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<?php declare(strict_types = 1);
namespace PHPStan\PhpDocParser\Ast;
use LogicException;
use PHPStan\PhpDocParser\Ast\ConstExpr\ConstExprNode;
use PHPStan\PhpDocParser\Ast\PhpDoc\PhpDocChildNode;
use PHPStan\PhpDocParser\Ast\PhpDoc\PhpDocTagValueNode;
use PHPStan\PhpDocParser\Ast\Type\TypeNode;
use function array_keys;
use function array_pop;
use function array_splice;
use function count;
use function get_class;
use function get_object_vars;
use function gettype;
use function is_array;
use function sprintf;
/**
* Inspired by https://github.com/nikic/PHP-Parser/tree/36a6dcd04e7b0285e8f0868f44bd4927802f7df1
*
* Copyright (c) 2011, Nikita Popov
* All rights reserved.
*/
final class NodeTraverser
{
/**
* If NodeVisitor::enterNode() returns DONT_TRAVERSE_CHILDREN, child nodes
* of the current node will not be traversed for any visitors.
*
* For subsequent visitors enterNode() will still be called on the current
* node and leaveNode() will also be invoked for the current node.
*/
public const DONT_TRAVERSE_CHILDREN = 1;
/**
* If NodeVisitor::enterNode() or NodeVisitor::leaveNode() returns
* STOP_TRAVERSAL, traversal is aborted.
*
* The afterTraverse() method will still be invoked.
*/
public const STOP_TRAVERSAL = 2;
/**
* If NodeVisitor::leaveNode() returns REMOVE_NODE for a node that occurs
* in an array, it will be removed from the array.
*
* For subsequent visitors leaveNode() will still be invoked for the
* removed node.
*/
public const REMOVE_NODE = 3;
/**
* If NodeVisitor::enterNode() returns DONT_TRAVERSE_CURRENT_AND_CHILDREN, child nodes
* of the current node will not be traversed for any visitors.
*
* For subsequent visitors enterNode() will not be called as well.
* leaveNode() will be invoked for visitors that has enterNode() method invoked.
*/
public const DONT_TRAVERSE_CURRENT_AND_CHILDREN = 4;
/** @var list<NodeVisitor> Visitors */
private array $visitors = [];
/** @var bool Whether traversal should be stopped */
private bool $stopTraversal;
/**
* @param list<NodeVisitor> $visitors
*/
public function __construct(array $visitors)
{
$this->visitors = $visitors;
}
/**
* Traverses an array of nodes using the registered visitors.
*
* @param Node[] $nodes Array of nodes
*
* @return Node[] Traversed array of nodes
*/
public function traverse(array $nodes): array
{
$this->stopTraversal = false;
foreach ($this->visitors as $visitor) {
$return = $visitor->beforeTraverse($nodes);
if ($return === null) {
continue;
}
$nodes = $return;
}
$nodes = $this->traverseArray($nodes);
foreach ($this->visitors as $visitor) {
$return = $visitor->afterTraverse($nodes);
if ($return === null) {
continue;
}
$nodes = $return;
}
return $nodes;
}
/**
* Recursively traverse a node.
*
* @param Node $node Node to traverse.
*
* @return Node Result of traversal (may be original node or new one)
*/
private function traverseNode(Node $node): Node
{
$subNodeNames = array_keys(get_object_vars($node));
foreach ($subNodeNames as $name) {
$subNode =& $node->$name;
if (is_array($subNode)) {
$subNode = $this->traverseArray($subNode);
if ($this->stopTraversal) {
break;
}
} elseif ($subNode instanceof Node) {
$traverseChildren = true;
$breakVisitorIndex = null;
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->enterNode($subNode);
if ($return === null) {
continue;
}
if ($return instanceof Node) {
$this->ensureReplacementReasonable($subNode, $return);
$subNode = $return;
} elseif ($return === self::DONT_TRAVERSE_CHILDREN) {
$traverseChildren = false;
} elseif ($return === self::DONT_TRAVERSE_CURRENT_AND_CHILDREN) {
$traverseChildren = false;
$breakVisitorIndex = $visitorIndex;
break;
} elseif ($return === self::STOP_TRAVERSAL) {
$this->stopTraversal = true;
break 2;
} else {
throw new LogicException(
'enterNode() returned invalid value of type ' . gettype($return),
);
}
}
if ($traverseChildren) {
$subNode = $this->traverseNode($subNode);
if ($this->stopTraversal) {
break;
}
}
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->leaveNode($subNode);
if ($return !== null) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($subNode, $return);
$subNode = $return;
} elseif ($return === self::STOP_TRAVERSAL) {
$this->stopTraversal = true;
break 2;
} elseif (is_array($return)) {
throw new LogicException(
'leaveNode() may only return an array ' .
'if the parent structure is an array',
);
} else {
throw new LogicException(
'leaveNode() returned invalid value of type ' . gettype($return),
);
}
}
if ($breakVisitorIndex === $visitorIndex) {
break;
}
}
}
}
return $node;
}
/**
* Recursively traverse array (usually of nodes).
*
* @param mixed[] $nodes Array to traverse
*
* @return mixed[] Result of traversal (may be original array or changed one)
*/
private function traverseArray(array $nodes): array
{
$doNodes = [];
foreach ($nodes as $i => &$node) {
if ($node instanceof Node) {
$traverseChildren = true;
$breakVisitorIndex = null;
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->enterNode($node);
if ($return === null) {
continue;
}
if ($return instanceof Node) {
$this->ensureReplacementReasonable($node, $return);
$node = $return;
} elseif (is_array($return)) {
$doNodes[] = [$i, $return];
continue 2;
} elseif ($return === self::REMOVE_NODE) {
$doNodes[] = [$i, []];
continue 2;
} elseif ($return === self::DONT_TRAVERSE_CHILDREN) {
$traverseChildren = false;
} elseif ($return === self::DONT_TRAVERSE_CURRENT_AND_CHILDREN) {
$traverseChildren = false;
$breakVisitorIndex = $visitorIndex;
break;
} elseif ($return === self::STOP_TRAVERSAL) {
$this->stopTraversal = true;
break 2;
} else {
throw new LogicException(
'enterNode() returned invalid value of type ' . gettype($return),
);
}
}
if ($traverseChildren) {
$node = $this->traverseNode($node);
if ($this->stopTraversal) {
break;
}
}
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->leaveNode($node);
if ($return !== null) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($node, $return);
$node = $return;
} elseif (is_array($return)) {
$doNodes[] = [$i, $return];
break;
} elseif ($return === self::REMOVE_NODE) {
$doNodes[] = [$i, []];
break;
} elseif ($return === self::STOP_TRAVERSAL) {
$this->stopTraversal = true;
break 2;
} else {
throw new LogicException(
'leaveNode() returned invalid value of type ' . gettype($return),
);
}
}
if ($breakVisitorIndex === $visitorIndex) {
break;
}
}
} elseif (is_array($node)) {
throw new LogicException('Invalid node structure: Contains nested arrays');
}
}
if (count($doNodes) > 0) {
while ([$i, $replace] = array_pop($doNodes)) {
array_splice($nodes, $i, 1, $replace);
}
}
return $nodes;
}
private function ensureReplacementReasonable(Node $old, Node $new): void
{
if ($old instanceof TypeNode && !$new instanceof TypeNode) {
throw new LogicException(sprintf('Trying to replace TypeNode with %s', get_class($new)));
}
if ($old instanceof ConstExprNode && !$new instanceof ConstExprNode) {
throw new LogicException(sprintf('Trying to replace ConstExprNode with %s', get_class($new)));
}
if ($old instanceof PhpDocChildNode && !$new instanceof PhpDocChildNode) {
throw new LogicException(sprintf('Trying to replace PhpDocChildNode with %s', get_class($new)));
}
if ($old instanceof PhpDocTagValueNode && !$new instanceof PhpDocTagValueNode) {
throw new LogicException(sprintf('Trying to replace PhpDocTagValueNode with %s', get_class($new)));
}
}
}
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