content: /**
   * Copyright (c) 2020, the Alpha Team.
   * All rights reserved.
   *
   * 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.grounder.instantiation;
  
  import java.util.List;
  
  import org.apache.commons.lang3.tuple.ImmutablePair;
  
  import at.ac.tuwien.kr.alpha.api.grounder.Substitution;
  import at.ac.tuwien.kr.alpha.api.programs.literals.Literal;
  import at.ac.tuwien.kr.alpha.commons.substitutions.BasicSubstitution;
  
  /**
   * A {@link LiteralInstantiationStrategy} finds and validates {@link BasicSubstitution}s for {@link Literal}s based on a specific definition of
   * when a {@link BasicSubstitution} is valid, i.e. what makes a literal "true", "false" or "unassigned".
   * 
   * Copyright (c) 2020, the Alpha Team.
   */
  public interface LiteralInstantiationStrategy {
  
  	/**
  	 * Computes the {@link AssignmentStatus} for the given {@link Literal} according to the rules of this {@link LiteralInstantiationStrategy}.
  	 * 
  	 * @param groundLiteral a ground {@link Literal} for which to compute an {@link AssignmentStatus}
  	 * @return the current {@link AssignmentStatus} for the given literal according to the rules of this {@link LiteralInstantiationStrategy}
  	 */
  	AssignmentStatus getTruthForGroundLiteral(Literal groundLiteral);
  
  	/**
  	 * Computes {@link BasicSubstitution}s that yield ground instances for a given literal and starting substitution along with the
  	 * {@link AssignmentStatus} of respective ground instances. Note that in all implementations it must hold that an {@link AssignmentStatus}
  	 * AS for a {@link BasicSubstitution} S as yielded by this method for a {@link Literal} lit is the same as the result of calling
  	 * <code>getTruthForGroundLiteral(lit.substitute(S))</code>, i.e. both methods must yield the same assignment status for the same ground
  	 * literal.
  	 * 
  	 * @param lit                 a non-ground {@link Literal} for which to compute substitutions.
  	 * @param partialSubstitution a (possibly empty) substitution to use as a starting point
  	 * @return a list of substitutions along with the assignment status of the respective ground atoms
  	 */
  	List<ImmutablePair<Substitution, AssignmentStatus>> getAcceptedSubstitutions(Literal lit, Substitution partialSubstitution);
  
  }
  