3 files changed, 126 insertions, 4 deletions

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 8f5718d97e..e6f8f73b9d 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -169,21 +169,21 @@ Boolean nvim_buf_attach(uint64_t channel_id,
         goto error;
       }
       cb.on_lines = v->data.luaref;
-      v->data.integer = LUA_NOREF;
+      v->data.luaref = LUA_NOREF;
     } else if (is_lua && strequal("on_changedtick", k.data)) {
       if (v->type != kObjectTypeLuaRef) {
         api_set_error(err, kErrorTypeValidation, "callback is not a function");
         goto error;
       }
       cb.on_changedtick = v->data.luaref;
-      v->data.integer = LUA_NOREF;
+      v->data.luaref = LUA_NOREF;
     } else if (is_lua && strequal("on_detach", k.data)) {
       if (v->type != kObjectTypeLuaRef) {
         api_set_error(err, kErrorTypeValidation, "callback is not a function");
         goto error;
       }
       cb.on_detach = v->data.luaref;
-      v->data.integer = LUA_NOREF;
+      v->data.luaref = LUA_NOREF;
     } else if (is_lua && strequal("utf_sizes", k.data)) {
       if (v->type != kObjectTypeBoolean) {
         api_set_error(err, kErrorTypeValidation, "utf_sizes must be boolean");
@@ -231,6 +231,90 @@ Boolean nvim_buf_detach(uint64_t channel_id,
   return true;
 }
 
+static void buf_clear_luahl(buf_T *buf, bool force)
+{
+  if (buf->b_luahl || force) {
+    executor_free_luaref(buf->b_luahl_start);
+    executor_free_luaref(buf->b_luahl_window);
+    executor_free_luaref(buf->b_luahl_line);
+    executor_free_luaref(buf->b_luahl_end);
+  }
+  buf->b_luahl_start = LUA_NOREF;
+  buf->b_luahl_window = LUA_NOREF;
+  buf->b_luahl_line = LUA_NOREF;
+  buf->b_luahl_end = LUA_NOREF;
+}
+
+/// Unstabilized interface for defining syntax hl in lua.
+///
+/// This is not yet safe for general use, lua callbacks will need to
+/// be restricted, like textlock and probably other stuff.
+///
+/// The API on_line/nvim__put_attr is quite raw and not intended to be the
+/// final shape. Ideally this should operate on chunks larger than a single
+/// line to reduce interpreter overhead, and generate annotation objects
+/// (bufhl/virttext) on the fly but using the same representation.
+void nvim__buf_set_luahl(uint64_t channel_id, Buffer buffer,
+                         DictionaryOf(LuaRef) opts, Error *err)
+  FUNC_API_LUA_ONLY
+{
+  buf_T *buf = find_buffer_by_handle(buffer, err);
+
+  if (!buf) {
+    return;
+  }
+
+  redraw_buf_later(buf, NOT_VALID);
+  buf_clear_luahl(buf, false);
+
+  for (size_t i = 0; i < opts.size; i++) {
+    String k = opts.items[i].key;
+    Object *v = &opts.items[i].value;
+    if (strequal("on_start", k.data)) {
+      if (v->type != kObjectTypeLuaRef) {
+        api_set_error(err, kErrorTypeValidation, "callback is not a function");
+        goto error;
+      }
+      buf->b_luahl_start = v->data.luaref;
+      v->data.luaref = LUA_NOREF;
+    } else if (strequal("on_window", k.data)) {
+      if (v->type != kObjectTypeLuaRef) {
+        api_set_error(err, kErrorTypeValidation, "callback is not a function");
+        goto error;
+      }
+      buf->b_luahl_window = v->data.luaref;
+      v->data.luaref = LUA_NOREF;
+    } else if (strequal("on_line", k.data)) {
+      if (v->type != kObjectTypeLuaRef) {
+        api_set_error(err, kErrorTypeValidation, "callback is not a function");
+        goto error;
+      }
+      buf->b_luahl_line = v->data.luaref;
+      v->data.luaref = LUA_NOREF;
+    } else {
+      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
+      goto error;
+    }
+  }
+  buf->b_luahl = true;
+  return;
+error:
+  buf_clear_luahl(buf, true);
+  buf->b_luahl = false;
+}
+
+void nvim__buf_redraw_range(Buffer buffer, Integer first, Integer last,
+                            Error *err)
+  FUNC_API_LUA_ONLY
+{
+  buf_T *buf = find_buffer_by_handle(buffer, err);
+  if (!buf) {
+    return;
+  }
+
+  redraw_buf_range_later(buf, (linenr_T)first+1, (linenr_T)last);
+}
+
 /// Sets a buffer line
 ///
 /// @deprecated use nvim_buf_set_lines instead.
@@ -1112,7 +1196,6 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start,
         return rv;
       }
       limit = v->data.integer;
-      v->data.integer = LUA_NOREF;
     } else {
       api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
       return rv;
diff --git a/src/nvim/api/private/helpers.h b/src/nvim/api/private/helpers.h
index 8930f252f6..048b937136 100644
--- a/src/nvim/api/private/helpers.h
+++ b/src/nvim/api/private/helpers.h
@@ -60,6 +60,12 @@
 #define ADD(array, item) \
   kv_push(array, item)
 
+#define FIXED_TEMP_ARRAY(name, fixsize) \
+  Array name = ARRAY_DICT_INIT; \
+  Object name##__items[fixsize]; \
+  args.size = fixsize; \
+  args.items = name##__items; \
+
 #define STATIC_CSTR_AS_STRING(s) ((String) {.data = s, .size = sizeof(s) - 1})
 
 /// Create a new String instance, putting data in allocated memory
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 19601b6539..2f59edee33 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -189,6 +189,15 @@ Dictionary nvim_get_hl_by_id(Integer hl_id, Boolean rgb, Error *err)
   return hl_get_attr_by_id(attrcode, rgb, err);
 }
 
+/// Gets a highlight group by name
+///
+/// similar to |hlID()|, but allocates a new ID if not present.
+Integer nvim_get_hl_id_by_name(String name)
+  FUNC_API_SINCE(7)
+{
+  return syn_check_group((const char_u *)name.data, (int)name.size);
+}
+
 /// Sends input-keys to Nvim, subject to various quirks controlled by `mode`
 /// flags. This is a blocking call, unlike |nvim_input()|.
 ///
@@ -2546,3 +2555,27 @@ Array nvim__inspect_cell(Integer grid, Integer row, Integer col, Error *err)
   }
   return ret;
 }
+
+/// Set attrs in nvim__buf_set_lua_hl callbacks
+///
+/// TODO(bfredl): This is rather pedestrian. The final
+/// interface should probably be derived from a reformed
+/// bufhl/virttext interface with full support for multi-line
+/// ranges etc
+void nvim__put_attr(Integer id, Integer c0, Integer c1)
+  FUNC_API_LUA_ONLY
+{
+  if (!lua_attr_active) {
+    return;
+  }
+  if (id == 0 || syn_get_final_id((int)id) == 0) {
+    return;
+  }
+  int attr = syn_id2attr((int)id);
+  c0 = MAX(c0, 0);
+  c1 = MIN(c1, (Integer)lua_attr_bufsize);
+  for (Integer c = c0; c < c1; c++) {
+    lua_attr_buf[c] = (sattr_T)hl_combine_attr(lua_attr_buf[c], (int)attr);
+  }
+  return;
+}