content: /**
   * Copyright (c) 2017-2018, the Alpha Team.
   * All rights reserved.
   * <p>
   * Additional changes made by Siemens.
   * <p>
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * <p>
   * 1) Redistributions of source code must retain the above copyright notice, this
   * list of conditions and the following disclaimer.
   * <p>
   * 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.
   * <p>
   * 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.commons.programs.literals;
  
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  
  import at.ac.tuwien.kr.alpha.api.grounder.Substitution;
  import at.ac.tuwien.kr.alpha.api.programs.atoms.BasicAtom;
  import at.ac.tuwien.kr.alpha.api.programs.literals.BasicLiteral;
  import at.ac.tuwien.kr.alpha.api.programs.literals.Literal;
  import at.ac.tuwien.kr.alpha.api.programs.terms.Term;
  import at.ac.tuwien.kr.alpha.api.programs.terms.VariableTerm;
  import at.ac.tuwien.kr.alpha.commons.programs.atoms.AbstractAtom;
  
  /**
   * Contains a potentially negated {@link BasicAtomImpl}.
   *
   * Copyright (c) 2017-2018, the Alpha Team.
   */
  class BasicLiteralImpl extends AbstractLiteral implements BasicLiteral {
  
  	BasicLiteralImpl(BasicAtom atom, boolean positive) {
  		super(atom, positive);
  	}
  
  	@Override
  	public BasicAtom getAtom() {
  		return (BasicAtom) atom;
  	}
  
  	/**
  	 * Returns a new copy of this literal whose {@link Literal#isNegated()} status is inverted
  	 */
  	@Override
  	public BasicLiteralImpl negate() {
  		return new BasicLiteralImpl(getAtom(), !positive);
  	}
  
  	/**
  	 * @see AbstractAtom#substitute(Substitution)
  	 */
  	@Override
  	public BasicLiteralImpl substitute(Substitution substitution) {
  		return new BasicLiteralImpl(getAtom().substitute(substitution), positive);
  	}
  
  	/**
  	 * Set of all variables occurring in the Atom that are potentially binding, i.e., variables in positive atoms.
  	 *
  	 * @return
  	 */
  	@Override
  	public Set<VariableTerm> getBindingVariables() {
  		if (!positive) {
  			// Negative literal has no binding variables.
  			return Collections.emptySet();
  		}
  		Set<VariableTerm> bindingVariables = new HashSet<>();
  		for (Term term : atom.getTerms()) {
  			bindingVariables.addAll(term.getOccurringVariables());
  		}
  		return bindingVariables;
  	}
  
  	/**
  	 * 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
  	 */
  	@Override
  	public Set<VariableTerm> getNonBindingVariables() {
  		if (positive) {
  			// Positive literal has only binding variables.
  			return Collections.emptySet();
  		}
  		Set<VariableTerm> nonbindingVariables = new HashSet<>();
  		for (Term term : atom.getTerms()) {
  			nonbindingVariables.addAll(term.getOccurringVariables());
  		}
  		return nonbindingVariables;
  	}
  }
  