/* A concept function that applies a binary concept function to multiple
 * arguments in sequence.

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 All rights reserved.
 Permission is hereby granted, without written agreement and without
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 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
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package ptolemy.data.ontologies.lattice;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import ptolemy.data.ontologies.Concept;
import ptolemy.data.ontologies.ConceptFunction;
import ptolemy.data.ontologies.Ontology;
import ptolemy.kernel.util.IllegalActionException;

///////////////////////////////////////////////////////////////////
//// ApplyBinaryFunctionToMultipleArguments

/** A concept function that applies a binary concept function to multiple
 *  arguments in sequence.
 *
 *  @author Charles Shelton
 *  @version $Id: ApplyBinaryFunctionToMultipleArguments.java 70402 2014-10-23 00:52:20Z cxh $
 *  @since Ptolemy II 10.0
 *  @Pt.ProposedRating Red (cshelton)
 *  @Pt.AcceptedRating Red (cshelton)
 */
public class ApplyBinaryFunctionToMultipleArguments extends ConceptFunction {

    /** Create a new ApplyBinaryFunctionToMultipleArguments concept function
     *  for the specified binary concept function and ontology.
     *  @param name The name of this function.
     *  @param inputOutputOntology The ontology over which this function is
     *   defined.
     *  @param binaryFunction The binary concept function to be applied to the
     *   input arguments
     *  @exception IllegalActionException Thrown if the given binary concept function
     *   is not specified to have exactly 2 arguments.
     */
    public ApplyBinaryFunctionToMultipleArguments(String name,
            Ontology inputOutputOntology, ConceptFunction binaryFunction)
                    throws IllegalActionException {
        super(name, false, new LinkedList<Ontology>(), inputOutputOntology);

        if (!binaryFunction.isNumberOfArgumentsFixed()
                || binaryFunction.getNumberOfArguments() != 2) {
            throw new IllegalActionException("The specified binary concept "
                    + "function " + binaryFunction.getName() + "must require "
                    + "exactly 2 arguments.");
        }
        _binaryFunction = binaryFunction;
    }

    ///////////////////////////////////////////////////////////////////
    ////                         protected methods                 ////

    /** Evaluate the concept function for the given list of arguments. If the
     *  list of arguments is empty, return null.  If there is only one concept
     *  in the argument list, return that concept.  If there are 2 or more
     *  concepts in the argument list, apply the specified binary concept
     *  function sequentially to all input values, and return the final result.
     *  @param argValues The list of concept arguments for which the function
     *   will be evaluated.
     *  @return The output concept value;
     *  @exception IllegalActionException Thrown if there is an error calculating
     *   the output concept result.
     */
    @Override
    protected Concept _evaluateFunction(List<Concept> argValues)
            throws IllegalActionException {

        if (argValues.isEmpty()) {
            return null;
        } else {
            Concept result = argValues.get(0);
            if (argValues.size() == 1) {
                return result;
            } else {
                for (int i = 1; i < argValues.size(); i++) {
                    List<Concept> binaryArgs = new ArrayList<Concept>(2);
                    binaryArgs.add(result);
                    binaryArgs.add(argValues.get(i));
                    result = _binaryFunction.evaluateFunction(binaryArgs);
                }

                return result;
            }
        }
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private variables                 ////

    /** The binary concept function to be applied to the given arguments for
     *  this concept function.
     */
    private ConceptFunction _binaryFunction;
}