implement update_highlights using lua

neovim/api/buffer.py

@@ -112,6 +112,29 @@ def clear_highlight(self, src_id, line_start=0, line_end=-1, async_=None,
         self.request('nvim_buf_clear_highlight', src_id,
                      line_start, line_end, async_=async_)
 
+    def update_highlights(self, src_id, hls, clear_start=0, clear_end=-1,
+                          clear=False, async_=True):
+        """Add or update highlights in batch to avoid unnecessary redraws.
+
+        A `src_id` must have been allocated prior to use of this function. Use
+        for instance `nvim.new_highlight_source()` to get a src_id for your
+        plugin.
+
+        `hls` should be a list of highlight items. Each item should be a list
+        or tuple on the form `("GroupName", linenr, col_start, col_end)` or
+        `("GroupName", linenr)` to highlight an entire line.
+
+        By default existing highlights are preserved. Specify a line range with
+        clear_start and clear_end to replace highlights in this range. As a
+        shorthand, use clear=True to clear the entire buffer before adding the
+        new highlights.
+        """
+        if clear and clear_start is None:
+            clear_start = 0
+        lua = self._session._get_lua_private()
+        lua.update_highlights(self, src_id, hls, clear_start, clear_end,
+                              async_=async_)
+
     @property
     def name(self):
         """Get the buffer name."""

neovim/api/nvim.py

@@ -19,6 +19,29 @@
 
 os_chdir = os.chdir
 
+lua_module = """
+local a = vim.api
+local function update_highlights(buf, src_id, hls, clear_first, clear_end)
+  if clear_first ~= nil then
+      a.nvim_buf_clear_highlight(buf, src_id, clear_first, clear_end)
+  end
+  for _,hl in pairs(hls) do
+    local group, line, col_start, col_end = unpack(hl)
+    if col_start == nil then
+      col_start = 0
+    end
+    if col_end == nil then
+      col_end = -1
+    end
+    a.nvim_buf_add_highlight(buf, src_id, group, line, col_start, col_end)
+  end
+end
+
+local chid = ...
+local mod = {update_highlights=update_highlights}
+_G["_pynvim_"..chid] = mod
+"""
+
 
 class Nvim(object):
 
@@ -116,6 +139,12 @@ def _to_nvim(self, obj):
             return ExtType(*obj.code_data)
         return obj
 
+    def _get_lua_private(self):
+        if not getattr(self._session, "_has_lua", False):
+            self.exec_lua(lua_module, self.channel_id)
+            self._session._has_lua = True
+        return getattr(self.lua, "_pynvim_{}".format(self.channel_id))
+
     def request(self, name, *args, **kwargs):
         r"""Send an API request or notification to nvim.
 

neovim/compat.py

@@ -40,7 +40,7 @@ def find_module(fullname, path):
 
 
 def check_async(async_, kwargs, default):
-    """Return a value of 'async' in kwargs or default when async_ is None
+    """Return a value of 'async' in kwargs or default when async_ is None.
 
     This helper function exists for backward compatibility (See #274).
     It shows a warning message when 'async' in kwargs is used to note users.

test/test_buffer.py

@@ -179,3 +179,11 @@ def test_set_items_for_range():
     r = vim.current.buffer.range(1, 3)
     r[1:3] = ['foo']*3
     eq(vim.current.buffer[:], ['a', 'foo', 'foo', 'foo', 'd', 'e'])
+
+# NB: we can't easily test the effect of this. But at least run the lua
+# function sync, so we know it runs without runtime error with simple args.
+@with_setup(setup=cleanup)
+def test_update_highlights():
+    vim.current.buffer[:] = ['a', 'b', 'c']
+    src_id = vim.new_highlight_source()
+    vim.current.buffer.update_highlights(src_id, [["Comment", 0, 0, -1], ("String", 1, 0, 1)], clear=True, async_=False)