MergePlugin.groovy

/*
 * Copyright 2002-2015 the original author or authors.
 *
 * 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.springframework.build.gradle

import org.gradle.api.*
import org.gradle.api.artifacts.Configuration
import org.gradle.api.artifacts.ProjectDependency;
import org.gradle.api.artifacts.maven.Conf2ScopeMapping
import org.gradle.api.plugins.MavenPlugin
import org.gradle.plugins.ide.eclipse.EclipsePlugin
import org.gradle.plugins.ide.idea.IdeaPlugin
import org.gradle.api.invocation.*

/**
 * Gradle plugin that allows projects to merged together. Primarily developed to
 * allow Spring to support multiple incompatible versions of third-party
 * dependencies (for example Hibernate v3 and v4).
 * <p>
 * The 'merge' extension should be used to define how projects are merged, for example:
 * <pre class="code">
 * configure(subprojects) {
 *     apply plugin: MergePlugin
 * }
 *
 * project("myproject") {
 * }
 *
 * project("myproject-extra") {
 *     merge.into = project("myproject")
 * }
 * </pre>
 * <p>
 * This plugin adds two new configurations:
 * <ul>
 * <li>merging - Contains the projects being merged into this project<li>
 * <li>runtimeMerge - Contains all dependencies that are merge projects. These are used
 * to allow an IDE to reference merge projects.</li>
 * <ul>
 *
 * @author Rob Winch
 * @author Phillip Webb
 */
class MergePlugin implements Plugin<Project> {

	private static boolean attachedProjectsEvaluated;

	public void apply(Project project) {
		project.plugins.apply(MavenPlugin)
		project.plugins.apply(EclipsePlugin)
		project.plugins.apply(IdeaPlugin)

		MergeModel model = project.extensions.create("merge", MergeModel)
		model.project = project
		project.configurations.create("merging")
		Configuration runtimeMerge = project.configurations.create("runtimeMerge")

		// Ensure the IDE can reference merged projects
		project.eclipse.classpath.plusConfigurations += [ runtimeMerge ]
		project.idea.module.scopes.PROVIDED.plus += [ runtimeMerge ]

		// Hook to perform the actual merge logic
		project.afterEvaluate{
			if (it.merge.into != null) {
				setup(it)
			}
			setupIdeDependencies(it)
		}

		// Hook to build runtimeMerge dependencies
		if (!attachedProjectsEvaluated) {
			project.gradle.projectsEvaluated{
				postProcessProjects(it)
			}
			attachedProjectsEvaluated  = true;
		}
	}

	private void setup(Project project) {
		project.merge.into.dependencies.add("merging", project)
		project.dependencies.add("provided", project.merge.into.sourceSets.main.output)
		project.dependencies.add("runtimeMerge", project.merge.into)
		setupTaskDependencies(project)
		setupMaven(project)
	}

	private void setupTaskDependencies(Project project) {
		// invoking a task will invoke the task with the same name on 'into' project
		["sourcesJar", "jar", "javadocJar", "javadoc", "install", "artifactoryPublish"].each {
			def task = project.tasks.findByPath(it)
			if (task) {
				task.enabled = false
				task.dependsOn(project.merge.into.tasks.findByPath(it))
			}
		}

		// update 'into' project artifacts to contain the source artifact contents
		project.merge.into.sourcesJar.from(project.sourcesJar.source)
		project.merge.into.jar.from(project.sourceSets.main.output)
		project.merge.into.javadoc {
			source += project.javadoc.source
			classpath += project.javadoc.classpath
		}
	}

	private void setupIdeDependencies(Project project) {
		project.configurations.each { c ->
			c.dependencies.findAll( { it instanceof org.gradle.api.artifacts.ProjectDependency } ).each { d ->
				d.dependencyProject.merge.from.each { from ->
					project.dependencies.add("runtimeMerge", from)
				}
			}
		}
	}

	private void setupMaven(Project project) {
		project.configurations.each { configuration ->
			Conf2ScopeMapping mapping = project.conf2ScopeMappings.getMapping([configuration])
			if (mapping.scope) {
				Configuration intoConfiguration = project.merge.into.configurations.create(
					project.name + "-" + configuration.name)
				configuration.excludeRules.each {
					configuration.exclude([
						(ExcludeRule.GROUP_KEY) : it.group,
						(ExcludeRule.MODULE_KEY) : it.module])
				}
				configuration.dependencies.each {
					def intoCompile = project.merge.into.configurations.getByName("compile")
					// Protect against changing a compile scope dependency (SPR-10218)
					if (!intoCompile.dependencies.contains(it)) {
						intoConfiguration.dependencies.add(it)
					}
				}
				def index = project.parent.childProjects.findIndexOf {p -> p.getValue() == project}
				project.merge.into.install.repositories.mavenInstaller.pom.scopeMappings.addMapping(
					mapping.priority + 100 + index, intoConfiguration, mapping.scope)
			}
		}
	}

	private postProcessProjects(Gradle gradle) {
		gradle.allprojects(new Action<Project>() {
			public void execute(Project project) {
				project.configurations.getByName("runtime").allDependencies.withType(ProjectDependency).each{
					Configuration dependsOnMergedFrom = it.dependencyProject.configurations.getByName("merging");
					dependsOnMergedFrom.dependencies.each{ dep ->
						project.dependencies.add("runtimeMerge", dep.dependencyProject)
					}
				}
			}
		});
	}
}

class MergeModel {
	Project project;
	Project into;
	List<Project> from = [];
	
	public void setInto(Project into) {
		this.into = into;
		into.merge.from.add(project);
	}
}