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<?php declare(strict_types=1);
namespace PhpParser;
class NodeTraverser implements NodeTraverserInterface
{
/**
* 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.
*/
const DONT_TRAVERSE_CHILDREN = 1;
/**
* If NodeVisitor::enterNode() or NodeVisitor::leaveNode() returns
* STOP_TRAVERSAL, traversal is aborted.
*
* The afterTraverse() method will still be invoked.
*/
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.
*/
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.
*/
const DONT_TRAVERSE_CURRENT_AND_CHILDREN = 4;
/** @var NodeVisitor[] Visitors */
protected $visitors = [];
/** @var bool Whether traversal should be stopped */
protected $stopTraversal;
public function __construct() {
// for BC
}
/**
* Adds a visitor.
*
* @param NodeVisitor $visitor Visitor to add
*/
public function addVisitor(NodeVisitor $visitor) {
$this->visitors[] = $visitor;
}
/**
* Removes an added visitor.
*
* @param NodeVisitor $visitor
*/
public function removeVisitor(NodeVisitor $visitor) {
foreach ($this->visitors as $index => $storedVisitor) {
if ($storedVisitor === $visitor) {
unset($this->visitors[$index]);
break;
}
}
}
/**
* 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) {
if (null !== $return = $visitor->beforeTraverse($nodes)) {
$nodes = $return;
}
}
$nodes = $this->traverseArray($nodes);
foreach ($this->visitors as $visitor) {
if (null !== $return = $visitor->afterTraverse($nodes)) {
$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)
*/
protected function traverseNode(Node $node) : Node {
foreach ($node->getSubNodeNames() 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 (null !== $return) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($subNode, $return);
$subNode = $return;
} elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
$traverseChildren = false;
} elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
$traverseChildren = false;
$breakVisitorIndex = $visitorIndex;
break;
} elseif (self::STOP_TRAVERSAL === $return) {
$this->stopTraversal = true;
break 2;
} else {
throw new \LogicException(
'enterNode() returned invalid value of type ' . gettype($return)
);
}
}
}
if ($traverseChildren) {
$subNode = $this->traverseNode($subNode);
if ($this->stopTraversal) {
break;
}
}
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->leaveNode($subNode);
if (null !== $return) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($subNode, $return);
$subNode = $return;
} elseif (self::STOP_TRAVERSAL === $return) {
$this->stopTraversal = true;
break 2;
} elseif (\is_array($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 array $nodes Array to traverse
*
* @return array Result of traversal (may be original array or changed one)
*/
protected 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 (null !== $return) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($node, $return);
$node = $return;
} elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
$traverseChildren = false;
} elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
$traverseChildren = false;
$breakVisitorIndex = $visitorIndex;
break;
} elseif (self::STOP_TRAVERSAL === $return) {
$this->stopTraversal = true;
break 2;
} else {
throw new \LogicException(
'enterNode() returned invalid value of type ' . gettype($return)
);
}
}
}
if ($traverseChildren) {
$node = $this->traverseNode($node);
if ($this->stopTraversal) {
break;
}
}
foreach ($this->visitors as $visitorIndex => $visitor) {
$return = $visitor->leaveNode($node);
if (null !== $return) {
if ($return instanceof Node) {
$this->ensureReplacementReasonable($node, $return);
$node = $return;
} elseif (\is_array($return)) {
$doNodes[] = [$i, $return];
break;
} elseif (self::REMOVE_NODE === $return) {
$doNodes[] = [$i, []];
break;
} elseif (self::STOP_TRAVERSAL === $return) {
$this->stopTraversal = true;
break 2;
} elseif (false === $return) {
throw new \LogicException(
'bool(false) return from leaveNode() no longer supported. ' .
'Return NodeTraverser::REMOVE_NODE instead'
);
} else {
throw new \LogicException(
'leaveNode() returned invalid value of type ' . gettype($return)
);
}
}
if ($breakVisitorIndex === $visitorIndex) {
break;
}
}
} elseif (\is_array($node)) {
throw new \LogicException('Invalid node structure: Contains nested arrays');
}
}
if (!empty($doNodes)) {
while (list($i, $replace) = array_pop($doNodes)) {
array_splice($nodes, $i, 1, $replace);
}
}
return $nodes;
}
private function ensureReplacementReasonable($old, $new) {
if ($old instanceof Node\Stmt && $new instanceof Node\Expr) {
throw new \LogicException(
"Trying to replace statement ({$old->getType()}) " .
"with expression ({$new->getType()}). Are you missing a " .
"Stmt_Expression wrapper?"
);
}
if ($old instanceof Node\Expr && $new instanceof Node\Stmt) {
throw new \LogicException(
"Trying to replace expression ({$old->getType()}) " .
"with statement ({$new->getType()})"
);
}
}
}