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/**
 * Copyright (c) 2002-2013 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.helpers;

import java.util.Arrays;

import org.neo4j.helpers.collection.Iterables;

/**
 * Common predicates
 */
public class Predicates
{
    public static  Predicate TRUE()
    {
        return new Predicate()
        {
            public boolean accept( T instance )
            {
                return true;
            }
        };
    }

    public static  Predicate not( final Predicate specification )
    {
        return new Predicate()
        {
            public boolean accept( T instance )
            {
                return !specification.accept( instance );
            }
        };
    }

    public static  AndPredicate and( final Predicate... predicates )
    {
        return and( Arrays.asList( predicates ) );
    }

    public static  AndPredicate and( final Iterable> predicates )
    {
        return new AndPredicate( predicates );
    }

    public static  OrPredicate or( final Predicate... predicates )
    {
        return or( Arrays.asList( predicates ) );
    }

    public static  OrPredicate or( final Iterable> predicates )
    {
        return new OrPredicate( predicates );
    }

    public static  Predicate equalTo( final T allowed )
    {
        return new Predicate()
        {
            @Override
            public boolean accept( T item )
            {
                return allowed == null ? item == null : allowed.equals( item );
            }
        };
    }

    public static  Predicate in( final T... allowed )
    {
        return in( Arrays.asList( allowed ) );
    }

    public static  Predicate in( final Iterable allowed )
    {
        return new Predicate()
        {
            public boolean accept( T item )
            {
                for ( T allow : allowed )
                {
                    if ( allow.equals( item ) )
                    {
                        return true;
                    }
                }
                return false;
            }
        };
    }

    public static  Predicate notNull()
    {
        return new Predicate()
        {
            @Override
            public boolean accept( T item )
            {
                return item != null;
            }
        };
    }

    public static  Predicate translate( final Function function,
                                                        final Predicate specification )
    {
        return new Predicate()
        {
            @Override
            public boolean accept( FROM item )
            {
                return specification.accept( function.apply( item ) );
            }
        };
    }

    public static class AndPredicate implements Predicate
    {
        private final Iterable> predicates;

        private AndPredicate( Iterable> predicates )
        {
            this.predicates = predicates;
        }

        public boolean accept( T instance )
        {
            for ( Predicate specification : predicates )
            {
                if ( !specification.accept( instance ) )
                {
                    return false;
                }
            }

            return true;
        }

        public AndPredicate and( Predicate... predicates )
        {
            Iterable> iterable = Iterables.iterable( predicates );
            Iterable> flatten = Iterables.flatten( this.predicates, iterable );
            return Predicates.and( flatten );
        }

        public OrPredicate or( Predicate... predicates )
        {
            return Predicates.or( Iterables.prepend( this, Arrays.asList( predicates ) ) );
        }
    }

    public static class OrPredicate implements Predicate
    {
        private final Iterable> predicates;

        private OrPredicate( Iterable> predicates )
        {
            this.predicates = predicates;
        }

        public boolean accept( T instance )
        {
            for ( Predicate specification : predicates )
            {
                if ( specification.accept( instance ) )
                {
                    return true;
                }
            }

            return false;
        }

        public AndPredicate and( Predicate... predicates )
        {
            return Predicates.and( Iterables.prepend( this, Arrays.asList( predicates ) ) );
        }

        public OrPredicate or( Predicate... predicates )
        {
            Iterable> iterable = Iterables.iterable( predicates );
            Iterable> flatten = Iterables.flatten( this.predicates, iterable );
            return Predicates.or( flatten );
        }
    }
}