<?php
/*
* This file is part of Psy Shell.
*
* (c) 2012-2025 Justin Hileman
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Psy\CodeCleaner;
use PhpParser\Node;
use PhpParser\Node\FunctionLike;
use PhpParser\Node\Stmt\Goto_;
use PhpParser\Node\Stmt\Label;
use Psy\Exception\FatalErrorException;
/**
* CodeCleanerPass for label context.
*
* This class partially emulates the PHP label specification.
* PsySH can not declare labels by sequentially executing lines with eval,
* but since it is not a syntax error, no error is raised.
* This class warns before invalid goto causes a fatal error.
* Since this is a simple checker, it does not block real fatal error
* with complex syntax. (ex. it does not parse inside function.)
*
* @see http://php.net/goto
*/
class LabelContextPass extends CodeCleanerPass
{
private int $functionDepth = 0;
private array $labelDeclarations = [];
private array $labelGotos = [];
/**
* @param array $nodes
*
* @return Node[]|null Array of nodes
*/
public function beforeTraverse(array $nodes)
{
$this->functionDepth = 0;
$this->labelDeclarations = [];
$this->labelGotos = [];
return null;
}
/**
* @return int|Node|null Replacement node (or special return value)
*/
public function enterNode(Node $node)
{
if ($node instanceof FunctionLike) {
$this->functionDepth++;
return null;
}
// node is inside function context
if ($this->functionDepth !== 0) {
return null;
}
if ($node instanceof Goto_) {
$this->labelGotos[\strtolower($node->name)] = $node->getStartLine();
} elseif ($node instanceof Label) {
$this->labelDeclarations[\strtolower($node->name)] = $node->getStartLine();
}
return null;
}
/**
* @param \PhpParser\Node $node
*
* @return int|Node|Node[]|null Replacement node (or special return value)
*/
public function leaveNode(Node $node)
{
if ($node instanceof FunctionLike) {
$this->functionDepth--;
}
return null;
}
/**
* @return Node[]|null Array of nodes
*/
public function afterTraverse(array $nodes)
{
foreach ($this->labelGotos as $name => $line) {
if (!isset($this->labelDeclarations[$name])) {
$msg = "'goto' to undefined label '{$name}'";
throw new FatalErrorException($msg, 0, \E_ERROR, null, $line);
}
}
return null;
}
}
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