/*
* Copyright 2015 MongoDB, Inc.
*
* 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 org.bson.codecs.configuration;
import org.bson.codecs.Codec;
import java.util.ArrayList;
import java.util.List;
import static java.util.Arrays.asList;
/**
* A helper class for creating and combining codecs, codec providers, and codec registries
*
* @since 3.0
*/
public final class CodecRegistries {
/**
* Creates a {@code CodecRegistry} from the provided list of {@code Codec} instances.
*
* <p>This registry can then be used alongside other registries. Typically used when adding extra codecs to existing codecs with the
* {@link #fromRegistries(CodecRegistry...)} )} helper.</p>
*
* @param codecs the {@code Codec} to create a registry for
* @return a {@code CodecRegistry} for the given list of {@code Codec} instances.
*/
public static CodecRegistry fromCodecs(final Codec<?>... codecs) {
return fromCodecs(asList(codecs));
}
/**
* Creates a {@code CodecRegistry} from the provided list of {@code Codec} instances.
*
* <p>This registry can then be used alongside other registries. Typically used when adding extra codecs to existing codecs with the
* {@link #fromRegistries(CodecRegistry...)} )} helper.</p>
*
* @param codecs the {@code Codec} to create a registry for
* @return a {@code CodecRegistry} for the given list of {@code Codec} instances.
*/
public static CodecRegistry fromCodecs(final List<? extends Codec<?>> codecs) {
return fromProviders(new MapOfCodecsProvider(codecs));
}
/**
* Creates a {@code CodecRegistry} from the provided list of {@code CodecProvider} instances.
*
* <p>The created instance can handle cycles of {@code Codec} dependencies, i.e when the construction of a {@code Codec} for class A
* requires the construction of a {@code Codec} for class B, and vice versa.</p>
*
* @param providers the codec provider
* @return a {@code CodecRegistry} with the ordered list of {@code CodecProvider} instances. The registry is also guaranteed to be an
* instance of {code CodecProvider}, so that when one is passed to {@link #fromRegistries(CodecRegistry...)} or {@link
* #fromRegistries(java.util.List)} it will be treated as a {@code CodecProvider} and properly resolve any dependencies between
* registries.
*/
public static CodecRegistry fromProviders(final CodecProvider... providers) {
return fromProviders(asList(providers));
}
/**
* Creates a {@code CodecRegistry} from the provided list of {@code CodecProvider} instances.
*
* <p>The created instance can handle cycles of {@code Codec} dependencies, i.e when the construction of a {@code Codec} for class A
* requires the construction of a {@code Codec} for class B, and vice versa.</p>
*
* @param providers the codec provider
* @return a {@code CodecRegistry} with the ordered list of {@code CodecProvider} instances. The registry is also guaranteed to be an
* instance of {code CodecProvider}, so that when one is passed to {@link #fromRegistries(CodecRegistry...)} or {@link
* #fromRegistries(java.util.List)} it will be treated as a {@code CodecProvider} and properly resolve any dependencies between
* registries.
*/
public static CodecRegistry fromProviders(final List<? extends CodecProvider> providers) {
return new ProvidersCodecRegistry(providers);
}
/**
* A {@code CodecRegistry} that combines the given {@code CodecRegistry} instances into a single registry.
*
* <p>The registries are checked in order until one returns a {@code Codec} for the requested {@code Class}.</p>
*
* <p>The created instance can handle cycles of {@code Codec} dependencies, i.e when the construction of a {@code Codec} for class A
* requires the construction of a {@code Codec} for class B, and vice versa.</p>
* <p>Any of the given registries that also implement {@code CodecProvider} will be treated as a {@code CodecProvider} instead of a
* {@code CodecRegistry}, which will ensure proper resolution of any dependencies between registries.</p>
*
* @param registries the preferred registry for {@code Codec} lookups
*
* @return a {@code CodecRegistry} that combines the list of {@code CodecRegistry} instances into a single one
*/
public static CodecRegistry fromRegistries(final CodecRegistry... registries) {
return fromRegistries(asList(registries));
}
/**
* A {@code CodecRegistry} that combines the given {@code CodecRegistry} instances into a single registry.
*
* <p>The registries are checked in order until one returns a {@code Codec} for the requested {@code Class}.</p>
*
* <p>The created instance can handle cycles of {@code Codec} dependencies, i.e when the construction of a {@code Codec} for class A
* requires the construction of a {@code Codec} for class B, and vice versa.</p>
* <p>Any of the given registries that also implement {@code CodecProvider} will be treated as a {@code CodecProvider} instead of a
* {@code CodecRegistry}, which will ensure proper resolution of any dependencies between registries.</p>
*
* @param registries the preferred registry for {@code Codec} lookups
*
* @return a {@code CodecRegistry} that combines the list of {@code CodecRegistry} instances into a single one
*/
public static CodecRegistry fromRegistries(final List<? extends CodecRegistry> registries) {
List<CodecProvider> providers = new ArrayList<CodecProvider>();
for (CodecRegistry registry : registries) {
providers.add(providerFromRegistry(registry));
}
return new ProvidersCodecRegistry(providers);
}
private static CodecProvider providerFromRegistry(final CodecRegistry innerRegistry) {
if (innerRegistry instanceof CodecProvider) {
return (CodecProvider) innerRegistry;
} else {
return new CodecProvider() {
@Override
public <T> Codec<T> get(final Class<T> clazz, final CodecRegistry outerRregistry) {
try {
return innerRegistry.get(clazz);
} catch (CodecConfigurationException e) {
return null;
}
}
};
}
}
private CodecRegistries() {
}
}