javaslang.collection.Queue Maven / Gradle / Ivy
/* / \____ _ _ ____ ______ / \ ____ __ _______
* / / \/ \ / \/ \ / /\__\/ // \/ \ // /\__\ JΛVΛSLΛNG
* _/ / /\ \ \/ / /\ \\__\\ \ // /\ \ /\\/ \ /__\ \ Copyright 2014-2016 Javaslang, http://javaslang.io
* /___/\_/ \_/\____/\_/ \_/\__\/__/\__\_/ \_// \__/\_____/ Licensed under the Apache License, Version 2.0
*/
package javaslang.collection;
import javaslang.*;
import javaslang.control.Option;
import java.io.Serializable;
import java.util.*;
import java.util.function.*;
import java.util.stream.Collector;
/**
* An immutable {@code Queue} stores elements allowing a first-in-first-out (FIFO) retrieval.
*
* Queue API:
*
*
* - {@link #dequeue()}
* - {@link #dequeueOption()}
* - {@link #enqueue(Object)}
* - {@link #enqueue(Object[])}
* - {@link #enqueueAll(Iterable)}
* - {@link #peek()}
* - {@link #peekOption()}
*
*
* A Queue internally consists of a front List containing the front elements of the Queue in the correct order and a
* rear List containing the rear elements of the Queue in reverse order.
*
* When the front list is empty, front and rear are swapped and rear is reversed. This implies the following queue
* invariant: {@code front.isEmpty() => rear.isEmpty()}.
*
* See Okasaki, Chris: Purely Functional Data Structures (p. 42 ff.). Cambridge, 2003.
*
* @param Component type of the Queue
* @author Daniel Dietrich
* @since 2.0.0
*/
public class Queue implements Kind1, T>, LinearSeq, Serializable {
private static final long serialVersionUID = 1L;
private static final Queue EMPTY = new Queue<>(List.empty(), List.empty());
private final List front;
private final List rear;
/**
* Creates a Queue consisting of a front List and a rear List.
*
* For a {@code Queue(front, rear)} the following invariant holds: {@code Queue is empty <=> front is empty}.
* In other words: If the Queue is not empty, the front List contains at least one element.
*
* @param front A List of front elements, in correct order.
* @param rear A List of rear elements, in reverse order.
*/
private Queue(List front, List rear) {
final boolean frontIsEmpty = front.isEmpty();
this.front = frontIsEmpty ? rear.reverse() : front;
this.rear = frontIsEmpty ? front : rear;
}
/**
* Returns a {@link java.util.stream.Collector} which may be used in conjunction with
* {@link java.util.stream.Stream#collect(java.util.stream.Collector)} to obtain a {@link javaslang.collection.Queue}
* .
*
* @param Component type of the Queue.
* @return A javaslang.collection.Queue Collector.
*/
public static Collector, Queue> collector() {
final Supplier> supplier = ArrayList::new;
final BiConsumer, T> accumulator = ArrayList::add;
final BinaryOperator> combiner = (left, right) -> {
left.addAll(right);
return left;
};
final Function, Queue> finisher = Queue::ofAll;
return Collector.of(supplier, accumulator, combiner, finisher);
}
/**
* Returns the empty Queue.
*
* @param Component type
* @return The empty Queue.
*/
@SuppressWarnings("unchecked")
public static Queue empty() {
return (Queue) EMPTY;
}
/**
* Narrows a widened {@code Queue} to {@code Queue}
* by performing a type safe-cast. This is eligible because immutable/read-only
* collections are covariant.
*
* @param queue An {@code Queue}.
* @param Component type of the {@code Queue}.
* @return the given {@code queue} instance as narrowed type {@code Queue}.
*/
@SuppressWarnings("unchecked")
public static Queue narrow(Queue queue) {
return (Queue) queue;
}
/**
* Returns a singleton {@code Queue}, i.e. a {@code Queue} of one element.
*
* @param element An element.
* @param The component type
* @return A new Queue instance containing the given element
*/
public static Queue of(T element) {
return Queue.ofAll(List.of(element));
}
/**
* Creates a Queue of the given elements.
*
* @param Component type of the Queue.
* @param elements Zero or more elements.
* @return A queue containing the given elements in the same order.
* @throws NullPointerException if {@code elements} is null
*/
@SuppressWarnings("varargs")
@SafeVarargs
public static Queue of(T... elements) {
Objects.requireNonNull(elements, "elements is null");
return Queue.ofAll(List.of(elements));
}
/**
* Creates a Queue of the given elements.
*
* @param Component type of the Queue.
* @param elements An Iterable of elements.
* @return A queue containing the given elements in the same order.
* @throws NullPointerException if {@code elements} is null
*/
@SuppressWarnings("unchecked")
public static Queue ofAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
if (elements instanceof Queue) {
return (Queue) elements;
} else if (!elements.iterator().hasNext()) {
return empty();
} else if (elements instanceof List) {
return new Queue<>((List) elements, List.empty());
} else {
return new Queue<>(List.ofAll(elements), List.empty());
}
}
/**
* Creates a Queue based on the elements of a boolean array.
*
* @param array a boolean array
* @return A new Seq of Boolean values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(boolean[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a byte array.
*
* @param array a byte array
* @return A new Queue of Byte values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(byte[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a char array.
*
* @param array a char array
* @return A new Queue of Character values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(char[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a double array.
*
* @param array a double array
* @return A new Queue of Double values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(double[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a float array.
*
* @param array a float array
* @return A new Queue of Float values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(float[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of an int array.
*
* @param array an int array
* @return A new Queue of Integer values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(int[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a long array.
*
* @param array a long array
* @return A new Queue of Long values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(long[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Creates a Queue based on the elements of a short array.
*
* @param array a short array
* @return A new Queue of Short values
* @throws NullPointerException if array is null
*/
public static Queue ofAll(short[] array) {
Objects.requireNonNull(array, "array is null");
return Queue.ofAll(List.ofAll(array));
}
/**
* Returns a Queue containing {@code n} values of a given Function {@code f}
* over a range of integer values from 0 to {@code n - 1}.
*
* @param Component type of the Queue
* @param n The number of elements in the Queue
* @param f The Function computing element values
* @return A Queue consisting of elements {@code f(0),f(1), ..., f(n - 1)}
* @throws NullPointerException if {@code f} is null
*/
public static Queue tabulate(int n, Function f) {
Objects.requireNonNull(f, "f is null");
return Collections.tabulate(n, f, Queue.empty(), Queue::of);
}
/**
* Returns a Queue containing {@code n} values supplied by a given Supplier {@code s}.
*
* @param Component type of the Queue
* @param n The number of elements in the Queue
* @param s The Supplier computing element values
* @return An Queue of size {@code n}, where each element contains the result supplied by {@code s}.
* @throws NullPointerException if {@code s} is null
*/
public static Queue fill(int n, Supplier s) {
Objects.requireNonNull(s, "s is null");
return Collections.fill(n, s, Queue.empty(), Queue::of);
}
public static Queue range(char from, char toExclusive) {
return Queue.ofAll(Iterator.range(from, toExclusive));
}
public static Queue rangeBy(char from, char toExclusive, int step) {
return Queue.ofAll(Iterator.rangeBy(from, toExclusive, step));
}
public static Queue rangeBy(double from, double toExclusive, double step) {
return Queue.ofAll(Iterator.rangeBy(from, toExclusive, step));
}
/**
* Creates a Queue of int numbers starting from {@code from}, extending to {@code toExclusive - 1}.
*
* Examples:
*
*
* Queue.range(0, 0) // = Queue()
* Queue.range(2, 0) // = Queue()
* Queue.range(-2, 2) // = Queue(-2, -1, 0, 1)
*
*
*
* @param from the first number
* @param toExclusive the last number + 1
* @return a range of int values as specified or {@code Nil} if {@code from >= toExclusive}
*/
public static Queue range(int from, int toExclusive) {
return Queue.ofAll(Iterator.range(from, toExclusive));
}
/**
* Creates a Queue of int numbers starting from {@code from}, extending to {@code toExclusive - 1},
* with {@code step}.
*
* Examples:
*
*
* Queue.rangeBy(1, 3, 1) // = Queue(1, 2)
* Queue.rangeBy(1, 4, 2) // = Queue(1, 3)
* Queue.rangeBy(4, 1, -2) // = Queue(4, 2)
* Queue.rangeBy(4, 1, 2) // = Queue()
*
*
*
* @param from the first number
* @param toExclusive the last number + 1
* @param step the step
* @return a range of long values as specified or {@code Nil} if
* {@code from >= toInclusive} and {@code step > 0} or
* {@code from <= toInclusive} and {@code step < 0}
* @throws IllegalArgumentException if {@code step} is zero
*/
public static Queue rangeBy(int from, int toExclusive, int step) {
return Queue.ofAll(Iterator.rangeBy(from, toExclusive, step));
}
/**
* Creates a Queue of long numbers starting from {@code from}, extending to {@code toExclusive - 1}.
*
* Examples:
*
*
* Queue.range(0L, 0L) // = Queue()
* Queue.range(2L, 0L) // = Queue()
* Queue.range(-2L, 2L) // = Queue(-2L, -1L, 0L, 1L)
*
*
*
* @param from the first number
* @param toExclusive the last number + 1
* @return a range of long values as specified or {@code Nil} if {@code from >= toExclusive}
*/
public static Queue range(long from, long toExclusive) {
return Queue.ofAll(Iterator.range(from, toExclusive));
}
/**
* Creates a Queue of long numbers starting from {@code from}, extending to {@code toExclusive - 1},
* with {@code step}.
*
* Examples:
*
*
* Queue.rangeBy(1L, 3L, 1L) // = Queue(1L, 2L)
* Queue.rangeBy(1L, 4L, 2L) // = Queue(1L, 3L)
* Queue.rangeBy(4L, 1L, -2L) // = Queue(4L, 2L)
* Queue.rangeBy(4L, 1L, 2L) // = Queue()
*
*
*
* @param from the first number
* @param toExclusive the last number + 1
* @param step the step
* @return a range of long values as specified or {@code Nil} if
* {@code from >= toInclusive} and {@code step > 0} or
* {@code from <= toInclusive} and {@code step < 0}
* @throws IllegalArgumentException if {@code step} is zero
*/
public static Queue rangeBy(long from, long toExclusive, long step) {
return Queue.ofAll(Iterator.rangeBy(from, toExclusive, step));
}
public static Queue rangeClosed(char from, char toInclusive) {
return Queue.ofAll(Iterator.rangeClosed(from, toInclusive));
}
public static Queue rangeClosedBy(char from, char toInclusive, int step) {
return Queue.ofAll(Iterator.rangeClosedBy(from, toInclusive, step));
}
public static Queue rangeClosedBy(double from, double toInclusive, double step) {
return Queue.ofAll(Iterator.rangeClosedBy(from, toInclusive, step));
}
/**
* Creates a Queue of int numbers starting from {@code from}, extending to {@code toInclusive}.
*
* Examples:
*
*
* Queue.rangeClosed(0, 0) // = Queue(0)
* Queue.rangeClosed(2, 0) // = Queue()
* Queue.rangeClosed(-2, 2) // = Queue(-2, -1, 0, 1, 2)
*
*
*
* @param from the first number
* @param toInclusive the last number
* @return a range of int values as specified or {@code Nil} if {@code from > toInclusive}
*/
public static Queue rangeClosed(int from, int toInclusive) {
return Queue.ofAll(Iterator.rangeClosed(from, toInclusive));
}
/**
* Creates a Queue of int numbers starting from {@code from}, extending to {@code toInclusive},
* with {@code step}.
*
* Examples:
*
*
* Queue.rangeClosedBy(1, 3, 1) // = Queue(1, 2, 3)
* Queue.rangeClosedBy(1, 4, 2) // = Queue(1, 3)
* Queue.rangeClosedBy(4, 1, -2) // = Queue(4, 2)
* Queue.rangeClosedBy(4, 1, 2) // = Queue()
*
*
*
* @param from the first number
* @param toInclusive the last number
* @param step the step
* @return a range of int values as specified or {@code Nil} if
* {@code from > toInclusive} and {@code step > 0} or
* {@code from < toInclusive} and {@code step < 0}
* @throws IllegalArgumentException if {@code step} is zero
*/
public static Queue rangeClosedBy(int from, int toInclusive, int step) {
return Queue.ofAll(Iterator.rangeClosedBy(from, toInclusive, step));
}
/**
* Creates a Queue of long numbers starting from {@code from}, extending to {@code toInclusive}.
*
* Examples:
*
*
* Queue.rangeClosed(0L, 0L) // = Queue(0L)
* Queue.rangeClosed(2L, 0L) // = Queue()
* Queue.rangeClosed(-2L, 2L) // = Queue(-2L, -1L, 0L, 1L, 2L)
*
*
*
* @param from the first number
* @param toInclusive the last number
* @return a range of long values as specified or {@code Nil} if {@code from > toInclusive}
*/
public static Queue rangeClosed(long from, long toInclusive) {
return Queue.ofAll(Iterator.rangeClosed(from, toInclusive));
}
/**
* Creates a Queue of long numbers starting from {@code from}, extending to {@code toInclusive},
* with {@code step}.
*
* Examples:
*
*
* Queue.rangeClosedBy(1L, 3L, 1L) // = Queue(1L, 2L, 3L)
* Queue.rangeClosedBy(1L, 4L, 2L) // = Queue(1L, 3L)
* Queue.rangeClosedBy(4L, 1L, -2L) // = Queue(4L, 2L)
* Queue.rangeClosedBy(4L, 1L, 2L) // = Queue()
*
*
*
* @param from the first number
* @param toInclusive the last number
* @param step the step
* @return a range of int values as specified or {@code Nil} if
* {@code from > toInclusive} and {@code step > 0} or
* {@code from < toInclusive} and {@code step < 0}
* @throws IllegalArgumentException if {@code step} is zero
*/
public static Queue rangeClosedBy(long from, long toInclusive, long step) {
return Queue.ofAll(Iterator.rangeClosedBy(from, toInclusive, step));
}
/**
* Removes an element from this Queue.
*
* @return a tuple containing the first element and the remaining elements of this Queue
* @throws java.util.NoSuchElementException if this Queue is empty
*/
public Tuple2> dequeue() {
if (isEmpty()) {
throw new NoSuchElementException("dequeue of empty Queue");
} else {
return Tuple.of(head(), tail());
}
}
/**
* Removes an element from this Queue.
*
* @return {@code None} if this Queue is empty, otherwise {@code Some} {@code Tuple} containing the first element and the remaining elements of this Queue
*/
public Option>> dequeueOption() {
return isEmpty() ? Option.none() : Option.some(dequeue());
}
/**
* Enqueues a new element.
*
* @param element The new element
* @return a new {@code Queue} instance, containing the new element
*/
public Queue enqueue(T element) {
return new Queue<>(front, rear.prepend(element));
}
/**
* Enqueues the given elements. A queue has FIFO order, i.e. the first of the given elements is
* the first which will be retrieved.
*
* @param elements Elements, may be empty
* @return a new {@code Queue} instance, containing the new elements
* @throws NullPointerException if elements is null
*/
@SuppressWarnings("unchecked")
public Queue enqueue(T... elements) {
Objects.requireNonNull(elements, "elements is null");
List temp = rear;
for (T element : elements) {
temp = temp.prepend(element);
}
return new Queue<>(front, temp);
}
/**
* Enqueues the given elements. A queue has FIFO order, i.e. the first of the given elements is
* the first which will be retrieved.
*
* @param elements An Iterable of elements, may be empty
* @return a new {@code Queue} instance, containing the new elements
* @throws NullPointerException if elements is null
*/
public Queue enqueueAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
List temp = rear;
for (T element : elements) {
temp = temp.prepend(element);
}
return new Queue<>(front, temp);
}
/**
* Returns the first element without modifying the Queue.
*
* @return the first element
* @throws java.util.NoSuchElementException if this Queue is empty
*/
public T peek() {
if (isEmpty()) {
throw new NoSuchElementException("peek of empty Queue");
} else {
return front.head();
}
}
/**
* Returns the first element without modifying the Queue.
*
* @return {@code None} if this Queue is empty, otherwise a {@code Some} containing the first element
*/
public Option peekOption() {
return isEmpty() ? Option.none() : Option.some(peek());
}
// -- Adjusted return types of Seq methods
@Override
public Queue append(T element) {
return enqueue(element);
}
@Override
public Queue appendAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
return enqueueAll(elements);
}
@Override
public Queue> combinations() {
return toList().combinations().map(Queue::ofAll).toQueue();
}
@Override
public Queue> combinations(int k) {
return toList().combinations(k).map(Queue::ofAll).toQueue();
}
@Override
public Iterator> crossProduct(int power) {
return Collections.crossProduct(Queue.empty(), this, power);
}
@Override
public Queue distinct() {
return toList().distinct().toQueue();
}
@Override
public Queue distinctBy(Comparator comparator) {
Objects.requireNonNull(comparator, "comparator is null");
return toList().distinctBy(comparator).toQueue();
}
@Override
public Queue distinctBy(Function keyExtractor) {
Objects.requireNonNull(keyExtractor, "keyExtractor is null");
return toList().distinctBy(keyExtractor).toQueue();
}
@Override
public Queue drop(long n) {
if (n <= 0) {
return this;
}
if (n >= length()) {
return empty();
}
return new Queue<>(front.drop(n), rear.dropRight(n - front.length()));
}
@Override
public Queue dropRight(long n) {
if (n <= 0) {
return this;
}
if (n >= length()) {
return empty();
}
return new Queue<>(front.dropRight(n - rear.length()), rear.drop(n));
}
@Override
public Queue dropUntil(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
return dropWhile(predicate.negate());
}
@Override
public Queue dropWhile(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
final List dropped = toList().dropWhile(predicate);
return dropped.length() == length() ? this : dropped.toQueue();
}
@Override
public Queue filter(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
final List filtered = toList().filter(predicate);
return filtered.length() == length() ? this : filtered.toQueue();
}
@Override
public Queue flatMap(Function> mapper) {
Objects.requireNonNull(mapper, "mapper is null");
if (isEmpty()) {
return empty();
} else {
return new Queue<>(front.flatMap(mapper), rear.flatMap(mapper));
}
}
@Override
public T get(int index) {
if (isEmpty()) {
throw new IndexOutOfBoundsException("get(" + index + ") on empty Queue");
}
if (index < 0) {
throw new IndexOutOfBoundsException("get(" + index + ")");
}
final int length = front.length();
if (index < length) {
return front.get(index);
} else {
final int rearIndex = index - length;
final int rearLength = rear.length();
if (rearIndex < rearLength) {
final int reverseRearIndex = rearLength - rearIndex - 1;
return rear.get(reverseRearIndex);
} else {
throw new IndexOutOfBoundsException(String.format("get(%s) on Queue of length %s", index, length()));
}
}
}
@Override
public Map> groupBy(Function classifier) {
return Collections.groupBy(this, classifier, Queue::ofAll);
}
@Override
public Iterator> grouped(long size) {
return sliding(size, size);
}
@Override
public boolean hasDefiniteSize() {
return true;
}
@Override
public T head() {
if (isEmpty()) {
throw new NoSuchElementException("head of empty queue");
} else {
return front.head();
}
}
@Override
public int indexOf(T element, int from) {
final int frontIndex = front.indexOf(element, from);
if (frontIndex != -1) {
return frontIndex;
} else {
// we need to reverse because we search the first occurrence
final int rearIndex = rear.reverse().indexOf(element, from - front.length());
return (rearIndex == -1) ? -1 : rearIndex + front.length();
}
}
@Override
public Queue init() {
if (isEmpty()) {
throw new UnsupportedOperationException("init of empty Queue");
} else if (rear.isEmpty()) {
return new Queue<>(front.init(), rear);
} else {
return new Queue<>(front, rear.tail());
}
}
@Override
public Option> initOption() {
return isEmpty() ? Option.none() : Option.some(init());
}
@Override
public Queue insert(int index, T element) {
if (index < 0) {
throw new IndexOutOfBoundsException("insert(" + index + ", e)");
}
final int length = front.length();
if (index <= length) {
return new Queue<>(front.insert(index, element), rear);
} else {
final int rearIndex = index - length;
final int rearLength = rear.length();
if (rearIndex <= rearLength) {
final int reverseRearIndex = rearLength - rearIndex;
return new Queue<>(front, rear.insert(reverseRearIndex, element));
} else {
throw new IndexOutOfBoundsException(
String.format("insert(%s, e) on Queue of length %s", index, length()));
}
}
}
@Override
public Queue insertAll(int index, Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
if (index < 0) {
throw new IndexOutOfBoundsException("insertAll(" + index + ", e)");
}
final int length = front.length();
if (index <= length) {
return new Queue<>(front.insertAll(index, elements), rear);
} else {
final int rearIndex = index - length;
final int rearLength = rear.length();
if (rearIndex <= rearLength) {
final int reverseRearIndex = rearLength - rearIndex;
return new Queue<>(front, rear.insertAll(reverseRearIndex, List.ofAll(elements).reverse()));
} else {
throw new IndexOutOfBoundsException(
String.format("insertAll(%s, e) on Queue of length %s", index, length()));
}
}
}
@Override
public Queue intersperse(T element) {
if (isEmpty()) {
return this;
} else if (rear.isEmpty()) {
return new Queue<>(front.intersperse(element), rear);
} else {
return new Queue<>(front.intersperse(element), rear.intersperse(element).append(element));
}
}
@Override
public boolean isEmpty() {
return front.isEmpty();
}
@Override
public boolean isTraversableAgain() {
return true;
}
@Override
public int lastIndexOf(T element, int end) {
return toList().lastIndexOf(element, end);
}
@Override
public int length() {
return front.length() + rear.length();
}
@Override
public Queue map(Function mapper) {
Objects.requireNonNull(mapper, "mapper is null");
return new Queue<>(front.map(mapper), rear.map(mapper));
}
@Override
public Queue padTo(int length, T element) {
if (length <= length()) {
return this;
}
return toList().padTo(length, element).toQueue();
}
@Override
public Queue patch(int from, Iterable that, int replaced) {
from = from < 0 ? 0 : from;
replaced = replaced < 0 ? 0 : replaced;
Queue result = take(from).appendAll(that);
from += replaced;
result = result.appendAll(drop(from));
return result;
}
@Override
public Tuple2, Queue> partition(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
return toList().partition(predicate).map(List::toQueue, List::toQueue);
}
@Override
public Queue peek(Consumer action) {
Objects.requireNonNull(action, "action is null");
if (!isEmpty()) {
action.accept(head());
}
return this;
}
@Override
public Queue> permutations() {
return toList().permutations().map(List::toQueue).toQueue();
}
@Override
public Queue prepend(T element) {
return new Queue<>(front.prepend(element), rear);
}
@Override
public Queue prependAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
return new Queue<>(front.prependAll(elements), rear);
}
@Override
public Queue remove(T element) {
final List removed = toList().remove(element);
return removed.length() == length() ? this : removed.toQueue();
}
@Override
public Queue removeFirst(Predicate predicate) {
final List removed = toList().removeFirst(predicate);
return removed.length() == length() ? this : removed.toQueue();
}
@Override
public Queue removeLast(Predicate predicate) {
final List removed = toList().removeLast(predicate);
return removed.length() == length() ? this : removed.toQueue();
}
@Override
public Queue removeAt(int index) {
return toList().removeAt(index).toQueue();
}
@Override
public Queue removeAll(T element) {
final List newFront = front.removeAll(element);
final List newRear = rear.removeAll(element);
return newFront.length() + newRear.length() == length() ? this : new Queue<>(newFront, newRear);
}
@Override
public Queue removeAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
final List newFront = front.removeAll(elements);
final List newRear = rear.removeAll(elements);
return newFront.length() + newRear.length() == length() ? this : new Queue<>(newFront, newRear);
}
@Override
public Queue replace(T currentElement, T newElement) {
final List newFront = front.replace(currentElement, newElement);
final List newRear = rear.replace(currentElement, newElement);
return newFront.size() + newRear.size() == 0 ? empty()
: newFront == front && newRear == rear ? this
: new Queue<>(newFront, newRear);
}
@Override
public Queue replaceAll(T currentElement, T newElement) {
final List newFront = front.replaceAll(currentElement, newElement);
final List newRear = rear.replaceAll(currentElement, newElement);
return newFront.size() + newRear.size() == 0 ? empty()
: newFront == front && newRear == rear ? this
: new Queue<>(newFront, newRear);
}
@Override
public Queue retainAll(Iterable elements) {
Objects.requireNonNull(elements, "elements is null");
final List newFront = front.retainAll(elements);
final List newRear = rear.retainAll(elements);
return newFront.size() + newRear.size() == 0 ? empty()
: newFront.size() + newRear.size() == size() ? this
: new Queue<>(newFront, newRear);
}
@Override
public Queue reverse() {
return isEmpty() ? this : toList().reverse().toQueue();
}
@Override
public Queue scan(T zero, BiFunction operation) {
return scanLeft(zero, operation);
}
@Override
public Queue scanLeft(U zero, BiFunction operation) {
Objects.requireNonNull(operation, "operation is null");
// prepends to the rear-list in O(1)
return Collections.scanLeft(this, zero, operation, Queue.empty(), Queue::append, Function.identity());
}
@Override
public Queue scanRight(U zero, BiFunction operation) {
// add elements in reverse order in O(1) and creates a Queue instance in O(1)
final List list = Collections.scanRight(this, zero, operation, List.empty(), List::prepend, Function.identity());
return Queue.ofAll(list);
}
@Override
public Queue slice(long beginIndex, long endIndex) {
return toList().slice(beginIndex, endIndex).toQueue();
}
@Override
public Iterator> sliding(long size) {
return sliding(size, 1);
}
@Override
public Iterator> sliding(long size, long step) {
return iterator().sliding(size, step).map(Queue::ofAll);
}
@Override
public Queue sorted() {
return toList().sorted().toQueue();
}
@Override
public Queue sorted(Comparator comparator) {
Objects.requireNonNull(comparator, "comparator is null");
return toList().sorted(comparator).toQueue();
}
@Override
public > Queue sortBy(Function mapper) {
return sortBy(U::compareTo, mapper);
}
@Override
public Queue sortBy(Comparator comparator, Function mapper) {
final Function domain = Function1.of(mapper::apply).memoized();
return toJavaStream()
.sorted((e1, e2) -> comparator.compare(domain.apply(e1), domain.apply(e2)))
.collect(collector());
}
@Override
public Tuple2, Queue> span(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
return toList().span(predicate).map(List::toQueue, List::toQueue);
}
@Override
public Tuple2, Queue> splitAt(long n) {
return toList().splitAt(n).map(List::toQueue, List::toQueue);
}
@Override
public Tuple2, Queue> splitAt(Predicate predicate) {
return toList().splitAt(predicate).map(List::toQueue, List::toQueue);
}
@Override
public Tuple2, Queue> splitAtInclusive(Predicate predicate) {
return toList().splitAtInclusive(predicate).map(List::toQueue, List::toQueue);
}
@Override
public boolean startsWith(Iterable that, int offset) {
return toList().startsWith(that, offset);
}
@Override
public Spliterator spliterator() {
return Spliterators.spliterator(iterator(), length(), Spliterator.ORDERED | Spliterator.IMMUTABLE);
}
@Override
public Queue subSequence(int beginIndex) {
return toList().subSequence(beginIndex).toQueue();
}
@Override
public Queue subSequence(int beginIndex, int endIndex) {
return toList().subSequence(beginIndex, endIndex).toQueue();
}
@Override
public Queue tail() {
if (isEmpty()) {
throw new UnsupportedOperationException("tail of empty Queue");
} else {
return new Queue<>(front.tail(), rear);
}
}
@Override
public Option> tailOption() {
return isEmpty() ? Option.none() : Option.some(tail());
}
@Override
public Queue take(long n) {
if (n <= 0) {
return empty();
}
if (n >= length()) {
return this;
}
final int frontLength = front.length();
if (n < frontLength) {
return new Queue<>(front.take(n), List.empty());
} else if (n == frontLength) {
return new Queue<>(front, List.empty());
} else {
return new Queue<>(front, rear.takeRight(n - frontLength));
}
}
@Override
public Queue takeRight(long n) {
if (n <= 0) {
return empty();
}
if (n >= length()) {
return this;
}
final int rearLength = rear.length();
if (n < rearLength) {
return new Queue<>(rear.take(n).reverse(), List.empty());
} else if (n == rearLength) {
return new Queue<>(rear.reverse(), List.empty());
} else {
return new Queue<>(front.takeRight(n - rearLength), rear);
}
}
@Override
public Queue takeUntil(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
return takeWhile(predicate.negate());
}
@Override
public Queue takeWhile(Predicate predicate) {
Objects.requireNonNull(predicate, "predicate is null");
final List taken = toList().takeWhile(predicate);
return taken.length() == length() ? this : taken.toQueue();
}
/**
* Transforms this {@code Queue}.
*
* @param f A transformation
* @param Type of transformation result
* @return An instance of type {@code U}
* @throws NullPointerException if {@code f} is null
*/
public U transform(Function, ? extends U> f) {
Objects.requireNonNull(f, "f is null");
return f.apply(this);
}
@Override
public Queue unit(Iterable iterable) {
return Queue.ofAll(iterable);
}
@Override
public Tuple2, Queue> unzip(
Function> unzipper) {
Objects.requireNonNull(unzipper, "unzipper is null");
return toList().unzip(unzipper).map(List::toQueue, List::toQueue);
}
@Override
public Tuple3, Queue, Queue> unzip3(Function> unzipper) {
Objects.requireNonNull(unzipper, "unzipper is null");
return toList().unzip3(unzipper).map(List::toQueue, List::toQueue, List::toQueue);
}
@Override
public Queue update(int index, T element) {
return toList().update(index, element).toQueue();
}
@SuppressWarnings("unchecked")
@Override
public Queue> zip(Iterable that) {
Objects.requireNonNull(that, "that is null");
return toList().zip((Iterable) that).toQueue();
}
@Override
public Queue> zipAll(Iterable that, T thisElem, U thatElem) {
Objects.requireNonNull(that, "that is null");
return toList().zipAll(that, thisElem, thatElem).toQueue();
}
@Override
public Queue> zipWithIndex() {
return toList().zipWithIndex().toQueue();
}
private Object readResolve() {
return isEmpty() ? EMPTY : this;
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
} else if (o instanceof Queue) {
final Queue that = (Queue) o;
return this.toList().equals(that.toList());
} else {
return false;
}
}
@Override
public int hashCode() {
return toList().hashCode();
}
@Override
public String stringPrefix() {
return "Queue";
}
@Override
public String toString() {
return mkString(stringPrefix() + "(", ", ", ")");
}
}