| /* |
| * Copyright (C) 2009 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 com.google.common.annotations.Beta; |
| import com.google.common.annotations.GwtCompatible; |
| |
| import java.io.Serializable; |
| import java.math.BigInteger; |
| import java.util.NoSuchElementException; |
| |
| /** |
| * A descriptor for a <i>discrete</i> {@code Comparable} domain such as all |
| * {@link Integer} instances. A discrete domain is one that supports the three basic |
| * operations: {@link #next}, {@link #previous} and {@link #distance}, according |
| * to their specifications. The methods {@link #minValue} and {@link #maxValue} |
| * should also be overridden for bounded types. |
| * |
| * <p>A discrete domain always represents the <i>entire</i> set of values of its |
| * type; it cannot represent partial domains such as "prime integers" or |
| * "strings of length 5." |
| * |
| * <p>See the Guava User Guide section on <a href= |
| * "http://code.google.com/p/guava-libraries/wiki/RangesExplained#Discrete_Domains"> |
| * {@code DiscreteDomain}</a>. |
| * |
| * @author Kevin Bourrillion |
| * @since 10.0 |
| */ |
| @GwtCompatible |
| @Beta |
| public abstract class DiscreteDomain<C extends Comparable> { |
| |
| /** |
| * Returns the discrete domain for values of type {@code Integer}. |
| * |
| * @since 14.0 (since 10.0 as {@code DiscreteDomains.integers()}) |
| */ |
| public static DiscreteDomain<Integer> integers() { |
| return IntegerDomain.INSTANCE; |
| } |
| |
| private static final class IntegerDomain extends DiscreteDomain<Integer> |
| implements Serializable { |
| private static final IntegerDomain INSTANCE = new IntegerDomain(); |
| |
| @Override public Integer next(Integer value) { |
| int i = value; |
| return (i == Integer.MAX_VALUE) ? null : i + 1; |
| } |
| |
| @Override public Integer previous(Integer value) { |
| int i = value; |
| return (i == Integer.MIN_VALUE) ? null : i - 1; |
| } |
| |
| @Override public long distance(Integer start, Integer end) { |
| return (long) end - start; |
| } |
| |
| @Override public Integer minValue() { |
| return Integer.MIN_VALUE; |
| } |
| |
| @Override public Integer maxValue() { |
| return Integer.MAX_VALUE; |
| } |
| |
| private Object readResolve() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public String toString() { |
| return "DiscreteDomain.integers()"; |
| } |
| |
| private static final long serialVersionUID = 0; |
| } |
| |
| /** |
| * Returns the discrete domain for values of type {@code Long}. |
| * |
| * @since 14.0 (since 10.0 as {@code DiscreteDomains.longs()}) |
| */ |
| public static DiscreteDomain<Long> longs() { |
| return LongDomain.INSTANCE; |
| } |
| |
| private static final class LongDomain extends DiscreteDomain<Long> |
| implements Serializable { |
| private static final LongDomain INSTANCE = new LongDomain(); |
| |
| @Override public Long next(Long value) { |
| long l = value; |
| return (l == Long.MAX_VALUE) ? null : l + 1; |
| } |
| |
| @Override public Long previous(Long value) { |
| long l = value; |
| return (l == Long.MIN_VALUE) ? null : l - 1; |
| } |
| |
| @Override public long distance(Long start, Long end) { |
| long result = end - start; |
| if (end > start && result < 0) { // overflow |
| return Long.MAX_VALUE; |
| } |
| if (end < start && result > 0) { // underflow |
| return Long.MIN_VALUE; |
| } |
| return result; |
| } |
| |
| @Override public Long minValue() { |
| return Long.MIN_VALUE; |
| } |
| |
| @Override public Long maxValue() { |
| return Long.MAX_VALUE; |
| } |
| |
| private Object readResolve() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public String toString() { |
| return "DiscreteDomain.longs()"; |
| } |
| |
| private static final long serialVersionUID = 0; |
| } |
| |
| /** |
| * Returns the discrete domain for values of type {@code BigInteger}. |
| * |
| * @since 15.0 |
| */ |
| public static DiscreteDomain<BigInteger> bigIntegers() { |
| return BigIntegerDomain.INSTANCE; |
| } |
| |
| private static final class BigIntegerDomain extends DiscreteDomain<BigInteger> |
| implements Serializable { |
| private static final BigIntegerDomain INSTANCE = new BigIntegerDomain(); |
| |
| private static final BigInteger MIN_LONG = |
| BigInteger.valueOf(Long.MIN_VALUE); |
| private static final BigInteger MAX_LONG = |
| BigInteger.valueOf(Long.MAX_VALUE); |
| |
| @Override public BigInteger next(BigInteger value) { |
| return value.add(BigInteger.ONE); |
| } |
| |
| @Override public BigInteger previous(BigInteger value) { |
| return value.subtract(BigInteger.ONE); |
| } |
| |
| @Override public long distance(BigInteger start, BigInteger end) { |
| return end.subtract(start).max(MIN_LONG).min(MAX_LONG).longValue(); |
| } |
| |
| private Object readResolve() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public String toString() { |
| return "DiscreteDomain.bigIntegers()"; |
| } |
| |
| private static final long serialVersionUID = 0; |
| } |
| |
| /** Constructor for use by subclasses. */ |
| protected DiscreteDomain() {} |
| |
| /** |
| * Returns the unique least value of type {@code C} that is greater than |
| * {@code value}, or {@code null} if none exists. Inverse operation to {@link |
| * #previous}. |
| * |
| * @param value any value of type {@code C} |
| * @return the least value greater than {@code value}, or {@code null} if |
| * {@code value} is {@code maxValue()} |
| */ |
| public abstract C next(C value); |
| |
| /** |
| * Returns the unique greatest value of type {@code C} that is less than |
| * {@code value}, or {@code null} if none exists. Inverse operation to {@link |
| * #next}. |
| * |
| * @param value any value of type {@code C} |
| * @return the greatest value less than {@code value}, or {@code null} if |
| * {@code value} is {@code minValue()} |
| */ |
| public abstract C previous(C value); |
| |
| /** |
| * Returns a signed value indicating how many nested invocations of {@link |
| * #next} (if positive) or {@link #previous} (if negative) are needed to reach |
| * {@code end} starting from {@code start}. For example, if {@code end = |
| * next(next(next(start)))}, then {@code distance(start, end) == 3} and {@code |
| * distance(end, start) == -3}. As well, {@code distance(a, a)} is always |
| * zero. |
| * |
| * <p>Note that this function is necessarily well-defined for any discrete |
| * type. |
| * |
| * @return the distance as described above, or {@link Long#MIN_VALUE} or |
| * {@link Long#MAX_VALUE} if the distance is too small or too large, |
| * respectively. |
| */ |
| public abstract long distance(C start, C end); |
| |
| /** |
| * Returns the minimum value of type {@code C}, if it has one. The minimum |
| * value is the unique value for which {@link Comparable#compareTo(Object)} |
| * never returns a positive value for any input of type {@code C}. |
| * |
| * <p>The default implementation throws {@code NoSuchElementException}. |
| * |
| * @return the minimum value of type {@code C}; never null |
| * @throws NoSuchElementException if the type has no (practical) minimum |
| * value; for example, {@link java.math.BigInteger} |
| */ |
| public C minValue() { |
| throw new NoSuchElementException(); |
| } |
| |
| /** |
| * Returns the maximum value of type {@code C}, if it has one. The maximum |
| * value is the unique value for which {@link Comparable#compareTo(Object)} |
| * never returns a negative value for any input of type {@code C}. |
| * |
| * <p>The default implementation throws {@code NoSuchElementException}. |
| * |
| * @return the maximum value of type {@code C}; never null |
| * @throws NoSuchElementException if the type has no (practical) maximum |
| * value; for example, {@link java.math.BigInteger} |
| */ |
| public C maxValue() { |
| throw new NoSuchElementException(); |
| } |
| |
| } |