Fix rendering of wide characters in the custom completion window (#641)

lua/cmp/entry.lua

@@ -198,27 +198,34 @@ entry.is_deprecated = function(self)
 end
 
 ---Return view information.
+---@param suggest_offset number
+---@param entries_buf number The buffer this entry will be rendered into.
 ---@return { abbr: { text: string, bytes: number, width: number, hl_group: string }, kind: { text: string, bytes: number, width: number, hl_group: string }, menu: { text: string, bytes: number, width: number, hl_group: string } }
-entry.get_view = function(self, suggest_offset)
+entry.get_view = function(self, suggest_offset, entries_buf)
   local item = self:get_vim_item(suggest_offset)
-  return self.cache:ensure({ 'get_view', self.resolved_completion_item and 1 or 0 }, function()
+  return self.cache:ensure({ 'get_view', self.resolved_completion_item and 1 or 0, entries_buf }, function()
     local view = {}
+    -- The result of vim.fn.strdisplaywidth depends on which buffer it was
+    -- called in because it reads the values of the option 'tabstop' when
+    -- rendering <Tab> characters.
+    vim.api.nvim_buf_call(entries_buf, function()
       view.abbr = {}
       view.abbr.text = item.abbr or ''
       view.abbr.bytes = #view.abbr.text
-    view.abbr.width = vim.str_utfindex(view.abbr.text)
+      view.abbr.width = vim.fn.strdisplaywidth(view.abbr.text)
       view.abbr.hl_group = self:is_deprecated() and 'CmpItemAbbrDeprecated' or 'CmpItemAbbr'
       view.kind = {}
       view.kind.text = item.kind or ''
       view.kind.bytes = #view.kind.text
-    view.kind.width = vim.str_utfindex(view.kind.text)
+      view.kind.width = vim.fn.strdisplaywidth(view.kind.text)
       view.kind.hl_group = 'CmpItemKind' .. types.lsp.CompletionItemKind[self:get_kind()]
       view.menu = {}
       view.menu.text = item.menu or ''
       view.menu.bytes = #view.menu.text
-    view.menu.width = vim.str_utfindex(view.menu.text)
+      view.menu.width = vim.fn.strdisplaywidth(view.menu.text)
       view.menu.hl_group = 'CmpItemMenu'
       view.dup = item.dup
+    end)
     return view
   end)
 end

lua/cmp/utils/buffer.lua

@@ -1,17 +1,30 @@
 local buffer = {}
 
-buffer.ensure = setmetatable({
-  cache = {},
-}, {
-  __call = function(self, name)
-    if not (self.cache[name] and vim.api.nvim_buf_is_valid(self.cache[name])) then
-      local buf = vim.api.nvim_create_buf(false, true)
+buffer.cache = {}
+
+---@return number buf
+buffer.get = function(name)
+  local buf = buffer.cache[name]
+  if buf and vim.api.nvim_buf_is_valid(buf) then
+    return buf
+  else
+    return nil
+  end
+end
+
+---@return number buf
+---@return boolean created_new
+buffer.ensure = function(name)
+  local created_new = false
+  local buf = buffer.get(name)
+  if not buf then
+    created_new = true
+    buf = vim.api.nvim_create_buf(false, true)
     vim.api.nvim_buf_set_option(buf, 'buftype', 'nofile')
     vim.api.nvim_buf_set_option(buf, 'bufhidden', 'hide')
-      self.cache[name] = buf
+    buffer.cache[name] = buf
+  end
+  return buf, created_new
 end
-    return self.cache[name]
-  end,
-})
 
 return buffer

lua/cmp/utils/window.lua

@@ -18,6 +18,7 @@ local api = require('cmp.utils.api')
 ---@field public swin2 number|nil
 ---@field public style cmp.WindowStyle
 ---@field public opt table<string, any>
+---@field public buffer_opt table<string, any>
 ---@field public cache cmp.Cache
 local window = {}
 
@@ -32,6 +33,7 @@ window.new = function()
   self.style = {}
   self.cache = cache.new()
   self.opt = {}
+  self.buffer_opt = {}
   return self
 end
 
@@ -54,6 +56,26 @@ window.option = function(self, key, value)
   end
 end
 
+---Set buffer option.
+---NOTE: If the buffer already visible, immediately applied to it.
+---@param key string
+---@param value any
+window.buffer_option = function(self, key, value)
+  if vim.fn.exists('+' .. key) == 0 then
+    return
+  end
+
+  if value == nil then
+    return self.buffer_opt[key]
+  end
+
+  self.buffer_opt[key] = value
+  local existing_buf = buffer.get(self.name)
+  if existing_buf then
+    vim.api.nvim_buf_set_option(existing_buf, key, value)
+  end
+end
+
 ---Set style.
 ---@param style cmp.WindowStyle
 window.set_style = function(self, style)
@@ -70,7 +92,13 @@ end
 ---Return buffer id.
 ---@return number
 window.get_buffer = function(self)
-  return buffer.ensure(self.name)
+  local buf, created_new = buffer.ensure(self.name)
+  if created_new then
+    for k, v in pairs(self.buffer_opt) do
+      vim.api.nvim_buf_set_option(buf, k, v)
+    end
+  end
+  return buf
 end
 
 ---Open window
@@ -89,7 +117,7 @@ window.open = function(self, style)
   else
     local s = misc.copy(self.style)
     s.noautocmd = true
-    self.win = vim.api.nvim_open_win(buffer.ensure(self.name), false, s)
+    self.win = vim.api.nvim_open_win(self:get_buffer(), false, s)
     for k, v in pairs(self.opt) do
       vim.api.nvim_win_set_option(self.win, k, v)
     end
@@ -251,9 +279,14 @@ window.get_content_height = function(self)
     vim.api.nvim_buf_get_changedtick(self:get_buffer()),
   }, function()
     local height = 0
-    for _, text in ipairs(vim.api.nvim_buf_get_lines(self:get_buffer(), 0, -1, false)) do
-      height = height + math.ceil(math.max(1, vim.str_utfindex(text)) / self.style.width)
+    local buf = self:get_buffer()
+    -- The result of vim.fn.strdisplaywidth depends on the buffer it was called
+    -- in (see comment in cmp.Entry.get_view).
+    vim.api.nvim_buf_call(buf, function()
+      for _, text in ipairs(vim.api.nvim_buf_get_lines(buf, 0, -1, false)) do
+        height = height + math.ceil(math.max(1, vim.fn.strdisplaywidth(text)) / self.style.width)
       end
+    end)
     return height
   end)
 end

lua/cmp/view/custom_entries_view.lua

@@ -32,6 +32,12 @@ custom_entries_view.new = function()
   self.entries_win:option('wrap', false)
   self.entries_win:option('scrolloff', 0)
   self.entries_win:option('winhighlight', 'Normal:Pmenu,FloatBorder:Pmenu,CursorLine:PmenuSel,Search:None')
+  -- This is done so that strdisplaywidth calculations for lines in the
+  -- custom_entries_view window exactly match with what is really displayed,
+  -- see comment in cmp.Entry.get_view. Setting tabstop to 1 makes all tabs be
+  -- always rendered one column wide, which removes the unpredictability coming
+  -- from variable width of the tab character.
+  self.entries_win:buffer_option('tabstop', 1)
   self.event = event.new()
   self.offset = -1
   self.active = false
@@ -48,7 +54,7 @@ custom_entries_view.new = function()
 
   vim.api.nvim_set_decoration_provider(custom_entries_view.ns, {
     on_win = function(_, win, buf, top, bot)
-      if win ~= self.entries_win.win then
+      if win ~= self.entries_win.win or buf ~= self.entries_win:get_buffer() then
         return
       end
 
@@ -56,7 +62,7 @@ custom_entries_view.new = function()
       for i = top, bot do
         local e = self.entries[i + 1]
         if e then
-          local v = e:get_view(self.offset)
+          local v = e:get_view(self.offset, buf)
           local o = SIDE_PADDING
           local a = 0
           for _, field in ipairs(fields) do
@@ -106,12 +112,13 @@ custom_entries_view.open = function(self, offset, entries)
   -- Apply window options (that might be changed) on the custom completion menu.
   self.entries_win:option('winblend', vim.o.pumblend)
 
+  local entries_buf = self.entries_win:get_buffer()
   local lines = {}
   local dedup = {}
   local preselect = 0
   local i = 1
   for _, e in ipairs(entries) do
-    local view = e:get_view(offset)
+    local view = e:get_view(offset, entries_buf)
     if view.dup == 1 or not dedup[e.completion_item.label] then
       dedup[e.completion_item.label] = true
       self.column_width.abbr = math.max(self.column_width.abbr, view.abbr.width)
@@ -125,7 +132,7 @@ custom_entries_view.open = function(self, offset, entries)
       i = i + 1
     end
   end
-  vim.api.nvim_buf_set_lines(self.entries_win:get_buffer(), 0, -1, false, lines)
+  vim.api.nvim_buf_set_lines(entries_buf, 0, -1, false, lines)
 
   local width = 0
   width = width + 1
@@ -193,10 +200,11 @@ custom_entries_view.draw = function(self)
   local botline = info.topline + info.height - 1
   local texts = {}
   local fields = config.get().formatting.fields
+  local entries_buf = self.entries_win:get_buffer()
   for i = topline, botline - 1 do
     local e = self.entries[i + 1]
     if e then
-      local view = e:get_view(self.offset)
+      local view = e:get_view(self.offset, entries_buf)
       local text = {}
       table.insert(text, string.rep(' ', SIDE_PADDING))
       for _, field in ipairs(fields) do
@@ -207,7 +215,7 @@ custom_entries_view.draw = function(self)
       table.insert(texts, table.concat(text, ''))
     end
   end
-  vim.api.nvim_buf_set_lines(self.entries_win:get_buffer(), topline, botline, false, texts)
+  vim.api.nvim_buf_set_lines(entries_buf, topline, botline, false, texts)
 
   if api.is_cmdline_mode() then
     vim.api.nvim_win_call(self.entries_win.win, function()