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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,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package org.javimmutable.collections.list;
import org.javimmutable.collections.Cursor;
import org.javimmutable.collections.JImmutableStack;
import org.javimmutable.collections.SplitableIterator;
import org.javimmutable.collections.common.StreamConstants;
import org.javimmutable.collections.cursors.Cursors;
import org.javimmutable.collections.cursors.SequenceCursor;
import org.javimmutable.collections.cursors.SingleValueCursor;
import org.javimmutable.collections.cursors.StandardCursor;
import org.javimmutable.collections.iterators.EmptyIterator;
import org.javimmutable.collections.iterators.SequenceIterator;
import org.javimmutable.collections.iterators.SingleValueIterator;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.util.ArrayList;
import java.util.List;
/**
* Singly linked list implementation of JImmutableStack that stores and retrieves values
* in the reverse order of the corresponding add() method calls. If forward or random
* access to stored values is required use JImmutableArrayList or JImmutableTreeList
* instead, but this class is significantly faster when its limitations are acceptable.
*/
@Immutable
public abstract class JImmutableLinkedStack
{
private static final EmptySequence EMPTY = new EmptySequence();
@SuppressWarnings("unchecked")
public static JImmutableStack of()
{
return (JImmutableStack)EMPTY;
}
public static JImmutableStack of(T value)
{
return new Single<>(value);
}
public static JImmutableStack of(List values)
{
JImmutableStack list = of();
for (T value : values) {
list = list.insert(value);
}
return list;
}
public static JImmutableStack of(T... values)
{
JImmutableStack list = of();
for (T value : values) {
list = list.insert(value);
}
return list;
}
private static abstract class Base
implements JImmutableStack
{
@Nonnull
public abstract JImmutableStack insert(@Nullable V value);
@Nonnull
@Override
public JImmutableStack getInsertableSelf()
{
return this;
}
@Nonnull
public abstract JImmutableStack getTail();
@Nonnull
@Override
public JImmutableStack remove()
{
return getTail();
}
@Override
public int getSpliteratorCharacteristics()
{
return StreamConstants.SPLITERATOR_ORDERED;
}
public List makeList()
{
final List answer = new ArrayList<>();
JImmutableStack next = this;
while (!next.isEmpty()) {
answer.add(next.getHead());
next = next.getTail();
}
return answer;
}
@Override
public boolean equals(Object o)
{
return (o instanceof JImmutableStack) && Cursors.areEqual(cursor(), ((JImmutableStack)o).cursor());
}
@Override
public int hashCode()
{
return Cursors.computeHashCode(cursor());
}
@Override
public String toString()
{
return Cursors.makeString(cursor());
}
}
private static class EmptySequence
extends Base
{
public boolean isEmpty()
{
return true;
}
public V getHead()
{
throw new UnsupportedOperationException();
}
@Nonnull
@Override
public JImmutableStack getTail()
{
return this;
}
@Nonnull
@Override
public JImmutableStack insert(@Nullable V value)
{
return new Single<>(value);
}
@Nonnull
public Cursor cursor()
{
return StandardCursor.of();
}
@Nonnull
@Override
public SplitableIterator iterator()
{
return EmptyIterator.of();
}
@Override
public void checkInvariants()
{
//no invariants
}
}
private static class Single
extends Base
{
private final V value;
private Single(V value)
{
this.value = value;
}
public boolean isEmpty()
{
return false;
}
public V getHead()
{
return value;
}
@Nonnull
@Override
public JImmutableStack getTail()
{
return of();
}
@Nonnull
@Override
public JImmutableStack insert(@Nullable V value)
{
return new Chain<>(value, this);
}
@Nonnull
public Cursor cursor()
{
return SingleValueCursor.of(value);
}
@Nonnull
@Override
public SplitableIterator iterator()
{
return SingleValueIterator.of(value);
}
@Override
public void checkInvariants()
{
//no invariants
}
}
private static class Chain
extends Base
{
private final V value;
private final JImmutableStack next;
private Chain(V value,
JImmutableStack next)
{
this.value = value;
this.next = next;
}
public boolean isEmpty()
{
return false;
}
public V getHead()
{
return value;
}
@Nonnull
@Override
public JImmutableStack getTail()
{
return next;
}
@Override
@Nonnull
public JImmutableStack insert(@Nullable V value)
{
return new Chain<>(value, this);
}
@Override
@Nonnull
public Cursor cursor()
{
return SequenceCursor.of(this);
}
@Nonnull
public SplitableIterator iterator()
{
return SequenceIterator.iterator(this);
}
@Override
public void checkInvariants()
{
//no invariants
}
}
}