feat: add support for LSP willRenameFiles (#184)

lua/oil/fs.lua

@@ -26,6 +26,13 @@ M.is_absolute = function(dir)
   end
 end
 
+M.abspath = function(path)
+  if not M.is_absolute(path) then
+    path = vim.fn.fnamemodify(path, ":p")
+  end
+  return path
+end
+
 ---@param path string
 ---@param cb fun(err: nil|string)
 M.touch = function(path, cb)
@@ -39,6 +46,38 @@ M.touch = function(path, cb)
   end)
 end
 
+--- Returns true if candidate is a subpath of root, or if they are the same path.
+---@param root string
+---@param candidate string
+---@return boolean
+M.is_subpath = function(root, candidate)
+  if candidate == "" then
+    return false
+  end
+  root = vim.fs.normalize(M.abspath(root))
+  -- Trim trailing "/" from the root
+  if root:find("/", -1) then
+    root = root:sub(1, -2)
+  end
+  candidate = vim.fs.normalize(M.abspath(candidate))
+  if M.is_windows then
+    root = root:lower()
+    candidate = candidate:lower()
+  end
+  if root == candidate then
+    return true
+  end
+  local prefix = candidate:sub(1, root:len())
+  if prefix ~= root then
+    return false
+  end
+
+  local candidate_starts_with_sep = candidate:find("/", root:len() + 1, true) == root:len() + 1
+  local root_ends_with_sep = root:find("/", root:len(), true) == root:len()
+
+  return candidate_starts_with_sep or root_ends_with_sep
+end
+
 ---@param path string
 ---@return string
 M.posix_to_os_path = function(path)