98 lines
2.3 KiB
Java
98 lines
2.3 KiB
Java
package serene.simple;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import java.util.function.Function;
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import static java.util.Arrays.asList;
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public class ListNode<T extends Node> extends Node implements Iterable<T> {
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public static final ListNode<?> EMPTY = new ListNode<>();
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public final T first;
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public final ListNode<T> rest;
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public final int length;
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public ListNode() {
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this.first = null;
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this.rest = null;
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this.length = 0;
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}
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public ListNode(T f, ListNode<T> r) {
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this.first = f;
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this.rest = r;
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this.length = r.length + 1;
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}
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@SafeVarargs
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public static <T extends Node> ListNode<T> list(T... objs) {
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return list(asList(objs));
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}
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public static <T extends Node> ListNode<T> list(List<T> objs) {
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ListNode<T> l = (ListNode<T>) EMPTY;
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for (int i = objs.size() - 1; i >= 0; i--) {
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l = l.cons(objs.get(i));
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}
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return l;
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}
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public ListNode<T> cons(T node) {
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return new ListNode<T>(node, this);
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}
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@Override
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public Object eval(Scope scope) {
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Function f = (Function) this.first().eval(scope);
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List<Object> args = new ArrayList<Object>();
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for (T node : this.rest) {
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args.add(node.eval(scope));
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}
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return f.apply(args.toArray());
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}
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public T first() {
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if (this != EMPTY) {
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return this.first;
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}
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return null;
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}
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public ListNode<T> rest() {
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if (this != EMPTY) {
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return this.rest;
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}
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return (ListNode<T>) EMPTY;
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}
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@Override
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public Iterator<T> iterator() {
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return new Iterator<T>() {
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private ListNode<T> l = ListNode.this;
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@Override
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public boolean hasNext() {
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return this.l != EMPTY;
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}
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@Override
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public T next() {
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if (this.l == EMPTY) {
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return null;
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}
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T first = this.l.first;
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this.l = this.l.rest;
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return first;
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}
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@Override
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public void remove() {
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throw new SereneException("Iterator is immutable");
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}
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};
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}
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}
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