Add getVisitorsForNode() method to NodeTraverser

[samsonasik]

@TomasVotruba here for your request rectorphp/rector-src#6232 (comment)

This is template config for getVisitorsForNode(), which on rector use case, we use for caching visitor by node.

https://github.com/rectorphp/rector-src/blob/4b30bc5d10e7c79867a6a13da3a75a1b2c844675/src/PhpParser/NodeTraverser/RectorNodeTraverser.php#L65-L82

so we can just override the method there :), we currently using vendor-patch for it:

https://github.com/rectorphp/vendor-patches/blob/18e174cbea7beaccb140cfcf03cca3097e95ee92/patches/nikic-php-parser-lib-phpparser-nodetraverser-php.patch

Original PR for this usage for caching on Rector side:

• Optimise checking the node types allowed for each rule rectorphp/rector-src#6232

[samsonasik]

Ready for review 👍

[carlos-granados]

In the case of Rector, this was used to optimise the running time by 20-30%. Probably other tools could benefit from similar optimisations

[TomasVotruba]

The 20-30 % speedup was really noticable across many mid-large size projects 👍
It would also open-up even more advanced speed improvements based on full node class -> visitor tree.

[nikic]

Should probably be protected and have array return type?

Would also be good to add a doc comment to explain that this is an extension point, as the method doesn't make a lot of sense in itself.

[samsonasik]

sure, updated to protected, add array return type, and add doc comment why it is needed.

[nikic]

It looks like adding this method makes NodeTraverser itself about 10% slower.

[samsonasik]

@nikic could you share script to verify the benchmark? Thank you.