ae.MappedList.java Source code

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Here is the source code for ae.MappedList.java

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/*
 * Copyright 2007-2008 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ae;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import com.google.appengine.api.datastore.Entity;
import com.google.common.base.Function;
import com.google.common.collect.Iterators;
import com.google.common.collect.ObjectArrays;

public class MappedList<E> implements List<E> {
    protected final List<Entity> entities;
    protected final Function<Entity, E> mapper;
    protected final Function<E, Entity> unmapper;
    protected final Class<E> type;

    public MappedList(final Class<E> type, final List<Entity> entities, final Function<Entity, E> mapper,
            final Function<E, Entity> unmapper) {
        this.entities = entities;
        this.mapper = mapper;
        this.unmapper = unmapper;
        this.type = type;
    }

    @Override
    public int size() {
        return this.entities.size();
    }

    @Override
    public boolean isEmpty() {
        return this.entities.isEmpty();
    }

    @Override
    public boolean contains(final Object o) {
        if (this.type.isInstance(o)) {
            return this.entities.contains(this.unmapper.apply(this.type.cast(o)));
        } else {
            return this.entities.contains(o);
        }
    }

    @Override
    public Iterator<E> iterator() {
        return Iterators.transform(this.entities.iterator(), this.mapper);
    }

    @Override
    public Object[] toArray() {
        return toArray(ObjectArrays.newArray(this.type, size()));
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T[] toArray(final T[] a) {
        final Object[] array;
        if (a.length < size()) {
            array = ObjectArrays.newArray(a.getClass(), size());
        } else {
            array = a;
        }

        for (int i = 0; i < array.length; i++) {
            array[i] = this.mapper.apply(this.entities.get(i));
        }

        if (array.length >= size()) {
            array[size()] = null;
        }

        return (T[]) array;
    }

    @Override
    public boolean add(final E e) {
        return this.entities.add(this.unmapper.apply(e));
    }

    @Override
    public boolean remove(final Object o) {
        if (this.type.isInstance(o)) {
            return this.entities.remove(this.unmapper.apply(this.type.cast(o)));
        } else {
            return this.entities.remove(o);
        }
    }

    @Override
    public boolean containsAll(final Collection<?> c) {
        for (final Object o : c) {
            if (!contains(o)) {
                return false;
            }
        }
        return true;
    }

    @Override
    public boolean addAll(final Collection<? extends E> c) {
        if (c == null || c.isEmpty()) {
            return false;
        }
        for (final E e : c) {
            add(e);
        }
        return true;
    }

    @Override
    public boolean addAll(final int index, final Collection<? extends E> c) {
        if (c == null || c.isEmpty()) {
            return false;
        }
        int i = index;
        for (final E e : c) {
            add(i++, e);
        }
        return true;
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        if (c == null || c.isEmpty()) {
            return false;
        }
        boolean changed = false;
        for (final Object o : c) {
            changed |= remove(o);
        }
        return changed;
    }

    @Override
    public boolean retainAll(final Collection<?> c) {
        if (c == null || c.isEmpty()) {
            final boolean result = !this.entities.isEmpty();
            this.entities.clear();
            return result;
        } else {
            final ArrayList<Object> l = new ArrayList<Object>(c.size());
            for (final Object o : c) {
                if (this.type.isInstance(o)) {
                    l.add(this.unmapper.apply(this.type.cast(o)));
                } else {
                    l.add(o);
                }
            }
            return this.entities.retainAll(l);
        }
    }

    @Override
    public void clear() {
        this.entities.clear();
    }

    @Override
    public E get(final int index) {
        final Entity e = this.entities.get(index);
        return e == null ? null : this.mapper.apply(e);
    }

    @Override
    public E set(final int index, final E element) {
        final Entity e = this.entities.set(index, element == null ? null : this.unmapper.apply(element));
        return e == null ? null : this.mapper.apply(e);
    }

    @Override
    public void add(final int index, final E element) {
        this.entities.add(index, element == null ? null : this.unmapper.apply(element));
    }

    @Override
    public E remove(final int index) {
        final Entity e = this.entities.remove(index);
        return e == null ? null : this.mapper.apply(e);
    }

    @Override
    public int indexOf(final Object o) {
        if (this.type.isInstance(o)) {
            return this.entities.indexOf(this.unmapper.apply(this.type.cast(o)));
        } else {
            return this.entities.indexOf(o);
        }
    }

    @Override
    public int lastIndexOf(final Object o) {
        if (this.type.isInstance(o)) {
            return this.entities.lastIndexOf(this.unmapper.apply(this.type.cast(o)));
        } else {
            return this.entities.lastIndexOf(o);
        }
    }

    @Override
    public ListIterator<E> listIterator() {
        return new MappedListIterator<E>(this.entities.listIterator(), this.mapper, this.unmapper);
    }

    @Override
    public ListIterator<E> listIterator(final int index) {
        return new MappedListIterator<E>(this.entities.listIterator(index), this.mapper, this.unmapper);
    }

    @Override
    public List<E> subList(final int fromIndex, final int toIndex) {
        return new MappedList<E>(this.type, this.entities.subList(fromIndex, toIndex), this.mapper, this.unmapper);
    }

}