https://github.com/nikic/PHP-Parser/

PhpParserCodeGeneration.php

<?php

$node = new \PHPParser_Node_Expr_MethodCall(new \PHPParser_Node_Expr_Variable('app'), 'match', array(
    new \PHPParser_Node_Scalar_String('/'),
    new \PHPParser_Node_Expr_Closure(array(
        'stmts'  => array(
            new \PHPParser_Node_Stmt_Return(
                new \PHPParser_Node_Expr_New(
                    new \PHPParser_Node_Name('\stdClass')
                )
            ),
        ),
        'params' => array(
            new \PHPParser_Node_Expr_Variable('someParam')
        ),
        'uses'   => array(
            new \PHPParser_Node_Expr_Variable('app')
        ),
    ), array())
));

$stmts = array($node);

$prettyPrinter = new \PHPParser_PrettyPrinter_Default();

echo $prettyPrinter->prettyPrint($stmts);die();