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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.
//
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//
// 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.
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// 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
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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package org.javimmutable.collections.array;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Arrays;
class TrieArrayBuilder
{
private final LeafBuilder leafBuilder = new LeafBuilder<>();
synchronized void clear()
{
leafBuilder.clear();
}
synchronized int size()
{
return leafBuilder.index;
}
synchronized void add(T value)
{
leafBuilder.add(value);
}
@Nonnull
synchronized TrieNode build()
{
return leafBuilder.build();
}
private static class LeafBuilder
{
private final TrieNode[] leaves;
private int offset;
private int index;
private BranchBuilder next;
@SuppressWarnings("unchecked")
private LeafBuilder()
{
leaves = new LeafTrieNode[32];
}
private void clear()
{
Arrays.fill(leaves, null);
offset = 0;
index = 0;
next = null;
}
private void add(T value)
{
leaves[offset] = LeafTrieNode.of(index, value);
index += 1;
offset += 1;
if (offset == 32) {
push();
}
}
private void push()
{
assert offset == 32;
TrieNode branch = new FullBranchTrieNode<>(0, TrieNode.computeValueCount(leaves), leaves.clone());
if (next == null) {
next = new BranchBuilder<>(5);
}
next.add(branch);
offset = 0;
}
private TrieNode build()
{
assert offset < 32;
TrieNode node = branchForBuild(leaves, offset, 0);
return resultForBuild(next, node);
}
}
private static class BranchBuilder
{
private final TrieNode[] nodes;
private final int shift;
private int offset;
private BranchBuilder next;
@SuppressWarnings("unchecked")
private BranchBuilder(int shift)
{
nodes = new TrieNode[32];
this.shift = shift;
}
private void add(TrieNode node)
{
nodes[offset] = node;
offset += 1;
if (offset == 32) {
push();
}
}
private void push()
{
assert offset == 32;
TrieNode branch = new FullBranchTrieNode<>(shift, TrieNode.computeValueCount(nodes), nodes.clone());
if (next == null) {
next = new BranchBuilder<>(shift + 5);
}
next.add(branch);
offset = 0;
}
private TrieNode build(@Nullable TrieNode extra)
{
assert offset < 32;
int length;
if (extra != null) {
nodes[offset] = extra;
length = offset + 1;
} else {
length = offset;
}
TrieNode node = branchForBuild(nodes, length, shift);
return resultForBuild(next, node);
}
}
private static TrieNode branchForBuild(@Nonnull TrieNode[] nodes,
int length,
int shift)
{
TrieNode branch;
switch (length) {
case 0:
branch = null;
break;
case 1:
branch = SingleBranchTrieNode.forBranchIndex(shift, 0, nodes[0]);
break;
case 32:
branch = new FullBranchTrieNode<>(shift, TrieNode.computeValueCount(nodes), nodes.clone());
break;
default:
branch = MultiBranchTrieNode.forEntries(shift, nodes, length);
break;
}
return branch;
}
private static TrieNode resultForBuild(@Nullable BranchBuilder next,
@Nullable TrieNode node)
{
if (next != null) {
return next.build(node);
} else if (node == null) {
return EmptyTrieNode.of();
} else {
return node;
}
}
}