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com.shapesecurity.functional.data.ConcatList Maven / Gradle / Ivy
/*
* 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 com.shapesecurity.functional.F;
import com.shapesecurity.functional.F2;
import org.jetbrains.annotations.NotNull;
public abstract class ConcatList {
private static final Empty EMPTY = new Empty<>();
private static BinaryTreeMonoid MONOID = new BinaryTreeMonoid<>();
public final int length;
protected ConcatList(int length) {
this.length = length;
}
@SuppressWarnings("unchecked")
@NotNull
public static ConcatList empty() {
return (ConcatList) EMPTY;
}
@NotNull
public static ConcatList single(@NotNull T scope) {
return new Leaf<>(scope);
}
@SuppressWarnings("unchecked")
public static Monoid> monoid() {
return (BinaryTreeMonoid) MONOID;
}
@NotNull
public final ImmutableList toList() {
return this.toList(ImmutableList.nil());
}
protected abstract ImmutableList toList(@NotNull ImmutableList acc);
@NotNull
public abstract B foldLeft(@NotNull F2 f, @NotNull B init);
@NotNull
public abstract B foldRight(@NotNull F2 f, @NotNull B init);
public abstract boolean isEmpty();
@NotNull
public abstract ConcatList append(@NotNull ConcatList rhs);
@NotNull
public final ConcatList append1(@NotNull T element) {
return this.append(ConcatList.single(element));
}
public abstract boolean exists(@NotNull F f);
@NotNull
public abstract Maybe find(@NotNull F f);
@NotNull
public abstract ConcatList reverse();
@NotNull
public abstract Maybe index(int index);
@NotNull
public abstract Maybe> update(int index, @NotNull T element);
public final static class Empty extends ConcatList {
private Empty() {
super(0);
}
@NotNull
@Override
protected ImmutableList toList(@NotNull ImmutableList acc) {
return acc;
}
@NotNull
@Override
public B foldLeft(@NotNull F2 f, @NotNull B init) {
return init;
}
@NotNull
@Override
public B foldRight(@NotNull F2 f, @NotNull B init) {
return init;
}
@Override
public boolean isEmpty() {
return true;
}
@SuppressWarnings("unchecked")
@NotNull
@Override
public ConcatList append(@NotNull ConcatList rhs) {
return (ConcatList) rhs;
}
@Override
public boolean exists(@NotNull F f) {
return false;
}
@NotNull
@Override
public Maybe find(@NotNull F f) {
return Maybe.nothing();
}
@NotNull
@Override
public ConcatList reverse() {
return this;
}
@NotNull
@Override
public Maybe index(int index) {
return Maybe.nothing();
}
@NotNull
@Override
public Maybe> update(int index, @NotNull T element) {
return Maybe.nothing();
}
}
public final static class Leaf extends ConcatList {
@NotNull
public final T data;
private Leaf(@NotNull T data) {
super(1);
this.data = data;
}
@NotNull
@Override
protected ImmutableList toList(@NotNull ImmutableList acc) {
return acc.cons(this.data);
}
@NotNull
@Override
public B foldLeft(@NotNull F2 f, @NotNull B init) {
return f.apply(init, this.data);
}
@NotNull
@Override
public B foldRight(@NotNull F2 f, @NotNull B init) {
return f.apply(this.data, init);
}
@Override
public boolean isEmpty() {
return false;
}
@SuppressWarnings("unchecked")
@NotNull
@Override
public ConcatList append(@NotNull ConcatList rhs) {
return new Fork<>(this, (ConcatList) rhs);
}
@Override
public boolean exists(@NotNull F f) {
return f.apply(this.data);
}
@NotNull
@Override
public Maybe find(@NotNull F f) {
if (f.apply(this.data)) {
return Maybe.just(this.data);
}
return Maybe.nothing();
}
@NotNull
@Override
public ConcatList reverse() {
return this;
}
@NotNull
@Override
public Maybe index(int index) {
return Maybe.iff(index == 0, this.data);
}
@NotNull
@Override
public Maybe> update(int index, @NotNull T element) {
return index == 0 ? Maybe.just(single(element)) : Maybe.nothing();
}
}
public final static class Fork extends ConcatList {
@NotNull
public final ConcatList left, right;
private Fork(@NotNull ConcatList left, @NotNull ConcatList right) {
super(left.length + right.length);
this.left = left;
this.right = right;
}
@NotNull
@Override
protected ImmutableList toList(@NotNull ImmutableList acc) {
return this.left.toList(this.right.toList(acc));
}
@NotNull
@Override
public B foldLeft(@NotNull F2 f, @NotNull B init) {
return this.right.foldLeft(f, this.left.foldLeft(f, init));
}
@NotNull
@Override
public B foldRight(@NotNull F2 f, @NotNull B init) {
return this.left.foldRight(f, this.right.foldRight(f, init));
}
@Override
public boolean isEmpty() {
return this.left.isEmpty() || this.right.isEmpty();
}
@SuppressWarnings("unchecked")
@NotNull
@Override
public ConcatList append(@NotNull ConcatList rhs) {
return new Fork<>(this, (ConcatList) rhs);
}
@Override
public boolean exists(@NotNull F f) {
return this.left.exists(f) || this.right.exists(f);
}
@NotNull
@Override
public Maybe find(@NotNull F f) {
Maybe foundLeft = this.left.find(f);
if (foundLeft.isNothing()) {
return this.right.find(f);
}
return foundLeft;
}
@NotNull
@Override
public Fork reverse() {
return new Fork<>(this.right.reverse(), this.left.reverse());
}
@NotNull
@Override
public Maybe index(int index) {
if (index >= this.length) {
return Maybe.nothing();
}
return index < this.left.length ? this.left.index(index) : this.right.index(index - this.left.length);
}
@NotNull
@Override
public Maybe> update(int index, @NotNull T element) {
if (index >= this.length) { return Maybe.nothing(); }
ConcatList left = this.left;
ConcatList right = this.right;
if (index < this.left.length) {
left = left.update(index, element).just();
} else {
right = right.update(index - this.left.length, element).just();
}
return Maybe.just(left.append(right));
}
}
private static class BinaryTreeMonoid implements Monoid> {
@NotNull
@Override
public ConcatList identity() {
return new Empty<>();
}
@NotNull
@Override
public ConcatList append(ConcatList a, ConcatList b) {
return a.append(b);
}
}
}
