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Library providing immutable/persistent collection classes for
Java. While collections are immutable they provide methods for
adding and removing values by creating new modified copies of
themselves. Each copy shares almost all of its structure with
other copies to minimize memory consumption.
///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2019, Burton Computer Corporation
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the
// distribution.
//
// Neither the name of the Burton Computer Corporation nor the names
// of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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package org.javimmutable.collections.list;
import org.javimmutable.collections.Func2;
import org.javimmutable.collections.Proc1Throws;
import org.javimmutable.collections.Sum1Throws;
import org.javimmutable.collections.indexed.IndexedHelper;
import org.javimmutable.collections.iterators.GenericIterator;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.util.StringJoiner;
import java.util.function.Consumer;
@Immutable
class BranchNode
extends AbstractNode
{
private final AbstractNode left;
private final AbstractNode right;
private final int size;
private final int depth;
BranchNode(@Nonnull AbstractNode left,
@Nonnull AbstractNode right)
{
this(left, right, left.size() + right.size());
}
BranchNode(@Nonnull AbstractNode left,
@Nonnull AbstractNode right,
int size)
{
assert !left.isEmpty();
assert !right.isEmpty();
this.left = left;
this.right = right;
this.size = size;
this.depth = 1 + Math.max(left.depth(), right.depth());
assert size > MultiValueNode.MAX_SIZE;
}
/**
* Low level build a new node from the specified child nodes.
* Assumes that the two nodes are already in balance. If the
* size of the resulting node is small enough a leaf is return.
* Otherwise a branch is returned.
*/
@Nonnull
private static AbstractNode join(@Nonnull AbstractNode left,
@Nonnull AbstractNode right)
{
final int size = left.size() + right.size();
if (size <= MultiValueNode.MAX_SIZE) {
return new MultiValueNode<>(left, right, size);
} else {
return new BranchNode<>(left, right, size);
}
}
/**
* Build a new node from the specified child nodes. Performs rotations if necessary to ensure the tree
* remains in balance (depths of two child branches stay within 1 of each other).
*/
@Nonnull
static AbstractNode balance(@Nonnull AbstractNode left,
@Nonnull AbstractNode right)
{
final int diff = left.depth() - right.depth();
if (diff > 1) {
return rotateRight(left, right);
} else if (diff < -1) {
return rotateLeft(right, left);
} else {
return join(left, right);
}
}
@Override
boolean isEmpty()
{
return size == 0;
}
@Override
int size()
{
return size;
}
@Override
int depth()
{
return depth;
}
@Override
T get(int index)
{
final int leftSize = left.size();
if (index < leftSize) {
return left.get(index);
} else {
return right.get(index - leftSize);
}
}
@Nonnull
@Override
AbstractNode append(T value)
{
return balance(left, right.append(value));
}
@Nonnull
@Override
AbstractNode append(@Nonnull AbstractNode node)
{
if (node.isEmpty()) {
return this;
}
final int diff = depth - node.depth();
if (diff < 0) {
return node.prepend(this);
} else if (diff <= 1) {
return new BranchNode<>(this, node);
} else {
return balance(left, right.append(node));
}
}
@Nonnull
@Override
AbstractNode prepend(T value)
{
return balance(left.prepend(value), right);
}
@Nonnull
@Override
AbstractNode prepend(@Nonnull AbstractNode node)
{
if (node.isEmpty()) {
return this;
}
final int diff = depth - node.depth();
if (diff < 0) {
return node.append(this);
} else if (diff <= 1) {
return new BranchNode<>(node, this);
} else {
return balance(left.prepend(node), right);
}
}
@Nonnull
@Override
AbstractNode assign(int index,
T value)
{
final int leftSize = left.size();
if (index < leftSize) {
return new BranchNode<>(left.assign(index, value), right);
} else {
return new BranchNode<>(left, right.assign(index - leftSize, value));
}
}
@Nonnull
@Override
AbstractNode insert(int index,
T value)
{
final int leftSize = left.size();
if (index < leftSize) {
return balance(left.insert(index, value), right);
} else if (index == leftSize && leftSize <= right.size()) {
return balance(left.insert(index, value), right);
} else {
return balance(left, right.insert(index - leftSize, value));
}
}
@Nonnull
@Override
AbstractNode delete(int index)
{
final int leftSize = left.size();
final AbstractNode newLeft, newRight;
if (index < leftSize) {
newLeft = left.delete(index);
newRight = right;
if (newLeft.isEmpty()) {
return right;
}
} else {
newLeft = left;
newRight = right.delete(index - leftSize);
if (newRight.isEmpty()) {
return left;
}
}
return balance(newLeft, newRight);
}
@Nonnull
@Override
AbstractNode deleteFirst()
{
final AbstractNode newLeft = left.deleteFirst();
if (newLeft.isEmpty()) {
return right;
} else {
return balance(newLeft, right);
}
}
@Nonnull
@Override
AbstractNode deleteLast()
{
final AbstractNode newRight = right.deleteLast();
if (newRight.isEmpty()) {
return left;
} else {
return balance(left, newRight);
}
}
@Override
void copyTo(T[] array,
int offset)
{
left.copyTo(array, offset);
right.copyTo(array, offset + left.size());
}
@Nonnull
@Override
AbstractNode prefix(int limit)
{
if (limit == size) {
return this;
} else if (limit == 0) {
return EmptyNode.instance();
} else {
final int leftSize = left.size();
if (limit <= leftSize) {
return left.prefix(limit);
} else {
return left.append(right.prefix(limit - leftSize));
}
}
}
@Nonnull
@Override
AbstractNode suffix(int offset)
{
if (offset == 0) {
return this;
} else if (offset == size) {
return EmptyNode.instance();
} else {
final int leftSize = left.size();
if (offset < leftSize) {
return left.suffix(offset).append(right);
} else {
return right.suffix(offset - leftSize);
}
}
}
@Nonnull
@Override
AbstractNode left()
{
return left;
}
@Nonnull
@Override
AbstractNode right()
{
return right;
}
@Nonnull
private static AbstractNode rotateRight(@Nonnull AbstractNode node,
@Nonnull AbstractNode parentRight)
{
final AbstractNode left = node.left();
final AbstractNode right = node.right();
if (left.depth() >= right.depth()) {
return join(left, join(right, parentRight));
} else {
return join(join(left, right.left()), join(right.right(), parentRight));
}
}
@Nonnull
private static AbstractNode rotateLeft(@Nonnull AbstractNode node,
@Nonnull AbstractNode parentLeft)
{
final AbstractNode left = node.left();
final AbstractNode right = node.right();
if (left.depth() > right.depth()) {
return join(join(parentLeft, left.left()), join(left.right(), right));
} else {
return join(join(parentLeft, left), right);
}
}
@Override
public void checkInvariants()
{
if (depth != Math.max(left.depth(), right.depth()) + 1) {
throw new RuntimeException(String.format("incorrect depth: depth=%d leftDepth=%d rightDepth=%d", depth, left.depth(), right.depth()));
}
if (Math.abs(left.depth() - right.depth()) > 1) {
throw new RuntimeException(String.format("invalid child depths: leftDepth=%d rightDepth=%d", left.depth(), right.depth()));
}
if (size != left.size() + right.size()) {
throw new RuntimeException(String.format("incorrect size: size=%d leftSize=%d rightSize=%d", size, left.size(), right.size()));
}
if (size <= MultiValueNode.MAX_SIZE) {
throw new RuntimeException(String.format("invalid size: size=%d leftSize=%d rightSize=%d", size, left.size(), right.size()));
}
if (left.isEmpty() || right.isEmpty()) {
throw new RuntimeException(String.format("branch node has an empty branch: leftSize=%d rightSize=%d", left.size(), right.size()));
}
left.checkInvariants();
right.checkInvariants();
}
@Override
public boolean equals(Object o)
{
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
BranchNode that = (BranchNode)o;
if (size != that.size) {
return false;
}
if (depth != that.depth) {
return false;
}
if (!left.equals(that.left)) {
return false;
}
return right.equals(that.right);
}
@Override
public int hashCode()
{
int result = left.hashCode();
result = 31 * result + right.hashCode();
result = 31 * result + size;
result = 31 * result + depth;
return result;
}
public String toString()
{
return new StringJoiner(", ", BranchNode.class.getSimpleName() + "[", "]")
.add("left=" + left)
.add("right=" + right)
.add("size=" + size)
.add("depth=" + depth)
.toString();
}
@Nullable
@Override
public GenericIterator.State iterateOverRange(@Nullable GenericIterator.State parent,
int offset,
int limit)
{
assert offset >= 0 && limit <= size && offset <= limit;
return GenericIterator.indexedState(parent, IndexedHelper.indexed(left, right), offset, limit);
}
@Override
public void forEach(Consumer action)
{
left.forEach(action);
right.forEach(action);
}
@Override
public void forEachThrows(@Nonnull Proc1Throws proc)
throws E
{
left.forEachThrows(proc);
right.forEachThrows(proc);
}
@Override
public V reduce(V sum,
Func2 accumulator)
{
sum = left.reduce(sum, accumulator);
sum = right.reduce(sum, accumulator);
return sum;
}
@Override
public V reduceThrows(V sum,
Sum1Throws accumulator)
throws E
{
sum = left.reduceThrows(sum, accumulator);
sum = right.reduceThrows(sum, accumulator);
return sum;
}
}