/*
* Copyright 2003-2016 JetBrains s.r.o.
*
* 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 jetbrains.mps.extapi.persistence.datasource;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.jetbrains.mps.openapi.persistence.datasource.DataSourceType;
import java.net.URL;
/**
* Service-provider interface for breeding new {@link DataSourceFactoryFromName} and
* {@link DataSourceFactoryFromURL} from the given data source type.
* Note that only core MPS developers are able to register it as a service.
* Other clients are welcome to use the platform-level extension point which is located at
* the <code>jetbrains.mps.persistence.DataSourceFactoryRuleRegistrar</code>
* See how <code>jetbrains.mps.persistence.FileDataSourceFactoryRule</code> is implemented and
* registered in the META-INF/services location.
*
* We provide functions here rather than register <code>DataSourceFactory</code>
* themselves since we need to expose the logic of constructing factory from a specified data source type (or url)
* For example: if we view a data source as a location in a file system
* and we need to differentiate the locations by file names or file name extensions or
* some specific folders in the path we are able to implement a <code>FileDataSource</code> which
* is attributed to a file location and a single <code>FileExtensionDataSourceType</code> which is defined
* exclusively by the file extension string.
*
* One method is used when creating a new data source and the second -- when reading models.
*
* @see DataSourceFactoryRuleService
* @author apyshkin
* @since 3.5
*/
public interface DataSourceFactoryRule {
/**
* Constructs a factory from a specified data source type.
* Might return null which means that the passed data source type does not satisfy
* the rule.
* @return a new data source factory based on the data source type information
* null if the provided data source type does not suit the rule preconditions.
*/
@Nullable
DataSourceFactoryFromName spawn(@NotNull DataSourceType dataSourceType);
/**
* Constructs a factory from a specified URL.
* Might return null which means that the passed argument does not satisfy
* the rule.
* @return a new data source factory based on the data source type information
* null if the provided data source type does not suit the rule preconditions.
*/
@Nullable
DataSourceFactoryFromURL spawn(@NotNull URL url);
}