Add 'is_absolute_path()' function

Also, the 'get_relative_path(pathA, pathB)' function has been made
case-insensitive. This is done to correctly calculate common folders
in case one of the entered paths has a case difference.

Author: Gasparoken

base/fs.cpp

@@ -1,5 +1,5 @@
 // LAF Base Library
-// Copyright (c) 2021-2024 Igara Studio S.A.
+// Copyright (c) 2021-2025 Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -35,6 +35,17 @@ const std::string::value_type* path_separators = "\\/";
 const std::string::value_type* path_separators = "/";
 #endif
 
+bool is_absolute_path(const std::string& path)
+{
+#ifdef LAF_WINDOWS
+  return (path.size() > 2 && path[1] == ':' && path[2] == path_separator) ||
+         // Absolute network path
+         (path.size() > 1 && path[0] == path_separator && path[1] == path_separator);
+#else
+  return !path.empty() && path[0] == path_separator;
+#endif
+}
+
 void make_all_directories(const std::string& path)
 {
   std::vector<std::string> parts;
@@ -194,7 +205,8 @@ std::string get_relative_path(const std::string& filename, const std::string& ba
   auto itFrom = baseDirs.begin();
   auto itTo = toParts.begin();
 
-  while (itFrom != baseDirs.end() && itTo != toParts.end() && *itFrom == *itTo) {
+  while (itFrom != baseDirs.end() && itTo != toParts.end() &&
+         base::string_to_lower(*itFrom) == base::string_to_lower((*itTo))) {
     ++itFrom;
     ++itTo;
   }

base/fs.h

@@ -1,5 +1,5 @@
 // LAF Base Library
-// Copyright (c) 2020-2024 Igara Studio S.A.
+// Copyright (c) 2020-2025 Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -28,6 +28,7 @@ extern const std::string::value_type* path_separators;
 
 bool is_file(const std::string& path);
 bool is_directory(const std::string& path);
+bool is_absolute_path(const std::string& path);
 
 size_t file_size(const std::string& path);