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/*
* 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.util.NoSuchElementException;
/**
* A descriptor for a <i>discrete</i> {@code Comparable} domain such as all
* {@link Integer}s. 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."
*
* @author Kevin Bourrillion
* @since 10.0
* @see DiscreteDomains
*/
@GwtCompatible
@Beta
public abstract class DiscreteDomain<C extends Comparable> {
/** 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#MIN_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();
}
}
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