PHP-Parser-sample.php

<?php

require __DIR__ . '/../vendor/autoload.php';

use PhpParser\Node;
use PhpParser\NodeTraverser;
use PhpParser\NodeVisitorAbstract;
use PhpParser\ParserFactory;

class MyNodeVisitor extends NodeVisitorAbstract
{
    public function leaveNode(Node $node) {
        if ($node instanceof Node\Scalar\String_) {
            $node->value = 'hello';
        }
    }
}

$code = <<<CODE
<?php
echo 'hi';
CODE;
$parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
$stmts = $parser->parse($code);

$traverser = new NodeTraverser;
$traverser->addVisitor(new MyNodeVisitor);
$stmts = $traverser->traverse($stmts);

$prettyPrinter = new PhpParser\PrettyPrinter\Standard();
echo $prettyPrinter->prettyPrintFile($stmts);