public function setMap($prefix, $paths)
{
if ($prefix) {
$prefix = ltrim($prefix, '\\');
}
if (!$prefix) {
$this->fallbackDirs = (array) $paths;
} else {
$length = strlen($prefix);
if ('\\' !== $prefix[$length - 1]) {
throw new \InvalidArgumentException("A non-empty PSR-4 prefix must end with a namespace separator.");
}
$this->prefixLengths[$prefix[0]][$prefix] = $length;
$this->prefixDirs[$prefix] = (array) $paths;
}
}