ReadableSchemaRegistry.java

/**
 * Copyright 2012, 2013 Turn, 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 com.turn.shapeshifter;

import com.turn.shapeshifter.ShapeshifterProtos.JsonSchema;

import java.util.List;

import com.google.common.collect.ImmutableList;
import com.google.protobuf.Descriptors.Descriptor;

/**
 * Defines the read operations on a registry of schema instances.
 *
 * @author jsilland
 */
public interface ReadableSchemaRegistry extends SchemaSource {

	/**
	 * An immutable, empty instance of readable schema registry.
	 */
	public static final ReadableSchemaRegistry EMPTY = new ReadableSchemaRegistry() {

		@Override
		public List<JsonSchema> getJsonSchemas() {
			return ImmutableList.of();
		}

		@Override
		public NamedSchema get(String name) {
			return null;
		}

		@Override
		public Schema get(Descriptor descriptor) {
			return AutoSchema.of(descriptor);
		}

		@Override
		public boolean contains(String name) {
			return false;
		}
	};

	/**
	 * Returns the schema identified by the given name, or {@code null} if
	 * no such schema is registered in this instance.
	 *
	 * @param name the name of the schema to look up
	 */
	public Schema get(String name);

	/**
	 * Generates the set of JSON Schemas that are known to this instance.
	 *
	 * @return The list of JSON Schemas.
	 * @throws JsonSchemaException
	 */
	public List<JsonSchema> getJsonSchemas() throws JsonSchemaException;

	/**
	 * Returns {@code true} if this registry contains a schema for the given
	 * name.
	 *
	 * @param name the identifier to look up
	 */
	public boolean contains(String name);

}