Add Experimental CFR support. Line numbers and comments are not currently supported.

build.gradle

@@ -57,6 +57,7 @@ dependencies {
 	// decompilers
 	implementation ('net.fabricmc:procyon-fabric-compilertools:0.5.35.13')
 	implementation ('org.jetbrains:intellij-fernflower:1.2.1.16')
+	implementation ('org.benf:cfr:0.150')
 
 	// source code remapping
 	implementation ('org.cadixdev:mercury:0.1.0.fabric-SNAPSHOT')

src/main/java/net/fabricmc/loom/LoomGradlePlugin.java

@@ -31,6 +31,7 @@ import org.gradle.api.Project;
 import org.gradle.api.tasks.TaskContainer;
 
 import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+import net.fabricmc.loom.decompilers.cfr.FabricCFRDecompiler;
 import net.fabricmc.loom.decompilers.fernflower.FabricFernFlowerDecompiler;
 import net.fabricmc.loom.providers.MappingsProvider;
 import net.fabricmc.loom.task.CleanEclipseRunsTask;
@@ -127,6 +128,7 @@ public class LoomGradlePlugin extends AbstractPlugin {
 
 		LoomGradleExtension extension = project.getExtensions().getByType(LoomGradleExtension.class);
 		extension.addDecompiler(new FabricFernFlowerDecompiler(project));
+		extension.addDecompiler(new FabricCFRDecompiler(project));
 
 		project.afterEvaluate((p) -> {
 			for (LoomDecompiler decompiler : extension.decompilers) {

src/main/java/net/fabricmc/loom/decompilers/cfr/FabricCFRDecompiler.java

@@ -0,0 +1,241 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.decompilers.cfr;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.function.Function;
+import java.util.jar.Attributes;
+import java.util.jar.JarEntry;
+import java.util.jar.JarOutputStream;
+import java.util.jar.Manifest;
+import java.util.stream.Collectors;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+import com.google.common.base.Charsets;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.io.ByteStreams;
+import org.benf.cfr.reader.api.CfrDriver;
+import org.benf.cfr.reader.api.ClassFileSource;
+import org.benf.cfr.reader.api.OutputSinkFactory;
+import org.benf.cfr.reader.api.SinkReturns;
+import org.benf.cfr.reader.bytecode.analysis.parse.utils.Pair;
+import org.gradle.api.Project;
+import org.gradle.api.internal.project.ProjectInternal;
+import org.gradle.internal.logging.progress.ProgressLogger;
+import org.gradle.internal.logging.progress.ProgressLoggerFactory;
+import org.gradle.internal.service.ServiceRegistry;
+
+import net.fabricmc.loom.api.decompilers.DecompilationMetadata;
+import net.fabricmc.loom.api.decompilers.LoomDecompiler;
+
+public class FabricCFRDecompiler implements LoomDecompiler {
+	private final Project project;
+
+	public FabricCFRDecompiler(Project project) {
+		this.project = project;
+	}
+
+	@Override
+	public String name() {
+		return "ExperimentalCfr";
+	}
+
+	@Override
+	public void decompile(Path compiledJar, Path sourcesDestination, Path linemapDestination, DecompilationMetadata metaData) {
+		project.getLogger().warn("!!!! The CFR decompiler support is currently incomplete, line numbers will not match up and there will be no javadocs in the generated source.");
+
+		// Setups the multi threaded logger, the thread id is used as the key to the ProgressLogger's
+		ServiceRegistry registry = ((ProjectInternal) project).getServices();
+		ProgressLoggerFactory factory = registry.get(ProgressLoggerFactory.class);
+		ProgressLogger progressGroup = factory.newOperation(getClass()).setDescription("Decompile");
+
+		Map<Long, ProgressLogger> loggerMap = new ConcurrentHashMap<>();
+		Function<Long, ProgressLogger> createLogger = (threadId) -> {
+			ProgressLogger pl = factory.newOperation(getClass(), progressGroup);
+			pl.setDescription("decompile worker");
+			pl.started();
+			return pl;
+		};
+
+		progressGroup.started();
+
+		Manifest manifest = new Manifest();
+		manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");
+		Set<String> addedDirectories = new HashSet<>();
+
+		try (OutputStream fos = Files.newOutputStream(sourcesDestination); JarOutputStream jos = new JarOutputStream(fos, manifest); ZipFile inputZip = new ZipFile(compiledJar.toFile())) {
+			CfrDriver driver = new CfrDriver.Builder()
+					.withOptions(ImmutableMap.of(
+							"renameillegalidents", "true",
+							"trackbytecodeloc", "true"
+					))
+					.withClassFileSource(new ClassFileSource() {
+						@Override
+						public void informAnalysisRelativePathDetail(String usePath, String classFilePath) {
+						}
+
+						@Override
+						public Collection<String> addJar(String jarPath) {
+							return null;
+						}
+
+						@Override
+						public String getPossiblyRenamedPath(String path) {
+							return path;
+						}
+
+						@Override
+						public Pair<byte[], String> getClassFileContent(String path) throws IOException {
+							ZipEntry zipEntry = inputZip.getEntry(path);
+
+							if (zipEntry == null) {
+								throw new FileNotFoundException(path);
+							}
+
+							try (InputStream inputStream = inputZip.getInputStream(zipEntry)) {
+								return Pair.make(ByteStreams.toByteArray(inputStream), path);
+							}
+						}
+					})
+					.withOutputSink(new OutputSinkFactory() {
+						@Override
+						public List<SinkClass> getSupportedSinks(SinkType sinkType, Collection<SinkClass> available) {
+							switch (sinkType) {
+								case PROGRESS:
+									return Collections.singletonList(SinkClass.STRING);
+								case JAVA:
+									return Collections.singletonList(SinkClass.DECOMPILED);
+								default:
+									return Collections.emptyList();
+							}
+						}
+
+						@SuppressWarnings("unchecked")
+						@Override
+						public <T> Sink<T> getSink(SinkType sinkType, SinkClass sinkClass) {
+							switch (sinkType) {
+								case PROGRESS:
+									return (p) -> project.getLogger().debug((String) p);
+								case JAVA:
+									return (Sink<T>) decompiledSink(jos, addedDirectories);
+								case EXCEPTION:
+									return (e) -> project.getLogger().error((String) e);
+							}
+
+							return null;
+						}
+					})
+					.build();
+
+			List<String> classes = Collections.list(inputZip.entries()).stream()
+									.map(ZipEntry::getName)
+									.filter(input -> input.endsWith(".class"))
+									.collect(Collectors.toList());
+
+			ExecutorService executorService = Executors.newFixedThreadPool(metaData.numberOfThreads);
+			List<Future<?>> futures = new LinkedList<>();
+
+			for (String clazz : classes) {
+				futures.add(executorService.submit(() -> {
+					loggerMap.computeIfAbsent(Thread.currentThread().getId(), createLogger).progress(clazz);
+					driver.analyse(Collections.singletonList(clazz));
+				}));
+			}
+
+			for (Future<?> future : futures) {
+				future.get();
+			}
+		} catch (IOException | InterruptedException | ExecutionException e) {
+			throw new RuntimeException("Failed to decompile", e);
+		} finally {
+			loggerMap.forEach((threadId, progressLogger) -> progressLogger.completed());
+		}
+	}
+
+	private static OutputSinkFactory.Sink<SinkReturns.Decompiled> decompiledSink(JarOutputStream jos, Set<String> addedDirectories) {
+		return decompiled -> {
+			String filename = decompiled.getPackageName().replace('.', '/');
+			if (!filename.isEmpty()) filename += "/";
+			filename += decompiled.getClassName() + ".java";
+
+			byte[] data = decompiled.getJava().getBytes(Charsets.UTF_8);
+
+			writeToJar(filename, data, jos, addedDirectories);
+		};
+	}
+
+	// TODO move to task queue?
+	private static synchronized void writeToJar(String filename, byte[] data, JarOutputStream jos, Set<String> addedDirectories) {
+		String[] path = filename.split("/");
+		String pathPart = "";
+
+		for (int i = 0; i < path.length - 1; i++) {
+			pathPart += path[i] + "/";
+
+			if (addedDirectories.add(pathPart)) {
+				JarEntry entry = new JarEntry(pathPart);
+				entry.setTime(new Date().getTime());
+
+				try {
+					jos.putNextEntry(entry);
+					jos.closeEntry();
+				} catch (IOException e) {
+					throw new RuntimeException(e);
+				}
+			}
+		}
+
+		JarEntry entry = new JarEntry(filename);
+		entry.setTime(new Date().getTime());
+		entry.setSize(data.length);
+
+		try {
+			jos.putNextEntry(entry);
+			jos.write(data);
+			jos.closeEntry();
+		} catch (IOException e) {
+			throw new RuntimeException(e);
+		}
+	}
+}