/*
* Copyright (C) 2011 The Guava Authors
*
* 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 com.google.common.collect;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Set;
import javax.annotation.Nullable;
/**
* A set of values of type {@code C} made up of zero or more <i>disjoint</i> {@linkplain Range
* ranges}.
*
* <p>It is guaranteed that {@linkplain Range#isConnected connected} ranges will be
* {@linkplain Range#span coalesced} together, and that {@linkplain Range#isEmpty empty} ranges
* will never be held in a {@code RangeSet}.
*
* <p>For a {@link Set} whose contents are specified by a {@link Range}, see {@link ContiguousSet}.
*
* @author Kevin Bourrillion
* @author Louis Wasserman
*/ abstract class RangeSet<C extends Comparable> {
RangeSet() {}
/**
* Determines whether any of this range set's member ranges contains {@code value}.
*/
public boolean contains(C value) {
return rangeContaining(value) != null;
}
/**
* Returns the unique range from this range set that {@linkplain Range#contains contains}
* {@code value}, or {@code null} if this range set does not contain {@code value}.
*/
public Range<C> rangeContaining(C value) {
checkNotNull(value);
for (Range<C> range : asRanges()) {
if (range.contains(value)) {
return range;
}
}
return null;
}
/**
* Returns a view of the {@linkplain Range#isConnected disconnected} ranges that make up this
* range set. The returned set may be empty. The iterators returned by its
* {@link Iterable#iterator} method return the ranges in increasing order of lower bound
* (equivalently, of upper bound).
*/
public abstract Set<Range<C>> asRanges();
/**
* Returns {@code true} if this range set contains no ranges.
*/
public boolean isEmpty() {
return asRanges().isEmpty();
}
/**
* Returns a view of the complement of this {@code RangeSet}.
*
* <p>The returned view supports the {@link #add} operation if this {@code RangeSet} supports
* {@link #remove}, and vice versa.
*/
public abstract RangeSet<C> complement();
/**
* A basic, simple implementation of {@link #complement}. This is not efficient on all methods;
* for example, {@link #rangeContaining} and {@link #encloses} are linear-time.
*/
static class StandardComplement<C extends Comparable> extends RangeSet<C> {
final RangeSet<C> positive;
public StandardComplement(RangeSet<C> positive) {
this.positive = positive;
}
@Override
public boolean contains(C value) {
return !positive.contains(value);
}
@Override
public void add(Range<C> range) {
positive.remove(range);
}
@Override
public void remove(Range<C> range) {
positive.add(range);
}
private transient Set<Range<C>> asRanges;
@Override
public final Set<Range<C>> asRanges() {
Set<Range<C>> result = asRanges;
return (result == null) ? asRanges = createAsRanges() : result;
}
Set<Range<C>> createAsRanges() {
return new AbstractSet<Range<C>>() {
@Override
public Iterator<Range<C>> iterator() {
final Iterator<Range<C>> positiveIterator = positive.asRanges().iterator();
return new AbstractIterator<Range<C>>() {
Cut<C> prevCut = Cut.belowAll();
@Override
protected Range<C> computeNext() {
while (positiveIterator.hasNext()) {
Cut<C> oldCut = prevCut;
Range<C> positiveRange = positiveIterator.next();
prevCut = positiveRange.upperBound;
if (oldCut.compareTo(positiveRange.lowerBound) < 0) {
return new Range<C>(oldCut, positiveRange.lowerBound);
}
}
Cut<C> posInfinity = Cut.aboveAll();
if (prevCut.compareTo(posInfinity) < 0) {
Range<C> result = new Range<C>(prevCut, posInfinity);
prevCut = posInfinity;
return result;
}
return endOfData();
}
};
}
@Override
public int size() {
return Iterators.size(iterator());
}
};
}
@Override
public RangeSet<C> complement() {
return positive;
}
}
/**
* Adds the specified range to this {@code RangeSet} (optional operation). That is, for equal
* range sets a and b, the result of {@code a.add(range)} is that {@code a} will be the minimal
* range set for which both {@code a.enclosesAll(b)} and {@code a.encloses(range)}.
*
* <p>Note that {@code range} will be {@linkplain Range#span(Range) coalesced} with any ranges in
* the range set that are {@linkplain Range#isConnected(Range) connected} with it. Moreover,
* if {@code range} is empty, this is a no-op.
*
* @throws UnsupportedOperationException if this range set does not support the {@code add}
* operation
*/
public void add(Range<C> range) {
throw new UnsupportedOperationException();
}
/**
* Removes the specified range from this {@code RangeSet} (optional operation). After this
* operation, if {@code range.contains(c)}, {@code this.contains(c)} will return {@code false}.
*
* <p>If {@code range} is empty, this is a no-op.
*
* @throws UnsupportedOperationException if this range set does not support the {@code remove}
* operation
*/
public void remove(Range<C> range) {
throw new UnsupportedOperationException();
}
/**
* Returns {@code true} if there exists a member range in this range set which
* {@linkplain Range#encloses encloses} the specified range.
*/
public boolean encloses(Range<C> otherRange) {
for (Range<C> range : asRanges()) {
if (range.encloses(otherRange)) {
return true;
}
}
return false;
}
/**
* Returns {@code true} if for each member range in {@code other} there exists a member range in
* this range set which {@linkplain Range#encloses encloses} it. It follows that
* {@code this.contains(value)} whenever {@code other.contains(value)}. Returns {@code true} if
* {@code other} is empty.
*
* <p>
* This is equivalent to checking if this range set {@link #encloses} each of the ranges in
* {@code other}.
*/
public boolean enclosesAll(RangeSet<C> other) {
for (Range<C> range : other.asRanges()) {
if (!encloses(range)) {
return false;
}
}
return true;
}
/**
* Adds all of the ranges from the specified range set to this range set (optional operation).
* After this operation, this range set is the minimal range set that
* {@linkplain #enclosesAll(RangeSet) encloses} both the original range set and {@code other}.
*
* <p>
* This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
*
* @throws UnsupportedOperationException if this range set does not support the {@code addAll}
* operation
*/
public void addAll(RangeSet<C> other) {
for (Range<C> range : other.asRanges()) {
this.add(range);
}
}
/**
* Removes all of the ranges from the specified range set from this range set (optional
* operation). After this operation, if {@code other.contains(c)}, {@code this.contains(c)} will
* return {@code false}.
*
* <p>
* This is equivalent to calling {@link #remove} on each of the ranges in {@code other} in turn.
*
* @throws UnsupportedOperationException if this range set does not support the {@code removeAll}
* operation
*/
public void removeAll(RangeSet<C> other) {
for (Range<C> range : other.asRanges()) {
this.remove(range);
}
}
/**
* Returns {@code true} if {@code obj} is another {@code RangeSet} that contains the same ranges
* according to {@link Range#equals(Object)}.
*/
@Override
public boolean equals(@Nullable Object obj) {
if (obj instanceof RangeSet) {
RangeSet<?> other = (RangeSet<?>) obj;
return this.asRanges().equals(other.asRanges());
}
return false;
}
@Override
public final int hashCode() {
return asRanges().hashCode();
}
/**
* Returns a readable string representation of this range set. For example, if this
* {@code RangeSet} consisted of {@code Ranges.closed(1, 3)} and {@code Ranges.greaterThan(4)},
* this might return {@code " [1‥3](4‥+∞)}"}.
*/
@Override
public final String toString() {
StringBuilder builder = new StringBuilder();
builder.append('{');
for (Range<C> range : asRanges()) {
builder.append(range);
}
builder.append('}');
return builder.toString();
}
}