/*
 * Copyright (C) 1999-2004 <a href="mailto:mandarax@jbdietrich.com">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.mandarax.kernel;


import org.mandarax.util.TermIterator;
import java.util.*;

/**
 * A term is either a variable, a name or a compound term containing a function.
 * Note that instances are usually created using a factory.
 * @see org.mandarax.kernel.LogicFactory
 * @author <A HREF="mailto:mandarax@jbdietrich.com">Jens Dietrich</A>
 * @version 3.3.1 <9 August 2004>
 * @since 1.0
 * Prova re-integration modifications
 * @author <A HREF="mailto:a.kozlenkov@city.ac.uk">Alex Kozlenkov</A>
 * @version 3.3.1 <9 August 2004>
 */
public interface Term extends SemanticsSupport, java.io.Serializable {

    /**
     * Get a term iterator for the subterms.
     * @return an iterator for all subterms
     */
    TermIterator allSubterms();

    /**
     * Apply a substitution to a term.
     * @return the term resulting from applying the replacement
     * @param r a replacement
     */
    Term apply(Replacement r);

    /**
     * Apply a minimal (least intrusive) substitution to a term.
     * @return the term resulting from applying the replacement
     * @param r a replacement
     * @param complexReplacements 
     */
    public Term applyMinimally(Collection r, Map complexReplacements);

    /**
     * Indicates whether the term containes variables.
     * @return true if the term contains variables, false otherwise
     */
    public boolean containsVariables();

	 /**
	 * Indicates whether the term contains the provided variable term.
	 * @return true if the term contains the variable term provided, false otherwise
	 * @param var a variable term
	 */
   public boolean containsVariable( VariableTerm var );

   /**
     * Get all subterms as array.
     * @return an array of all subterms
     */
    Term[] getAllSubterms();

	 void getAllSubtermsA( List result );
	 void getAllSubtermsA( List result, boolean left );

	 public boolean getAllSubtermsB( List result, Iterator aux );
	 public boolean getAllSubtermsB( List result, Iterator aux, boolean left );

    /**
     * Get the type of the term.
     * @return the type of the term
     */
    Class getType();

    /**
     * Indicates whether the term is compound.
     * @return true if this is a compound term, false otherwise
     */
    public boolean isCompound();

    /**
     * Indicates whether the term is a constant.
     * @return true if this is a constant term, false otherwise
     */
    public boolean isConstant();

    /**
     * Indicates whether the term is a variable.
     * @return true if this is a variable term, false otherwise
     */
    public boolean isVariable();

    /**
     * Resolve a term. This operation is most meaningfull for
     * complex terms : if supported, the function should be performed using its semantic.
     * <br>
     * In version 3.2, a session parameter has been added. A session provides a context that
     * allows to "resolve" terms locally, i.e., w.r.t. an InferenceEngine session.
     * Most implementations can ignore this parameter.
     * @param session a session object
     * @see org.mandarax.kernel.ComplexTerm#resolve
     * @return the result of resolving the term
     * @throws java.lang.UnsupportedOperationException
     * @throws java.lang.IllegalArgumentException
     */
    Object resolve(Session session) throws UnsupportedOperationException, IllegalArgumentException;

//    /**
//     * Prova version taken from older Mandarax.
//     * Resolve a term. This operation is most meaningfull for
//     * complex terms : if supported, the function
//     * should be performed using its semantic.
//     * @see org.mandarax.kernel.ComplexTerm#resolve
//     * @return the result of resolving the term
//     * @throws java.lang.UnsupportedOperationException
//     * @throws java.lang.IllegalArgumentException
//     */
//    Object resolve()
//        throws UnsupportedOperationException, IllegalArgumentException;

    /**
     * Indicates whether the object is the same as the parameter.
     * @return boolean
     * @param t org.mandarax.kernel.Term
     */
    boolean sameAs(Term t);

}
