292 lines
10 KiB
PHP
292 lines
10 KiB
PHP
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<?php declare(strict_types=1);
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namespace PhpParser;
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class NodeTraverser implements NodeTraverserInterface
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{
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/**
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* If NodeVisitor::enterNode() returns DONT_TRAVERSE_CHILDREN, child nodes
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* of the current node will not be traversed for any visitors.
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*
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* For subsequent visitors enterNode() will still be called on the current
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* node and leaveNode() will also be invoked for the current node.
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*/
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const DONT_TRAVERSE_CHILDREN = 1;
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/**
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* If NodeVisitor::enterNode() or NodeVisitor::leaveNode() returns
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* STOP_TRAVERSAL, traversal is aborted.
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*
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* The afterTraverse() method will still be invoked.
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*/
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const STOP_TRAVERSAL = 2;
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/**
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* If NodeVisitor::leaveNode() returns REMOVE_NODE for a node that occurs
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* in an array, it will be removed from the array.
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*
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* For subsequent visitors leaveNode() will still be invoked for the
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* removed node.
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*/
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const REMOVE_NODE = 3;
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/**
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* If NodeVisitor::enterNode() returns DONT_TRAVERSE_CURRENT_AND_CHILDREN, child nodes
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* of the current node will not be traversed for any visitors.
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*
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* For subsequent visitors enterNode() will not be called as well.
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* leaveNode() will be invoked for visitors that has enterNode() method invoked.
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*/
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const DONT_TRAVERSE_CURRENT_AND_CHILDREN = 4;
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/** @var NodeVisitor[] Visitors */
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protected $visitors = [];
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/** @var bool Whether traversal should be stopped */
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protected $stopTraversal;
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public function __construct() {
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// for BC
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}
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/**
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* Adds a visitor.
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*
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* @param NodeVisitor $visitor Visitor to add
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*/
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public function addVisitor(NodeVisitor $visitor) {
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$this->visitors[] = $visitor;
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}
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/**
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* Removes an added visitor.
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*
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* @param NodeVisitor $visitor
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*/
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public function removeVisitor(NodeVisitor $visitor) {
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foreach ($this->visitors as $index => $storedVisitor) {
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if ($storedVisitor === $visitor) {
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unset($this->visitors[$index]);
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break;
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}
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}
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}
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/**
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* Traverses an array of nodes using the registered visitors.
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*
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* @param Node[] $nodes Array of nodes
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*
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* @return Node[] Traversed array of nodes
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*/
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public function traverse(array $nodes) : array {
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$this->stopTraversal = false;
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foreach ($this->visitors as $visitor) {
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if (null !== $return = $visitor->beforeTraverse($nodes)) {
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$nodes = $return;
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}
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}
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$nodes = $this->traverseArray($nodes);
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foreach ($this->visitors as $visitor) {
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if (null !== $return = $visitor->afterTraverse($nodes)) {
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$nodes = $return;
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}
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}
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return $nodes;
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}
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/**
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* Recursively traverse a node.
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*
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* @param Node $node Node to traverse.
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*
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* @return Node Result of traversal (may be original node or new one)
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*/
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protected function traverseNode(Node $node) : Node {
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foreach ($node->getSubNodeNames() as $name) {
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$subNode =& $node->$name;
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if (\is_array($subNode)) {
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$subNode = $this->traverseArray($subNode);
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if ($this->stopTraversal) {
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break;
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}
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} elseif ($subNode instanceof Node) {
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$traverseChildren = true;
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$breakVisitorIndex = null;
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foreach ($this->visitors as $visitorIndex => $visitor) {
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$return = $visitor->enterNode($subNode);
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if (null !== $return) {
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if ($return instanceof Node) {
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$this->ensureReplacementReasonable($subNode, $return);
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$subNode = $return;
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} elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
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$traverseChildren = false;
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} elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
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$traverseChildren = false;
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$breakVisitorIndex = $visitorIndex;
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break;
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} elseif (self::STOP_TRAVERSAL === $return) {
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$this->stopTraversal = true;
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break 2;
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} else {
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throw new \LogicException(
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'enterNode() returned invalid value of type ' . gettype($return)
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);
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}
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}
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}
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if ($traverseChildren) {
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$subNode = $this->traverseNode($subNode);
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if ($this->stopTraversal) {
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break;
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}
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}
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foreach ($this->visitors as $visitorIndex => $visitor) {
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$return = $visitor->leaveNode($subNode);
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if (null !== $return) {
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if ($return instanceof Node) {
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$this->ensureReplacementReasonable($subNode, $return);
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$subNode = $return;
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} elseif (self::STOP_TRAVERSAL === $return) {
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$this->stopTraversal = true;
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break 2;
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} elseif (\is_array($return)) {
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throw new \LogicException(
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'leaveNode() may only return an array ' .
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'if the parent structure is an array'
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);
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} else {
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throw new \LogicException(
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'leaveNode() returned invalid value of type ' . gettype($return)
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);
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}
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}
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if ($breakVisitorIndex === $visitorIndex) {
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break;
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}
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}
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}
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}
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return $node;
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}
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/**
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* Recursively traverse array (usually of nodes).
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*
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* @param array $nodes Array to traverse
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*
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* @return array Result of traversal (may be original array or changed one)
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*/
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protected function traverseArray(array $nodes) : array {
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$doNodes = [];
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foreach ($nodes as $i => &$node) {
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if ($node instanceof Node) {
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$traverseChildren = true;
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$breakVisitorIndex = null;
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foreach ($this->visitors as $visitorIndex => $visitor) {
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$return = $visitor->enterNode($node);
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if (null !== $return) {
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if ($return instanceof Node) {
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$this->ensureReplacementReasonable($node, $return);
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$node = $return;
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} elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
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$traverseChildren = false;
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} elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
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$traverseChildren = false;
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$breakVisitorIndex = $visitorIndex;
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break;
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} elseif (self::STOP_TRAVERSAL === $return) {
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$this->stopTraversal = true;
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break 2;
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} else {
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throw new \LogicException(
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'enterNode() returned invalid value of type ' . gettype($return)
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);
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}
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}
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}
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if ($traverseChildren) {
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$node = $this->traverseNode($node);
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if ($this->stopTraversal) {
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break;
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}
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}
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foreach ($this->visitors as $visitorIndex => $visitor) {
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$return = $visitor->leaveNode($node);
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if (null !== $return) {
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if ($return instanceof Node) {
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$this->ensureReplacementReasonable($node, $return);
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$node = $return;
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} elseif (\is_array($return)) {
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$doNodes[] = [$i, $return];
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break;
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} elseif (self::REMOVE_NODE === $return) {
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$doNodes[] = [$i, []];
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break;
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} elseif (self::STOP_TRAVERSAL === $return) {
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$this->stopTraversal = true;
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break 2;
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} elseif (false === $return) {
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throw new \LogicException(
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'bool(false) return from leaveNode() no longer supported. ' .
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'Return NodeTraverser::REMOVE_NODE instead'
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);
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} else {
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throw new \LogicException(
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'leaveNode() returned invalid value of type ' . gettype($return)
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);
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}
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}
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if ($breakVisitorIndex === $visitorIndex) {
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break;
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}
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}
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} elseif (\is_array($node)) {
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throw new \LogicException('Invalid node structure: Contains nested arrays');
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}
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}
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if (!empty($doNodes)) {
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while (list($i, $replace) = array_pop($doNodes)) {
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array_splice($nodes, $i, 1, $replace);
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}
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}
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return $nodes;
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}
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private function ensureReplacementReasonable($old, $new) {
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if ($old instanceof Node\Stmt && $new instanceof Node\Expr) {
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throw new \LogicException(
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"Trying to replace statement ({$old->getType()}) " .
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"with expression ({$new->getType()}). Are you missing a " .
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"Stmt_Expression wrapper?"
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);
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}
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if ($old instanceof Node\Expr && $new instanceof Node\Stmt) {
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throw new \LogicException(
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"Trying to replace expression ({$old->getType()}) " .
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"with statement ({$new->getType()})"
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);
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}
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}
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}
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