org.apache.maven.model.building.ModelCacheTag Maven / Gradle / Ivy

/*
 * 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.apache.maven.model.building;

import org.apache.maven.model.DependencyManagement;
import org.apache.maven.model.Model;

/**
 * Describes a tag used by the model builder to access a {@link ModelCache}. This interface basically aggregates a name
 * and a class to provide some type safety when working with the otherwise untyped cache.
 *
 * @author Benjamin Bentmann
 * @param  The type of data associated with the tag.
 */
interface ModelCacheTag {

    /**
     * Gets the name of the tag.
     *
     * @return The name of the tag, must not be {@code null}.
     */
    String getName();

    /**
     * Gets the type of data associated with this tag.
     *
     * @return The type of data, must not be {@code null}.
     */
    Class getType();

    /**
     * Creates a copy of the data suitable for storage in the cache. The original data to store can be mutated after the
     * cache is populated but the state of the cache must not change so we need to make a copy.
     *
     * @param data The data to store in the cache, must not be {@code null}.
     * @return The data being stored in the cache, never {@code null}.
     */
    T intoCache(T data);

    /**
     * Creates a copy of the data suitable for retrieval from the cache. The retrieved data can be mutated after the
     * cache is queried but the state of the cache must not change so we need to make a copy.
     *
     * @param data The data to retrieve from the cache, must not be {@code null}.
     * @return The data being retrieved from the cache, never {@code null}.
     */
    T fromCache(T data);

    /**
     * The tag used to denote raw model data.
     */
    ModelCacheTag RAW = new ModelCacheTag() {

        @Override
        public String getName() {
            return "raw";
        }

        @Override
        public Class getType() {
            return ModelData.class;
        }

        @Override
        public ModelData intoCache(ModelData data) {
            Model model = (data.getModel() != null) ? data.getModel().clone() : null;
            return new ModelData(data.getSource(), model, data.getGroupId(), data.getArtifactId(), data.getVersion());
        }

        @Override
        public ModelData fromCache(ModelData data) {
            return intoCache(data);
        }
    };

    /**
     * The tag used to denote an effective dependency management section from an imported model.
     */
    ModelCacheTag IMPORT = new ModelCacheTag() {

        @Override
        public String getName() {
            return "import";
        }

        @Override
        public Class getType() {
            return DependencyManagement.class;
        }

        @Override
        public DependencyManagement intoCache(DependencyManagement data) {
            return (data != null) ? data.clone() : null;
        }

        @Override
        public DependencyManagement fromCache(DependencyManagement data) {
            return intoCache(data);
        }
    };
}