feat: Add handling of cursor(+-<num>) for row and column (#2)

* Add handling of cursor(+-<num>) for row and column

* Move common code to function

Move common code to get cursore-relative position to a local function.
Also use relative='cursor' for window options instead of computing
relative to editor

Author: anihm136

lua/popup/init.lua

@@ -91,19 +91,38 @@ function popup.create(what, vim_options)
   }
 
   local win_opts = {}
+  win_opts.relative = "editor"
+
+  local cursor_relative_pos = function(pos_str, dim)
+    assert(string.find(pos_str,'^cursor'), "Invalid value for " .. dim)
+    win_opts.relative = 'cursor'
+    local line = 0
+    if (pos_str):match "cursor%+(%d+)" then
+      line = line + tonumber((pos_str):match "cursor%+(%d+)")
+    elseif (pos_str):match "cursor%-(%d+)" then
+      line = line - tonumber((pos_str):match "cursor%-(%d+)")
+    end
+    return line
+  end
 
   if vim_options.line then
-    -- TODO: Need to handle "cursor", "cursor+1", ...
-    win_opts.row = vim_options.line
+    if type(vim_options.line) == 'string' then
+      win_opts.row = cursor_relative_pos(vim_options.line, "row")
+    else
+      win_opts.row = vim_options.line
+    end
   else
     -- TODO: It says it needs to be "vertically cenetered"?...
     -- wut is that.
     win_opts.row = 0
   end
 
   if vim_options.col then
-    -- TODO: Need to handle "cursor", "cursor+1", ...
-    win_opts.col = vim_options.col
+    if type(vim_options.col) == 'string' then
+      win_opts.col = cursor_relative_pos(vim_options.col, "col")
+    else
+      win_opts.col = vim_options.col
+    end
   else
     -- TODO: It says it needs to be "horizontally cenetered"?...
     win_opts.col = 0
@@ -157,8 +176,6 @@ function popup.create(what, vim_options)
   --   textpropwin
   --   textpropid
 
-  win_opts.relative = "editor"
-
   local win_id
   if vim_options.hidden then
     assert(false, "I have not implemented this yet and don't know how")