content: /**
   * Copyright (c) 2016-2020, 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.atoms;
  
  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.Term;
  import at.ac.tuwien.kr.alpha.api.programs.terms.VariableTerm;
  import at.ac.tuwien.kr.alpha.commons.programs.terms.Terms;
  
  /**
   * An Atom is the common superclass of all representations of ASP atoms used by Alpha.
   */
  public abstract class AbstractAtom implements Atom {
  
  	/**
  	 * Creates a new Atom that represents this Atom, but has the given term list instead.
  	 *
  	 * @param terms the terms to set.
  	 * @return a new Atom with the given terms set.
  	 */
  	@Override
  	public abstract Atom withTerms(List<Term> terms);
  
  	/**
  	 * Returns the set of all variables occurring in the Atom.
  	 */
  	@Override
  	public Set<VariableTerm> getOccurringVariables() {
  		return toLiteral().getOccurringVariables();
  	}
  
  	/**
  	 * This method applies a substitution to the atom. Note that, depending on the atom and the substitution, the
  	 * resulting atom may still contain variables.
  	 *
  	 * @param substitution the variable substitution to apply.
  	 * @return the atom resulting from the application of the substitution.
  	 */
  	@Override
  	public abstract Atom substitute(Substitution substitution);
  
  	@Override
  	public abstract List<Term> getTerms();
  
  	@Override
  	public abstract Predicate getPredicate();
  
  	/**
  	 * Returns whether this atom is ground, i.e., variable-free.
  	 *
  	 * @return true iff the terms of this atom contain no {@link VariableTermImpl}.
  	 */
  	@Override
  	public abstract boolean isGround();
  
  	@Override
  	public abstract Literal toLiteral(boolean positive);
  
  	@Override
  	public Atom renameVariables(String newVariablePrefix) {
  		return this.substitute(Terms.renameVariables(getOccurringVariables(), newVariablePrefix));
  	}
  
  	@Override
  	public abstract boolean equals(Object o);
  
  	@Override
  	public abstract int hashCode();
  
  }
  