Removes the final path component of a path, using the platform's path separator to split the path. Will not remove the root component of a Windows path, like "C:\\" or "\\\\server_name\\". Ignores trailing path separators, and leaves no trailing path separators.
Source
static String parentOf(String path) {
int rootEnd = -1;
if (Platform.isWindows) {
if (path.startsWith(_absoluteWindowsPathPattern)) {
// Root ends at first / or \ after the first two characters.
rootEnd = path.indexOf(new RegExp(r'[/\\]'), 2);
if (rootEnd == -1) return path;
} else if (path.startsWith('\\') || path.startsWith('/')) {
rootEnd = 0;
}
} else if (path.startsWith('/')) {
rootEnd = 0;
}
// Ignore trailing slashes.
// All non-trivial cases have separators between two non-separators.
int pos = path.lastIndexOf(_parentRegExp);
if (pos > rootEnd) {
return path.substring(0, pos + 1);
} else if (rootEnd > -1) {
return path.substring(0, rootEnd + 1);
} else {
return '.';
}
}