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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) 2017, 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.hash.hamt;
import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Cursorable;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.SplitableIterable;
import org.javimmutable.collections.SplitableIterator;
import org.javimmutable.collections.common.ArrayHelper;
import org.javimmutable.collections.common.MutableDelta;
import org.javimmutable.collections.cursors.LazyMultiCursor;
import org.javimmutable.collections.cursors.SingleValueCursor;
import org.javimmutable.collections.cursors.StandardCursor;
import org.javimmutable.collections.hash.collision_map.CollisionMap;
import org.javimmutable.collections.iterators.EmptyIterator;
import org.javimmutable.collections.iterators.LazyMultiIterator;
import org.javimmutable.collections.iterators.SingleValueIterator;
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;
@Nullable
private final T value;
@Nonnull
private final HamtNode[] children;
private HamtBranchNode(int bitmask,
@Nullable T value,
@Nonnull HamtNode[] children)
{
this.bitmask = bitmask;
this.value = value;
this.children = children;
}
@SuppressWarnings("unchecked")
static HamtNode forLeafExpansion(int hashCode,
@Nonnull T value)
{
if (hashCode == 0) {
return new HamtBranchNode<>(0, value, EMPTY_NODES);
} 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(remainder, value);
return new HamtBranchNode<>(bit, null, children);
}
}
@Override
public Holder find(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey)
{
if (hashCode == 0) {
if (value != null) {
return collisionMap.findValue(value, hashKey);
} else {
return Holders.of();
}
}
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) {
if (value != null) {
return collisionMap.getValueOr(value, hashKey, defaultValue);
} else {
return 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,
@Nonnull MutableDelta sizeDelta)
{
final HamtNode[] children = this.children;
final int bitmask = this.bitmask;
final T thisValue = this.value;
if (hashCode == 0) {
final T newValue = collisionMap.update(thisValue, hashKey, value, sizeDelta);
if (thisValue == newValue) {
return this;
} else {
return new HamtBranchNode<>(bitmask, newValue, children);
}
}
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(null, hashKey, value, sizeDelta));
final HamtNode[] newChildren = ArrayHelper.insert(this, children, childIndex, newChild);
return new HamtBranchNode<>(bitmask | bit, thisValue, newChildren);
} else {
final HamtNode child = children[childIndex];
final HamtNode newChild = child.assign(collisionMap, remainder, hashKey, value, sizeDelta);
if (newChild == child) {
return this;
} else {
final HamtNode[] newChildren = ArrayHelper.assign(children, childIndex, newChild);
return new HamtBranchNode<>(bitmask, thisValue, newChildren);
}
}
}
@Override
@Nonnull
public HamtNode delete(@Nonnull CollisionMap collisionMap,
int hashCode,
@Nonnull K hashKey,
@Nonnull MutableDelta sizeDelta)
{
final int bitmask = this.bitmask;
final HamtNode[] children = this.children;
final T value = this.value;
if (hashCode == 0) {
if (value != null) {
final T newValue = collisionMap.delete(value, hashKey, sizeDelta);
if (newValue == value) {
return this;
} else if (newValue == null) {
if (bitmask == 0) {
return HamtEmptyNode.of();
} else {
return createForDelete(bitmask, null, children);
}
} else {
return new HamtBranchNode<>(bitmask, newValue, children);
}
} else {
return this;
}
}
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, sizeDelta);
if (newChild == child) {
return this;
} else if (newChild.isEmpty()) {
if (children.length == 1) {
if (value == null) {
return HamtEmptyNode.of();
} else {
return new HamtLeafNode<>(0, value);
}
} else {
final HamtNode[] newChildren = ArrayHelper.delete(this, children, childIndex);
return createForDelete(bitmask & ~bit, value, newChildren);
}
} else {
final HamtNode[] newChildren = ArrayHelper.assign(children, childIndex, newChild);
return createForDelete(bitmask, value, newChildren);
}
}
}
private HamtNode createForDelete(int bitmask,
T value,
@Nonnull HamtNode[] children)
{
if ((value == null) && (children.length == 1)) {
final HamtNode child = children[0];
if (child instanceof HamtLeafNode) {
final HamtLeafNode leaf = (HamtLeafNode)child;
return leaf.liftNode(Integer.numberOfTrailingZeros(bitmask));
}
if (child instanceof HamtBranchNode) {
final HamtBranchNode branch = (HamtBranchNode)child;
if (branch.value != null && branch.children.length == 0) {
return new HamtLeafNode<>(Integer.numberOfTrailingZeros(bitmask), branch.value);
}
}
}
return new HamtBranchNode<>(bitmask, value, children);
}
@Override
public boolean isEmpty()
{
return bitmask == 0 && value == null;
}
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];
}
@Override
@Nonnull
public SplitableIterator> iterator(CollisionMap collisionMap)
{
return LazyMultiIterator.transformed(indexedForIterator(), node -> () -> iteratorHelper(node.iterator(), collisionMap));
}
@Nonnull
private SplitableIterator> iteratorHelper(SplitableIterator value,
CollisionMap collisionMap)
{
return LazyMultiIterator.transformed(value, t -> () -> collisionMap.iterator(t));
}
@Nonnull
@Override
public SplitableIterator iterator()
{
return LazyMultiIterator.iterator(indexedForIterator());
}
@Override
@Nonnull
public Cursor> cursor(CollisionMap collisionMap)
{
return LazyMultiCursor.transformed(indexedForCursor(), node -> () -> cursorHelper(node.cursor(), collisionMap));
}
@Nonnull
private Cursor> cursorHelper(Cursor value,
CollisionMap collisionMap)
{
return LazyMultiCursor.transformed(value, t -> () -> collisionMap.cursor(t));
}
@Nonnull
@Override
public Cursor cursor()
{
return LazyMultiCursor.cursor(indexedForCursor());
}
@Override
public String toString()
{
return "(" + value + ",0x" + Integer.toHexString(bitmask) + "," + children.length + ")";
}
@Override
public void checkInvariants()
{
if ((value == null) && (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();
}
}
private Indexed> indexedForIterator()
{
return new Indexed>()
{
@Override
public SplitableIterable get(int index)
{
if (index == 0) {
if (value != null) {
return () -> SingleValueIterator.of(value);
} else {
return () -> EmptyIterator.of();
}
} else {
return children[index - 1];
}
}
@Override
public int size()
{
return children.length + 1;
}
};
}
private Indexed> indexedForCursor()
{
return new Indexed>()
{
@Override
public Cursorable get(int index)
{
if (index == 0) {
if (value != null) {
return () -> SingleValueCursor.of(value);
} else {
return () -> StandardCursor.of();
}
} else {
return children[index - 1];
}
}
@Override
public int size()
{
return children.length + 1;
}
};
}
}