feat: place cursor at first tab stop on snippet preview

Author: Saghen

lua/blink/cmp/accept/preview.lua

@@ -3,20 +3,30 @@ local function preview(item, previous_text_edit)
   local text_edits_lib = require('blink.cmp.accept.text-edits')
   local text_edit = text_edits_lib.get_from_item(item)
 
+  -- with auto_insert, we may have to undo the previous preview
+  if previous_text_edit ~= nil then text_edit.range = text_edits_lib.get_undo_text_edit_range(previous_text_edit) end
+
   -- for snippets, expand them with the default property names
+  local cursor_pos = {
+    text_edit.range.start.line + 1,
+    text_edit.range.start.character + #text_edit.newText,
+  }
   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
 
-  if previous_text_edit ~= nil then text_edit.range = text_edits_lib.get_undo_text_edit_range(previous_text_edit) end
+    -- place the cursor at the first tab stop
+    local tabstops = require('blink.cmp.sources.snippets.utils').get_tab_stops(text_edit.newText)
+    if tabstops and #tabstops > 0 then
+      cursor_pos[1] = text_edit.range.start.line + tabstops[1].line
+      cursor_pos[2] = text_edit.range.start.character + tabstops[1].character
+    end
+  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,
-  })
+  vim.api.nvim_win_set_cursor(0, cursor_pos)
 
+  -- return so that it can be undone in the future
   return text_edit
 end
 

lua/blink/cmp/sources/snippets/utils.lua

@@ -58,4 +58,27 @@ function utils.read_snippet(snippet, fallback)
   return snippets
 end
 
+function utils.get_tab_stops(snippet)
+  local expanded_snippet = require('blink.cmp.sources.snippets.utils').safe_parse(snippet)
+  if not expanded_snippet then return end
+
+  local tabstops = {}
+  local grammar = require('vim.lsp._snippet_grammar')
+  local line = 1
+  local character = 1
+  for _, child in ipairs(expanded_snippet.data.children) do
+    local lines = tostring(child) == '' and {} or vim.split(tostring(child), '\n')
+    line = line + math.max(#lines - 1, 0)
+    character = #lines == 0 and character or #lines > 1 and #lines[#lines] or (character + #lines[#lines])
+    vim.print('Line: ' .. line .. ' Character: ' .. character)
+    if child.type == grammar.NodeType.Placeholder or child.type == grammar.NodeType.Tabstop then
+      vim.print(child)
+      table.insert(tabstops, { index = child.data.tabstop, line = line, character = character })
+    end
+  end
+
+  table.sort(tabstops, function(a, b) return a.index < b.index end)
+  return tabstops
+end
+
 return utils