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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.
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///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2021, 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,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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package org.javimmutable.collections.list;
import org.javimmutable.collections.Indexed;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.NotThreadSafe;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
@NotThreadSafe
class TreeBuilder
{
private final T[] buffer;
private int count;
private int size;
private BranchBuilder parent;
@SuppressWarnings("unchecked")
TreeBuilder()
{
buffer = (T[])new Object[MultiValueNode.MAX_SIZE];
}
void clear()
{
Arrays.fill(buffer, null);
count = 0;
size = 0;
parent = null;
}
@Nonnull
AbstractNode build()
{
AbstractNode answer;
switch (count) {
case 0:
answer = EmptyNode.instance();
break;
case 1:
answer = new OneValueNode<>(buffer[0]);
break;
default:
answer = new MultiValueNode<>(buffer, count);
break;
}
if (parent != null) {
answer = parent.build(answer);
}
return answer;
}
int size()
{
return size;
}
void combineWith(@Nonnull TreeBuilder other)
{
final AbstractNode a = build();
final AbstractNode b = other.build();
final AbstractNode ab = a.append(b);
rebuild(ab);
}
/**
* Clears any existing data in this builder and then populates the builder with
* nodes from the provided tree. At each level of the tree it creates a parent
* branch using the left node and proceeds further using the right node.
* At the leaf all values are copied into the buffer.
*/
void rebuild(@Nonnull AbstractNode node)
{
count = 0;
size = node.size();
parent = null;
while (node.depth() > 0) {
parent = new BranchBuilder<>(parent, node.left());
node = node.right();
}
for (T t : node) {
buffer[count++] = t;
}
}
void add(T value)
{
buffer[count++] = value;
if (count == MultiValueNode.MAX_SIZE) {
final AbstractNode leaf = new MultiValueNode<>(buffer, count);
if (parent == null) {
parent = new BranchBuilder<>(leaf);
} else {
parent.add(leaf);
}
count = 0;
}
size += 1;
}
void add(@Nonnull Iterator source)
{
while (source.hasNext()) {
add(source.next());
}
}
void add(@Nonnull Iterable source)
{
add(source.iterator());
}
@SafeVarargs
final void add(K... source)
{
for (K k : source) {
add(k);
}
}
void add(@Nonnull Indexed source,
int offset,
int limit)
{
for (int i = offset; i < limit; ++i) {
add(source.get(i));
}
}
void add(@Nonnull Indexed source)
{
add(source, 0, source.size());
}
@Nonnull
static AbstractNode nodeFromIndexed(@Nonnull Indexed source)
{
return nodeFromIndexed(source, 0, source.size());
}
@Nonnull
static AbstractNode nodeFromIndexed(@Nonnull Indexed source,
int offset,
int limit)
{
final int sourceSize = limit - offset;
if (sourceSize == 0) {
return EmptyNode.instance();
}
final List> nodes = new ArrayList<>(1 + sourceSize / MultiValueNode.MAX_SIZE);
int o = offset;
while (o < limit) {
final int nodeSize = Math.min(MultiValueNode.MAX_SIZE, limit - o);
if (nodeSize == 1) {
nodes.add(new OneValueNode<>(source.get(o)));
} else {
nodes.add(new MultiValueNode<>(source.subArray(o, o + nodeSize), nodeSize));
}
o += nodeSize;
}
int nodeCount = nodes.size();
while (nodeCount > 1) {
int writeIndex = 0;
int readIndex = 0;
int remaining = nodeCount;
while (remaining > 0) {
if (remaining > 1) {
nodes.set(writeIndex, BranchNode.balance(nodes.get(readIndex), nodes.get(readIndex + 1)));
readIndex += 2;
writeIndex += 1;
remaining -= 2;
} else {
nodes.set(writeIndex - 1, nodes.get(writeIndex - 1).append(nodes.get(readIndex)));
readIndex += 1;
remaining -= 1;
}
}
nodeCount = writeIndex;
}
return nodes.get(0);
}
@Nonnull
static AbstractNode nodeFromIterator(@Nonnull Iterator values)
{
TreeBuilder builder = new TreeBuilder<>();
builder.add(values);
return builder.build();
}
void checkInvariants()
{
if (size != computeSize()) {
throw new IllegalStateException("size mismatch");
}
if (parent != null) {
parent.checkInvariants();
}
}
private int computeSize()
{
int answer = count;
if (parent != null) {
answer += parent.computeSize();
}
return answer;
}
private static class BranchBuilder
{
private BranchBuilder parent;
private AbstractNode buffer;
private BranchBuilder(@Nonnull BranchBuilder parent,
@Nonnull AbstractNode node)
{
this.parent = parent;
buffer = node;
}
private BranchBuilder(@Nonnull AbstractNode node)
{
buffer = node;
}
private void add(@Nonnull AbstractNode node)
{
if (buffer == null) {
buffer = node;
} else {
final AbstractNode branch = new BranchNode<>(buffer, node);
if (parent == null) {
parent = new BranchBuilder<>(branch);
} else {
parent.add(branch);
}
buffer = null;
}
}
@Nonnull
private AbstractNode build(@Nonnull AbstractNode extra)
{
AbstractNode answer;
if (buffer == null) {
answer = extra;
} else {
answer = buffer.append(extra);
}
if (parent != null) {
answer = parent.build(answer);
}
return answer;
}
private int computeSize()
{
int answer = 0;
if (buffer != null) {
answer += buffer.size();
}
if (parent != null) {
answer += parent.computeSize();
}
return answer;
}
private void checkInvariants()
{
if (buffer == null && parent == null) {
throw new IllegalStateException("buffer is null");
}
if (parent != null) {
parent.checkInvariants();
}
}
}
}