org.jclouds.apis.Apis.java Source code

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Here is the source code for org.jclouds.apis.Apis.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.jclouds.apis;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.filter;
import static com.google.common.collect.Iterables.find;
import static org.jclouds.reflect.Reflection2.typeToken;

import java.util.NoSuchElementException;
import java.util.ServiceLoader;

import org.jclouds.View;
import org.jclouds.osgi.ApiRegistry;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.reflect.TypeToken;

/**
 * The Apis class provides static methods for accessing apis.
 * 
 * @author Jeremy Whitlock <jwhitlock@apache.org>
 */
public class Apis {

    private static enum IdFunction implements Function<ApiMetadata, String> {
        INSTANCE;

        @Override
        public String apply(ApiMetadata input) {
            return input.getId();
        }

    }

    public static Function<ApiMetadata, String> idFunction() {
        return IdFunction.INSTANCE;
    }

    /**
     * Returns the apis located on the classpath via {@link java.util.ServiceLoader}.
     * 
     * @return all available apis loaded from classpath via ServiceLoader
     */
    private static Iterable<ApiMetadata> fromServiceLoader() {
        return ServiceLoader.load(ApiMetadata.class);
    }

    /**
     * Returns all available apis.
     * 
     * @return all available apis
     */
    public static Iterable<ApiMetadata> all() {
        return ImmutableSet.<ApiMetadata>builder().addAll(fromServiceLoader()).addAll(ApiRegistry.fromRegistry())
                .build();
    }

    /**
     * Returns the first api with the provided id
     * 
     * @param id
     *           the id of the api to return
     * 
     * @return the api with the given id
     * 
     * @throws NoSuchElementException
     *            whenever there are no apis with the provided id
     */
    public static ApiMetadata withId(String id) throws NoSuchElementException {
        return find(all(), ApiPredicates.id(id));
    }

    /**
     * Returns all apis who's contexts are assignable from the parameter
     * 
     * @param type
     *           the type of the context to search for
     * 
     * @return the apis with contexts assignable from given type
     */
    public static Iterable<ApiMetadata> contextAssignableFrom(TypeToken<?> type) {
        return filter(all(), ApiPredicates.contextAssignableFrom(type));
    }

    /**
     * Returns all apis who's contexts are assignable from the parameter
     * 
     * @param type
     *           the type of the context to search for
     * 
     * @return the apis with contexts assignable from given type
     */
    public static Iterable<ApiMetadata> viewableAs(TypeToken<? extends View> type) {
        return filter(all(), ApiPredicates.viewableAs(type));
    }

    public static Iterable<ApiMetadata> viewableAs(Class<? extends View> type) {
        return filter(all(), ApiPredicates.viewableAs(typeToken(type)));
    }

    /**
     * Returns the type of context
     * 
     * @param type
     *           the type of the context to search for
     * 
     * @return the apis with contexts transformable to the given type
     */
    public static TypeToken<?> findView(final ApiMetadata apiMetadata, final TypeToken<?> view)
            throws NoSuchElementException {
        checkNotNull(apiMetadata, "apiMetadata must be defined");
        checkNotNull(view, "context must be defined");
        return Iterables.find(apiMetadata.getViews(), new Predicate<TypeToken<?>>() {

            @Override
            public boolean apply(TypeToken<?> input) {
                return view.isAssignableFrom(input);
            }

        });
    }
}