content: /**
   * Copyright (c) 2016-2020, 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.commons.programs.atoms;
  
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  
  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.atoms.BasicAtom;
  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.commons.programs.literals.Literals;
  import at.ac.tuwien.kr.alpha.commons.programs.terms.Terms;
  import at.ac.tuwien.kr.alpha.commons.util.Util;
  
  /**
   * Represents ordinary ASP atoms.
   */
  class BasicAtomImpl extends AbstractAtom implements BasicAtom {
  	private final Predicate predicate;
  	private final List<Term> terms;
  	private final boolean ground;
  
  	/**
  	 * Creates a positive BasicAtom over predicate and terms.
  	 * 
  	 * @param predicate
  	 * @param terms
  	 */
  	BasicAtomImpl(Predicate predicate, List<Term> terms) {
  		if (terms.size() != predicate.getArity()) {
  			throw new IllegalArgumentException(
  					"Cannot create Atom with terms: " + terms + " - Predicate " + predicate.getName() + " has incompatible arity " + predicate.getArity());
  		}
  
  		this.predicate = predicate;
  		this.terms = terms;
  
  		boolean ground = true;
  		for (Term term : terms) {
  			if (!term.isGround()) {
  				ground = false;
  				break;
  			}
  		}
  
  		this.ground = ground;
  	}
  
  	BasicAtomImpl(Predicate predicate, Term... terms) {
  		this(predicate, Arrays.asList(terms));
  	}
  
  	BasicAtomImpl(Predicate predicate) {
  		this(predicate, Collections.emptyList());
  	}
  
  	@Override
  	public Predicate getPredicate() {
  		return predicate;
  	}
  
  	@Override
  	public List<Term> getTerms() {
  		return terms;
  	}
  
  	@Override
  	public boolean isGround() {
  		return ground;
  	}
  
  	@Override
  	public BasicAtomImpl substitute(Substitution substitution) {
  		return new BasicAtomImpl(predicate, terms.stream()
  				.map(t -> t.substitute(substitution))
  				.collect(Collectors.toList()));
  	}
  
  	@Override
  	public BasicAtomImpl normalizeVariables(String prefix, int counterStartingValue) {
  		List<Term> renamedTerms = Terms.renameTerms(terms, prefix, counterStartingValue);
  		return new BasicAtomImpl(predicate, renamedTerms);
  	}
  
  	@Override
  	public Literal toLiteral(boolean positive) {
  		return Literals.fromAtom(this, positive);
  	}
  
  	@Override
  	public String toString() {
  		final String prefix = predicate.getName();
  		if (terms.isEmpty()) {
  			return prefix;
  		}
  
  		return Util.join(prefix + "(", terms, ")");
  	}
  
  	@Override
  	public int compareTo(Atom o) {
  		if (this.terms.size() != o.getTerms().size()) {
  			return this.terms.size() - o.getTerms().size();
  		}
  
  		int result = this.predicate.compareTo(o.getPredicate());
  
  		if (result != 0) {
  			return result;
  		}
  
  		for (int i = 0; i < terms.size(); i++) {
  			result = terms.get(i).compareTo(o.getTerms().get(i));
  			if (result != 0) {
  				return result;
  			}
  		}
  
  		return 0;
  	}
  
  	@Override
  	public boolean equals(Object o) {
  		if (this == o) {
  			return true;
  		}
  		if (o == null || getClass() != o.getClass()) {
  			return false;
  		}
  
  		BasicAtomImpl that = (BasicAtomImpl) o;
  
  		return predicate.equals(that.predicate) && terms.equals(that.terms);
  	}
  
  	@Override
  	public int hashCode() {
  		return 31 * predicate.hashCode() + terms.hashCode();
  	}
  
  	@Override
  	public Atom withTerms(List<Term> terms) {
  		return new BasicAtomImpl(predicate, terms);
  	}
  
  }
  