dirname method
Implementation
String dirname(String path) {
if (path.length == 0) return '.';
var hasRoot = path[0] == '/';
var end = -1;
var matchedSlash = true;
for (var i = path.length - 1; i >= 1; --i) {
if (path[i] == '/') {
if (!matchedSlash) {
end = i;
break;
}
} else {
// We saw the first non-path separator
matchedSlash = false;
}
}
if (end == -1) return hasRoot ? '/' : '.';
if (hasRoot && end == 1) return '//';
return path.substring(0, end);
}