {
@@ -4424,14 +4425,21 @@ void draw_virt_text(buf_T *buf, int col_off, int *end_col, int max_col)
 
       while (col < max_col) {
         if (!*s.p) {
-          if (virt_pos == kv_size(vt)) {
+          if (virt_pos >= kv_size(vt)) {
+            break;
+          }
+          virt_attr = 0;
+          do {
+            s.p = kv_A(vt, virt_pos).text;
+            int hl_id = kv_A(vt, virt_pos).hl_id;
+            virt_attr = hl_combine_attr(virt_attr,
+                                        hl_id > 0 ? syn_id2attr(hl_id) : 0);
+            virt_pos++;
+          } while (!s.p && virt_pos < kv_size(vt));
+          // TODO: y w0t m8
+          if (!s.p) {
             break;
           }
-          s.p = kv_A(vt, virt_pos).text;
-          int hl_id = kv_A(vt, virt_pos).hl_id;
-          virt_attr = hl_id > 0 ? syn_id2attr(hl_id) : 0;
-          virt_pos++;
-          continue;
         }
         int attr;
         bool through = false;