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Functional programming library
/*
* Copyright 2014 Shape Security, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.shapesecurity.functional.data;
import java.util.ArrayList;
import com.shapesecurity.functional.F;
import com.shapesecurity.functional.F2;
import com.shapesecurity.functional.Pair;
import org.jetbrains.annotations.NotNull;
public final class NonEmptyImmutableList extends ImmutableList {
@NotNull
public final T head;
@NotNull
public final ImmutableList tail;
protected NonEmptyImmutableList(@NotNull T head, @NotNull final ImmutableList tail) {
super(tail.length + 1);
this.head = head;
this.tail = tail;
}
@NotNull
public ImmutableList tail() {
return tail;
}
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof NonEmptyImmutableList)) {
return false;
}
NonEmptyImmutableList list = (NonEmptyImmutableList) o;
return this.head.equals(list.head) && this.tail().equals(list.tail());
}
@NotNull
@Override
public A foldLeft(@NotNull F2 f, @NotNull A init) {
ImmutableList list = this;
while (list instanceof NonEmptyImmutableList) {
init = f.apply(init, ((NonEmptyImmutableList) list).head);
list = ((NonEmptyImmutableList) list).tail();
}
return init;
}
@NotNull
@Override
public A foldRight(@NotNull F2 f, @NotNull A init) {
return f.apply(this.head, this.tail().foldRight(f, init));
}
@NotNull
public T reduceLeft(@NotNull F2 f) {
return this.tail.foldLeft(f, this.head);
}
@NotNull
public T reduceRight(@NotNull F2 f) {
return this.init().foldRight(f, this.last());
}
@NotNull
@Override
public Maybe maybeHead() {
return Maybe.just(this.head);
}
@NotNull
@Override
public Maybe maybeLast() {
if (this.tail().isEmpty()) {
return Maybe.just(this.head);
}
return this.tail().maybeLast();
}
@NotNull
@Override
public Maybe> maybeTail() {
return Maybe.just(this.tail());
}
@NotNull
@Override
public Maybe> maybeInit() {
if (this.tail().isEmpty()) {
return Maybe.just(nil());
}
return this.tail().maybeInit().map(t -> t.cons(this.head));
}
@NotNull
public final T last() {
NonEmptyImmutableList nel = this;
while (true) {
if (nel.tail().isEmpty()) {
return nel.head;
}
nel = (NonEmptyImmutableList) nel.tail();
}
}
@NotNull
public final ImmutableList init() {
if (this.tail().isEmpty()) {
return nil();
}
return cons(this.head, ((NonEmptyImmutableList) this.tail()).init());
}
@NotNull
@Override
public ImmutableList filter(@NotNull F f) {
@SuppressWarnings("unchecked")
T[] result = (T[]) new Object[length];
ImmutableList list = this;
int j = 0;
for (int i = 0; i < length; i++) {
T el = ((NonEmptyImmutableList) list).head;
if (f.apply(el)) {
result[j] = el;
j++;
}
list = ((NonEmptyImmutableList) list).tail;
}
return fromBounded(result, 0, j);
}
@NotNull
@Override
public NonEmptyImmutableList map(@NotNull F f) {
@SuppressWarnings("unchecked")
B[] result = (B[]) new Object[length];
ImmutableList list = this;
for (int i = 0; i < length; i++) {
result[i] = f.apply(((NonEmptyImmutableList) list).head);
list = ((NonEmptyImmutableList) list).tail;
}
return (NonEmptyImmutableList) from(result);
}
@Override
@NotNull
public final NonEmptyImmutableList mapWithIndex(@NotNull F2 f) {
int length = this.length;
@SuppressWarnings("unchecked")
B[] result = (B[]) new Object[length];
ImmutableList list = this;
for (int i = 0; i < length; i++) {
result[i] = f.apply(i, ((NonEmptyImmutableList) list).head);
list = ((NonEmptyImmutableList) list).tail();
}
return (NonEmptyImmutableList) from(result);
}
@NotNull
@Override
public ImmutableList take(int n) {
if (n <= 0) {
return nil();
}
@SuppressWarnings("unchecked")
T[] result = (T[]) new Object[n];
ImmutableList list = this;
for (int i = 0; i < n; i++) {
result[i] = ((NonEmptyImmutableList) list).head;
list = ((NonEmptyImmutableList) list).tail;
}
return from(result);
}
@NotNull
@Override
public ImmutableList drop(int n) {
if (n <= 0) {
return this;
}
ImmutableList list = this;
while (n > 0) {
if (list instanceof NonEmptyImmutableList) {
list = ((NonEmptyImmutableList) list).tail;
n--;
}
}
return list;
}
@NotNull
@Override
public Maybe> toNonEmptyList() {
return Maybe.just(this);
}
@NotNull
@Override
public Maybe decons(@NotNull F2, B> f) {
return Maybe.just(f.apply(this.head, this.tail()));
}
@NotNull
@Override
public ImmutableList zipWith(@NotNull F2 f, @NotNull ImmutableList list) {
ImmutableList list1 = this;
ImmutableList list2 = list;
int n = Math.min(list1.length, list2.length);
@SuppressWarnings("unchecked")
C[] result = (C[]) new Object[n];
for (int i = 0; i < n; i++) {
result[i] = f.apply(((NonEmptyImmutableList) list1).head, ((NonEmptyImmutableList) list2).head);
list1 = ((NonEmptyImmutableList) list1).tail;
list2 = ((NonEmptyImmutableList) list2).tail;
}
return from(result);
}
@Override
public boolean isEmpty() {
return false;
}
@NotNull
@Override
public ImmutableList append(@NotNull ImmutableList list) {
if (list.length == 0) {
return this;
}
@SuppressWarnings("unchecked")
T[] copy = toArray((T[]) new Object[length]);
@SuppressWarnings("unchecked")
ImmutableList listT = (ImmutableList) list;
for (int i = copy.length - 1; i >= 0; i--) {
listT = cons(copy[i], listT);
}
return listT;
}
@Override
public boolean exists(@NotNull F f) {
NonEmptyImmutableList list = this;
while (true) {
if (f.apply(list.head)) {
return true;
}
if (list.tail instanceof Nil) {
return false;
}
list = ((NonEmptyImmutableList) list.tail);
}
}
@Override
public boolean contains(@NotNull T a) {
NonEmptyImmutableList list = this;
while (true) {
if (list.head == a) {
return true;
}
if (list.tail instanceof Nil) {
return false;
}
list = ((NonEmptyImmutableList) list.tail);
}
}
@NotNull
@Override
public Pair, ImmutableList> span(@NotNull F f) {
@SuppressWarnings("unchecked")
T[] result = (T[]) new Object[length];
ImmutableList list = this;
int j = 0;
for (int i = 0; i < length; i++) {
T el = ((NonEmptyImmutableList) list).head;
if (f.apply(el)) {
result[j] = el;
j++;
} else {
break;
}
list = ((NonEmptyImmutableList) list).tail;
}
return Pair.make(fromBounded(result, 0, j), list);
}
@NotNull
@Override
public ImmutableList flatMap(@NotNull F> f) {
ArrayList result = new ArrayList<>();
ImmutableList list = this;
while (list instanceof NonEmptyImmutableList) {
ImmutableList bucket = f.apply(((NonEmptyImmutableList) list).head);
while (bucket instanceof NonEmptyImmutableList) {
result.add(((NonEmptyImmutableList) bucket).head);
bucket = ((NonEmptyImmutableList) bucket).tail;
}
list = ((NonEmptyImmutableList) list).tail;
}
return from(result);
}
@NotNull
@Override
public ImmutableList removeAll(@NotNull F f) {
return filter(x -> !f.apply(x));
}
@NotNull
@Override
public NonEmptyImmutableList reverse() {
@SuppressWarnings("unchecked")
T[] result = (T[]) new Object[length];
ImmutableList list = this;
for (int i = 0; i < length; i++) {
result[length - i - 1] = ((NonEmptyImmutableList) list).head;
list = ((NonEmptyImmutableList) list).tail;
}
return (NonEmptyImmutableList) from(result);
}
@NotNull
@Override
public Pair> mapAccumL(@NotNull F2> f, @NotNull B acc) {
@SuppressWarnings("unchecked")
C[] result = (C[]) new Object[length];
ImmutableList list = this;
for (int i = 0; i < length; i++) {
Pair pair = f.apply(acc, ((NonEmptyImmutableList) list).head);
acc = pair.a;
result[i] = pair.b;
list = ((NonEmptyImmutableList) list).tail;
}
return new Pair<>(acc, from(result));
}
@Override
protected int calcHashCode() {
int start = HashCodeBuilder.init();
start = HashCodeBuilder.put(start, "List");
start = HashCodeBuilder.put(start, head);
return HashCodeBuilder.put(start, tail);
}
}