refactor(lua): rewrite vim.highlight.range() (#28986)

- Use getregionpos().
- Use a single extmark for non-blockwise selection.

runtime/lua/vim/highlight.lua

@@ -20,8 +20,8 @@ M.priorities = {
 --- @class vim.highlight.range.Opts
 --- @inlinedoc
 ---
---- Type of range. See [setreg()]
---- (default: `'charwise'`)
+--- Type of range. See [getregtype()]
+--- (default: `'v'` i.e. charwise)
 --- @field regtype? string
 ---
 --- Indicates whether the range is end-inclusive
@@ -49,20 +49,49 @@ function M.range(bufnr, ns, higroup, start, finish, opts)
   local priority = opts.priority or M.priorities.user
   local scoped = opts._scoped or false
 
-  -- TODO: in case of 'v', 'V' (not block), this should calculate equivalent
-  -- bounds (row, col, end_row, end_col) as multiline regions are natively
-  -- supported now
-  local region = vim.region(bufnr, start, finish, regtype, inclusive)
-  for linenr, cols in pairs(region) do
-    local end_row
-    if cols[2] == -1 then
-      end_row = linenr + 1
-      cols[2] = 0
+  local pos1 = type(start) == 'string' and vim.fn.getpos(start)
+    or { bufnr, start[1] + 1, start[2] + 1, 0 }
+  local pos2 = type(finish) == 'string' and vim.fn.getpos(finish)
+    or { bufnr, finish[1] + 1, finish[2] + 1, 0 }
+
+  local buf_line_count = vim.api.nvim_buf_line_count(bufnr)
+  pos1[2] = math.min(pos1[2], buf_line_count)
+  pos2[2] = math.min(pos2[2], buf_line_count)
+
+  if pos1[2] <= 0 or pos1[3] <= 0 or pos2[2] <= 0 or pos2[3] <= 0 then
+    return
+  end
+
+  vim.api.nvim_buf_call(bufnr, function()
+    local max_col1 = vim.fn.col({ pos1[2], '$' })
+    pos1[3] = math.min(pos1[3], max_col1)
+    local max_col2 = vim.fn.col({ pos2[2], '$' })
+    pos2[3] = math.min(pos2[3], max_col2)
+  end)
+
+  local region = vim.fn.getregionpos(pos1, pos2, {
+    type = regtype,
+    exclusive = not inclusive,
+    eol = true,
+  })
+  -- For non-blockwise selection, use a single extmark.
+  if regtype == 'v' or regtype == 'V' then
+    region = { { region[1][1], region[#region][2] } }
+  end
+
+  for _, res in ipairs(region) do
+    local start_row = res[1][2] - 1
+    local start_col = res[1][3] - 1
+    local end_row = res[2][2] - 1
+    local end_col = res[2][3]
+    if regtype == 'V' then
+      end_row = end_row + 1
+      end_col = 0
     end
-    api.nvim_buf_set_extmark(bufnr, ns, linenr, cols[1], {
+    api.nvim_buf_set_extmark(bufnr, ns, start_row, start_col, {
       hl_group = higroup,
       end_row = end_row,
-      end_col = cols[2],
+      end_col = end_col,
       priority = priority,
       strict = false,
       scoped = scoped,