feat: add ghost text

closes #8

docs/config.norg

@@ -55,6 +55,17 @@ version: 1.1.1
    ---@field snippet_expansion fun(string): nil
    @end
 
+** Selection behavior
+   With the selection behavior the user can determine what happens when selecting an entry. This can
+   either be `select` or `insert`. Selecting will just select the entry and do nothing else. Insert
+   will actually insert the text of the entry (this is not necessarily the whole text).
+
+   #tangle
+   @code lua
+   --- Behavior when selecting entry
+   ---@field selection_behavior "select"|"insert"
+   @end
+
 ** Keyword pattern
    Pattern used to determine keywords, used to determine what to use for filtering and what to
    remove if insert text is used.
@@ -104,6 +115,15 @@ version: 1.1.1
   ---@field type_icons neocomplete.config.ui.type_icons
   @end
 
+*** Ghost text
+    with this option the user can determine if ghost text should be displayed. Ghost text is just
+    virtual text which shows a preview of the entry.
+    #tangle
+    @code lua
+    --- Whether to show ghost text
+    ---@field ghost_text boolean
+    @end
+
 ** Menu
    This configuration should allow you to completely adapt the completion menu to your likings.
    #tangle
@@ -144,12 +164,12 @@ version: 1.1.1
    You could do that like this:
    @code lua
    format_entry = function(entry)
-       return {
-           -- The first section with the two chunks for the label and the icon
-           { { entry.label .. " ", "MyRedHlGroup" }, { entry.kind, "HighlightKind" .. entry.kind } }
-           -- The second section for the source
-           { { entry.source, "MyBlueHlGroup" } }
-       }
+   return {
+   -- The first section with the two chunks for the label and the icon
+   { { entry.label .. " ", "MyRedHlGroup" }, { entry.kind, "HighlightKind" .. entry.kind } }
+   -- The second section for the source
+   { { entry.source, "MyBlueHlGroup" } }
+   }
    end,
    alignment = { "left", "right" }
    @end

docs/entry.norg

@@ -9,7 +9,7 @@ categories: [
     types
 ]
 created: 2023-11-15T17:42:46+0100
-updated: 2024-06-18T19:19:29+0100
+updated: 2024-06-23T14:32:14+0100
 tangle: {
     languages: {
         lua: ../lua/neocomplete/types/entry.lua
@@ -39,7 +39,7 @@ version: 1.1.1
    ---@field new fun(completion_item: lsp.CompletionItem, source: neocomplete.internal_source): neocomplete.entry
    @end
 
-* Get insert text
+** Get insert text
   This function is used to get the text that will be inserted for the entry. This is important for
   the ghost text.
    #tangle
@@ -48,6 +48,17 @@ version: 1.1.1
    ---@field get_insert_text fun(self: neocomplete.entry): string
    @end
 
+** Get insert word
+   This function is used to get part of the text that will be inserted for the entry. It just uses
+   a pattern to match the insert text and get the beginning of it which matches a vim `word`. This
+   is often e.g. the method name but without the parentheses and parameter names. That function is
+   used for the `insert` selection behavior.
+   #tangle
+   @code lua
+   --- Get insert word
+   ---@field get_insert_word fun(self: neocomplete.entry): string
+   @end
+
 * Fields
 ** Source
    This is the source from which the entry came. This is important for using the right keyword

lua/neocomplete/config.lua

@@ -57,10 +57,12 @@ config.defaults = {
             Value = " 󰎠 ",
             Variable = "  ",
         },
+        ghost_text = true,
     },
     snippet_expansion = function(snippet_body)
         vim.snippet.expand(snippet_body)
     end,
+    selection_behavior = "select",
     keyword_pattern = [[\%(-\?\d\+\%(\.\d\+\)\?\|\h\w*\%(-\w*\)*\)]],
     enabled = function()
         local enabled = true

lua/neocomplete/core.lua

@@ -7,6 +7,7 @@ function core.new()
     local self = setmetatable({}, { __index = core })
     self.context = require("neocomplete.context").new()
     self.menu = require("neocomplete.menu").new()
+    self.blocked = false
     return self
 end
 
@@ -51,7 +52,17 @@ function core.setup(self)
     })
 end
 
+function core:block()
+    self.blocked = true
+    return vim.schedule_wrap(function()
+        self.blocked = false
+    end)
+end
+
 function core.on_change(self)
+    if self.blocked then
+        return
+    end
     self.context = require("neocomplete.context").new(self.context)
     if not self.context:changed() then
         return

lua/neocomplete/entry.lua

@@ -25,4 +25,22 @@ function Entry:get_insert_text()
     return text
 end
 
+function Entry:get_insert_word()
+    local completion_item = self.completion_item
+    local text
+    if completion_item.textEdit then
+        text = completion_item.textEdit.newText
+    elseif completion_item.insertText then
+        text = completion_item.insertText
+    else
+        text = completion_item.label
+    end
+    -- Snippet
+    if completion_item.insertTextFormat == 2 then
+        text = vim.fn.matchstrpos(text, [[^\w\+]])[1]
+    end
+    ---@type string
+    return text
+end
+
 return Entry

lua/neocomplete/ghost_text.lua

@@ -0,0 +1,41 @@
+local ghost_text = {}
+
+local ns = vim.api.nvim_create_namespace("neocomplete.ghost_text")
+
+---@param entry neocomplete.entry
+---@param offset integer
+function ghost_text.show(entry, offset)
+    -- TODO: allow multiline text
+    vim.api.nvim_buf_clear_namespace(vim.api.nvim_get_current_buf(), ns, 0, -1)
+    local cursor = vim.api.nvim_win_get_cursor(0)
+    local select_behavior = require("neocomplete.config").options.selection_behavior
+    if select_behavior == "select" then
+        local text = entry:get_insert_text()
+        local text_after_filter = text:sub(offset + 1)
+        vim.api.nvim_buf_set_extmark(vim.api.nvim_get_current_buf(), ns, cursor[1] - 1, cursor[2], {
+            virt_text = { { text_after_filter, "@neocomplete.ghost_text" } },
+            virt_text_pos = "inline",
+        })
+    elseif select_behavior == "select" then
+        vim.o.ul = vim.o.ul
+        -- TODO: allow going back to original (filter) text
+        local word = entry:get_insert_word()
+        local unblock = require("neocomplete").core:block()
+        -- vim.api.nvim_buf_set_text(0, cursor[1] - 1, cursor[2] - offset, cursor[1] - 1, cursor[2], { word })
+        -- vim.api.nvim_win_set_cursor(0, { cursor[1], cursor[2] - offset + #word })
+        vim.api.nvim_feedkeys(vim.keycode(string.rep("<BS>", offset) .. word), "i", false)
+        unblock()
+        local text = entry:get_insert_text()
+        local text_after_word = text:sub(#word + 1)
+        vim.api.nvim_buf_set_extmark(vim.api.nvim_get_current_buf(), ns, cursor[1] - 1, cursor[2], {
+            virt_text = { { text_after_word, "@neocomplete.ghost_text" } },
+            virt_text_pos = "inline",
+        })
+    end
+end
+
+function ghost_text.hide()
+    vim.api.nvim_buf_clear_namespace(vim.api.nvim_get_current_buf(), ns, 0, -1)
+end
+
+return ghost_text

lua/neocomplete/highlights.lua

@@ -17,4 +17,5 @@ hl("@neocomplete.selected", { link = "Visual", default = true })
 hl("@neocomplete.match", { link = "Special", default = true })
 hl("@neocomplete.menu", { link = "NormalFloat", default = true })
 hl("@neocomplete.scrollbar", { link = "PmenuSbar", default = true })
-hl("@neocomplete.entry", { italic = true })
+hl("@neocomplete.entry", { italic = true, default = true })
+hl("@neocomplete.ghost_text", { link = "Comment", default = true })

lua/neocomplete/menu/init.lua

@@ -80,6 +80,7 @@ function Menu:close()
     -- TODO: reset more things?
     pcall(vim.api.nvim_win_close, self.winnr, true)
     pcall(vim.api.nvim_win_close, self.scrollbar.win, true)
+    require("neocomplete.ghost_text").hide()
     Menu.winnr = nil
 end
 
@@ -96,7 +97,6 @@ function Menu:set_scroll(direction)
     local bottom_visible = vim.fn.line("w$", self.winnr)
     local visible_amount = bottom_visible - top_visible + 1
     local selected_line = self.index
-    print(visible_amount)
     if selected_line == 0 then
         scroll_to_line(1)
         return
@@ -119,6 +119,26 @@ function Menu:select_next(count)
     end
     self:set_scroll(1)
     self:draw()
+    local line = vim.api.nvim_get_current_line()
+    local cursor = vim.api.nvim_win_get_cursor(0)
+    local cursor_col = cursor[2]
+    local line_to_cursor = line:sub(1, cursor_col)
+    local entry = self:get_active_entry()
+    if not entry then
+        return
+    end
+    local word_boundary = vim.fn.match(line_to_cursor, entry.source:get_keyword_pattern() .. "$")
+
+    local prefix
+    if word_boundary == -1 then
+        prefix = ""
+    else
+        prefix = line:sub(word_boundary + 1, cursor_col)
+    end
+
+    if entry and self.config.ui.ghost_text then
+        require("neocomplete.ghost_text").show(entry, #prefix)
+    end
 end
 
 function Menu:select_prev(count)

lua/neocomplete/types/config.lua

@@ -4,6 +4,8 @@
 ---@field ui neocomplete.config.ui
 --- Function used to expand snippets
 ---@field snippet_expansion fun(string): nil
+--- Behavior when selecting entry
+---@field selection_behavior "select"|"insert"
 --- Pattern used to determine keywords
 ---@field keyword_pattern string
 --- Configuration for the ui of neocomplete
@@ -16,14 +18,16 @@
 ---@field docs_view neocomplete.config.ui.docs
 --- The icons for the different compltion item kinds
 ---@field type_icons neocomplete.config.ui.type_icons
+--- Whether to show ghost text
+---@field ghost_text boolean
 --- Configuration of the completion menu of neocomplete.nvim
 ---@class neocomplete.config.ui.menu
 --- Maximum height of the menu
 ---@field max_height integer
 --- The border of the completion menu
 ---@field border string|string[]|string[][]
 --- Character used for the scrollbar
----@field scrollbar string
+---@field scrollbar string?
 --- Position of the menu
 ---@field position "auto"|"bottom"|"top"
 --- How an entry should be formatted

lua/neocomplete/types/entry.lua

@@ -5,6 +5,8 @@
 ---@field new fun(completion_item: lsp.CompletionItem, source: neocomplete.internal_source): neocomplete.entry
 --- Get insert text
 ---@field get_insert_text fun(self: neocomplete.entry): string
+--- Get insert word
+---@field get_insert_word fun(self: neocomplete.entry): string
 --- Source from which the entry came
 ---@field source neocomplete.internal_source
 --- Matches in filter text