feat(lua): conversion between extmark positions

runtime/doc/lua.txt

@@ -4000,6 +4000,9 @@ comparisons and conversions between various types of positions.
       • {to_cursor}   (`fun(pos: vim.Pos): [integer, integer]`) See
                       |Pos:to_cursor()|.
       • {cursor}      (`fun(pos: [integer, integer])`) See |Pos:cursor()|.
+      • {to_extmark}  (`fun(pos: vim.Pos): [integer, integer]`) See
+                      |Pos:to_extmark()|.
+      • {extmark}     (`fun(pos: [integer, integer])`) See |Pos:extmark()|.
 
 
 Pos:cursor({pos})                                               *Pos:cursor()*
@@ -4008,6 +4011,12 @@ Pos:cursor({pos})                                               *Pos:cursor()*
     Parameters: ~
       • {pos}  (`[integer, integer]`)
 
+Pos:extmark({pos})                                             *Pos:extmark()*
+    Creates a new |vim.Pos| from extmark position.
+
+    Parameters: ~
+      • {pos}  (`[integer, integer]`)
+
 Pos:lsp({buf}, {pos}, {position_encoding})                         *Pos:lsp()*
     Creates a new |vim.Pos| from `lsp.Position`.
 
@@ -4036,6 +4045,15 @@ Pos:to_cursor({pos})                                         *Pos:to_cursor()*
     Return: ~
         (`[integer, integer]`)
 
+Pos:to_extmark({pos})                                       *Pos:to_extmark()*
+    Converts |vim.Pos| to extmark position.
+
+    Parameters: ~
+      • {pos}  (`vim.Pos`) See |vim.Pos|.
+
+    Return: ~
+        (`[integer, integer]`)
+
 Pos:to_lsp({pos}, {position_encoding})                          *Pos:to_lsp()*
     Converts |vim.Pos| to `lsp.Position`.
 

runtime/lua/vim/pos.lua

@@ -191,6 +191,20 @@ function Pos.cursor(pos)
   return Pos.new(pos[1] - 1, pos[2])
 end
 
+--- Converts |vim.Pos| to extmark position.
+---@param pos vim.Pos
+---@return [integer, integer]
+function Pos.to_extmark(pos)
+  return { pos.row, pos.col }
+end
+
+--- Creates a new |vim.Pos| from extmark position.
+---@param pos [integer, integer]
+function Pos.extmark(pos)
+  local row, col = unpack(pos)
+  return Pos.new(row, col)
+end
+
 -- Overload `Range.new` to allow calling this module as a function.
 setmetatable(Pos, {
   __call = function(_, ...)