org.javimmutable.collections.list.BranchNode Maven / Gradle / Ivy
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package org.javimmutable.collections.list;
import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.MutableBuilder;
import org.javimmutable.collections.cursors.LazyCursor;
import org.javimmutable.collections.cursors.MultiCursor;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
/**
* Node implementation containing other nodes. Prefix and suffix nodes can contain nodes
* of any depth and size (including empty) while body nodes array contains only full nodes
* of exactly depth - 1. This allows fast access to the body nodes by a computed offset
* based on size but also quick adds and deletes from either end using the prefix and suffix
* nodes. Once a BranchNode reaches its theoretical limit based on depth any insert triggers
* the creation of a new higher depth node containing the branch so that the new parent's prefix
* or suffix can contain the new value.
*
* @param
*/
@Immutable
class BranchNode
implements Node
{
private final int depth;
private final int size;
private final Node prefix; // possibly empty and can be any depth
private final Node[] nodes; // all of these are full and have depth - 1
private final Node suffix; // possibly empty and can be any depth
private BranchNode(int depth,
int size,
Node prefix,
Node[] nodes,
Node suffix)
{
assert nodes.length <= 32;
assert size <= ListHelper.sizeForDepth(depth);
this.depth = depth;
this.size = size;
this.prefix = prefix;
this.nodes = nodes;
this.suffix = suffix;
}
BranchNode(T prefixValue,
Node node)
{
this(node.getDepth() + 1,
node.size() + 1,
new LeafNode(prefixValue),
ListHelper.allocateSingleNode(node),
EmptyNode.of());
assert node.isFull();
}
BranchNode(Node node,
T suffixValue)
{
this(node.getDepth() + 1,
node.size() + 1,
EmptyNode.of(),
ListHelper.allocateSingleNode(node),
new LeafNode(suffixValue));
assert node.isFull();
}
static Builder builder()
{
return new Builder();
}
static BranchNode forTesting(int depth,
Node prefix,
Node[] nodes,
Node suffix)
{
return new BranchNode(depth,
prefix.size() + (nodes.length * 32) + suffix.size(),
prefix,
nodes.clone(),
suffix);
}
@Override
public boolean isEmpty()
{
return size == 0;
}
@Override
public boolean isFull()
{
return size == ListHelper.sizeForDepth(depth);
}
@Override
public int size()
{
return size;
}
@Override
public int getDepth()
{
return depth;
}
private static Node forDelete(int size,
Node prefix,
Node[] nodes,
Node suffix)
{
if (nodes.length == 0) {
if (prefix.isEmpty()) {
return suffix;
} else if (suffix.isEmpty()) {
return prefix;
} else {
int depth = 1 + Math.max(prefix.getDepth(), suffix.getDepth());
return new BranchNode(depth, size, prefix, nodes, suffix);
}
} else if ((nodes.length == 1) && prefix.isEmpty() && suffix.isEmpty()) {
return nodes[0];
} else {
int depth = 1 + nodes[0].getDepth();
return new BranchNode(depth, size, prefix, nodes, suffix);
}
}
@Override
public Node deleteFirst()
{
if (!prefix.isEmpty()) {
return forDelete(size - 1, prefix.deleteFirst(), nodes, suffix);
}
if (nodes.length > 0) {
Node newPrefix = nodes[0];
Node[] newNodes = ListHelper.allocateNodes(nodes.length - 1);
System.arraycopy(nodes, 1, newNodes, 0, newNodes.length);
return forDelete(size - 1, newPrefix.deleteFirst(), newNodes, suffix);
}
if (!suffix.isEmpty()) {
return suffix.deleteFirst();
}
throw new IllegalStateException();
}
@Override
public Node deleteLast()
{
if (!suffix.isEmpty()) {
return forDelete(size - 1, prefix, nodes, suffix.deleteLast());
}
if (nodes.length > 0) {
Node newSuffix = nodes[nodes.length - 1];
Node[] newNodes = ListHelper.allocateNodes(nodes.length - 1);
System.arraycopy(nodes, 0, newNodes, 0, newNodes.length);
return forDelete(size - 1, prefix, newNodes, newSuffix.deleteLast());
}
if (!prefix.isEmpty()) {
return prefix.deleteLast();
}
throw new IllegalStateException();
}
@Override
public Node insertFirst(T value)
{
if (isFull()) {
return new BranchNode(value, this);
}
if (prefix.getDepth() < (depth - 1)) {
return new BranchNode(depth, size + 1, prefix.insertFirst(value), nodes, suffix);
}
assert prefix.getDepth() == (depth - 1);
assert !prefix.isFull();
Node[] newNodes;
Node newPrefix = prefix.insertFirst(value);
if (newPrefix.isFull()) {
newNodes = ListHelper.allocateNodes(nodes.length + 1);
System.arraycopy(nodes, 0, newNodes, 1, nodes.length);
newNodes[0] = newPrefix;
newPrefix = EmptyNode.of();
} else {
newNodes = nodes;
}
return new BranchNode(depth, size + 1, newPrefix, newNodes, suffix);
}
@Override
public Node insertLast(T value)
{
if (isFull()) {
return new BranchNode(this, value);
}
if (suffix.getDepth() < (depth - 1)) {
return new BranchNode(depth, size + 1, prefix, nodes, suffix.insertLast(value));
}
assert suffix.getDepth() == (depth - 1);
assert !suffix.isFull();
Node[] newNodes;
Node newSuffix = suffix.insertLast(value);
if (newSuffix.isFull()) {
newNodes = ListHelper.allocateNodes(nodes.length + 1);
System.arraycopy(nodes, 0, newNodes, 0, nodes.length);
newNodes[nodes.length] = newSuffix;
newSuffix = EmptyNode.of();
} else {
newNodes = nodes;
}
return new BranchNode(depth, size + 1, prefix, newNodes, newSuffix);
}
@Override
public boolean containsIndex(int index)
{
return (index >= 0) && (index < size);
}
@Override
public T get(int index)
{
if (prefix.containsIndex(index)) {
return prefix.get(index);
}
index -= prefix.size();
final int fullNodeSize = ListHelper.sizeForDepth(depth - 1);
int arrayIndex = index / fullNodeSize;
if (arrayIndex < nodes.length) {
return nodes[arrayIndex].get(index - (arrayIndex * fullNodeSize));
}
index -= nodes.length * fullNodeSize;
if (suffix.containsIndex(index)) {
return suffix.get(index);
}
throw new IndexOutOfBoundsException();
}
@Override
public Node assign(int index,
T value)
{
if (prefix.containsIndex(index)) {
return new BranchNode(depth, size, prefix.assign(index, value), nodes, suffix);
}
index -= prefix.size();
final int fullNodeSize = ListHelper.sizeForDepth(depth - 1);
int arrayIndex = index / fullNodeSize;
if (arrayIndex < nodes.length) {
Node[] newNodes = nodes.clone();
newNodes[arrayIndex] = nodes[arrayIndex].assign(index - (arrayIndex * fullNodeSize), value);
return new BranchNode(depth, size, prefix, newNodes, suffix);
}
index -= nodes.length * fullNodeSize;
if (suffix.containsIndex(index)) {
return new BranchNode(depth, size, prefix, nodes, suffix.assign(index, value));
}
throw new IndexOutOfBoundsException();
}
@Nonnull
@Override
public Cursor cursor()
{
MultiCursor.Builder builder = MultiCursor.builder();
builder = builder.add(LazyCursor.of(prefix));
for (Node node : nodes) {
builder = builder.add(LazyCursor.of(node));
}
builder = builder.add(LazyCursor.of(suffix));
return builder.build();
}
@Override
public void checkInvariants()
{
if (nodes.length > 32) {
throw new IllegalStateException();
}
if ((nodes.length == 32) && !(prefix.isEmpty() && suffix.isEmpty())) {
throw new IllegalStateException();
}
for (Node node : nodes) {
if ((node.getDepth() != (depth - 1)) || !node.isFull()) {
throw new IllegalStateException();
}
}
int computedSize = prefix.size() + suffix.size();
for (Node node : nodes) {
computedSize += node.size();
}
if (computedSize != size) {
throw new IllegalStateException();
}
if (prefix.isFull() && (prefix.getDepth() == (depth - 1))) {
throw new IllegalStateException();
}
if (suffix.isFull() && (suffix.getDepth() == (depth - 1))) {
throw new IllegalStateException();
}
prefix.checkInvariants();
for (Node node : nodes) {
node.checkInvariants();
}
suffix.checkInvariants();
}
static class Builder
implements MutableBuilder>
{
private final List leaves = new ArrayList();
@Nonnull
@Override
public Builder add(T value)
{
leaves.add(value);
return this;
}
@Nonnull
@Override
public Node build()
{
int nodeCount = leaves.size();
if (nodeCount == 0) {
return EmptyNode.of();
}
if (nodeCount <= 32) {
return LeafNode.fromList(leaves, 0, nodeCount);
}
List> nodes = new ArrayList>();
int offset = 0;
while (offset < nodeCount) {
nodes.add(LeafNode.fromList(leaves, offset, Math.min(offset + 32, nodeCount)));
offset += 32;
}
nodeCount = nodes.size();
// loop invariant - all nodes except last one are always full
// last one is possibly full
int depth = 2;
while (nodeCount > 1) {
int dstOffset = 0;
int srcOffset = 0;
// fill all full nodes
while (nodeCount > 32) {
Node[] newNodes = ListHelper.allocateNodes(32);
for (int i = 0; i < 32; ++i) {
newNodes[i] = nodes.get(srcOffset++);
}
nodes.set(dstOffset++, new BranchNode(depth, ListHelper.sizeForDepth(depth), EmptyNode.of(), newNodes, EmptyNode.of()));
nodeCount -= 32;
}
// collect remaining nodes
Node lastNode = nodes.get(srcOffset + (nodeCount - 1));
if ((lastNode.getDepth() == (depth - 1)) && lastNode.isFull()) {
// all remaining nodes are full
Node[] newNodes = ListHelper.allocateNodes(nodeCount);
for (int i = 0; i < newNodes.length; ++i) {
newNodes[i] = nodes.get(srcOffset++);
}
nodes.set(dstOffset++, new BranchNode(depth, ListHelper.sizeForDepth(depth - 1) * newNodes.length, EmptyNode.of(), newNodes, EmptyNode.of()));
} else {
// all but last remaining nodes are full
Node[] newNodes = ListHelper.allocateNodes(nodeCount - 1);
for (int i = 0; i < newNodes.length; ++i) {
newNodes[i] = nodes.get(srcOffset++);
}
nodes.set(dstOffset++, new BranchNode(depth, (ListHelper.sizeForDepth(depth - 1) * newNodes.length) + lastNode.size(), EmptyNode.of(), newNodes, lastNode));
}
nodeCount = dstOffset;
depth += 1;
}
assert nodeCount == 1;
return nodes.get(0);
}
@Nonnull
@Override
public Builder add(Cursor source)
{
for (Cursor cursor = source.start(); cursor.hasValue(); cursor = cursor.next()) {
add(cursor.getValue());
}
return this;
}
@Nonnull
@Override
public Builder add(Iterator source)
{
while (source.hasNext()) {
add(source.next());
}
return this;
}
@Nonnull
@Override
public Builder add(Collection source)
{
add(source.iterator());
return this;
}
@Nonnull
@Override
public Builder add(K... source)
{
for (T value : source) {
add(value);
}
return this;
}
@Nonnull
@Override
public Builder add(Indexed source)
{
return add(source, 0, source.size());
}
@Nonnull
@Override
public Builder add(Indexed source,
int offset,
int limit)
{
for (int i = offset; i < limit; ++i) {
add(source.get(i));
}
return this;
}
}
}
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