feat: current buffer fuzzy find improvements (#694)

If you don't want to have a previewer disable it with `:Telescope current_buffer_fuzzy_find previewer=false`
To ignore empty lines do: `:Telescope current_buffer_fuzzy_find skip_empty_lines=true`

lua/telescope/builtin/files.lua

@@ -329,29 +329,30 @@ files.treesitter = function(opts)
 end
 
 files.current_buffer_fuzzy_find = function(opts)
+  -- All actions are on the current buffer
+  local bufnr = vim.api.nvim_get_current_buf()
+  local filename = vim.fn.expand(vim.api.nvim_buf_get_name(bufnr))
+
   local lines = vim.api.nvim_buf_get_lines(0, 0, -1, false)
   local lines_with_numbers = {}
-  for k, v in ipairs(lines) do
-    table.insert(lines_with_numbers, {k, v})
-  end
 
-  local bufnr = vim.api.nvim_get_current_buf()
+  for lnum, line in ipairs(lines) do
+    table.insert(lines_with_numbers, {
+      lnum = lnum,
+      line = line,
+      bufnr = bufnr,
+      filename = filename,
+    })
+  end
 
   pickers.new(opts, {
     prompt_title = 'Current Buffer Fuzzy',
     finder = finders.new_table {
       results = lines_with_numbers,
-      entry_maker = function(enumerated_line)
-        return {
-          bufnr = bufnr,
-          display = enumerated_line[2],
-          ordinal = enumerated_line[2],
-
-          lnum = enumerated_line[1],
-        }
-      end
+      entry_maker = opts.entry_maker or make_entry.gen_from_buffer_lines(opts),
     },
     sorter = conf.generic_sorter(opts),
+    previewer = conf.grep_previewer(opts),
     attach_mappings = function()
       action_set.select:enhance {
         post = function()

lua/telescope/make_entry.lua

@@ -680,6 +680,38 @@ function make_entry.gen_from_highlights()
   end
 end
 
+function make_entry.gen_from_buffer_lines(opts)
+  local displayer = entry_display.create {
+    separator = ' │ ',
+    items = {
+      { width = 5 },
+      { remaining = true },
+    },
+  }
+
+  local make_display = function(entry)
+    return displayer {
+      { entry.lnum, opts.lnum_highlight_group or 'TelescopeResultsSpecialComment' },
+      entry.line
+    }
+  end
+
+  return function(entry)
+    if opts.skip_empty_lines and string.match(entry.line, '^$') then
+      return
+    end
+
+    return {
+      valid = true,
+      ordinal = entry.line,
+      display = make_display,
+      filename = entry.filename,
+      lnum = entry.lnum,
+      line = entry.line,
+    }
+  end
+end
+
 function make_entry.gen_from_vimoptions()
   local process_one_opt = function(o)
     local ok, value_origin