CSpanningTree.java

/*
 * @cond LICENSE
 * ######################################################################################
 * # LGPL License                                                                       #
 * #                                                                                    #
 * # This file is part of the LightJason AgentSpeak(L++)                                #
 * # Copyright (c) 2015-19, LightJason (info@lightjason.org)                            #
 * # This program 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 3 of the                 #
 * # License, or (at your option) any later version.                                    #
 * #                                                                                    #
 * # This program 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 program. If not, see http://www.gnu.org/licenses/                  #
 * ######################################################################################
 * @endcond
 */

package org.lightjason.agentspeak.action.builtin.graph;

import com.google.common.base.Function;
import edu.uci.ics.jung.algorithms.shortestpath.PrimMinimumSpanningTree;
import edu.uci.ics.jung.graph.DelegateTree;
import edu.uci.ics.jung.graph.Graph;
import org.lightjason.agentspeak.action.builtin.IBuiltinAction;
import org.lightjason.agentspeak.language.CCommon;
import org.lightjason.agentspeak.language.CRawTerm;
import org.lightjason.agentspeak.language.ITerm;
import org.lightjason.agentspeak.language.execution.IContext;
import org.lightjason.agentspeak.language.fuzzy.CFuzzyValue;
import org.lightjason.agentspeak.language.fuzzy.IFuzzyValue;

import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import java.util.Collections;
import java.util.List;
import java.util.Map;


/**
 * creates a minimal spanning tree of any graph instance.
 * The action creates from each graph argument a spanning
 * tree, the first map instance will be used as weight-map,
 * a tuple of the string "defaultweight" and a numeric value
 * defines the default weight value of the weight-map
 * (the default value is zero), the action never fails
 *
 * {@code
    [SP1|SP2] = graph/spanningtree( Graph1, Graph2 );
    [SP3|SP4] = graph/spanningtree( "defaultweight", 3, WeightMap, Graph3, Graph4 );
 * }
 */
public final class CSpanningTree extends IBuiltinAction
{
    /**
     * serial id
     */
    private static final long serialVersionUID = -367284435336974616L;

    @Nonnegative
    @Override
    public final int minimalArgumentNumber()
    {
        return 1;
    }

    @Nonnull
    @Override
    public final IFuzzyValue<Boolean> execute( final boolean p_parallel, @Nonnull final IContext p_context,
                                               @Nonnull final List<ITerm> p_argument, @Nonnull final List<ITerm> p_return )
    {
        final double l_defaultcost = CCommon.flatten( p_argument )
                                            .filter( i -> CCommon.rawvalueAssignableTo( i, Number.class ) )
                                            .findFirst()
                                            .map( ITerm::<Number>raw )
                                            .map( Number::doubleValue )
                                            .orElse( 0D );

        final Map<?, Number> l_costmap = CCommon.flatten( p_argument )
                                                .filter( i -> CCommon.rawvalueAssignableTo( i, Map.class ) )
                                                .findFirst()
                                                .map( ITerm::<Map<?, Number>>raw )
                                                .orElseGet( Collections::emptyMap );

        final Function<Object, Double> l_weightfunction = e -> l_costmap.getOrDefault( e, l_defaultcost ).doubleValue();
        final PrimMinimumSpanningTree<Object, Object> l_treefactory = new PrimMinimumSpanningTree<>( DelegateTree.getFactory(), l_weightfunction );

        // --- filter graphs ---
        CCommon.flatten( p_argument )
               .filter( i -> CCommon.rawvalueAssignableTo( i, Graph.class ) )
               .map( ITerm::<Graph<Object, Object>>raw )
               .map( l_treefactory )
               .map( CRawTerm::from )
               .forEach( p_return::add );

        return CFuzzyValue.from( true );
    }
}