perf(utils): faster split_path (#1902)

Author: pynappo

lua/neo-tree/utils/init.lua

@@ -1135,21 +1135,34 @@ M.split_path = function(path)
   if prefix and vim.startswith(prefix, path) then
     return nil, path
   end
+
+  -- this is more than just a root path
   if path:sub(-1) == M.path_separator then
     -- trim it off
     path = path:sub(1, -2)
   end
 
-  local rest_of_path = prefix and path:sub(#prefix + 1) or path
-  local rest_parts = vim.split(rest_of_path, M.path_separator, { plain = true })
-  local name = table.remove(rest_parts)
-  local parentPath = (prefix or "") .. table.concat(rest_parts, M.path_separator)
+  local last_separator_index
+  local i = prefix and #prefix + 1 or 1
+  local j
+  repeat
+    j = path:find(M.path_separator, i, true)
+    if j then
+      last_separator_index = j
+      i = j + 1
+    end
+  until not j
 
-  if #parentPath == 0 then
-    return prefix, name
+  if not last_separator_index then
+    if not prefix then
+      return nil, path
+    end
+    return prefix, path:sub(#prefix + 1)
   end
 
-  return parentPath, name
+  local parent_path = path:sub(1, last_separator_index - 1)
+  local tail = path:sub(last_separator_index + 1)
+  return parent_path, tail
 end
 
 ---Joins arbitrary number of paths together.

tests/neo-tree/utils/path_spec.lua

@@ -104,6 +104,7 @@ describe("utils path functions", function()
 
       -- Absolute paths
       assert.are.same({ "/a", "b" }, { utils.split_path("/a/b") })
+      assert.are.same({ "/a/b/c/d", "e" }, { utils.split_path("/a/b/c/d/e") })
       assert.are.same({ "/", "a" }, { utils.split_path("/a") })
 
       -- Edge cases