package org.matheclipse.core.reflection.system;

import org.matheclipse.core.eval.exception.Validate;
import org.matheclipse.core.eval.interfaces.IFunctionEvaluator;
import org.matheclipse.core.expression.F;
import org.matheclipse.core.interfaces.IAST;
import org.matheclipse.core.interfaces.IExpr;
import org.matheclipse.core.interfaces.INumber;
import org.matheclipse.core.interfaces.ISymbol;

/**
 * Gets the signum value of a complex number
 * 
 * @return 0 for this == 0;

 *         +1 for
 *         real(this) > 0 || ( real(this) == 0 && imaginary(this) > 0 )
 *         ;

 *         -1 for
 *         real(this) < 0 || ( real(this) == 0 && imaginary(this) < 0 )
 */
public class SignCmp implements IFunctionEvaluator {

	public SignCmp() {
	}

	public IExpr evaluate(final IAST ast) {
		Validate.checkSize(ast, 2);

		if (ast.arg1().isNumber()) {
			final int signum = ((INumber) ast.arg1()).complexSign();
			return F.integer(signum);
		}
		return null;
	}

	public IExpr numericEval(final IAST ast) {
		return evaluate(ast);
	}

	public void setUp(final ISymbol symbol) {
		symbol.setAttributes(ISymbol.LISTABLE);
	}

}