content: /**
   * Copyright (c) 2016-2018, 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.core.programs.atoms;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  
  import at.ac.tuwien.kr.alpha.api.grounder.Substitution;
  import at.ac.tuwien.kr.alpha.api.programs.Predicate;
  import at.ac.tuwien.kr.alpha.api.programs.atoms.Atom;
  import at.ac.tuwien.kr.alpha.api.programs.literals.Literal;
  import at.ac.tuwien.kr.alpha.api.programs.terms.ConstantTerm;
  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.Predicates;
  import at.ac.tuwien.kr.alpha.commons.programs.terms.Terms;
  import at.ac.tuwien.kr.alpha.commons.util.Util;
  
  public class ChoiceAtom implements Atom {
  
  	public static final Predicate ON = Predicates.getPredicate("ChoiceOn", 1, true, true);
  	public static final Predicate OFF = Predicates.getPredicate("ChoiceOff", 1, true, true);
  
  	private final Predicate predicate;
  	private final ConstantTerm<String> term;
  
  	private ChoiceAtom(Predicate predicate, ConstantTerm<String> term) {
  		this.predicate = predicate;
  		this.term = term;
  	}
  
  	private ChoiceAtom(Predicate predicate, int id) {
  		this(predicate, Terms.newConstant(Integer.toString(id)));
  	}
  
  	public static ChoiceAtom on(int id) {
  		return new ChoiceAtom(ON, id);
  	}
  
  	public static ChoiceAtom off(int id) {
  		return new ChoiceAtom(OFF, id);
  	}
  
  	@Override
  	public Predicate getPredicate() {
  		return predicate;
  	}
  
  	@Override
  	public List<Term> getTerms() {
  		return Collections.singletonList(term);
  	}
  
  	@Override
  	public boolean isGround() {
  		// NOTE: Term is a ConstantTerm, which is ground by definition.
  		return true;
  	}
  
  	@Override
  	public Literal toLiteral(boolean negated) {
  		throw new UnsupportedOperationException("ChoiceAtom cannot be literalized");
  	}
  
  	@Override
  	public ChoiceAtom substitute(Substitution substitution) {
  		return this;
  	}
  
  	@Override
  	public String toString() {
  		return Util.join(predicate.getName() + "(", getTerms(), ")");
  	}
  
  	@Override
  	public Atom withTerms(List<Term> terms) {
  		throw new UnsupportedOperationException("Changing terms is not supported for ChoiceAtoms!");
  	}
  
  	@Override
  	public int hashCode() {
  		final int prime = 31;
  		int result = 1;
  		result = prime * result + ((this.predicate == null) ? 0 : this.predicate.hashCode());
  		result = prime * result + ((this.getTerms() == null) ? 0 : this.getTerms().hashCode());
  		return result;
  	}
  
  	@Override
  	public boolean equals(Object obj) {
  		if (this == obj) {
  			return true;
  		}
  		if (obj == null) {
  			return false;
  		}
  		if (!(obj instanceof ChoiceAtom)) {
  			return false;
  		}
  		ChoiceAtom other = (ChoiceAtom) obj;
  		if (this.predicate == null) {
  			if (other.predicate != null) {
  				return false;
  			}
  		} else if (!this.predicate.equals(other.predicate)) {
  			return false;
  		}
  		if (this.getTerms() == null) {
  			if (other.getTerms() != null) {
  				return false;
  			}
  		} else if (!this.getTerms().equals(other.getTerms())) {
  			return false;
  		}
  		return true;
  	}
  
  	@Override
  	public Set<VariableTerm> getOccurringVariables() {
  		return Collections.emptySet();
  	}
  
  	@Override
  	public Atom renameVariables(String newVariablePrefix) {
  		throw new UnsupportedOperationException("ChoiceAtom does not have any variables to rename!");
  	}
  }