feat: add selectioncount component (#959)

README.md

@@ -252,6 +252,7 @@ sections = {lualine_a = {'mode'}}
 - `mode` (vim mode)
 - `progress` (%progress in file)
 - `searchcount` (number of search matches when hlsearch is active)
+- `selectioncount` (number of selected characters or lines)
 - `tabs` (shows currently available tabs)
 - `windows` (shows currently available windows)
 

lua/lualine/components/selectioncount.lua

@@ -0,0 +1,16 @@
+local function selectioncount()
+  local mode = vim.fn.mode(true)
+  local line_start, col_start = vim.fn.line("v"), vim.fn.col("v")
+  local line_end, col_end = vim.fn.line("."), vim.fn.col(".")
+  if mode:match("") then
+      return string.format('%dx%d', math.abs(line_start-line_end)+1, math.abs(col_start-col_end)+1)
+  elseif mode:match("V") or line_start ~= line_end then
+    return math.abs(line_start - line_end) + 1
+  elseif mode:match("v") then
+    return math.abs(col_start - col_end) + 1
+  else
+      return ''
+  end
+end
+
+return selectioncount