InstantiatingIterators.java

/* 
 * The MIT License
 *
 * Copyright 2013 Tim Boudreau.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.mastfrog.acteurbase;

import com.mastfrog.giulius.Dependencies;
import com.mastfrog.util.collections.CollectionUtils;
import com.mastfrog.util.collections.Converter;
import java.util.Iterator;
import java.util.List;
import javax.inject.Inject;

/**
 * Creates a typed iterator over a List<Object> which may contain either
 * objects of the given type, or class objects of subtypes of the type, in which
 * case they should be instantiated using Guice and the instance returned.
 *
 * @author Tim Boudreau
 */
public final class InstantiatingIterators {

    private final Dependencies deps;

    @Inject
    InstantiatingIterators(Dependencies deps) {
        this.deps = deps;
    }

    public <T> Iterable<T> iterable(List<Object> obj, final Class<? extends T> type) {
        return CollectionUtils.<T>toIterable(CollectionUtils.<Object, T>convertedIterator(new Converter<T, Object>() {

            @Override
            public Object unconvert(T r) {
                return r;
            }

            @Override
            public T convert(Object t) {
                if (t instanceof Class<?>) {
                    return type.cast(deps.getInstance((Class<?>) t));
                } else {
                    return type.cast(t);
                }
            }
        }, new PermissiveIterator<Object>(obj)));
    }

    /**
     * Iterator which, intentionally, allows items to be added
     * while iterating.
     * @param <T> The type
     */
    static class PermissiveIterator<T> implements Iterator<T> {

        private volatile int ix = 0;
        private final List<T> objs;

        public PermissiveIterator(List<T> objs) {
            this.objs = objs;
        }

        @Override
        public boolean hasNext() {
            return ix < objs.size();
        }

        @Override
        public T next() {
            return objs.get(ix++);
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException("Not supported.");
        }
    }
}