From ee7ac469c6f0f15a2d75991ef053a18d93e01756 Mon Sep 17 00:00:00 2001
From: Ashkan Kiani <ashkan.k.kiani@gmail.com>
Date: Fri, 20 Dec 2019 22:49:29 -0800
Subject: [PATCH] LSP: Use async completion for omnifunc. (#11578)

---
 runtime/lua/vim/lsp.lua           | 49 +++++++++++++------------------
 runtime/lua/vim/lsp/callbacks.lua |  5 ++--
 2 files changed, 23 insertions(+), 31 deletions(-)

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index 501cc6f670..0ecf57f50c 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -858,39 +858,30 @@ function lsp.omnifunc(findstart, base)
     end
   end
 
-  if findstart == 1 then
-    -- First, just return the current cursor column, we only really need that
-    return vim.fn.col('.')
-  else
-    -- Then, perform standard completion request
-    log.info("base ", base)
+  -- Then, perform standard completion request
+  local _ = log.info() and log.info("base ", base)
 
-    local pos = vim.api.nvim_win_get_cursor(0)
-    local line = vim.api.nvim_get_current_line()
-    local line_to_cursor = line:sub(1, pos[2])
-    local _ = log.trace() and log.trace("omnifunc.line", pos, line)
+  local pos = vim.api.nvim_win_get_cursor(0)
+  local line = vim.api.nvim_get_current_line()
+  local line_to_cursor = line:sub(1, pos[2])
+  local _ = log.trace() and log.trace("omnifunc.line", pos, line)
 
-    -- Get the start postion of the current keyword
-    local textMatch = vim.fn.match(line_to_cursor, '\\k*$')
-    local params = util.make_position_params()
+  -- Get the start postion of the current keyword
+  local textMatch = vim.fn.match(line_to_cursor, '\\k*$')
+  local params = util.make_position_params()
 
-    -- TODO handle timeout error differently? Like via an error?
-    local client_responses = lsp.buf_request_sync(bufnr, 'textDocument/completion', params) or {}
-    local matches = {}
-    for _, response in pairs(client_responses) do
-      -- TODO how to handle errors?
-      if not response.error then
-        local data = response.result
-        local completion_items = util.text_document_completion_list_to_complete_items(data or {})
-        local _ = log.trace() and log.trace("omnifunc.completion_items", completion_items)
-        vim.list_extend(matches, completion_items)
-      end
-    end
+  local items = {}
+  lsp.buf_request(bufnr, 'textDocument/completion', params, function(err, _, result)
+    if err or not result then return end
+    local matches = util.text_document_completion_list_to_complete_items(result)
+    -- TODO(ashkan): is this the best way to do this?
+    vim.list_extend(items, matches)
+    vim.fn.complete(textMatch+1, items)
+  end)
 
-    -- Instead of returning matches call complete instead
-    vim.fn.complete(textMatch+1, matches)
-    return {}
-  end
+  -- Return -2 to signal that we should continue completion so that we can
+  -- async complete.
+  return -2
 end
 
 function lsp.client_is_stopped(client_id)
diff --git a/runtime/lua/vim/lsp/callbacks.lua b/runtime/lua/vim/lsp/callbacks.lua
index a3cd521b86..794140ee2e 100644
--- a/runtime/lua/vim/lsp/callbacks.lua
+++ b/runtime/lua/vim/lsp/callbacks.lua
@@ -62,9 +62,10 @@ M['textDocument/completion'] = function(_, _, result)
   local row, col = unpack(api.nvim_win_get_cursor(0))
   local line = assert(api.nvim_buf_get_lines(0, row-1, row, false)[1])
   local line_to_cursor = line:sub(col+1)
+  local textMatch = vim.fn.match(line_to_cursor, '\\k*$')
 
-  local matches = util.text_document_completion_list_to_complete_items(result, line_to_cursor)
-  vim.fn.complete(col, matches)
+  local matches = util.text_document_completion_list_to_complete_items(result)
+  vim.fn.complete(textMatch+1, matches)
 end
 
 M['textDocument/hover'] = function(_, method, result)