Experimental: Ghost text (#119)

* Inline suggest experimental

* Fix flicker

* Fix ci fails

* Reduce flicker

* Improve menu functions

* Default false

* README.md

* Add require

* Rename inline_preview to ghost_text

lua/cmp/config/default.lua

@@ -61,6 +61,10 @@ return function()
       end
     },
 
+    experimental = {
+      ghost_text = false,
+    },
+
     sources = {},
   }
 end

lua/cmp/core.lua

@@ -1,5 +1,6 @@
 local debug = require('cmp.utils.debug')
 local char = require('cmp.utils.char')
+local str = require('cmp.utils.str')
 local pattern = require('cmp.utils.pattern')
 local async = require('cmp.utils.async')
 local keymap = require('cmp.utils.keymap')
@@ -18,6 +19,16 @@ core.SOURCE_TIMEOUT = 500
 ---Suspending state.
 core.suspending = false
 
+core.GHOST_TEXT_NS = vim.api.nvim_create_namespace('cmp:GHOST_TEXT');
+
+vim.api.nvim_set_decoration_provider(core.GHOST_TEXT_NS, {
+  on_win = function()
+    if config.get().experimental.ghost_text then
+      core.ghost_text(core.menu:get_first_entry())
+    end
+  end,
+})
+
 ---@type cmp.Menu
 core.menu = menu.new({
   on_select = function(e)
@@ -27,6 +38,43 @@ core.menu = menu.new({
   end,
 })
 
+---Show ghost text if possible
+---@param e cmp.Entry
+core.ghost_text = function(e)
+  if not e then
+    return
+  end
+
+  local ctx = context.new()
+  if ctx.cursor_after_line ~= '' then
+    return
+  end
+
+  local diff = ctx.cursor.col - e:get_offset()
+  local text = e:get_insert_text()
+  if e.completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
+    text = vim.lsp.util.parse_snippet(text)
+  end
+  text = string.sub(str.oneline(text), diff + 1)
+  if #text > 0 then
+    vim.api.nvim_buf_set_extmark(
+      ctx.bufnr,
+      core.GHOST_TEXT_NS,
+      ctx.cursor.row - 1,
+      ctx.cursor.col - 1,
+      {
+        right_gravity = true,
+        virt_text = { { text, 'Comment' } },
+        virt_text_pos = 'overlay',
+        virt_text_win_col = ctx.cursor.col - 1,
+        hl_mode = 'blend',
+        priority = 0,
+        ephemeral = true,
+      }
+    )
+  end
+end
+
 ---@type table<number, cmp.Source>
 core.sources = {}
 

lua/cmp/menu.lua

@@ -193,58 +193,39 @@ end
 ---Geta current active entry
 ---@return cmp.Entry|nil
 menu.get_active_entry = function(self)
-  local completed_item = vim.v.completed_item or {}
-  if vim.fn.pumvisible() == 0 or not completed_item.user_data then
+  if vim.fn.pumvisible() == 0 or not (vim.v.completed_item or {}).user_data then
     return nil
   end
-
-  local id = completed_item.user_data.cmp
-  if id then
-    return self.entry_map[id]
-  end
-  return nil
+  return self:get_selected_entry()
 end
 
 ---Get current selected entry
 ---@return cmp.Entry|nil
 menu.get_selected_entry = function(self)
-  local e = self:get_active_entry()
-  if e then
-    return e
+  if not self:is_valid_mode() then
+    return nil
   end
 
   local selected = vim.fn.complete_info({ 'selected' }).selected
   if selected == -1 then
     return nil
   end
-  local items = vim.fn.complete_info({ 'items' }).items
-
-  local completed_item = items[math.max(selected, 0) + 1] or {}
-  if not completed_item.user_data then
-    return nil
-  end
-
-  local id = completed_item.user_data.cmp
-  if id then
-    return self.entry_map[id]
-  end
-  return nil
+  return self.entries[math.max(selected, 0) + 1]
 end
 
 ---Get first entry
 ---@param self cmp.Entry|nil
 menu.get_first_entry = function(self)
-  local info = vim.fn.complete_info({ 'items' })
-  local completed_item = info.items[1] or {}
-  if not completed_item.user_data then
+  if not self:is_valid_mode() then
     return nil
   end
+  return self.entries[1]
+end
 
-  local id = completed_item.user_data.cmp
-  if id then
-    return self.entry_map[id]
-  end
-  return nil
+---Return the completion menu is visible or not.
+---@return boolean
+menu.is_valid_mode = function()
+  return vim.fn.complete_info({ 'mode' }).mode == 'eval'
 end
 
 return menu

lua/cmp/types/cmp.lua

@@ -57,6 +57,7 @@ cmp.PreselectMode.None = 'none'
 ---@field public event cmp.EventConfig
 ---@field public mapping table<string, fun(core: cmp.Core, fallback: function)>
 ---@field public sources cmp.SourceConfig[]
+---@field public experimental cmp.ExperimentalConfig
 
 ---@class cmp.CompletionConfig
 ---@field public autocomplete cmp.TriggerEvent[]
@@ -88,6 +89,9 @@ cmp.PreselectMode.None = 'none'
 ---@class cmp.EventConfig
 ---@field on_confirm_done function(e: cmp.Entry)
 
+---@class cmp.ExperimentalConfig
+---@field public ghost_text boolean
+
 ---@class cmp.SourceConfig
 ---@field public name string
 ---@field public opts table