feat: more robust preview for auto_insert mode

closes #117

Author: Saghen

lua/blink/cmp/accept/init.lua

@@ -4,6 +4,11 @@ local brackets_lib = require('blink.cmp.accept.brackets')
 --- Applies a completion item to the current buffer
 --- @param item blink.cmp.CompletionItem
 local function accept(item)
+  -- create an undo point
+  if require('blink.cmp.config').accept.create_undo_point then
+    vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes('<C-g>u', true, true, true), 'n', true)
+  end
+
   item = vim.deepcopy(item)
   item.textEdit = text_edits_lib.get_from_item(item)
 

lua/blink/cmp/accept/preview.lua

@@ -0,0 +1,21 @@
+--- @param item blink.cmp.CompletionItem
+local function preview(item)
+  local text_edits_lib = require('blink.cmp.accept.text-edits')
+  local text_edit = text_edits_lib.get_from_item(item)
+
+  -- for snippets, expand them with the default property names
+  if item.insertTextFormat == vim.lsp.protocol.InsertTextFormat.Snippet then
+    local expanded_snippet = require('blink.cmp.sources.snippets.utils').safe_parse(text_edit.newText)
+    text_edit.newText = expanded_snippet and tostring(expanded_snippet) or text_edit.newText
+  end
+
+  text_edits_lib.apply_text_edits(item.client_id, { text_edit })
+  vim.api.nvim_win_set_cursor(0, {
+    text_edit.range.start.line + 1,
+    text_edit.range.start.character + #text_edit.newText,
+  })
+
+  return text_edit
+end
+
+return preview

lua/blink/cmp/accept/text-edits.lua

@@ -1,6 +1,8 @@
 local config = require('blink.cmp.config')
 local text_edits = {}
 
+--- @param item blink.cmp.CompletionItem
+--- @return lsp.TextEdit
 function text_edits.get_from_item(item)
   -- Adjust the position of the text edit to be the current cursor position
   -- since the data might be outdated. We compare the cursor column position
@@ -17,12 +19,28 @@ function text_edits.get_from_item(item)
   return text_edits.guess_text_edit(item)
 end
 
+--- @param client_id number
+--- @param edits lsp.TextEdit[]
 function text_edits.apply_text_edits(client_id, edits)
   local client = vim.lsp.get_client_by_id(client_id)
   local offset_encoding = client ~= nil and client.offset_encoding or 'utf-16'
   vim.lsp.util.apply_text_edits(edits, vim.api.nvim_get_current_buf(), offset_encoding)
 end
 
+--- @param text_edit lsp.TextEdit
+function text_edits.undo_text_edit(text_edit)
+  text_edit = vim.deepcopy(text_edit)
+  local lines = vim.split(text_edit.newText, '\n')
+  local range = text_edit.range
+
+  range['end'].line = range.start.line + #lines - 1
+  range['end'].character = lines[#lines] and #lines[#lines] or 0
+  text_edit.newText = ''
+
+  vim.lsp.util.apply_text_edits({ text_edit }, vim.api.nvim_get_current_buf(), 'utf-16')
+end
+
+--- @param item blink.cmp.CompletionItem
 function text_edits.apply_additional_text_edits(item)
   -- Apply additional text edits
   -- LSPs can either include these in the initial response or require a resolve
@@ -38,7 +56,8 @@ function text_edits.apply_additional_text_edits(item)
   end
 end
 
--- todo: doesnt work when the item contains characters not included in the context regex
+--- @param item blink.cmp.CompletionItem
+--- todo: doesnt work when the item contains characters not included in the context regex
 function text_edits.guess_text_edit(item)
   local word = item.textEditText or item.insertText or item.label
 

lua/blink/cmp/init.lua

@@ -142,12 +142,7 @@ cmp.accept = function()
   local item = cmp.windows.autocomplete.get_selected_item()
   if item == nil then return end
 
-  -- create an undo point
-  if require('blink.cmp.config').accept.create_undo_point then
-    vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes('<C-g>u', true, true, true), 'n', true)
-  end
-
-  vim.schedule(function() require('blink.cmp.accept')(item) end)
+  vim.schedule(function() cmp.windows.autocomplete.accept() end)
   return true
 end
 

lua/blink/cmp/windows/autocomplete.lua

@@ -158,39 +158,37 @@ function autocomplete.listen_on_position_update(callback)
   table.insert(autocomplete.event_targets.on_position_update, callback)
 end
 
----------- Selection ----------
+---------- Selection/Accept ----------
+
+function autocomplete.accept()
+  local selected_item = autocomplete.get_selected_item()
+  if selected_item == nil then return end
+
+  -- undo the preview if it exists
+  if autocomplete.preview_text_edit ~= nil and autocomplete.preview_context_id == autocomplete.context.id then
+    text_edits_lib.undo_text_edit(autocomplete.preview_text_edit)
+  end
+
+  -- apply
+  require('blink.cmp.accept')(selected_item)
+  return true
+end
 
 --- @param line number
 local function select(line)
-  local prev_selected_item = autocomplete.get_selected_item()
-
   autocomplete.set_has_selected(true)
   vim.api.nvim_win_set_cursor(autocomplete.win:get_win(), { line, 0 })
 
   local selected_item = autocomplete.get_selected_item()
 
   -- when auto_insert is enabled, we immediately apply the text edit
-  -- todo: move this to the accept module
   if config.windows.autocomplete.selection == 'auto_insert' and selected_item ~= nil then
     require('blink.cmp.trigger.completion').suppress_events_for_callback(function()
-      local text_edit = text_edits_lib.get_from_item(selected_item)
-
-      if selected_item.insertTextFormat == vim.lsp.protocol.InsertTextFormat.Snippet then
-        text_edit.newText = selected_item.label
-      end
-
-      if
-        prev_selected_item ~= nil and prev_selected_item.insertTextFormat == vim.lsp.protocol.InsertTextFormat.Snippet
-      then
-        local current_col = vim.api.nvim_win_get_cursor(0)[2]
-        text_edit.range.start.character = current_col - #prev_selected_item.label
+      if autocomplete.preview_text_edit ~= nil and autocomplete.preview_context_id == autocomplete.context.id then
+        text_edits_lib.undo_text_edit(autocomplete.preview_text_edit)
       end
-
-      text_edits_lib.apply_text_edits(selected_item.client_id, { text_edit })
-      vim.api.nvim_win_set_cursor(0, {
-        text_edit.range.start.line + 1,
-        text_edit.range.start.character + #text_edit.newText,
-      })
+      autocomplete.preview_text_edit = require('blink.cmp.accept.preview')(selected_item)
+      autocomplete.preview_context_id = autocomplete.context.id
     end)
   end