extmarks: better linewise/charwise handling

lua/u/range.lua

@@ -93,6 +93,8 @@ end
 --- @param bufnr number
 --- @param id number
 function Range.from_extmark(bufnr, id)
+  local mode = 'v'
+
   ---@type integer, integer, vim.api.keyset.extmark_details | nil
   local start_row0, start_col0, details =
     unpack(vim.api.nvim_buf_get_extmark_by_id(bufnr, NS, id, { details = true }))
@@ -100,15 +102,16 @@ function Range.from_extmark(bufnr, id)
   local start = Pos.new(bufnr, start_row0 + 1, start_col0 + 1)
   local stop = details and Pos.new(bufnr, details.end_row + 1, details.end_col)
 
-  local max_line_num = vim.api.nvim_buf_line_count(bufnr)
-  if stop and stop.lnum > max_line_num then
-    stop.lnum = max_line_num
-    stop.col = Pos.MAX_COL
-    stop = stop:as_real()
-  end
-  if stop and stop.col == 0 then stop = stop:must_next(-1) end
+  -- Check for invalid extmark range:
+  if stop and stop < start then return Range.new(stop) end
 
-  return Range.new(start, stop, 'v')
+  if stop and stop.col == 0 then
+    mode = 'V'
+    stop = stop:must_next(-1)
+    stop.col = Pos.MAX_COL
+  end
+
+  return Range.new(start, stop, mode)
 end
 
 --- @param bufnr? number
@@ -371,9 +374,15 @@ end
 
 function Range:save_to_extmark()
   local r = self:to_charwise()
+  local end_row = r.stop.lnum - 1
+  local end_col = r.stop.col
+  if self.mode == 'V' then
+    end_row = end_row + 1
+    end_col = 0
+  end
   local id = vim.api.nvim_buf_set_extmark(r.start.bufnr, NS, r.start.lnum - 1, r.start.col - 1, {
-    end_row = r.stop.lnum - 1,
-    end_col = r.stop.col,
+    end_row = end_row,
+    end_col = end_col,
   })
   return ExtmarkRange.new(r.start.bufnr, id)
 end

spec/range_spec.lua

@@ -627,7 +627,7 @@ describe('Range', function()
       'the lazy dog',
     }, function()
       -- Construct a range over 'fox jumps'
-      local r = Range.new(Pos.new(nil, 2, 1), Pos.new(nil, 3, Pos.MAX_COL), 'V')
+      local r = Range.new(Pos.new(nil, 2, 1), Pos.new(nil, 3, 5), 'v')
       local extrange = r:save_to_extmark()
       assert.are.same({ 'fox', 'jumps' }, extrange:range():lines())
       -- change 'jumps' to 'leaps':
@@ -642,4 +642,29 @@ describe('Range', function()
       assert.are.same({ 'fox', 'leaps' }, extrange:range():lines())
     end)
   end)
+
+  it('can save linewise extmark', function()
+    withbuf({
+      'The quick brown',
+      'fox',
+      'jumps',
+      'over',
+      'the lazy dog',
+    }, function()
+      -- Construct a range over 'fox jumps'
+      local r = Range.new(Pos.new(nil, 2, 1), Pos.new(nil, 3, Pos.MAX_COL), 'V')
+      local extrange = r:save_to_extmark()
+      assert.are.same({ 'fox', 'jumps' }, extrange:range():lines())
+
+      local extmark = vim.api.nvim_buf_get_extmark_by_id(
+        extrange.bufnr,
+        vim.api.nvim_create_namespace 'u.range',
+        extrange.id,
+        { details = true }
+      )
+      local row0, col0, details = unpack(extmark)
+      assert.are.same({ 1, 0 }, { row0, col0 })
+      assert.are.same({ 3, 0 }, { details.end_row, details.end_col })
+    end)
+  end)
 end)