Dépôt officiel du code source de l'ERP OpenConcerto

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 2011 OpenConcerto, by ILM Informatique. All rights reserved.

 *

 * The contents of this file are subject to the terms of the GNU General Public License Version 3

 * only ("GPL"). You may not use this file except in compliance with the License. You can obtain a

 * copy of the License at http://www.gnu.org/licenses/gpl-3.0.html See the License for the specific

 * language governing permissions and limitations under the License.

 *

 * When distributing the software, include this License Header Notice in each file.

 */

 package org.openconcerto.utils.cc;

import org.openconcerto.utils.CompareUtils;

import java.util.ArrayList;

import java.util.Collection;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.ListIterator;

import java.util.RandomAccess;

import java.util.Set;

import java.util.function.BiPredicate;

/**

 * Allow to create a proxy object which uses a {@link HashingStrategy}.

 *

 * @author Sylvain

 */

public class CustomEquals {

    static public final <T> boolean nullSafeEquals(final T o1, final T o2, final BiPredicate<? super T, ? super T> equal) {

        if (o1 == null)

            return o2 == null;

        else if (o2 == null)

            return false;

        else

            return equal.test(o1, o2);

    }

    static private final HashingStrategy<Object> DEFAULT = new HashingStrategy<Object>() {

        @Override

        public boolean equals(Object object1, Object object2) {

            return CompareUtils.equals(object1, object2);

        }

        @Override

        public int computeHashCode(Object object) {

            return object == null ? 0 : object.hashCode();

        }

    };

    static private final HashingStrategy<Object> IDENTITY = new HashingStrategy<Object>() {

        @Override

        public boolean equals(Object object1, Object object2) {

            return object1 == object2;

        }

        @Override

        public int computeHashCode(Object object) {

            return System.identityHashCode(object);

        }

    };

    static public HashingStrategy<Object> getDefault() {

        return DEFAULT;

    }

    static public HashingStrategy<Object> getIdentity() {

        return IDENTITY;

    }

    // only create sets if necessary

    static public final <S, T1 extends S, T2 extends S> boolean equals(final Set<T1> s1, final Set<T2> s2, final HashingStrategy<S> s) {

        return equals(s1, s2, s, true);

    }

    static public final <S, T1 extends S, T2 extends S> boolean equals(final List<T1> s1, final List<T2> s2, final HashingStrategy<S> s) {

        return equals(s1, s2, s, false);

    }

    /**

     * Test equality of 2 collections using the passed strategy.

     *

     * @param <S> type of strategy.

     * @param <T1> type of first collection.

     * @param <T2> type of second collection.

     * @param s1 the first collection.

     * @param s2 the second collection.

     * @param s the hashing strategy, <code>null</code> meaning the {@link #getDefault() default}.

     * @param set <code>true</code> if the passed collections should be used as a {@link Set},

     *        <code>false</code> for a {@link List}.

     * @return <code>true</code> if the 2 collections are equal using the passed parameters.

     */

    static public final <S, T1 extends S, T2 extends S> boolean equals(final Collection<T1> s1, final Collection<T2> s2, final HashingStrategy<S> s, final boolean set) {

        final Collection<?> sA, sB;

        // if the caller ask that the collections are compared using Set or List make sure that they

        // already are.

        final Class<?> clazz = set ? Set.class : List.class;

        if ((s == null || s == DEFAULT) && clazz.isInstance(s1) && clazz.isInstance(s2)) {

            sA = s1;

            sB = s2;

            // boolean to only create collections if necessary (don't make callers create the empty

            // collections)

        } else if (set) {

            sA = ProxyFull.createSet(s, s1);

            sB = ProxyFull.createSet(s, s2);

        } else {

            sA = ProxyFull.createList(s, s1);

            sB = ProxyFull.createList(s, s2);

        }

        assert clazz.isInstance(sA) && clazz.isInstance(sB);

        return CompareUtils.equals(sA, sB);

    }

    static public final <S, T1 extends S> int indexOf(final List<T1> s1, final S o, final HashingStrategy<S> s) {

        return indexOf(s1, o, s::equals);

    }

    static public final <S, T1 extends S> int indexOf(final List<T1> s1, final S o, final BiPredicate<S, S> s) {

        if (s1 instanceof RandomAccess) {

            final int stop = s1.size();

            for (int i = 0; i < stop; i++) {

                if (s.test(s1.get(i), o))

                    return i;

            }

        } else {

            final ListIterator<T1> listIter = s1.listIterator();

            while (listIter.hasNext()) {

                final T1 item = listIter.next();

                if (s.test(item, o))

                    return listIter.previousIndex();

            }

        }

        return -1;

    }

    static public class ProxyFull<S, E extends S> implements ProxyItf<E> {

        static public final <S, E extends S> Set<ProxyFull<S, E>> createSet(final HashingStrategy<S> strategy, final Collection<E> coll) {

            return wrap(strategy, coll, new LinkedHashSet<ProxyFull<S, E>>());

        }

        static public final <S, E extends S> List<ProxyFull<S, E>> createList(final HashingStrategy<S> strategy, final Collection<E> coll) {

            return wrap(strategy, coll, new ArrayList<ProxyFull<S, E>>());

        }

        static public final <S, E extends S, C extends Collection<? super ProxyFull<S, E>>> C wrap(final HashingStrategy<S> strategy, final Collection<E> coll, final C res) {

            for (final E item : coll) {

                res.add(new ProxyFull<S, E>(item, strategy));

            }

            return res;

        }

        private final E delegate;

        private final HashingStrategy<S> strategy;

        /**

         * Create a proxy object that use a strategy to implement {@link #equals(Object)} and

         * {@link #hashCode()}.

         *

         * @param delegate the object to use.

         * @param strategy the strategy, <code>null</code> meaning use default implementation.

         */

        public ProxyFull(final E delegate, final HashingStrategy<S> strategy) {

            this.delegate = delegate;

            /**

             * Allow null strategy since the caller doesn't have to deal with generic limitations :

             *

             * <pre>

             * HashingStrategy<Constraint> strategy = sameSystem ? null : Constraint.getInterSystemHashStrategy();

             * </pre>

             *

             * Otherwise if one have HashingStrategy<Object> and

             * HashingStrategy<Constraint> ProxyFull.createSet() can't be called since no Java

             * type can hold both those instances. In this class the two cases are handled

             * explicitly.

             */

            this.strategy = strategy;

        }

        @Override

        public final E getDelegate() {

            return this.delegate;

        }

        @Override

        public final HashingStrategy<S> getStrategy() {

            return this.strategy;

        }

        private final HashingStrategy<?> getInternalStrategy() {

            return this.strategy != null ? this.strategy : DEFAULT;

        }

        @Override

        public int hashCode() {

            // don't use getInternalStrategy() to avoid java warning

            if (this.strategy == null)

                return DEFAULT.computeHashCode(this.getDelegate());

            else

                return this.getStrategy().computeHashCode(this.getDelegate());

        }

        @Override

        public boolean equals(Object obj) {

            if (this == obj)

                return true;

            if (!(obj instanceof ProxyFull))

                return false;

            final ProxyFull<?, ?> other = (ProxyFull<?, ?>) obj;

            // null and DEFAULT mean the same

            if (other.getInternalStrategy() != this.getInternalStrategy())

                return false;

            // OK since same instance of strategy

            @SuppressWarnings("unchecked")

            final S delegate2 = (S) other.getDelegate();

            final E delegate = this.getDelegate();

            if (delegate == delegate2)

                return true;

            // don't use getInternalStrategy() to avoid java warning

            if (this.strategy == null)

                return DEFAULT.equals(this.getDelegate(), delegate2);

            else

                return this.strategy.equals(this.getDelegate(), delegate2);

        }

        @Override

        public String toString() {

            return this.getClass().getSimpleName() + " using strategy " + this.getStrategy() + " for " + this.getDelegate();

        }

    }

    /**

     * A proxy object which uses a {@link HashingStrategy}.

     *

     * @author Sylvain

     * @param <E> type of item

     */

    static public interface ProxyItf<E> {

        public E getDelegate();

        public HashingStrategy<? super E> getStrategy();

    }

    static public final <S, E extends S> Set<ProxyItf<E>> createSet(final HashingStrategy<S> strategy, final Collection<E> coll) {

        return ProxyFull.wrap(strategy, coll, new LinkedHashSet<ProxyItf<E>>());

    }

    static public final <S, E extends S> List<ProxyItf<E>> createList(final HashingStrategy<S> strategy, final Collection<E> coll) {

        return ProxyFull.wrap(strategy, coll, new ArrayList<ProxyItf<E>>());

    }

    static public final <T> Set<T> unwrapToSet(final Collection<? extends ProxyItf<T>> coll) {

        return unwrap(coll, new LinkedHashSet<T>());

    }

    static public final <T> List<T> unwrapToList(final Collection<? extends ProxyItf<T>> coll) {

        return unwrap(coll, new ArrayList<T>());

    }

    static public final <T, C extends Collection<? super T>> C unwrap(final Collection<? extends ProxyItf<T>> coll, final C res) {

        for (final ProxyItf<T> item : coll) {

            res.add(item.getDelegate());

        }

        return res;

    }

    /**

     * A simple subclass to save some typing and improve legibility.

     *

     * @author Sylvain

     * @param <E> type of item

     */

    static public class Proxy<E> extends ProxyFull<E, E> {

        public Proxy(E delegate, HashingStrategy<E> strategy) {

            super(delegate, strategy);

        }

    }

    private CustomEquals() {

    }

}