/**
 * Copyright (c) 2017-2018, the Alpha Team.
 * All rights reserved.
 * 
 * Additional changes made by Siemens.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1) Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * 
 * 2) Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package at.ac.tuwien.kr.alpha.common.atoms;

import at.ac.tuwien.kr.alpha.common.Predicate;
import at.ac.tuwien.kr.alpha.common.terms.Term;
import at.ac.tuwien.kr.alpha.common.terms.VariableTerm;
import at.ac.tuwien.kr.alpha.grounder.Substitution;
import org.apache.commons.collections4.SetUtils;

import java.util.Collections;
import java.util.List;
import java.util.Set;

/**
 * Contains a potentially negated {@link Atom}
 * 
 * Copyright (c) 2017-2018, the Alpha Team.
 */
public class Literal {
	protected final Atom atom;
	protected final boolean negated;
	
	public Literal(Atom atom, boolean negated) {
		this.atom = atom;
		this.negated = negated;
	}

	public Atom getAtom() {
		return atom;
	}

	public boolean isNegated() {
		return negated;
	}

	/**
	 * Returns a new copy of this literal whose {@link Literal#isNegated()} status is inverted
	 * (if the atom cannot be negated, the literal may be returned without creating a copy)
	 */
	public Literal negate() {
		return new Literal(atom, !negated);
	}

	/**
	 * @see Atom#substitute(Substitution)
	 */
	public Literal substitute(Substitution substitution) {
		return new Literal(atom.substitute(substitution), negated);
	}

	/**
	 * Set of all variables occurring in the Atom that are potentially binding, i.e., variables in positive atoms.
	 * 
	 * @return
	 */
	public Set<VariableTerm> getBindingVariables() {
		if (isNegated()) {
			return Collections.emptySet();
		} else {
			return atom.getBindingVariables();
		}
	}

	/**
	 * Set of all variables occurring in the Atom that are never binding, not even in positive atoms, e.g., variables in intervals or built-in atoms.
	 * 
	 * @return
	 */
	public Set<VariableTerm> getNonBindingVariables() {
		if (isNegated()) {
			return SetUtils.union(atom.getBindingVariables(), atom.getNonBindingVariables());
		} else {
			return Collections.emptySet();
		}
	}

	/**
	 * @see Atom#getPredicate()
	 */
	public Predicate getPredicate() {
		return atom.getPredicate();
	}

	/**
	 * @see Atom#getTerms()
	 */
	public List<Term> getTerms() {
		return atom.getTerms();
	}

	/**
	 * @see Atom#isGround()
	 */
	public boolean isGround() {
		return atom.isGround();
	}
	
	@Override
	public String toString() {
		return (negated ? "not " : "") + atom.toString();
	}
}

@@ -3679,11 +3679,353 @@
 ng();%0A%09%7D
+%0A%0A%09@Override%0A%09public boolean equals(Object o) %7B%0A%09%09if (this == o) %7B%0A%09%09%09return true;%0A%09%09%7D%0A%09%09if (o == null %7C%7C getClass() != o.getClass()) %7B%0A%09%09%09return false;%0A%09%09%7D%0A%0A%09%09Literal that = (Literal) o;%0A%0A%09%09return atom.equals(that.atom) && negated == that.negated;%0A%09%7D%0A%0A%09@Override%0A%09public int hashCode() %7B%0A%09%09return 12 * atom.hashCode() + (negated ? 1 : 0);%0A%09%7D
 %0A%7D%0A

implement hashCode and equals in Literal