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package org.psjava.ds.numbersystrem;

public class IntegerNumberSystem implements IntegerDivisableNumberSystem {

	private static final IntegerNumberSystem INSTANCE = new IntegerNumberSystem();

	public static IntegerNumberSystem getInstance() {
		return INSTANCE;
	}

	private IntegerNumberSystem() {
	}

	@Override
	public Integer getZero() {
		return Integer.valueOf(0);
	}

	@Override
	public Integer getByInt(int v) {
		return v;
	}

	@Override
	public boolean isPositive(Integer v) {
		return v.intValue() > 0;
	}

	@Override
	public boolean isZero(Integer v) {
		return v.intValue() == 0;
	}

	@Override
	public boolean isNegative(Integer v) {
		return v.intValue() < 0;
	}

	@Override
	public int getSign(Integer v) {
		return Integer.signum(v);
	}

	@Override
	public boolean areEqual(Integer o1, Integer o2) {
		return o1.equals(o2);
	}

	@Override
	public Integer getOne() {
		return Integer.valueOf(1);
	}

	@Override
	public boolean isOne(Integer v) {
		return v.intValue() == 1;
	}

	@Override
	public Integer add(Integer v1, Integer v2) {
		return safeCastFromLong((long) v1 + (long) v2);
	}

	@Override
	public Integer subtract(Integer minuend, Integer subtrahend) {
		return safeCastFromLong((long) minuend - (long) subtrahend);
	}

	@Override
	public Integer multiply(Integer v1, Integer v2) {
		return safeCastFromLong((long) v1 * (long) v2);
	}

	@Override
	public Integer integerDivide(Integer dividend, Integer divisor) {
		return Integer.valueOf(dividend / divisor);
	}

	@Override
	public Integer integerRemainder(Integer dividend, Integer divisor) {
		return Integer.valueOf(dividend % divisor);
	}

	private Integer safeCastFromLong(long v) {
		if (v != (int) v)
			throw OverflowException.create();
		return Integer.valueOf((int) v);
	}

	@Override
	public int compare(Integer o1, Integer o2) {
		return o1.compareTo(o2);
	}

}