/
SignedNumeral.java
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/
SignedNumeral.java
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/*
* Copyright 2020 Emory University
*
* 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 edu.emory.cs.algebraic;
/** @author Jinho D. Choi */
public abstract class SignedNumeral<T extends SignedNumeral<T>> implements Numeral<T> {
/** The sign of this numeral. */
protected Sign sign;
/**
* Creates a signed numeral.
* the default sign is {@link Sign#POSITIVE}.
*/
public SignedNumeral() {
this(Sign.POSITIVE);
}
/**
* Creates a signed numeral.
* @param sign the sign of this numeral.
*/
public SignedNumeral(Sign sign) {
this.sign = sign;
}
/** @return true if this numeral is positive; otherwise, false. */
public boolean isPositive() {
return sign == Sign.POSITIVE;
}
/** @return true if this numeral is negative; otherwise, false. */
public boolean isNegative() {
return sign == Sign.NEGATIVE;
}
/** Flips the sign of this numeral. */
public void flipSign() {
sign = isPositive() ? Sign.NEGATIVE : Sign.POSITIVE;
}
/**
* Subtracts `n` from this numeral.
* @param n the numeral to be subtracted.
*/
public void subtract(T n) {
n.flipSign();
add(n);
n.flipSign();
}
/**
* Multiplies `n` to this numeral.
* @param n the numeral to be multiplied.
*/
public abstract void multiply(T n);
}