use PhpParser\Parser;
use PhpParser\Lexer;
use SemanticDiff\Diff\Factory;
use SemanticDiff\Status;

$phpParser = new Parser(new Lexer);

$diff = (new Factory)->createDiff(
    $phpParser->parse($oldPhpCode),
    $phpParser->parse($newPhpCode)
);

$status = $diff->getStatus();

/*
 * $status is now one of:
 *  Status::NO_CHANGES
 *  Status::API_ADDITIONS
 *  Status::INTERNAL_CHANGES
 *  Status::API_CHANGES
 *  Status::INCOMPATIBLE_API
 */