org.javimmutable.collections.list.BranchNode Maven / Gradle / Ivy
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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 reverse()
{
return new BranchNode<>(right.reverse(), left.reverse(), size);
}
@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;
}
}
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