Add progress listeners

src/main/java/net/fabricmc/mappingio/FlatMappingVisitor.java

@@ -49,10 +49,11 @@ default void visitMetadata(String key, String value) throws IOException { }
 
 	/**
 	 * Determine whether the mapping content (classes and anything below, metadata if not part of the header) should be visited.
+	 * Lazy callers, which don't know beforehand how many elements they're going to have (e.g. mapping readers), must pass -1.
 	 *
 	 * @return true if content is to be visited, false otherwise
 	 */
-	default boolean visitContent() throws IOException {
+	default boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
 		return true;
 	}
 

src/main/java/net/fabricmc/mappingio/MappingReader.java

@@ -135,24 +135,24 @@ public static List<String> getNamespaces(Reader reader, MappingFormat format) th
 		}
 	}
 
-	public static void read(Path file, MappingVisitor visitor) throws IOException {
-		read(file, null, visitor);
+	public static void read(Path file, MappingVisitor visitor, ProgressListener progressListener) throws IOException {
+		read(file, null, visitor, progressListener);
 	}
 
-	public static void read(Path file, MappingFormat format, MappingVisitor visitor) throws IOException {
+	public static void read(Path file, MappingFormat format, MappingVisitor visitor, ProgressListener progressListener) throws IOException {
 		if (format == null) {
 			format = detectFormat(file);
 			if (format == null) throw new IOException("invalid/unsupported mapping format");
 		}
 
 		if (format.hasSingleFile()) {
 			try (Reader reader = Files.newBufferedReader(file)) {
-				read(reader, format, visitor);
+				read(reader, format, visitor, progressListener);
 			}
 		} else {
 			switch (format) {
 			case ENIGMA_DIR:
-				EnigmaDirReader.read(file, visitor);
+				EnigmaDirReader.read(file, visitor, progressListener);
 				break;
 			case MCP_DIR:
 				throw new UnsupportedOperationException(); // TODO: implement
@@ -162,11 +162,11 @@ public static void read(Path file, MappingFormat format, MappingVisitor visitor)
 		}
 	}
 
-	public static void read(Reader reader, MappingVisitor visitor) throws IOException {
-		read(reader, null, visitor);
+	public static void read(Reader reader, MappingVisitor visitor, ProgressListener progressListener) throws IOException {
+		read(reader, null, visitor, progressListener);
 	}
 
-	public static void read(Reader reader, MappingFormat format, MappingVisitor visitor) throws IOException {
+	public static void read(Reader reader, MappingFormat format, MappingVisitor visitor, ProgressListener progressListener) throws IOException {
 		if (format == null) {
 			if (!reader.markSupported()) reader = new BufferedReader(reader);
 			reader.mark(DETECT_HEADER_LEN);
@@ -179,23 +179,23 @@ public static void read(Reader reader, MappingFormat format, MappingVisitor visi
 
 		switch (format) {
 		case TINY_FILE:
-			Tiny1FileReader.read(reader, visitor);
+			Tiny1FileReader.read(reader, visitor, progressListener);
 			break;
 		case TINY_2_FILE:
-			Tiny2FileReader.read(reader, visitor);
+			Tiny2FileReader.read(reader, visitor, progressListener);
 			break;
 		case ENIGMA_FILE:
-			EnigmaFileReader.read(reader, visitor);
+			EnigmaFileReader.read(reader, visitor, progressListener);
 			break;
 		case SRG_FILE:
-			SrgFileReader.read(reader, visitor);
+			SrgFileReader.read(reader, visitor, progressListener);
 			break;
 		case TSRG_FILE:
 		case TSRG_2_FILE:
-			TsrgFileReader.read(reader, visitor);
+			TsrgFileReader.read(reader, visitor, progressListener);
 			break;
 		case PROGUARD_FILE:
-			ProGuardFileReader.read(reader, visitor);
+			ProGuardFileReader.read(reader, visitor, progressListener);
 			break;
 		default:
 			throw new IllegalStateException();

src/main/java/net/fabricmc/mappingio/MappingVisitor.java

@@ -73,10 +73,11 @@ default void visitMetadata(String key, String value) throws IOException { }
 
 	/**
 	 * Determine whether the mapping content (classes and anything below, metadata if not part of the header) should be visited.
+	 * Lazy callers, which don't know beforehand how many elements they're going to have (e.g. mapping readers), must pass -1.
 	 *
 	 * @return true if content is to be visited, false otherwise
 	 */
-	default boolean visitContent() throws IOException {
+	default boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
 		return true;
 	}
 

src/main/java/net/fabricmc/mappingio/MappingWriter.java

@@ -30,25 +30,25 @@
 import net.fabricmc.mappingio.format.tiny.Tiny2FileWriter;
 
 public interface MappingWriter extends Closeable, MappingVisitor {
-	static MappingWriter create(Path file, MappingFormat format) throws IOException {
+	static MappingWriter create(Path file, MappingFormat format, ProgressListener progressListener) throws IOException {
 		if (format.hasSingleFile()) {
-			return create(Files.newBufferedWriter(file), format);
+			return create(Files.newBufferedWriter(file), format, progressListener);
 		} else {
 			switch (format) {
-			case ENIGMA_DIR: return new EnigmaDirWriter(file, true);
+			case ENIGMA_DIR: return new EnigmaDirWriter(file, true, progressListener);
 			default: throw new UnsupportedOperationException("format "+format+" is not implemented");
 			}
 		}
 	}
 
-	static MappingWriter create(Writer writer, MappingFormat format) throws IOException {
+	static MappingWriter create(Writer writer, MappingFormat format, ProgressListener progressListener) throws IOException {
 		if (!format.hasSingleFile()) throw new IllegalArgumentException("format "+format+" is not applicable to a single writer");
 
 		switch (format) {
-		case TINY_FILE: return new Tiny1FileWriter(writer);
-		case TINY_2_FILE: return new Tiny2FileWriter(writer, false);
-		case ENIGMA_FILE: return new EnigmaFileWriter(writer);
-		case PROGUARD_FILE: return new ProGuardFileWriter(writer);
+		case TINY_FILE: return new Tiny1FileWriter(writer, progressListener);
+		case TINY_2_FILE: return new Tiny2FileWriter(writer, false, progressListener);
+		case ENIGMA_FILE: return new EnigmaFileWriter(writer, progressListener);
+		case PROGUARD_FILE: return new ProGuardFileWriter(writer, progressListener);
 		default: throw new UnsupportedOperationException("format "+format+" is not implemented");
 		}
 	}

src/main/java/net/fabricmc/mappingio/ProgressListener.java

@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2023 FabricMC
+ *
+ * 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 net.fabricmc.mappingio;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Nullable;
+
+public abstract class ProgressListener {
+	protected ProgressListener(LogLevel logLevel) {
+		this.logLevel = logLevel;
+		this.forwarder = this instanceof Forwarder ? (Forwarder) this : new Forwarder(logLevel, this);
+	}
+
+	/**
+	 * Sets the progress listener's total amount of steps and provides a name for the job.
+	 * If the total amount of steps isn't known beforehand, {@code totalWork} must be set to -1.
+	 * Can only be called once.
+	 */
+	protected abstract void init(int totalWork, String title);
+
+	/**
+	 * Indicates the start of a new step being processed, and optionally gives it a name.
+	 */
+	protected abstract void startStep(LogLevel logLevel, @Nullable String stepName);
+
+	/**
+	 * Updates the name of the current step.
+	 */
+	protected abstract void updateMessage(LogLevel logLevel, @Nullable String stepName);
+
+	/**
+	 * Indicates that all steps have finished processing.
+	 * After that point, further method invocations are illegal.
+	 */
+	protected abstract void finish();
+
+	/**
+	 * Determines the granularity of progress reports the progress listener wishes to receive.
+	 */
+	public enum LogLevel {
+		FILES,
+		CLASSES,
+		MEMBERS;
+
+		public boolean allows(LogLevel logLevel) {
+			if (logLevel.compareTo(this) <= 0) {
+				return true;
+			}
+
+			return false;
+		}
+	}
+
+	/**
+	 * Class which forwards only applicable log levels to the passed receiver,
+	 * and automatically checks for illegal calls.
+	 */
+	@ApiStatus.Internal
+	public final class Forwarder extends ProgressListener {
+		private Forwarder(LogLevel logLevel, ProgressListener receiver) {
+			super(logLevel);
+
+			this.receiver = receiver;
+		}
+
+		@Override
+		public void init(int totalWork, String title) {
+			assertNotFinished();
+
+			if (initialized && receiver != NOP) {
+				throw new RuntimeException("Progress listener can only be initialized once!");
+			}
+
+			receiver.init(totalWork, title);
+			initialized = true;
+		}
+
+		@Override
+		public void startStep(LogLevel logLevel, @Nullable String stepName) {
+			assertNotFinished();
+
+			if (this.logLevel.allows(logLevel)) {
+				receiver.startStep(logLevel, stepName);
+			}
+		}
+
+		@Override
+		public void updateMessage(LogLevel logLevel, @Nullable String stepName) {
+			assertNotFinished();
+
+			if (this.logLevel.allows(logLevel)) {
+				receiver.updateMessage(logLevel, stepName);
+			}
+		}
+
+		@Override
+		public void finish() {
+			assertNotFinished();
+			receiver.finish();
+			finished = true;
+		}
+
+		private void assertNotFinished() {
+			if (finished && receiver != NOP) {
+				throw new RuntimeException("Illegal method invocation, progress listener has already finished!");
+			}
+		}
+
+		private final ProgressListener receiver;
+		private boolean initialized;
+		private boolean finished;
+	}
+
+	/**
+	 * No-op progress listener that ignores all events.
+	 */
+	public static final ProgressListener NOP = new ProgressListener(LogLevel.FILES) {
+		@Override
+		public void init(int totalWork, String title) {
+		}
+
+		@Override
+		public void startStep(LogLevel logLevel, @Nullable String stepName) {
+		}
+
+		@Override
+		public void updateMessage(LogLevel logLevel, @Nullable String stepName) {
+		}
+
+		@Override
+		public void finish() {
+		}
+	};
+
+	/**
+	 * Finest log level the progress listener accepts.
+	 */
+	public final LogLevel logLevel;
+
+	/**
+	 * Public-facing progress listener interface for progress passers to interact with,
+	 * which automatically checks for illegal calls and only forwards the applicable
+	 * log levels to the actual {@link ProgressListener}.
+	 */
+	@ApiStatus.Internal
+	public final Forwarder forwarder;
+}

src/main/java/net/fabricmc/mappingio/adapter/FlatAsRegularMappingVisitor.java

@@ -70,8 +70,8 @@ public void visitMetadata(String key, String value) throws IOException {
 	}
 
 	@Override
-	public boolean visitContent() throws IOException {
-		return next.visitContent();
+	public boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
+		return next.visitContent(classCount, fieldCount, methodCount, methodArgCount, methodVarCount, commentCount, metadataCount);
 	}
 
 	@Override

src/main/java/net/fabricmc/mappingio/adapter/ForwardingMappingVisitor.java

@@ -58,8 +58,8 @@ public void visitMetadata(String key, String value) throws IOException {
 	}
 
 	@Override
-	public boolean visitContent() throws IOException {
-		return next.visitContent();
+	public boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
+		return next.visitContent(classCount, fieldCount, methodCount, methodArgCount, methodVarCount, commentCount, metadataCount);
 	}
 
 	@Override

src/main/java/net/fabricmc/mappingio/adapter/MappingNsCompleter.java

@@ -92,10 +92,10 @@ public void visitMetadata(String key, String value) throws IOException {
 	}
 
 	@Override
-	public boolean visitContent() throws IOException {
+	public boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
 		relayHeaderOrMetadata = true; // for in-content metadata
 
-		return next.visitContent();
+		return next.visitContent(classCount, fieldCount, methodCount, methodArgCount, methodVarCount, commentCount, metadataCount);
 	}
 
 	@Override

src/main/java/net/fabricmc/mappingio/adapter/MappingSourceNsSwitch.java

@@ -132,12 +132,16 @@ public void visitMetadata(String key, String value) throws IOException {
 	}
 
 	@Override
-	public boolean visitContent() throws IOException {
+	public boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
 		if (!classMapReady) return true;
 
 		relayHeaderOrMetadata = true; // for in-content metadata
 
-		return next.visitContent();
+		if (dropMissingNewSrcName) {
+			return next.visitContent(-1, -1, -1, -1, -1, -1, -1);
+		} else {
+			return next.visitContent(classCount, fieldCount, methodCount, methodArgCount, methodVarCount, commentCount, metadataCount);
+		}
 	}
 
 	@Override

src/main/java/net/fabricmc/mappingio/adapter/RegularAsFlatMappingVisitor.java

@@ -64,8 +64,8 @@ public void visitMetadata(String key, String value) throws IOException {
 	}
 
 	@Override
-	public boolean visitContent() throws IOException {
-		return next.visitContent();
+	public boolean visitContent(int classCount, int fieldCount, int methodCount, int methodArgCount, int methodVarCount, int commentCount, int metadataCount) throws IOException {
+		return next.visitContent(classCount, fieldCount, methodCount, methodArgCount, methodVarCount, commentCount, metadataCount);
 	}
 
 	@Override