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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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package org.javimmutable.collections.hash.hamt;
import org.javimmutable.collections.Func1;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.Proc2;
import org.javimmutable.collections.Proc2Throws;
import org.javimmutable.collections.Sum2;
import org.javimmutable.collections.Sum2Throws;
import org.javimmutable.collections.common.ArrayHelper;
import org.javimmutable.collections.common.CollisionMap;
import org.javimmutable.collections.iterators.GenericIterator;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
@Immutable
public class HamtBranchNode
implements ArrayHelper.Allocator>,
HamtNode
{
private static final HamtBranchNode[] EMPTY_NODES = new HamtBranchNode[0];
static final int SHIFT = 5;
static final int MASK = 0x1f;
private final int bitmask;
@Nonnull
private final CollisionMap.Node value;
@Nonnull
private final HamtNode[] children;
private final int size;
HamtBranchNode(int bitmask,
@Nonnull CollisionMap.Node value,
@Nonnull HamtNode[] children,
int size)
{
this.bitmask = bitmask;
this.value = value;
this.children = children;
this.size = size;
}
@SuppressWarnings("unchecked")
static HamtNode forLeafExpansion(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull CollisionMap.Node value)
{
if (hashCode == 0) {
return new HamtBranchNode<>(0, value, EMPTY_NODES, collisionMap.size(value));
} else {
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final HamtNode[] children = new HamtNode[1];
children[0] = forLeafExpansion(collisionMap, remainder, value);
return new HamtBranchNode<>(bit, collisionMap.emptyNode(), children, collisionMap.size(value));
}
}
@Override
public int size(@Nonnull CollisionMap collisionMap)
{
return size;
}
@Override
public Holder find(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey)
{
if (hashCode == 0) {
return collisionMap.findValue(value, hashKey);
}
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final int bitmask = this.bitmask;
if ((bitmask & bit) == 0) {
return Holders.of();
} else {
final int childIndex = realIndex(bitmask, bit);
return children[childIndex].find(collisionMap, remainder, hashKey);
}
}
@Override
public V getValueOr(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey,
V defaultValue)
{
if (hashCode == 0) {
return collisionMap.getValueOr(value, hashKey, defaultValue);
}
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final int bitmask = this.bitmask;
if ((bitmask & bit) == 0) {
return defaultValue;
} else {
final int childIndex = realIndex(bitmask, bit);
return children[childIndex].getValueOr(collisionMap, remainder, hashKey, defaultValue);
}
}
@Override
@Nonnull
public HamtNode assign(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey,
@Nullable V value)
{
final HamtNode[] children = this.children;
final int bitmask = this.bitmask;
final CollisionMap.Node thisValue = this.value;
if (hashCode == 0) {
final CollisionMap.Node newValue = collisionMap.update(thisValue, hashKey, value);
if (thisValue == newValue) {
return this;
} else {
return new HamtBranchNode<>(bitmask, newValue, children, size - collisionMap.size(thisValue) + collisionMap.size(newValue));
}
}
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final int childIndex = realIndex(bitmask, bit);
if ((bitmask & bit) == 0) {
final HamtNode newChild = new HamtLeafNode<>(remainder, collisionMap.update(collisionMap.emptyNode(), hashKey, value));
final HamtNode[] newChildren = ArrayHelper.insert(this, children, childIndex, newChild);
return new HamtBranchNode<>(bitmask | bit, thisValue, newChildren, size + 1);
} else {
final HamtNode child = children[childIndex];
final HamtNode newChild = child.assign(collisionMap, remainder, hashKey, value);
if (newChild == child) {
return this;
} else {
final HamtNode[] newChildren = ArrayHelper.assign(children, childIndex, newChild);
return new HamtBranchNode<>(bitmask, thisValue, newChildren, size - child.size(collisionMap) + newChild.size(collisionMap));
}
}
}
@Nonnull
@Override
public HamtNode update(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey,
@Nonnull Func1, V> generator)
{
final HamtNode[] children = this.children;
final int bitmask = this.bitmask;
final CollisionMap.Node thisValue = this.value;
if (hashCode == 0) {
final CollisionMap.Node newValue = collisionMap.update(thisValue, hashKey, generator);
if (thisValue == newValue) {
return this;
} else {
return new HamtBranchNode<>(bitmask, newValue, children, size - collisionMap.size(thisValue) + collisionMap.size(newValue));
}
}
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final int childIndex = realIndex(bitmask, bit);
if ((bitmask & bit) == 0) {
final HamtNode newChild = new HamtLeafNode<>(remainder, collisionMap.update(collisionMap.emptyNode(), hashKey, generator));
final HamtNode[] newChildren = ArrayHelper.insert(this, children, childIndex, newChild);
return new HamtBranchNode<>(bitmask | bit, thisValue, newChildren, size + 1);
} else {
final HamtNode child = children[childIndex];
final HamtNode newChild = child.update(collisionMap, remainder, hashKey, generator);
if (newChild == child) {
return this;
} else {
final HamtNode[] newChildren = ArrayHelper.assign(children, childIndex, newChild);
return new HamtBranchNode<>(bitmask, thisValue, newChildren, size - child.size(collisionMap) + newChild.size(collisionMap));
}
}
}
@Override
@Nonnull
public HamtNode delete(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey)
{
final int bitmask = this.bitmask;
final HamtNode[] children = this.children;
final CollisionMap.Node value = this.value;
if (hashCode == 0) {
final CollisionMap.Node newValue = collisionMap.delete(value, hashKey);
final int newSize = this.size - collisionMap.size(value) + collisionMap.size(newValue);
if (newValue == value) {
return this;
} else if (collisionMap.size(newValue) == 0) {
if (bitmask == 0) {
return HamtEmptyNode.of();
} else {
return createForDelete(collisionMap, bitmask, newValue, children, newSize);
}
} else {
return new HamtBranchNode<>(bitmask, newValue, children, newSize);
}
}
final int index = hashCode & MASK;
final int remainder = hashCode >>> SHIFT;
final int bit = 1 << index;
final int childIndex = realIndex(bitmask, bit);
if ((bitmask & bit) == 0) {
return this;
} else {
final HamtNode child = children[childIndex];
final HamtNode newChild = child.delete(collisionMap, remainder, hashKey);
final int newSize = size - child.size(collisionMap) + newChild.size(collisionMap);
if (newChild == child) {
return this;
} else if (newChild.isEmpty(collisionMap)) {
if (children.length == 1) {
if (collisionMap.size(value) == 0) {
return HamtEmptyNode.of();
} else {
return new HamtLeafNode<>(0, value);
}
} else {
final HamtNode[] newChildren = ArrayHelper.delete(this, children, childIndex);
return createForDelete(collisionMap, bitmask & ~bit, value, newChildren, newSize);
}
} else {
final HamtNode[] newChildren = ArrayHelper.assign(children, childIndex, newChild);
return createForDelete(collisionMap, bitmask, value, newChildren, newSize);
}
}
}
private HamtNode createForDelete(@Nonnull CollisionMap collisionMap,
int bitmask,
CollisionMap.Node value,
@Nonnull HamtNode[] children,
int newSize)
{
if (collisionMap.size(value) == 0 && children.length == 1) {
final HamtNode child = children[0];
if (child instanceof HamtLeafNode) {
final HamtLeafNode leaf = (HamtLeafNode)child;
assert newSize == leaf.size(collisionMap);
return leaf.liftNode(Integer.numberOfTrailingZeros(bitmask));
}
if (child instanceof HamtBranchNode) {
final HamtBranchNode branch = (HamtBranchNode)child;
if (collisionMap.size(branch.value) > 0 && branch.children.length == 0) {
assert newSize == collisionMap.size(branch.value);
return new HamtLeafNode<>(Integer.numberOfTrailingZeros(bitmask), branch.value);
}
}
}
return new HamtBranchNode<>(bitmask, value, children, newSize);
}
@Override
public boolean isEmpty(@Nonnull CollisionMap collisionMap)
{
return bitmask == 0 && collisionMap.size(value) == 0;
}
private static int realIndex(int bitmask,
int bit)
{
return Integer.bitCount(bitmask & (bit - 1));
}
@SuppressWarnings("unchecked")
@Nonnull
@Override
public HamtNode[] allocate(int size)
{
return new HamtNode[size];
}
@Nullable
@Override
public GenericIterator.State> iterateOverRange(@Nonnull CollisionMap collisionMap,
@Nullable GenericIterator.State> parent,
int offset,
int limit)
{
assert offset >= 0 && offset <= limit && limit <= size;
return GenericIterator.indexedState(parent, indexedForIterator(collisionMap), offset, limit);
}
@Override
public void forEach(@Nonnull CollisionMap collisionMap,
@Nonnull Proc2 proc)
{
collisionMap.forEach(value, proc);
for (HamtNode child : children) {
child.forEach(collisionMap, proc);
}
}
@Override
public void forEachThrows(@Nonnull CollisionMap collisionMap,
@Nonnull Proc2Throws proc)
throws E
{
collisionMap.forEachThrows(value, proc);
for (HamtNode child : children) {
child.forEachThrows(collisionMap, proc);
}
}
@Override
public R reduce(@Nonnull CollisionMap collisionMap,
R sum,
@Nonnull Sum2 proc)
{
sum = collisionMap.reduce(value, sum, proc);
for (HamtNode child : children) {
sum = child.reduce(collisionMap, sum, proc);
}
return sum;
}
@Override
public R reduceThrows(@Nonnull CollisionMap collisionMap,
R sum,
@Nonnull Sum2Throws proc)
throws E
{
sum = collisionMap.reduceThrows(value, sum, proc);
for (HamtNode child : children) {
sum = child.reduceThrows(collisionMap, sum, proc);
}
return sum;
}
@Override
public String toString()
{
return "(" + value + ",0x" + Integer.toHexString(bitmask) + "," + children.length + ")";
}
private int computeSize(@Nonnull CollisionMap collisionMap)
{
int answer = collisionMap.size(value);
for (HamtNode child : children) {
answer += child.size(collisionMap);
}
return answer;
}
@Override
public void checkInvariants(@Nonnull CollisionMap collisionMap)
{
if (size != computeSize(collisionMap)) {
throw new IllegalStateException(String.format("incorrect size: expected=%d actual=%d", computeSize(collisionMap), size));
}
if (collisionMap.size(value) == 0 && children.length == 1) {
if (children[0] instanceof HamtLeafNode) {
// we should have replaced ourselves with a leaf
throw new IllegalStateException();
}
}
for (HamtNode child : children) {
child.checkInvariants(collisionMap);
}
}
@Nonnull
private Indexed>> indexedForIterator(@Nonnull CollisionMap collisionMap)
{
return new Indexed>>()
{
@Override
public GenericIterator.Iterable> get(int index)
{
if (index == 0) {
return collisionMap.genericIterable(value);
} else {
return children[index - 1].genericIterable(collisionMap);
}
}
@Override
public int size()
{
return 1 + children.length;
}
};
}
}