com.github.javaparser.ast.Node Maven / Gradle / Ivy
/*
* Copyright (C) 2007-2010 Júlio Vilmar Gesser.
* Copyright (C) 2011, 2013-2020 The JavaParser Team.
*
* This file is part of JavaParser.
*
* JavaParser can be used either under the terms of
* a) the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* b) the terms of the Apache License
*
* You should have received a copy of both licenses in LICENCE.LGPL and
* LICENCE.APACHE. Please refer to those files for details.
*
* JavaParser is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*/
package com.github.javaparser.ast;
import com.github.javaparser.HasParentNode;
import com.github.javaparser.Position;
import com.github.javaparser.Range;
import com.github.javaparser.TokenRange;
import com.github.javaparser.ast.comments.BlockComment;
import com.github.javaparser.ast.comments.Comment;
import com.github.javaparser.ast.comments.LineComment;
import com.github.javaparser.ast.nodeTypes.NodeWithRange;
import com.github.javaparser.ast.nodeTypes.NodeWithTokenRange;
import com.github.javaparser.ast.observer.AstObserver;
import com.github.javaparser.ast.observer.ObservableProperty;
import com.github.javaparser.ast.observer.PropagatingAstObserver;
import com.github.javaparser.ast.visitor.CloneVisitor;
import com.github.javaparser.ast.visitor.EqualsVisitor;
import com.github.javaparser.ast.visitor.HashCodeVisitor;
import com.github.javaparser.ast.visitor.Visitable;
import com.github.javaparser.metamodel.*;
import com.github.javaparser.printer.PrettyPrinter;
import com.github.javaparser.printer.PrettyPrinterConfiguration;
import com.github.javaparser.resolution.SymbolResolver;
import com.github.javaparser.resolution.types.ResolvedType;
import java.util.*;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import static com.github.javaparser.ast.Node.Parsedness.PARSED;
import static com.github.javaparser.ast.Node.TreeTraversal.PREORDER;
import static java.util.Collections.emptySet;
import static java.util.Collections.unmodifiableList;
import static java.util.Spliterator.DISTINCT;
import static java.util.Spliterator.NONNULL;
import com.github.javaparser.ast.Node;
import com.github.javaparser.metamodel.NodeMetaModel;
import com.github.javaparser.metamodel.JavaParserMetaModel;
/**
* Base class for all nodes of the abstract syntax tree.
* Construction
* The tree is built by instantiating the required nodes, then adding them to other nodes.
* If it is the parser who is building the tree, it will use the largest constructor,
* the one with "range" as the first parameter.
* If you want to manually instantiate nodes, we suggest to...
*
* - use a convenience method, like "addStatement(...)", or if none are available...
* - use a convenient constructor, like ClassOrInterfaceType(String name), or if none are available...
* - use the default constructor.
* - Alternatively, use one of the JavaParser.parse(snippet) methods.
*
* ... and use the various methods on the node to initialize it further, if needed.
* Parent/child
* The parent node field is managed automatically and can be seen as read only.
* Note that there is only one parent,
* and trying to use the same node in two places will lead to unexpected behaviour.
* It is advised to clone() a node before moving it around.
*
Comments
* Each Node can have one associated comment which describes it and
* a number of "orphan comments" which it contains but are not specifically
* associated to any child.
*
Positions
* When the parser creates nodes, it sets their source code position in the "range" field.
* When you manually instantiate nodes, their range is not set.
* The top left character is position 1, 1.
* Note that since this is an abstract syntax tree,
* it leaves out a lot of text from the original source file,
* like where braces or comma's are exactly.
* Therefore there is no position information on everything in the original source file.
*
Observers
* It is possible to add observers to the the tree.
* Any change in the tree is sent as an event to any observers watching.
*
Visitors
* The most comfortable way of working with an abstract syntax tree is using visitors.
* You can use one of the visitors in the visitor package, or extend one of them.
* A visitor can be "run" by calling accept on a node:
*
node.accept(visitor, argument);
* where argument is an object of your choice (often simply null.)
*
* @author Julio Vilmar Gesser
*/
public abstract class Node implements Cloneable, HasParentNode, Visitable, NodeWithRange, NodeWithTokenRange {
/**
* Different registration mode for observers on nodes.
*/
public enum ObserverRegistrationMode {
/**
* Notify exclusively for changes happening on this node alone.
*/
JUST_THIS_NODE,
/**
* Notify for changes happening on this node and all its descendants existing at the moment in
* which the observer was registered. Nodes attached later will not be observed.
*/
THIS_NODE_AND_EXISTING_DESCENDANTS,
/**
* Notify for changes happening on this node and all its descendants. The descendants existing at the moment in
* which the observer was registered will be observed immediately. As new nodes are attached later they are
* automatically registered to be observed.
*/
SELF_PROPAGATING
}
public enum Parsedness {
PARSED, UNPARSABLE
}
/**
* This can be used to sort nodes on position.
*/
public static Comparator> NODE_BY_BEGIN_POSITION = (a, b) -> {
if (a.getRange().isPresent() && b.getRange().isPresent()) {
return a.getRange().get().begin.compareTo(b.getRange().get().begin);
}
if (a.getRange().isPresent() || b.getRange().isPresent()) {
if (a.getRange().isPresent()) {
return 1;
}
return -1;
}
return 0;
};
private static PrettyPrinterConfiguration toStringPrettyPrinterConfiguration = new PrettyPrinterConfiguration();
protected static final PrettyPrinterConfiguration prettyPrinterNoCommentsConfiguration = new PrettyPrinterConfiguration().setPrintComments(false);
@InternalProperty
private Range range;
@InternalProperty
private TokenRange tokenRange;
@InternalProperty
private Node parentNode;
@InternalProperty
private List childNodes = new LinkedList<>();
@InternalProperty
private List orphanComments = new LinkedList<>();
@InternalProperty
private IdentityHashMap, Object> data = null;
@OptionalProperty
private Comment comment;
@InternalProperty
private Set observers = new HashSet<>();
@InternalProperty
private Parsedness parsed = PARSED;
protected Node(TokenRange tokenRange) {
setTokenRange(tokenRange);
}
/**
* Called in every constructor for node specific code.
* It can't be written in the constructor itself because it will
* be overwritten during code generation.
*/
protected void customInitialization() {
}
/**
* This is a comment associated with this node.
*
* @return comment property
*/
@Generated("com.github.javaparser.generator.core.node.PropertyGenerator")
public Optional getComment() {
return Optional.ofNullable(comment);
}
/**
* @return the range of characters in the source code that this node covers.
*/
public Optional getRange() {
return Optional.ofNullable(range);
}
/**
* @return the range of tokens that this node covers.
*/
public Optional getTokenRange() {
return Optional.ofNullable(tokenRange);
}
public Node setTokenRange(TokenRange tokenRange) {
this.tokenRange = tokenRange;
if (tokenRange == null || !(tokenRange.getBegin().getRange().isPresent() && tokenRange.getEnd().getRange().isPresent())) {
range = null;
} else {
range = new Range(tokenRange.getBegin().getRange().get().begin, tokenRange.getEnd().getRange().get().end);
}
return this;
}
/**
* @param range the range of characters in the source code that this node covers. null can be used to indicate that
* no range information is known, or that it is not of interest.
*/
public Node setRange(Range range) {
if (this.range == range) {
return this;
}
notifyPropertyChange(ObservableProperty.RANGE, this.range, range);
this.range = range;
return this;
}
/**
* Use this to store additional information to this node.
*
* @param comment to be set
*/
public Node setComment(final Comment comment) {
if (this.comment == comment) {
return this;
}
notifyPropertyChange(ObservableProperty.COMMENT, this.comment, comment);
if (this.comment != null) {
this.comment.setCommentedNode(null);
}
this.comment = comment;
if (comment != null) {
this.comment.setCommentedNode(this);
}
return this;
}
/**
* Use this to store additional information to this node.
*
* @param comment to be set
*/
public final Node setLineComment(String comment) {
return setComment(new LineComment(comment));
}
/**
* Use this to store additional information to this node.
*
* @param comment to be set
*/
public final Node setBlockComment(String comment) {
return setComment(new BlockComment(comment));
}
/**
* @return pretty printed source code for this node and its children.
* Formatting can be configured with Node.setToStringPrettyPrinterConfiguration.
*/
@Override
public final String toString() {
return new PrettyPrinter(toStringPrettyPrinterConfiguration).print(this);
}
/**
* @return pretty printed source code for this node and its children.
* Formatting can be configured with parameter prettyPrinterConfiguration.
*/
public final String toString(PrettyPrinterConfiguration prettyPrinterConfiguration) {
return new PrettyPrinter(prettyPrinterConfiguration).print(this);
}
@Override
public final int hashCode() {
return HashCodeVisitor.hashCode(this);
}
@Override
public boolean equals(final Object obj) {
if (obj == null || !(obj instanceof Node)) {
return false;
}
return EqualsVisitor.equals(this, (Node) obj);
}
@Override
public Optional getParentNode() {
return Optional.ofNullable(parentNode);
}
/**
* Contains all nodes that have this node set as their parent.
* You can add and remove nodes from this list by adding or removing nodes from the fields of this node.
*
* @return all nodes that have this node as their parent.
*/
public List getChildNodes() {
return unmodifiableList(childNodes);
}
public void addOrphanComment(Comment comment) {
orphanComments.add(comment);
comment.setParentNode(this);
}
public boolean removeOrphanComment(Comment comment) {
boolean removed = orphanComments.remove(comment);
if (removed) {
notifyPropertyChange(ObservableProperty.COMMENT, comment, null);
comment.setParentNode(null);
}
return removed;
}
/**
* This is a list of Comment which are inside the node and are not associated
* with any meaningful AST Node.
*
* For example, comments at the end of methods (immediately before the parenthesis)
* or at the end of CompilationUnit are orphan comments.
*
* When more than one comment preceeds a statement, the one immediately preceding it
* it is associated with the statements, while the others are orphans.
*
* Changes to this list are not persisted.
*
* @return all comments that cannot be attributed to a concept
*/
public List getOrphanComments() {
return new LinkedList<>(orphanComments);
}
/**
* This is the list of Comment which are contained in the Node either because
* they are properly associated to one of its children or because they are floating
* around inside the Node
*
* @return all Comments within the node as a list
*/
public List getAllContainedComments() {
List comments = new LinkedList<>();
comments.addAll(getOrphanComments());
for (Node child : getChildNodes()) {
child.getComment().ifPresent(comments::add);
comments.addAll(child.getAllContainedComments());
}
return comments;
}
/**
* Assign a new parent to this node, removing it
* from the list of children of the previous parent, if any.
*
* @param newParentNode node to be set as parent
*/
@Override
public Node setParentNode(Node newParentNode) {
if (newParentNode == parentNode) {
return this;
}
observers.forEach(o -> o.parentChange(this, parentNode, newParentNode));
// remove from old parent, if any
if (parentNode != null) {
final List parentChildNodes = parentNode.childNodes;
for (int i = 0; i < parentChildNodes.size(); i++) {
if (parentChildNodes.get(i) == this) {
parentChildNodes.remove(i);
}
}
}
parentNode = newParentNode;
// add to new parent, if any
if (parentNode != null) {
parentNode.childNodes.add(this);
}
return this;
}
protected void setAsParentNodeOf(Node childNode) {
if (childNode != null) {
childNode.setParentNode(getParentNodeForChildren());
}
}
/**
* @deprecated Use {@link Position#ABSOLUTE_BEGIN_LINE}
*/
@Deprecated
public static final int ABSOLUTE_BEGIN_LINE = Position.ABSOLUTE_BEGIN_LINE;
/**
* @deprecated Use {@link Position#ABSOLUTE_END_LINE}
*/
@Deprecated
public static final int ABSOLUTE_END_LINE = Position.ABSOLUTE_END_LINE;
public void tryAddImportToParentCompilationUnit(Class clazz) {
findAncestor(CompilationUnit.class).ifPresent(p -> p.addImport(clazz));
}
/**
* Recursively finds all nodes of a certain type.
*
* @param clazz the type of node to find.
* @deprecated use {@link Node#findAll(Class)} but be aware that findAll also considers the initial node.
*/
@Deprecated
public List getChildNodesByType(Class clazz) {
List nodes = new ArrayList<>();
for (Node child : getChildNodes()) {
if (clazz.isInstance(child)) {
nodes.add(clazz.cast(child));
}
nodes.addAll(child.getChildNodesByType(clazz));
}
return nodes;
}
/**
* @deprecated use {@link Node#findAll(Class)} but be aware that findAll also considers the initial node.
*/
@Deprecated
public List getNodesByType(Class clazz) {
return getChildNodesByType(clazz);
}
/**
* Gets data for this node using the given key.
*
* @param The type of the data.
* @param key The key for the data
* @return The data.
* @throws IllegalStateException if the key was not set in this node.
* @see Node#containsData(DataKey)
* @see DataKey
*/
@SuppressWarnings("unchecked")
public M getData(final DataKey key) {
if (data == null) {
throw new IllegalStateException("No data of this type found. Use containsData to check for this first.");
}
M value = (M) data.get(key);
if (value == null) {
throw new IllegalStateException("No data of this type found. Use containsData to check for this first.");
}
return value;
}
/**
* This method was added to support the clone method.
*
* @return all known data keys.
*/
public Set> getDataKeys() {
if (data == null) {
return emptySet();
}
return data.keySet();
}
/**
* Sets data for this node using the given key.
* For information on creating DataKey, see {@link DataKey}.
*
* @param The type of data
* @param key The singleton key for the data
* @param object The data object
* @see DataKey
*/
public void setData(DataKey key, M object) {
if (data == null) {
data = new IdentityHashMap<>();
}
data.put(key, object);
}
/**
* @return does this node have data for this key?
* @see DataKey
*/
public boolean containsData(DataKey key) {
if (data == null) {
return false;
}
return data.containsKey(key);
}
/**
* Remove data by key.
*
* @see DataKey
*/
public void removeData(DataKey key) {
if (data != null) {
data.remove(key);
}
}
/**
* Try to remove this node from the parent
*
* @return true if removed, false if it is a required property of the parent, or if the parent isn't set.
* @throws RuntimeException if it fails in an unexpected way
*/
public boolean remove() {
if (parentNode == null) {
return false;
}
return parentNode.remove(this);
}
/**
* Try to replace this node in the parent with the supplied node.
*
* @return true if removed, or if the parent isn't set.
* @throws RuntimeException if it fails in an unexpected way
*/
public boolean replace(Node node) {
if (parentNode == null) {
return false;
}
return parentNode.replace(this, node);
}
/**
* Forcibly removes this node from the AST.
* If it cannot be removed from the parent with remove(),
* it will try to remove its parent instead,
* until it finds a node that can be removed,
* or no parent can be found.
*
* Since everything at CompilationUnit level is removable,
* this method will only (silently) fail when the node is in a detached AST fragment.
*/
public void removeForced() {
if (!remove()) {
getParentNode().ifPresent(Node::remove);
}
}
@Override
public Node getParentNodeForChildren() {
return this;
}
protected void setAsParentNodeOf(NodeList list) {
if (list != null) {
list.setParentNode(getParentNodeForChildren());
}
}
public
void notifyPropertyChange(ObservableProperty property, P oldValue, P newValue) {
this.observers.forEach(o -> o.propertyChange(this, property, oldValue, newValue));
}
@Override
public void unregister(AstObserver observer) {
this.observers.remove(observer);
}
@Override
public void register(AstObserver observer) {
this.observers.add(observer);
}
/**
* Register a new observer for the given node. Depending on the mode specified also descendants, existing
* and new, could be observed. For more details see ObserverRegistrationMode.
*/
public void register(AstObserver observer, ObserverRegistrationMode mode) {
if (mode == null) {
throw new IllegalArgumentException("Mode should be not null");
}
switch(mode) {
case JUST_THIS_NODE:
register(observer);
break;
case THIS_NODE_AND_EXISTING_DESCENDANTS:
registerForSubtree(observer);
break;
case SELF_PROPAGATING:
registerForSubtree(PropagatingAstObserver.transformInPropagatingObserver(observer));
break;
default:
throw new UnsupportedOperationException("This mode is not supported: " + mode);
}
}
/**
* Register the observer for the current node and all the contained node and nodelists, recursively.
*/
public void registerForSubtree(AstObserver observer) {
register(observer);
this.getChildNodes().forEach(c -> c.registerForSubtree(observer));
for (PropertyMetaModel property : getMetaModel().getAllPropertyMetaModels()) {
if (property.isNodeList()) {
NodeList nodeList = (NodeList) property.getValue(this);
if (nodeList != null)
nodeList.register(observer);
}
}
}
@Override
public boolean isRegistered(AstObserver observer) {
return this.observers.contains(observer);
}
@Generated("com.github.javaparser.generator.core.node.RemoveMethodGenerator")
public boolean remove(Node node) {
if (node == null)
return false;
if (comment != null) {
if (node == comment) {
removeComment();
return true;
}
}
return false;
}
@Generated("com.github.javaparser.generator.core.node.RemoveMethodGenerator")
public Node removeComment() {
return setComment((Comment) null);
}
@Override
@Generated("com.github.javaparser.generator.core.node.CloneGenerator")
public Node clone() {
return (Node) accept(new CloneVisitor(), null);
}
/**
* @return get JavaParser specific node introspection information.
*/
@Generated("com.github.javaparser.generator.core.node.GetMetaModelGenerator")
public NodeMetaModel getMetaModel() {
return JavaParserMetaModel.nodeMetaModel;
}
/**
* @return whether this node was successfully parsed or not.
* If it was not, only the range and tokenRange fields will be valid.
*/
public Parsedness getParsed() {
return parsed;
}
/**
* Used by the parser to flag unparsable nodes.
*/
public Node setParsed(Parsedness parsed) {
this.parsed = parsed;
return this;
}
public static PrettyPrinterConfiguration getToStringPrettyPrinterConfiguration() {
return toStringPrettyPrinterConfiguration;
}
public static void setToStringPrettyPrinterConfiguration(PrettyPrinterConfiguration toStringPrettyPrinterConfiguration) {
Node.toStringPrettyPrinterConfiguration = toStringPrettyPrinterConfiguration;
}
@Generated("com.github.javaparser.generator.core.node.ReplaceMethodGenerator")
public boolean replace(Node node, Node replacementNode) {
if (node == null)
return false;
if (comment != null) {
if (node == comment) {
setComment((Comment) replacementNode);
return true;
}
}
return false;
}
/**
* Finds the root node of this AST by finding the topmost parent.
*/
public Node findRootNode() {
Node n = this;
while (n.getParentNode().isPresent()) {
n = n.getParentNode().get();
}
return n;
}
/**
* @return the containing CompilationUnit, or empty if this node is not inside a compilation unit.
*/
public Optional findCompilationUnit() {
Node rootNode = findRootNode();
if (rootNode instanceof CompilationUnit) {
return Optional.of((CompilationUnit) rootNode);
}
return Optional.empty();
}
protected SymbolResolver getSymbolResolver() {
return findCompilationUnit().map(cu -> {
if (cu.containsData(SYMBOL_RESOLVER_KEY)) {
return cu.getData(SYMBOL_RESOLVER_KEY);
} else {
throw new IllegalStateException("Symbol resolution not configured: to configure consider setting a SymbolResolver in the ParserConfiguration");
}
}).orElseThrow(() -> new IllegalStateException("The node is not inserted in a CompilationUnit"));
}
// We need to expose it because we will need to use it to inject the SymbolSolver
public static final DataKey SYMBOL_RESOLVER_KEY = new DataKey() {
};
public enum TreeTraversal {
PREORDER, BREADTHFIRST, POSTORDER, PARENTS, DIRECT_CHILDREN
}
private Iterator treeIterator(TreeTraversal traversal) {
switch(traversal) {
case BREADTHFIRST:
return new BreadthFirstIterator(this);
case POSTORDER:
return new PostOrderIterator(this);
case PREORDER:
return new PreOrderIterator(this);
case DIRECT_CHILDREN:
return new DirectChildrenIterator(this);
case PARENTS:
return new ParentsVisitor(this);
default:
throw new IllegalArgumentException("Unknown traversal choice.");
}
}
private Iterable treeIterable(TreeTraversal traversal) {
return () -> treeIterator(traversal);
}
/**
* Make a stream of nodes using traversal algorithm "traversal".
*/
public Stream stream(TreeTraversal traversal) {
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(treeIterator(traversal), NONNULL | DISTINCT), false);
}
/**
* Make a stream of nodes using pre-order traversal.
*/
public Stream stream() {
return StreamSupport.stream(Spliterators.spliteratorUnknownSize(treeIterator(PREORDER), NONNULL | DISTINCT), false);
}
/**
* Walks the AST, calling the consumer for every node, with traversal algorithm "traversal".
*
This is the most general walk method. All other walk and findAll methods are based on this.
*/
public void walk(TreeTraversal traversal, Consumer consumer) {
// Could be implemented as a call to the above walk method, but this is a little more efficient.
for (Node node : treeIterable(traversal)) {
consumer.accept(node);
}
}
/**
* Walks the AST, calling the consumer for every node with pre-order traversal.
*/
public void walk(Consumer consumer) {
walk(PREORDER, consumer);
}
/**
* Walks the AST with pre-order traversal, calling the consumer for every node of type "nodeType".
*/
public void walk(Class nodeType, Consumer consumer) {
walk(TreeTraversal.PREORDER, node -> {
if (nodeType.isAssignableFrom(node.getClass())) {
consumer.accept(nodeType.cast(node));
}
});
}
/**
* Walks the AST with pre-order traversal, returning all nodes of type "nodeType".
*/
public List findAll(Class nodeType) {
final List found = new ArrayList<>();
walk(nodeType, found::add);
return found;
}
/**
* Walks the AST with pre-order traversal, returning all nodes of type "nodeType" that match the predicate.
*/
public List findAll(Class nodeType, Predicate predicate) {
final List found = new ArrayList<>();
walk(nodeType, n -> {
if (predicate.test(n))
found.add(n);
});
return found;
}
/**
* Walks the AST, applying the function for every node, with traversal algorithm "traversal". If the function
* returns something else than null, the traversal is stopped and the function result is returned.
This is the
* most general findFirst method. All other findFirst methods are based on this.
*/
public Optional findFirst(TreeTraversal traversal, Function> consumer) {
for (Node node : treeIterable(traversal)) {
final Optional result = consumer.apply(node);
if (result.isPresent()) {
return result;
}
}
return Optional.empty();
}
/**
* Walks the AST with pre-order traversal, returning the first node of type "nodeType" or empty() if none is found.
*/
public Optional findFirst(Class nodeType) {
return findFirst(TreeTraversal.PREORDER, node -> {
if (nodeType.isAssignableFrom(node.getClass())) {
return Optional.of(nodeType.cast(node));
}
return Optional.empty();
});
}
/**
* Walks the AST with pre-order traversal, returning the first node of type "nodeType" that matches "predicate" or empty() if none is
* found.
*/
public Optional findFirst(Class nodeType, Predicate predicate) {
return findFirst(TreeTraversal.PREORDER, node -> {
if (nodeType.isAssignableFrom(node.getClass())) {
final N castNode = nodeType.cast(node);
if (predicate.test(castNode)) {
return Optional.of(castNode);
}
}
return Optional.empty();
});
}
/**
* Determines whether this node is an ancestor of the given node. A node is not an ancestor of itself.
*
* @param descendant the node for which to determine whether it has this node as an ancestor.
* @return {@code true} if this node is an ancestor of the given node, and {@code false} otherwise.
* @see HasParentNode#isDescendantOf(Node)
*/
public boolean isAncestorOf(Node descendant) {
return this != descendant && findFirst(Node.class, n -> n == descendant).isPresent();
}
/**
* Performs a breadth-first node traversal starting with a given node.
*
* @see Breadth-first traversal
*/
public static class BreadthFirstIterator implements Iterator {
private final Queue queue = new LinkedList<>();
public BreadthFirstIterator(Node node) {
queue.add(node);
}
@Override
public boolean hasNext() {
return !queue.isEmpty();
}
@Override
public Node next() {
Node next = queue.remove();
queue.addAll(next.getChildNodes());
return next;
}
}
/**
* Performs a simple traversal over all nodes that have the passed node as their parent.
*/
public static class DirectChildrenIterator implements Iterator {
private final Iterator childrenIterator;
public DirectChildrenIterator(Node node) {
childrenIterator = new ArrayList<>(node.getChildNodes()).iterator();
}
@Override
public boolean hasNext() {
return childrenIterator.hasNext();
}
@Override
public Node next() {
return childrenIterator.next();
}
}
/**
* Iterates over the parent of the node, then the parent's parent, then the parent's parent's parent, until running
* out of parents.
*/
public static class ParentsVisitor implements Iterator {
private Node node;
public ParentsVisitor(Node node) {
this.node = node;
}
@Override
public boolean hasNext() {
return node.getParentNode().isPresent();
}
@Override
public Node next() {
node = node.getParentNode().orElse(null);
return node;
}
}
/**
* Performs a pre-order (or depth-first) node traversal starting with a given node.
*
* @see Pre-order traversal
*/
public static class PreOrderIterator implements Iterator {
private final Stack stack = new Stack<>();
public PreOrderIterator(Node node) {
stack.add(node);
}
@Override
public boolean hasNext() {
return !stack.isEmpty();
}
@Override
public Node next() {
Node next = stack.pop();
List children = next.getChildNodes();
for (int i = children.size() - 1; i >= 0; i--) {
stack.add(children.get(i));
}
return next;
}
}
/**
* Performs a post-order (or leaves-first) node traversal starting with a given node.
*
* @see Post-order traversal
*/
public static class PostOrderIterator implements Iterator {
private final Stack> nodesStack = new Stack<>();
private final Stack cursorStack = new Stack<>();
private final Node root;
private boolean hasNext = true;
public PostOrderIterator(Node root) {
this.root = root;
fillStackToLeaf(root);
}
private void fillStackToLeaf(Node node) {
while (true) {
List childNodes = new ArrayList<>(node.getChildNodes());
if (childNodes.isEmpty()) {
break;
}
nodesStack.push(childNodes);
cursorStack.push(0);
node = childNodes.get(0);
}
}
@Override
public boolean hasNext() {
return hasNext;
}
@Override
public Node next() {
final List nodes = nodesStack.peek();
final int cursor = cursorStack.peek();
final boolean levelHasNext = cursor < nodes.size();
if (levelHasNext) {
Node node = nodes.get(cursor);
fillStackToLeaf(node);
return nextFromLevel();
} else {
nodesStack.pop();
cursorStack.pop();
hasNext = !nodesStack.empty();
if (hasNext) {
return nextFromLevel();
}
return root;
}
}
private Node nextFromLevel() {
final List nodes = nodesStack.peek();
final int cursor = cursorStack.pop();
cursorStack.push(cursor + 1);
return nodes.get(cursor);
}
}
}