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.grounder;
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedHashSet;
  import java.util.Set;
  
  import org.apache.commons.lang3.tuple.ImmutablePair;
  
  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.commons.substitutions.Instance;
  
  public class WorkingMemory {
  	protected HashMap<Predicate, ImmutablePair<IndexedInstanceStorage, IndexedInstanceStorage>> workingMemory = new HashMap<>();
  	private HashSet<IndexedInstanceStorage> modifiedWorkingMemories = new LinkedHashSet<>();
  
  	public boolean contains(Predicate predicate) {
  		return workingMemory.containsKey(predicate);
  	}
  
  	public void initialize(Predicate predicate) {
  		if (workingMemory.containsKey(predicate)) {
  			return;
  		}
  
  		IndexedInstanceStorage pos = new IndexedInstanceStorage(predicate, true);
  		IndexedInstanceStorage neg = new IndexedInstanceStorage(predicate, false);
  		// Index all positions of the storage (may impair efficiency)
  		for (int i = 0; i < predicate.getArity(); i++) {
  			pos.addIndexPosition(i);
  			neg.addIndexPosition(i);
  		}
  
  		workingMemory.put(predicate, new ImmutablePair<>(pos, neg));
  	}
  
  	public IndexedInstanceStorage get(Literal literal) {
  		return get(literal.getAtom(), !literal.isNegated());
  	}
  
  	public IndexedInstanceStorage get(Atom atom, boolean value) {
  		return get(atom.getPredicate(), value);
  	}
  
  	public IndexedInstanceStorage get(Predicate predicate, boolean value) {
  		ImmutablePair<IndexedInstanceStorage, IndexedInstanceStorage> pair = workingMemory.get(predicate);
  		if (value) {
  			return pair.getLeft();
  		} else {
  			return pair.getRight();
  		}
  	}
  
  	public void addInstance(Atom atom, boolean value) {
  		addInstance(atom.getPredicate(), value, new Instance(atom.getTerms()));
  	}
  
  	public void addInstance(Predicate predicate, boolean value, Instance instance) {
  		IndexedInstanceStorage storage = get(predicate, value);
  
  		if (!storage.containsInstance(instance)) {
  			storage.addInstance(instance);
  			modifiedWorkingMemories.add(storage);
  		}
  	}
  
  	public void addInstances(Predicate predicate, boolean value, Iterable<Instance> instances) {
  		IndexedInstanceStorage storage = get(predicate, value);
  
  		for (Instance instance : instances) {
  			if (!storage.containsInstance(instance)) {
  				storage.addInstance(instance);
  				modifiedWorkingMemories.add(storage);
  			}
  		}
  	}
  
  	public void reset() {
  		modifiedWorkingMemories = new LinkedHashSet<>();
  	}
  
  	public Set<IndexedInstanceStorage> modified() {
  		return modifiedWorkingMemories;
  	}
  }
  