Best way to remove node with traverseNodesWithCallable in 0.17.1?

[timmipetit]

Question

Rector 0.17.1 removed effectively removed removeNode. In some of our custom rules we have some code that looks like this:

 $this->traverseNodesWithCallable((array) $classMethod->stmts, function (Node $subNode) : ?Node {
    if(someConditionThatWeDecide()) {
        $this->removeNode($subNode);
    }
});

What is the best way moving forward for code like this? When changing the traverseNodesWithCallable into a foreach($node->stmts as $key => $subNode) we obviously get less subnodes to process and have to add some extra code to get the nodes that we want. Is this the correct way?

[samsonasik]

You can define more Node inside getNodeTypes() method to point to the correct target node, and using unset() to specific key of stmt, like what I did in laminas-servicemanager-migration, there is stmt_key for that:

https://github.com/laminas/laminas-servicemanager-migration/pull/131/files#diff-40da94022f21a80bb7c833406e6092f80e0015c1c7b8f0e2121102affedb86bd

You can also traverse with StmtsAwareInterface, with "beware", ensure that the stmt is the correct stmt_key by StmtsAwareInterface that wrap it, like what I did in cakephp/upgrade:

https://github.com/cakephp/upgrade/pull/236/files#diff-a0b234faceec43fc851a50273b309febcaeda01b537e32eb8f57fd7310496051

Assuming you're trying to remove a MethodCall inside, you need remove the Stmt that wraps it. The node to be removed is the Stmt, and there is a stmt_key attribute for that, but that is depends of "parent" FunctionLike, so to ensure you remove the correct current Stmt, you need to assign $currentStmt when found, something like this pseudo code:

use Rector\Core\Contract\PhpParser\Node\StmtsAwareInterface;
use PhpParser\Node\Stmt;
use PhpParser\NodeTraverser;
use Rector\NodeTypeResolver\Node\AttributeKey;

// ...

$parentStmt = null;
$currentStmtKey = null;
$hasChanged = false;
$this->traverseNodesWithCallable(
        (array) $classMethod->stmts, 
        function (Node $subNode) use ($classMethod, &$parentStmt, &$currentStmtKey, &$hasChanged): ?Node {
                // maybe removal will be inside Closure or If, etc
                if ($subNode instanceof StmtsAwareInterface) {
                     $parentStmt = $subNode;
                     return null;
                }

                if ($subNode instanceof Stmt) {
                    $currentStmtKey = $subNode->getAttribute(AttributeKey::STMT_KEY);
                    return null;
                }
                
                // here you remove the Stmt if method call is "foo"
                if ($this->isName($methodCall->name, 'foo')) {
                          // first level, just remove by subnode key
                          if (! $parentStmt instanceof Node) {
                                  unset($classMethod->stmts[$currentStmtKey]);
                          } else {
                                  unset($parentStmt->stmts[$currentStmtKey]);
                          }
                          $hasChanged = true;
                }
               
                return null;
});

if ($hasChanged) {
    return $node;
}

return null;

I will prepare a blog post for that :)