AK: Use canonicalized_path in LexicalPath::relative_path

This avoids construction of LexicalPath objects.

AK/LexicalPath.cpp

@@ -121,21 +121,34 @@ String LexicalPath::canonicalized_path(String path)
  return builder.to_string();
 }
 
-String LexicalPath::relative_path(String absolute_path, String const& prefix)
+String LexicalPath::relative_path(StringView const& a_path, StringView const& a_prefix)
 {
- if (!LexicalPath { absolute_path }.is_absolute() || !LexicalPath { prefix }.is_absolute())
+ if (!a_path.starts_with('/') || !a_prefix.starts_with('/')) {
+ // FIXME: This should probably VERIFY or return an Optional<String>.
  return {};
+ }
+
+ if (a_path == a_prefix)
+ return ".";
 
- if (!absolute_path.starts_with(prefix))
- return absolute_path;
+ // NOTE: Strip optional trailing slashes, except if the full path is only "/".
+ auto path = canonicalized_path(a_path);
+ auto prefix = canonicalized_path(a_prefix);
 
- size_t prefix_length = LexicalPath { prefix }.string().length();
- if (prefix != "/")
- prefix_length++;
- if (prefix_length >= absolute_path.length())
- return {};
+ if (path == prefix)
+ return ".";
+
+ // NOTE: Handle this special case first.
+ if (prefix == "/"sv)
+ return path.substring_view(1);
+
+ // NOTE: This means the prefix is a direct child of the path.
+ if (path.starts_with(prefix) && path[prefix.length()] == '/') {
+ return path.substring_view(prefix.length() + 1);
+ }
 
- return absolute_path.substring(prefix_length);
+ // FIXME: It's still possible to generate a relative path in this case, it just needs some "..".
+ return path;
 }
 
 LexicalPath LexicalPath::append(StringView const& value) const

AK/LexicalPath.h

@@ -33,7 +33,7 @@ class LexicalPath {
  [[nodiscard]] LexicalPath parent() const;
 
  [[nodiscard]] static String canonicalized_path(String);
- [[nodiscard]] static String relative_path(String absolute_path, String const& prefix);
+ [[nodiscard]] static String relative_path(StringView const& absolute_path, StringView const& prefix);
 
  template<typename... S>
  [[nodiscard]] static LexicalPath join(String const& first, S&&... rest)