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/*
* Copyright (C) 2002-2021 Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package it.unimi.dsi.fastutil.objects;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.SortedSet;
import java.util.NoSuchElementException;
/**
* A type-specific AVL tree set with a fast, small-footprint implementation.
*
*
* The iterators provided by this class are type-specific
* {@link it.unimi.dsi.fastutil.BidirectionalIterator bidirectional iterators}.
* Moreover, the iterator returned by {@code iterator()} can be safely cast to a
* type-specific {@linkplain java.util.ListIterator list iterator}.
*/
public class ObjectAVLTreeSet extends AbstractObjectSortedSet
implements
java.io.Serializable,
Cloneable,
ObjectSortedSet {
/** A reference to the root entry. */
protected transient Entry tree;
/** Number of elements in this set. */
protected int count;
/** The entry of the first element of this set. */
protected transient Entry firstEntry;
/** The entry of the last element of this set. */
protected transient Entry lastEntry;
/** This set's comparator, as provided in the constructor. */
protected Comparator storedComparator;
/**
* This set's actual comparator; it may differ from {@link #storedComparator}
* because it is always a type-specific comparator, so it could be derived from
* the former by wrapping.
*/
protected transient Comparator actualComparator;
private static final long serialVersionUID = -7046029254386353130L;
{
allocatePaths();
}
/**
* Creates a new empty tree set.
*/
public ObjectAVLTreeSet() {
tree = null;
count = 0;
}
/**
* Generates the comparator that will be actually used.
*
*
* When a given {@link Comparator} is specified and stored in
* {@link #storedComparator}, we must check whether it is type-specific. If it
* is so, we can used directly, and we store it in {@link #actualComparator}.
* Otherwise, we adapt it using a helper static method.
*/
private void setActualComparator() {
actualComparator = storedComparator;
}
/**
* Creates a new empty tree set with the given comparator.
*
* @param c
* a {@link Comparator} (even better, a type-specific comparator).
*/
public ObjectAVLTreeSet(final Comparator c) {
this();
storedComparator = c;
setActualComparator();
}
/**
* Creates a new tree set copying a given set.
*
* @param c
* a collection to be copied into the new tree set.
*/
public ObjectAVLTreeSet(final Collection c) {
this();
addAll(c);
}
/**
* Creates a new tree set copying a given sorted set (and its
* {@link Comparator}).
*
* @param s
* a {@link SortedSet} to be copied into the new tree set.
*/
public ObjectAVLTreeSet(final SortedSet s) {
this(s.comparator());
addAll(s);
}
/**
* Creates a new tree set copying a given type-specific collection.
*
* @param c
* a type-specific collection to be copied into the new tree set.
*/
public ObjectAVLTreeSet(final ObjectCollection c) {
this();
addAll(c);
}
/**
* Creates a new tree set copying a given type-specific sorted set (and its
* {@link Comparator}).
*
* @param s
* a type-specific sorted set to be copied into the new tree set.
*/
public ObjectAVLTreeSet(final ObjectSortedSet s) {
this(s.comparator());
addAll(s);
}
/**
* Creates a new tree set using elements provided by a type-specific iterator.
*
* @param i
* a type-specific iterator whose elements will fill the set.
*/
public ObjectAVLTreeSet(final Iterator i) {
while (i.hasNext())
add(i.next());
}
/**
* Creates a new tree set and fills it with the elements of a given array using
* a given {@link Comparator}.
*
* @param a
* an array whose elements will be used to fill the set.
* @param offset
* the first element to use.
* @param length
* the number of elements to use.
* @param c
* a {@link Comparator} (even better, a type-specific comparator).
*/
public ObjectAVLTreeSet(final K[] a, final int offset, final int length, final Comparator c) {
this(c);
ObjectArrays.ensureOffsetLength(a, offset, length);
for (int i = 0; i < length; i++)
add(a[offset + i]);
}
/**
* Creates a new tree set and fills it with the elements of a given array.
*
* @param a
* an array whose elements will be used to fill the set.
* @param offset
* the first element to use.
* @param length
* the number of elements to use.
*/
public ObjectAVLTreeSet(final K[] a, final int offset, final int length) {
this(a, offset, length, null);
}
/**
* Creates a new tree set copying the elements of an array.
*
* @param a
* an array to be copied into the new tree set.
*/
public ObjectAVLTreeSet(final K[] a) {
this();
int i = a.length;
while (i-- != 0)
add(a[i]);
}
/**
* Creates a new tree set copying the elements of an array using a given
* {@link Comparator}.
*
* @param a
* an array to be copied into the new tree set.
* @param c
* a {@link Comparator} (even better, a type-specific comparator).
*/
public ObjectAVLTreeSet(final K[] a, final Comparator c) {
this(c);
int i = a.length;
while (i-- != 0)
add(a[i]);
}
/*
* The following methods implements some basic building blocks used by all
* accessors. They are (and should be maintained) identical to those used in
* AVLTreeMap.drv.
*
* The add()/remove() code is derived from Ben Pfaff's GNU libavl
* (https://adtinfo.org/). If you want to understand what's going on, you should
* have a look at the literate code contained therein first.
*/
/**
* Compares two keys in the right way.
*
*
* This method uses the {@link #actualComparator} if it is non-{@code null}.
* Otherwise, it resorts to primitive type comparisons or to
* {@link Comparable#compareTo(Object) compareTo()}.
*
* @param k1
* the first key.
* @param k2
* the second key.
* @return a number smaller than, equal to or greater than 0, as usual (i.e.,
* when k1 < k2, k1 = k2 or k1 > k2, respectively).
*/
@SuppressWarnings("unchecked")
final int compare(final K k1, final K k2) {
return actualComparator == null ? (((Comparable) (k1)).compareTo(k2)) : actualComparator.compare(k1, k2);
}
/**
* Returns the entry corresponding to the given key, if it is in the tree;
* {@code null}, otherwise.
*
* @param k
* the key to search for.
* @return the corresponding entry, or {@code null} if no entry with the given
* key exists.
*/
private Entry findKey(final K k) {
Entry e = tree;
int cmp;
while (e != null && (cmp = compare(k, e.key)) != 0)
e = cmp < 0 ? e.left() : e.right();
return e;
}
/**
* Locates a key.
*
* @param k
* a key.
* @return the last entry on a search for the given key; this will be the given
* key, if it present; otherwise, it will be either the smallest greater
* key or the greatest smaller key.
*/
final Entry locateKey(final K k) {
Entry e = tree, last = tree;
int cmp = 0;
while (e != null && (cmp = compare(k, e.key)) != 0) {
last = e;
e = cmp < 0 ? e.left() : e.right();
}
return cmp == 0 ? e : last;
}
/**
* This vector remembers the path followed during the current insertion. It
* suffices for about 232 entries.
*/
private transient boolean dirPath[];
private void allocatePaths() {
dirPath = new boolean[48];
}
@Override
public boolean add(final K k) {
if (tree == null) { // The case of the empty tree is treated separately.
count++;
tree = lastEntry = firstEntry = new Entry<>(k);
} else {
Entry p = tree, q = null, y = tree, z = null, e = null, w = null;
int cmp, i = 0;
while (true) {
if ((cmp = compare(k, p.key)) == 0)
return false;
if (p.balance() != 0) {
i = 0;
z = q;
y = p;
}
if (dirPath[i++] = cmp > 0) {
if (p.succ()) {
count++;
e = new Entry<>(k);
if (p.right == null)
lastEntry = e;
e.left = p;
e.right = p.right;
p.right(e);
break;
}
q = p;
p = p.right;
} else {
if (p.pred()) {
count++;
e = new Entry<>(k);
if (p.left == null)
firstEntry = e;
e.right = p;
e.left = p.left;
p.left(e);
break;
}
q = p;
p = p.left;
}
}
p = y;
i = 0;
while (p != e) {
if (dirPath[i])
p.incBalance();
else
p.decBalance();
p = dirPath[i++] ? p.right : p.left;
}
if (y.balance() == -2) {
Entry x = y.left;
if (x.balance() == -1) {
w = x;
if (x.succ()) {
x.succ(false);
y.pred(x);
} else
y.left = x.right;
x.right = y;
x.balance(0);
y.balance(0);
} else {
assert x.balance() == 1;
w = x.right;
x.right = w.left;
w.left = x;
y.left = w.right;
w.right = y;
if (w.balance() == -1) {
x.balance(0);
y.balance(1);
} else if (w.balance() == 0) {
x.balance(0);
y.balance(0);
} else {
x.balance(-1);
y.balance(0);
}
w.balance(0);
if (w.pred()) {
x.succ(w);
w.pred(false);
}
if (w.succ()) {
y.pred(w);
w.succ(false);
}
}
} else if (y.balance() == +2) {
Entry x = y.right;
if (x.balance() == 1) {
w = x;
if (x.pred()) {
x.pred(false);
y.succ(x);
} else
y.right = x.left;
x.left = y;
x.balance(0);
y.balance(0);
} else {
assert x.balance() == -1;
w = x.left;
x.left = w.right;
w.right = x;
y.right = w.left;
w.left = y;
if (w.balance() == 1) {
x.balance(0);
y.balance(-1);
} else if (w.balance() == 0) {
x.balance(0);
y.balance(0);
} else {
x.balance(1);
y.balance(0);
}
w.balance(0);
if (w.pred()) {
y.succ(w);
w.pred(false);
}
if (w.succ()) {
x.pred(w);
w.succ(false);
}
}
} else
return true;
if (z == null)
tree = w;
else {
if (z.left == y)
z.left = w;
else
z.right = w;
}
}
return true;
}
/**
* Finds the parent of an entry.
*
* @param e
* a node of the tree.
* @return the parent of the given node, or {@code null} for the root.
*/
private Entry parent(final Entry e) {
if (e == tree)
return null;
Entry x, y, p;
x = y = e;
while (true) {
if (y.succ()) {
p = y.right;
if (p == null || p.left != e) {
while (!x.pred())
x = x.left;
p = x.left;
}
return p;
} else if (x.pred()) {
p = x.left;
if (p == null || p.right != e) {
while (!y.succ())
y = y.right;
p = y.right;
}
return p;
}
x = x.left;
y = y.right;
}
}
@SuppressWarnings("unchecked")
@Override
public boolean remove(final Object k) {
if (tree == null)
return false;
int cmp;
Entry p = tree, q = null;
boolean dir = false;
final K kk = (K) k;
while (true) {
if ((cmp = compare(kk, p.key)) == 0)
break;
else if (dir = cmp > 0) {
q = p;
if ((p = p.right()) == null)
return false;
} else {
q = p;
if ((p = p.left()) == null)
return false;
}
}
if (p.left == null)
firstEntry = p.next();
if (p.right == null)
lastEntry = p.prev();
if (p.succ()) {
if (p.pred()) {
if (q != null) {
if (dir)
q.succ(p.right);
else
q.pred(p.left);
} else
tree = dir ? p.right : p.left;
} else {
p.prev().right = p.right;
if (q != null) {
if (dir)
q.right = p.left;
else
q.left = p.left;
} else
tree = p.left;
}
} else {
Entry r = p.right;
if (r.pred()) {
r.left = p.left;
r.pred(p.pred());
if (!r.pred())
r.prev().right = r;
if (q != null) {
if (dir)
q.right = r;
else
q.left = r;
} else
tree = r;
r.balance(p.balance());
q = r;
dir = true;
} else {
Entry s;
while (true) {
s = r.left;
if (s.pred())
break;
r = s;
}
if (s.succ())
r.pred(s);
else
r.left = s.right;
s.left = p.left;
if (!p.pred()) {
p.prev().right = s;
s.pred(false);
}
s.right = p.right;
s.succ(false);
if (q != null) {
if (dir)
q.right = s;
else
q.left = s;
} else
tree = s;
s.balance(p.balance());
q = r;
dir = false;
}
}
Entry y;
while (q != null) {
y = q;
q = parent(y);
if (!dir) {
dir = q != null && q.left != y;
y.incBalance();
if (y.balance() == 1)
break;
else if (y.balance() == 2) {
Entry x = y.right;
assert x != null;
if (x.balance() == -1) {
Entry w;
assert x.balance() == -1;
w = x.left;
x.left = w.right;
w.right = x;
y.right = w.left;
w.left = y;
if (w.balance() == 1) {
x.balance(0);
y.balance(-1);
} else if (w.balance() == 0) {
x.balance(0);
y.balance(0);
} else {
assert w.balance() == -1;
x.balance(1);
y.balance(0);
}
w.balance(0);
if (w.pred()) {
y.succ(w);
w.pred(false);
}
if (w.succ()) {
x.pred(w);
w.succ(false);
}
if (q != null) {
if (dir)
q.right = w;
else
q.left = w;
} else
tree = w;
} else {
if (q != null) {
if (dir)
q.right = x;
else
q.left = x;
} else
tree = x;
if (x.balance() == 0) {
y.right = x.left;
x.left = y;
x.balance(-1);
y.balance(+1);
break;
}
assert x.balance() == 1;
if (x.pred()) {
y.succ(true);
x.pred(false);
} else
y.right = x.left;
x.left = y;
y.balance(0);
x.balance(0);
}
}
} else {
dir = q != null && q.left != y;
y.decBalance();
if (y.balance() == -1)
break;
else if (y.balance() == -2) {
Entry x = y.left;
assert x != null;
if (x.balance() == 1) {
Entry w;
assert x.balance() == 1;
w = x.right;
x.right = w.left;
w.left = x;
y.left = w.right;
w.right = y;
if (w.balance() == -1) {
x.balance(0);
y.balance(1);
} else if (w.balance() == 0) {
x.balance(0);
y.balance(0);
} else {
assert w.balance() == 1;
x.balance(-1);
y.balance(0);
}
w.balance(0);
if (w.pred()) {
x.succ(w);
w.pred(false);
}
if (w.succ()) {
y.pred(w);
w.succ(false);
}
if (q != null) {
if (dir)
q.right = w;
else
q.left = w;
} else
tree = w;
} else {
if (q != null) {
if (dir)
q.right = x;
else
q.left = x;
} else
tree = x;
if (x.balance() == 0) {
y.left = x.right;
x.right = y;
x.balance(+1);
y.balance(-1);
break;
}
assert x.balance() == -1;
if (x.succ()) {
y.pred(true);
x.succ(false);
} else
y.left = x.right;
x.right = y;
y.balance(0);
x.balance(0);
}
}
}
}
count--;
return true;
}
@SuppressWarnings("unchecked")
@Override
public boolean contains(final Object k) {
return findKey((K) k) != null;
}
@SuppressWarnings("unchecked")
public K get(final Object k) {
final Entry entry = findKey((K) k);
return entry == null ? null : entry.key;
}
@Override
public void clear() {
count = 0;
tree = null;
firstEntry = lastEntry = null;
}
/**
* This class represent an entry in a tree set.
*
*
* We use the only "metadata", i.e., {@link Entry#info}, to store information
* about balance, predecessor status and successor status.
*
*
* Note that since the class is recursive, it can be considered equivalently a
* tree.
*/
private static final class Entry implements Cloneable {
/** If the bit in this mask is true, {@link #right} points to a successor. */
private static final int SUCC_MASK = 1 << 31;
/** If the bit in this mask is true, {@link #left} points to a predecessor. */
private static final int PRED_MASK = 1 << 30;
/**
* The bits in this mask hold the node balance info. You can get it just by
* casting to byte.
*/
private static final int BALANCE_MASK = 0xFF;
/** The key of this entry. */
K key;
/** The pointers to the left and right subtrees. */
Entry left, right;
/**
* This integers holds different information in different bits (see
* {@link #SUCC_MASK}, {@link #PRED_MASK} and {@link #BALANCE_MASK}).
*/
int info;
Entry() {
}
/**
* Creates a new entry with the given key.
*
* @param k
* a key.
*/
Entry(final K k) {
this.key = k;
info = SUCC_MASK | PRED_MASK;
}
/**
* Returns the left subtree.
*
* @return the left subtree ({@code null} if the left subtree is empty).
*/
Entry left() {
return (info & PRED_MASK) != 0 ? null : left;
}
/**
* Returns the right subtree.
*
* @return the right subtree ({@code null} if the right subtree is empty).
*/
Entry right() {
return (info & SUCC_MASK) != 0 ? null : right;
}
/**
* Checks whether the left pointer is really a predecessor.
*
* @return true if the left pointer is a predecessor.
*/
boolean pred() {
return (info & PRED_MASK) != 0;
}
/**
* Checks whether the right pointer is really a successor.
*
* @return true if the right pointer is a successor.
*/
boolean succ() {
return (info & SUCC_MASK) != 0;
}
/**
* Sets whether the left pointer is really a predecessor.
*
* @param pred
* if true then the left pointer will be considered a predecessor.
*/
void pred(final boolean pred) {
if (pred)
info |= PRED_MASK;
else
info &= ~PRED_MASK;
}
/**
* Sets whether the right pointer is really a successor.
*
* @param succ
* if true then the right pointer will be considered a successor.
*/
void succ(final boolean succ) {
if (succ)
info |= SUCC_MASK;
else
info &= ~SUCC_MASK;
}
/**
* Sets the left pointer to a predecessor.
*
* @param pred
* the predecessr.
*/
void pred(final Entry pred) {
info |= PRED_MASK;
left = pred;
}
/**
* Sets the right pointer to a successor.
*
* @param succ
* the successor.
*/
void succ(final Entry succ) {
info |= SUCC_MASK;
right = succ;
}
/**
* Sets the left pointer to the given subtree.
*
* @param left
* the new left subtree.
*/
void left(final Entry left) {
info &= ~PRED_MASK;
this.left = left;
}
/**
* Sets the right pointer to the given subtree.
*
* @param right
* the new right subtree.
*/
void right(final Entry right) {
info &= ~SUCC_MASK;
this.right = right;
}
/**
* Returns the current level of the node.
*
* @return the current level of this node.
*/
int balance() {
return (byte) info;
}
/**
* Sets the level of this node.
*
* @param level
* the new level of this node.
*/
void balance(int level) {
info &= ~BALANCE_MASK;
info |= (level & BALANCE_MASK);
}
/** Increments the level of this node. */
void incBalance() {
info = info & ~BALANCE_MASK | ((byte) info + 1) & 0xFF;
}
/** Decrements the level of this node. */
protected void decBalance() {
info = info & ~BALANCE_MASK | ((byte) info - 1) & 0xFF;
}
/**
* Computes the next entry in the set order.
*
* @return the next entry ({@code null}) if this is the last entry).
*/
Entry next() {
Entry next = this.right;
if ((info & SUCC_MASK) == 0)
while ((next.info & PRED_MASK) == 0)
next = next.left;
return next;
}
/**
* Computes the previous entry in the set order.
*
* @return the previous entry ({@code null}) if this is the first entry).
*/
Entry prev() {
Entry prev = this.left;
if ((info & PRED_MASK) == 0)
while ((prev.info & SUCC_MASK) == 0)
prev = prev.right;
return prev;
}
@Override
@SuppressWarnings("unchecked")
public Entry clone() {
Entry c;
try {
c = (Entry) super.clone();
} catch (CloneNotSupportedException cantHappen) {
throw new InternalError();
}
c.key = key;
c.info = info;
return c;
}
@Override
public boolean equals(final Object o) {
if (!(o instanceof Entry))
return false;
Entry e = (Entry) o;
return java.util.Objects.equals(key, e.key);
}
@Override
public int hashCode() {
return ((key).hashCode());
}
@Override
public String toString() {
return String.valueOf(key);
}
/*
* public void prettyPrint() { prettyPrint(0); }
*
* public void prettyPrint(int level) { if (pred()) { for (int i = 0; i < level;
* i++) System.err.print(" "); System.err.println("pred: " + left); } else if
* (left != null) left.prettyPrint(level +1); for (int i = 0; i < level; i++)
* System.err.print(" "); System.err.println(key + " (" + level() + ")"); if
* (succ()) { for (int i = 0; i < level; i++) System.err.print(" ");
* System.err.println("succ: " + right); } else if (right != null)
* right.prettyPrint(level + 1); }
*/
}
/*
* public void prettyPrint() { System.err.println("size: " + count); if (tree !=
* null) tree.prettyPrint(); }
*/
@Override
public int size() {
return count;
}
@Override
public boolean isEmpty() {
return count == 0;
}
@Override
public K first() {
if (tree == null)
throw new NoSuchElementException();
return firstEntry.key;
}
@Override
public K last() {
if (tree == null)
throw new NoSuchElementException();
return lastEntry.key;
}
/**
* An iterator on the whole range.
*
*
* This class can iterate in both directions on a threaded tree.
*/
private class SetIterator implements ObjectListIterator {
/**
* The entry that will be returned by the next call to
* {@link java.util.ListIterator#previous()} (or {@code null} if no previous
* entry exists).
*/
Entry prev;
/**
* The entry that will be returned by the next call to
* {@link java.util.ListIterator#next()} (or {@code null} if no next entry
* exists).
*/
Entry next;
/**
* The last entry that was returned (or {@code null} if we did not iterate or
* used {@link #remove()}).
*/
Entry curr;
/**
* The current index (in the sense of a {@link java.util.ListIterator}). Note
* that this value is not meaningful when this {@link SetIterator} has been
* created using the nonempty constructor.
*/
int index = 0;
SetIterator() {
next = firstEntry;
}
SetIterator(final K k) {
if ((next = locateKey(k)) != null) {
if (compare(next.key, k) <= 0) {
prev = next;
next = next.next();
} else
prev = next.prev();
}
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public boolean hasPrevious() {
return prev != null;
}
void updateNext() {
next = next.next();
}
Entry nextEntry() {
if (!hasNext())
throw new NoSuchElementException();
curr = prev = next;
index++;
updateNext();
return curr;
}
@Override
public K next() {
return nextEntry().key;
}
@Override
public K previous() {
return previousEntry().key;
}
void updatePrevious() {
prev = prev.prev();
}
Entry previousEntry() {
if (!hasPrevious())
throw new NoSuchElementException();
curr = next = prev;
index--;
updatePrevious();
return curr;
}
@Override
public int nextIndex() {
return index;
}
@Override
public int previousIndex() {
return index - 1;
}
@Override
public void remove() {
if (curr == null)
throw new IllegalStateException();
/*
* If the last operation was a next(), we are removing an entry that preceeds
* the current index, and thus we must decrement it.
*/
if (curr == prev)
index--;
next = prev = curr;
updatePrevious();
updateNext();
ObjectAVLTreeSet.this.remove(curr.key);
curr = null;
}
}
@Override
public ObjectBidirectionalIterator iterator() {
return new SetIterator();
}
@Override
public ObjectBidirectionalIterator iterator(final K from) {
return new SetIterator(from);
}
@Override
public Comparator comparator() {
return actualComparator;
}
@Override
public ObjectSortedSet headSet(final K to) {
return new Subset((null), true, to, false);
}
@Override
public ObjectSortedSet tailSet(final K from) {
return new Subset(from, false, (null), true);
}
@Override
public ObjectSortedSet subSet(final K from, final K to) {
return new Subset(from, false, to, false);
}
/**
* A subset with given range.
*
*
* This class represents a subset. One has to specify the left/right limits
* (which can be set to -∞ or ∞). Since the subset is a view on the
* set, at a given moment it could happen that the limits of the range are not
* any longer in the main set. Thus, things such as
* {@link java.util.SortedSet#first()} or {@link java.util.SortedSet#size()}
* must be always computed on-the-fly.
*/
private final class Subset extends AbstractObjectSortedSet implements java.io.Serializable, ObjectSortedSet {
private static final long serialVersionUID = -7046029254386353129L;
/** The start of the subset range, unless {@link #bottom} is true. */
K from;
/** The end of the subset range, unless {@link #top} is true. */
K to;
/** If true, the subset range starts from -∞. */
boolean bottom;
/** If true, the subset range goes to ∞. */
boolean top;
/**
* Creates a new subset with given key range.
*
* @param from
* the start of the subset range.
* @param bottom
* if true, the first parameter is ignored and the range starts from
* -∞.
* @param to
* the end of the subset range.
* @param top
* if true, the third parameter is ignored and the range goes to
* ∞.
*/
public Subset(final K from, final boolean bottom, final K to, final boolean top) {
if (!bottom && !top && ObjectAVLTreeSet.this.compare(from, to) > 0)
throw new IllegalArgumentException(
"Start element (" + from + ") is larger than end element (" + to + ")");
this.from = from;
this.bottom = bottom;
this.to = to;
this.top = top;
}
@Override
public void clear() {
final SubsetIterator i = new SubsetIterator();
while (i.hasNext()) {
i.next();
i.remove();
}
}
/**
* Checks whether a key is in the subset range.
*
* @param k
* a key.
* @return true if is the key is in the subset range.
*/
final boolean in(final K k) {
return (bottom || ObjectAVLTreeSet.this.compare(k, from) >= 0)
&& (top || ObjectAVLTreeSet.this.compare(k, to) < 0);
}
@SuppressWarnings("unchecked")
@Override
public boolean contains(final Object k) {
return in((K) k) && ObjectAVLTreeSet.this.contains(k);
}
@Override
public boolean add(final K k) {
if (!in(k))
throw new IllegalArgumentException("Element (" + k + ") out of range ["
+ (bottom ? "-" : String.valueOf(from)) + ", " + (top ? "-" : String.valueOf(to)) + ")");
return ObjectAVLTreeSet.this.add(k);
}
@SuppressWarnings("unchecked")
@Override
public boolean remove(final Object k) {
if (!in((K) k))
return false;
return ObjectAVLTreeSet.this.remove(k);
}
@Override
public int size() {
final SubsetIterator i = new SubsetIterator();
int n = 0;
while (i.hasNext()) {
n++;
i.next();
}
return n;
}
@Override
public boolean isEmpty() {
return !new SubsetIterator().hasNext();
}
@Override
public Comparator comparator() {
return actualComparator;
}
@Override
public ObjectBidirectionalIterator iterator() {
return new SubsetIterator();
}
@Override
public ObjectBidirectionalIterator iterator(final K from) {
return new SubsetIterator(from);
}
@Override
public ObjectSortedSet headSet(final K to) {
if (top)
return new Subset(from, bottom, to, false);
return compare(to, this.to) < 0 ? new Subset(from, bottom, to, false) : this;
}
@Override
public ObjectSortedSet tailSet(final K from) {
if (bottom)
return new Subset(from, false, to, top);
return compare(from, this.from) > 0 ? new Subset(from, false, to, top) : this;
}
@Override
public ObjectSortedSet subSet(K from, K to) {
if (top && bottom)
return new Subset(from, false, to, false);
if (!top)
to = compare(to, this.to) < 0 ? to : this.to;
if (!bottom)
from = compare(from, this.from) > 0 ? from : this.from;
if (!top && !bottom && from == this.from && to == this.to)
return this;
return new Subset(from, false, to, false);
}
/**
* Locates the first entry.
*
* @return the first entry of this subset, or {@code null} if the subset is
* empty.
*/
public ObjectAVLTreeSet.Entry firstEntry() {
if (tree == null)
return null;
// If this subset goes to -infinity, we return the main set first entry;
// otherwise, we locate the start of the set.
ObjectAVLTreeSet.Entry e;
if (bottom)
e = firstEntry;
else {
e = locateKey(from);
// If we find either the start or something greater we're OK.
if (compare(e.key, from) < 0)
e = e.next();
}
// Finally, if this subset doesn't go to infinity, we check that the resulting
// key isn't greater than the end.
if (e == null || !top && compare(e.key, to) >= 0)
return null;
return e;
}
/**
* Locates the last entry.
*
* @return the last entry of this subset, or {@code null} if the subset is
* empty.
*/
public ObjectAVLTreeSet.Entry lastEntry() {
if (tree == null)
return null;
// If this subset goes to infinity, we return the main set last entry;
// otherwise, we locate the end of the set.
ObjectAVLTreeSet.Entry e;
if (top)
e = lastEntry;
else {
e = locateKey(to);
// If we find something smaller than the end we're OK.
if (compare(e.key, to) >= 0)
e = e.prev();
}
// Finally, if this subset doesn't go to -infinity, we check that the resulting
// key isn't smaller than the start.
if (e == null || !bottom && compare(e.key, from) < 0)
return null;
return e;
}
@Override
public K first() {
ObjectAVLTreeSet.Entry e = firstEntry();
if (e == null)
throw new NoSuchElementException();
return e.key;
}
@Override
public K last() {
ObjectAVLTreeSet.Entry e = lastEntry();
if (e == null)
throw new NoSuchElementException();
return e.key;
}
/**
* An iterator for subranges.
*
*
* This class inherits from {@link SetIterator}, but overrides the methods that
* update the pointer after a {@link java.util.ListIterator#next()} or
* {@link java.util.ListIterator#previous()}. If we would move out of the range
* of the subset we just overwrite the next or previous entry with {@code null}.
*/
private final class SubsetIterator extends SetIterator {
SubsetIterator() {
next = firstEntry();
}
SubsetIterator(final K k) {
this();
if (next != null) {
if (!bottom && compare(k, next.key) < 0)
prev = null;
else if (!top && compare(k, (prev = lastEntry()).key) >= 0)
next = null;
else {
next = locateKey(k);
if (compare(next.key, k) <= 0) {
prev = next;
next = next.next();
} else
prev = next.prev();
}
}
}
@Override
void updatePrevious() {
prev = prev.prev();
if (!bottom && prev != null && ObjectAVLTreeSet.this.compare(prev.key, from) < 0)
prev = null;
}
@Override
void updateNext() {
next = next.next();
if (!top && next != null && ObjectAVLTreeSet.this.compare(next.key, to) >= 0)
next = null;
}
}
}
/**
* Returns a deep copy of this tree set.
*
*
* This method performs a deep copy of this tree set; the data stored in the
* set, however, is not cloned. Note that this makes a difference only for
* object keys.
*
* @return a deep copy of this tree set.
*/
@Override
@SuppressWarnings("unchecked")
public Object clone() {
ObjectAVLTreeSet c;
try {
c = (ObjectAVLTreeSet) super.clone();
} catch (CloneNotSupportedException cantHappen) {
throw new InternalError();
}
c.allocatePaths();
if (count != 0) {
// Also this apparently unfathomable code is derived from GNU libavl.
Entry e, p, q, rp = new Entry<>(), rq = new Entry<>();
p = rp;
rp.left(tree);
q = rq;
rq.pred(null);
while (true) {
if (!p.pred()) {
e = p.left.clone();
e.pred(q.left);
e.succ(q);
q.left(e);
p = p.left;
q = q.left;
} else {
while (p.succ()) {
p = p.right;
if (p == null) {
q.right = null;
c.tree = rq.left;
c.firstEntry = c.tree;
while (c.firstEntry.left != null)
c.firstEntry = c.firstEntry.left;
c.lastEntry = c.tree;
while (c.lastEntry.right != null)
c.lastEntry = c.lastEntry.right;
return c;
}
q = q.right;
}
p = p.right;
q = q.right;
}
if (!p.succ()) {
e = p.right.clone();
e.succ(q.right);
e.pred(q);
q.right(e);
}
}
}
return c;
}
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
int n = count;
SetIterator i = new SetIterator();
s.defaultWriteObject();
while (n-- != 0)
s.writeObject(i.next());
}
/**
* Reads the given number of entries from the input stream, returning the
* corresponding tree.
*
* @param s
* the input stream.
* @param n
* the (positive) number of entries to read.
* @param pred
* the entry containing the key that preceeds the first key in the
* tree.
* @param succ
* the entry containing the key that follows the last key in the
* tree.
*/
@SuppressWarnings("unchecked")
private Entry readTree(final java.io.ObjectInputStream s, final int n, final Entry pred, final Entry succ)
throws java.io.IOException, ClassNotFoundException {
if (n == 1) {
final Entry top = new Entry<>((K) s.readObject());
top.pred(pred);
top.succ(succ);
return top;
}
if (n == 2) {
/*
* We handle separately this case so that recursion will always* be on nonempty
* subtrees.
*/
final Entry top = new Entry<>((K) s.readObject());
top.right(new Entry<>((K) s.readObject()));
top.right.pred(top);
top.balance(1);
top.pred(pred);
top.right.succ(succ);
return top;
}
// The right subtree is the largest one.
final int rightN = n / 2, leftN = n - rightN - 1;
final Entry top = new Entry<>();
top.left(readTree(s, leftN, pred, top));
top.key = (K) s.readObject();
top.right(readTree(s, rightN, top, succ));
if (n == (n & -n))
top.balance(1); // Quick test for determining whether n is a power of 2.
return top;
}
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
/*
* The storedComparator is now correctly set, but we must restore on-the-fly the
* actualComparator.
*/
setActualComparator();
allocatePaths();
if (count != 0) {
tree = readTree(s, count, null, null);
Entry e;
e = tree;
while (e.left() != null)
e = e.left();
firstEntry = e;
e = tree;
while (e.right() != null)
e = e.right();
lastEntry = e;
}
}
}