package api;

import java.util.ArrayList;

import java.util.Collection;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

/** Factory to create various types of lookup instances.

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 * @version 1.0

 */

public final class Lookups {

    private Lookups() {

    }

    public static Lookup fixed(final Object... instances) {

        return new Lookup() {

            @Override

            public <T> T lookup(Class<T> clazz) {

                for (Object obj : instances) {

                    if (clazz.isInstance(obj)) {

                        return clazz.cast(obj);

                    }

                }

                return null;

            }

            @Override

            public <T> Collection<? extends T> lookupAll(Class<T> clazz) {

                List<T> result = new ArrayList<T>();

                for (Object obj : instances) {

                    if (clazz.isInstance(obj)) {

                        result.add(clazz.cast(obj));

                    }

                }

                return result;

            }

            @Override

            public <T> Set<Class<? extends T>> lookupAllClasses(Class<T> clazz) {

                Set<Class<? extends T>> result = new HashSet<Class<? extends T>>();

                for (Object obj : instances) {

                    if (clazz.isInstance(obj)) {

                        result.add(obj.getClass().asSubclass(clazz));

                    }

                }

                return result;

            }

        };

    }

}