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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
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// Copyright (c) 2017, Burton Computer Corporation
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package org.javimmutable.collections.array;
import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Holders;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.SplitableIterator;
import org.javimmutable.collections.common.MutableDelta;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;
@Immutable
public class SingleBranchTrieNode
extends TrieNode
{
private final int shift;
private final int branchIndex;
private final TrieNode child;
private SingleBranchTrieNode(int shift,
int branchIndex,
TrieNode child)
{
assert shift >= 0;
this.shift = shift;
this.branchIndex = branchIndex;
this.child = child;
}
static SingleBranchTrieNode forIndex(int shift,
int index,
TrieNode child)
{
final int branchIndex = (index >>> shift) & 0x1f;
return new SingleBranchTrieNode<>(shift, branchIndex, child);
}
static SingleBranchTrieNode forBranchIndex(int shift,
int branchIndex,
TrieNode child)
{
return new SingleBranchTrieNode<>(shift, branchIndex, child);
}
@Override
public boolean isEmpty()
{
return false;
}
@Override
public T getValueOr(int shift,
int index,
T defaultValue)
{
assert this.shift == shift;
final int branchIndex = (index >>> shift) & 0x1f;
return (this.branchIndex == branchIndex) ? child.getValueOr(shift - 5, index, defaultValue) : defaultValue;
}
@Override
public Holder find(int shift,
int index)
{
assert this.shift == shift;
final int branchIndex = (index >>> shift) & 0x1f;
return (this.branchIndex == branchIndex) ? child.find(shift - 5, index) : Holders.of();
}
@Override
public TrieNode assign(int shift,
int index,
T value,
MutableDelta sizeDelta)
{
assert this.shift == shift;
final int branchIndex = (index >>> shift) & 0x1f;
if (this.branchIndex == branchIndex) {
TrieNode newChild = child.assign(shift - 5, index, value, sizeDelta);
return selectNodeForUpdateResult(shift, branchIndex, newChild);
} else {
return MultiBranchTrieNode.forBranchIndex(shift, this.branchIndex, child).assign(shift, index, value, sizeDelta);
}
}
@Override
public TrieNode delete(int shift,
int index,
MutableDelta sizeDelta)
{
assert this.shift == shift;
final int branchIndex = (index >>> shift) & 0x1f;
if (this.branchIndex != branchIndex) {
return this;
} else {
final TrieNode newChild = child.delete(shift - 5, index, sizeDelta);
return selectNodeForDeleteResult(shift, branchIndex, newChild);
}
}
@Override
public int getShift()
{
return shift;
}
@Override
public boolean isLeaf()
{
return false;
}
@Override
public TrieNode trimmedToMinimumDepth()
{
return (branchIndex == 0) ? child.trimmedToMinimumDepth() : this;
}
@Nonnull
@Override
public SplitableIterator> iterator()
{
return child.iterator();
}
@Nonnull
@Override
public Cursor> cursor()
{
return child.cursor();
}
@Override
public void checkInvariants()
{
if (shift < 0 || shift > ROOT_SHIFT) {
throw new IllegalStateException("illegal shift value: " + shift);
}
if (branchIndex < 0 || branchIndex >= 32) {
throw new IllegalStateException("illegal branchIndex value: " + branchIndex);
}
child.checkInvariants();
}
// for tests
int getBranchIndex()
{
return branchIndex;
}
// for tests
TrieNode getChild()
{
return child;
}
private TrieNode selectNodeForUpdateResult(int shift,
int branchIndex,
TrieNode newChild)
{
assert newChild.isLeaf() || (newChild.getShift() == (shift - 5));
return (newChild == child) ? this : new SingleBranchTrieNode<>(shift, branchIndex, newChild);
}
private TrieNode selectNodeForDeleteResult(int shift,
int branchIndex,
TrieNode newChild)
{
if (newChild == child) {
return this;
} else if (newChild.isEmpty()) {
return of();
} else if (newChild.isLeaf()) {
return newChild;
} else {
assert newChild.getShift() == (shift - 5);
return new SingleBranchTrieNode<>(shift, branchIndex, newChild);
}
}
}