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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) 2019, Burton Computer Corporation
// All rights reserved.
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package org.javimmutable.collections.array;
import org.javimmutable.collections.Holder;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.indexed.IndexedArray;
import org.javimmutable.collections.iterators.GenericIterator;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
@Immutable
class FullBranchTrieNode
extends TrieNode
{
private final int shift;
private final int valueCount;
private final TrieNode[] entries;
FullBranchTrieNode(int shift,
int valueCount,
TrieNode[] entries)
{
assert shift != ROOT_SHIFT;
this.shift = shift;
this.valueCount = valueCount;
this.entries = entries;
}
static FullBranchTrieNode fromSource(int index,
Indexed source,
int offset)
{
assert (source.size() - offset) >= 32;
TrieNode[] entries = MultiBranchTrieNode.allocate(32);
for (int i = 0; i < 32; ++i) {
entries[i] = LeafTrieNode.of(index++, source.get(offset++));
}
return new FullBranchTrieNode<>(0, computeValueCount(entries), entries);
}
@Override
public int valueCount()
{
return valueCount;
}
@Override
public boolean isEmpty()
{
return false;
}
@Override
public T getValueOr(int shift,
int index,
T defaultValue)
{
assert this.shift == shift;
final int childIndex = (index >>> shift) & 0x1f;
return entries[childIndex].getValueOr(shift - 5, index, defaultValue);
}
@Override
public Holder find(int shift,
int index)
{
assert this.shift == shift;
final int childIndex = (index >>> shift) & 0x1f;
return entries[childIndex].find(shift - 5, index);
}
@Override
public TrieNode assign(int shift,
int index,
T value)
{
assert this.shift == shift;
final int childIndex = (index >>> shift) & 0x1f;
final TrieNode child = entries[childIndex];
final TrieNode newChild = child.assign(shift - 5, index, value);
if (newChild == child) {
return this;
} else {
return createUpdatedEntries(shift, childIndex, newChild);
}
}
@Override
public TrieNode delete(int shift,
int index)
{
assert this.shift == shift;
final int childIndex = (index >>> shift) & 0x1f;
final TrieNode child = entries[childIndex];
final TrieNode newChild = child.delete(shift - 5, index);
return createDeleteResultNode(shift, childIndex, child, newChild);
}
@Override
public int getShift()
{
return shift;
}
@Override
public boolean isLeaf()
{
return false;
}
@Nullable
@Override
public GenericIterator.State> iterateOverRange(@Nullable GenericIterator.State> parent,
int offset,
int limit)
{
return GenericIterator.indexedState(parent, IndexedArray.retained(entries), offset, limit);
}
@Override
public void checkInvariants()
{
if (shift < 0 || shift > ROOT_SHIFT) {
throw new IllegalStateException("illegal shift value: " + shift);
}
if (entries.length != 32) {
throw new IllegalStateException("unexpected entries size: expected=32 actual=" + entries.length);
}
if (valueCount != computeValueCount(entries)) {
throw new IllegalStateException("unexpected valueCount: expected=" + valueCount + " actual=" + computeValueCount(entries));
}
for (TrieNode entry : entries) {
entry.checkInvariants();
}
}
private TrieNode createUpdatedEntries(int shift,
int childIndex,
TrieNode newChild)
{
assert newChild.isLeaf() || (newChild.getShift() == (shift - 5));
final int newValueCount = valueCount - entries[childIndex].valueCount() + newChild.valueCount();
TrieNode[] newEntries = entries.clone();
newEntries[childIndex] = newChild;
return new FullBranchTrieNode<>(shift, newValueCount, newEntries);
}
private TrieNode createDeleteResultNode(int shift,
int childIndex,
TrieNode child,
TrieNode newChild)
{
if (newChild == child) {
return this;
} else if (newChild.isEmpty()) {
final int newValueCount = valueCount - child.valueCount() + newChild.valueCount();
return MultiBranchTrieNode.fullWithout(shift, newValueCount, entries, childIndex);
} else {
return createUpdatedEntries(shift, childIndex, newChild);
}
}
}