Adds tree iterators based on CPS defunctionalization
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70e2911852
commit
84161ab2ed
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@ -0,0 +1,386 @@
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package net.abhinavsarkar.algorist;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import java.util.function.Consumer;
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class TreeIerators {
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public static void main(String[] args) {
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Tree<String> tree =
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new Tree<>(new Tree<>(new Tree<>(null, "x", null), "a", null),
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"b",
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new Tree<>(new Tree<>(null, "o", null), "c", new Tree<>(null, "r", null)));
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// InOrderIterator
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InOrderIterator.iterateRecursive(tree, System.out::print);
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System.out.println("\tInOrderIterator.iterateRecursive");
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InOrderIterator.iterateCPS(tree, System.out::print, () -> {});
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System.out.println("\tInOrderIterator.iterateCPS");
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InOrderIterator.iterateDefCPS(tree, System.out::print, null);
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System.out.println("\tInOrderIterator.iterateDefCPS");
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InOrderIterator.iterate(tree, System.out::print, null);
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System.out.println("\tInOrderIterator.iterate");
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InOrderIterator<String> inOrderIterator = new InOrderIterator<>(tree);
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while (inOrderIterator.hasNext()) {
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System.out.print(inOrderIterator.next());
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}
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System.out.println("\tInOrderIterator");
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System.out.println();
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// PreOrderIterator
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PreOrderIterator.iterateRecursive(tree, System.out::print);
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System.out.println("\tPreOrderIterator.iterateRecursive");
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PreOrderIterator.iterateCPS(tree, System.out::print, () -> {});
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System.out.println("\tPreOrderIterator.iterateCPS");
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PreOrderIterator.iterateDefCPS(tree, System.out::print, null);
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System.out.println("\tPreOrderIterator.iterateDefCPS");
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PreOrderIterator.iterate(tree, System.out::print, null);
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System.out.println("\tPreOrderIterator.iterate");
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PreOrderIterator<String> preOrderIterator = new PreOrderIterator<>(tree);
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while (preOrderIterator.hasNext()) {
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System.out.print(preOrderIterator.next());
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}
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System.out.println("\tPreOrderIterator");
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System.out.println();
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PostOrderIterator.iterateRecursive(tree, System.out::print);
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System.out.println("\tPostOrderIterator.iterateRecursive");
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// PostOrderIterator
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PostOrderIterator.iterateCPS(tree, System.out::print, () -> {});
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System.out.println("\tPostOrderIterator.iterateCPS");
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PostOrderIterator.iterateDefCPS(tree, System.out::print, null);
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System.out.println("\tPostOrderIterator.iterateDefCPS");
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PostOrderIterator.iterate(tree, System.out::print, null);
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System.out.println("\tPostOrderIterator.iterate");
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PostOrderIterator<String> postOrderIterator = new PostOrderIterator<>(tree);
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while (postOrderIterator.hasNext()) {
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System.out.print(postOrderIterator.next());
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}
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System.out.println("\tPostOrderIterator");
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}
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}
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class Tree<T> {
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Tree<T> left;
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T content;
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Tree<T> right;
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Tree(Tree<T> left, T content, Tree<T> right) {
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this.left = left;
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this.content = content;
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this.right = right;
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}
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@Override
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public String toString() {
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return content.toString();
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}
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}
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class InOrderIterator<T> implements Iterator<T> {
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private static class Cont<T> {
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Tree<T> tree;
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Cont<T> next;
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Cont(Tree<T> tree, Cont<T> next) {
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this.tree = tree;
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this.next = next;
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}
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}
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static <T> void iterateRecursive(Tree<T> tree, Consumer<T> action) {
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if (tree != null) {
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iterateRecursive(tree.left, action);
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action.accept(tree.content);
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iterateRecursive(tree.right, action);
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}
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}
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static <T> void iterateCPS(Tree<T> tree, Consumer<T> action, Runnable cont) {
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if (tree != null) {
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iterateCPS(tree.left, action, () -> {
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action.accept(tree.content);
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iterateCPS(tree.right, action, cont);
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});
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} else {
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cont.run();
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}
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}
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static <T> void iterateDefCPS(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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if (tree != null) {
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iterateDefCPS(tree.left, action, new Cont<>(tree, cont));
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} else {
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if (cont != null) {
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action.accept(cont.tree.content);
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iterateDefCPS(cont.tree.right, action, cont.next);
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} else {
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return;
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}
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}
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}
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static <T> void iterate(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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while (true) {
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if (tree != null) {
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cont = new Cont<>(tree, cont);
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tree = tree.left;
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} else {
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if (cont != null) {
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action.accept(cont.tree.content);
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tree = cont.tree.right;
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cont = cont.next;
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} else {
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return;
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}
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}
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}
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}
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private Tree<T> tree;
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private Cont<T> cont;
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InOrderIterator(Tree<T> tree) {
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this.tree = tree;
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}
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@Override
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public boolean hasNext() {
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return tree != null || cont != null;
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}
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@Override
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public T next() {
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while (hasNext()) {
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if (tree != null) {
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cont = new Cont<>(tree, cont);
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tree = tree.left;
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} else {
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if (cont != null) {
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T content = cont.tree.content;
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tree = cont.tree.right;
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cont = cont.next;
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return content;
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}
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}
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}
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throw new NoSuchElementException();
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}
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}
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class PreOrderIterator<T> implements Iterator<T> {
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private static class Cont<T> {
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Tree<T> tree;
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Cont<T> next;
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Cont(Tree<T> tree, Cont<T> next) {
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this.tree = tree;
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this.next = next;
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}
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}
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static <T> void iterateRecursive(Tree<T> tree, Consumer<T> action) {
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if (tree != null) {
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action.accept(tree.content);
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iterateRecursive(tree.left, action);
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iterateRecursive(tree.right, action);
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}
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}
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static <T> void iterateCPS(Tree<T> tree, Consumer<T> action, Runnable cont) {
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if (tree != null) {
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action.accept(tree.content);
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iterateCPS(tree.left, action, () -> iterateCPS(tree.right, action, cont));
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} else {
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cont.run();
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}
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}
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static <T> void iterateDefCPS(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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if (tree != null) {
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action.accept(tree.content);
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iterateDefCPS(tree.left, action, tree.right != null ? new Cont<>(tree.right, cont) : cont);
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} else {
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if (cont != null) {
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iterateDefCPS(cont.tree, action, cont.next);
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} else {
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return;
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}
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}
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}
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static <T> void iterate(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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while (true) {
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if (tree != null) {
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action.accept(tree.content);
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if (tree.right != null) {
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cont = new Cont<>(tree.right, cont);
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}
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tree = tree.left;
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} else {
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if (cont != null) {
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tree = cont.tree;
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cont = cont.next;
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} else {
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return;
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}
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}
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}
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}
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private Tree<T> tree;
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private Cont<T> cont;
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PreOrderIterator(Tree<T> tree) {
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this.tree = tree;
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}
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@Override
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public boolean hasNext() {
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return tree != null || cont != null;
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}
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@Override
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public T next() {
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while (hasNext()) {
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if (tree != null) {
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T content = tree.content;
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if (tree.right != null) {
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cont = new Cont<>(tree.right, cont);
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}
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tree = tree.left;
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return content;
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} else {
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if (cont != null) {
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tree = cont.tree;
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cont = cont.next;
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}
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}
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}
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throw new NoSuchElementException();
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}
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}
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class PostOrderIterator<T> implements Iterator<T> {
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static class Cont<T> {
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Tree<T> tree;
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boolean isRight;
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Cont<T> next;
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Cont(Tree<T> tree, boolean isRight, Cont<T> next) {
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this.tree = tree;
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this.next = next;
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this.isRight = isRight;
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}
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}
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static <T> void iterateRecursive(Tree<T> tree, Consumer<T> action) {
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if (tree != null) {
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iterateRecursive(tree.left, action);
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iterateRecursive(tree.right, action);
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action.accept(tree.content);
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}
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}
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static <T> void iterateCPS(Tree<T> tree, Consumer<T> action, Runnable cont) {
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if (tree != null) {
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iterateCPS(tree.left, action, () -> iterateCPS(tree.right, action, () -> {
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action.accept(tree.content);
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cont.run();
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}));
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} else {
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cont.run();
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}
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}
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static <T> void iterateDefCPS(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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if (cont == null && tree == null) {
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return;
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}
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if (tree != null) {
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cont = new Cont<>(tree, false, cont);
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iterateDefCPS(tree.left, action, tree.right != null ? new Cont<>(tree.right, true, cont) : cont);
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} else {
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if (!cont.isRight) {
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action.accept(cont.tree.content);
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}
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iterateDefCPS(cont.isRight ? cont.tree : null, action, cont.next);
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}
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}
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static <T> void iterate(Tree<T> tree, Consumer<T> action, Cont<T> cont) {
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while (tree != null || cont != null) {
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if (tree != null) {
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cont = new Cont<>(tree, false, cont);
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cont = tree.right != null ? new Cont<>(tree.right, true, cont) : cont;
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tree = tree.left;
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} else {
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if (!cont.isRight) {
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action.accept(cont.tree.content);
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tree = null;
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} else {
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tree = cont.tree;
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}
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cont = cont.next;
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}
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}
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}
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private Tree<T> tree;
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private Cont<T> cont;
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PostOrderIterator(Tree<T> tree) {
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this.tree = tree;
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}
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@Override
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public boolean hasNext() {
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return tree != null || cont != null;
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}
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@Override
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public T next() {
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while (hasNext()) {
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if (tree != null) {
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cont = new Cont<>(tree, false, cont);
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cont = tree.right != null ? new Cont<>(tree.right, true, cont) : cont;
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tree = tree.left;
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} else {
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T content = null;
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if (!cont.isRight) {
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content = cont.tree.content;
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tree = null;
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} else {
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tree = cont.tree;
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}
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cont = cont.next;
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if (content != null) {
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return content;
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}
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}
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}
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throw new NoSuchElementException();
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}
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}
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