Unify VFS interfaces

src/org/rascalmpl/ideservices/GsonUtils.java

@@ -84,6 +84,7 @@ public class GsonUtils {
      */
     static {
         writer.setRationalsAsString(true);
+        writer.setFileLocationsAsPathOnly(false);
         typeMappings = List.of(
             new TypeMapping(IBool.class, tf.boolType()),
             new TypeMapping(ICollection.class), // IList, IMap, ISet

src/org/rascalmpl/library/lang/json/internal/JsonValueWriter.java

@@ -67,6 +67,7 @@ public class JsonValueWriter {
     private IFunction formatters;
     private boolean explicitConstructorNames = false;
     private boolean explicitDataTypes;
+    private boolean fileLocationsAsPathOnly = true;
 
     /** helper class for number serialization without quotes */
     private static class RascalNumber extends Number {
@@ -163,6 +164,11 @@ public JsonValueWriter setExplicitDataTypes(boolean setting) {
         return this;
     }
 
+    public JsonValueWriter setFileLocationsAsPathOnly(boolean setting) {
+        this.fileLocationsAsPathOnly = setting;
+        return this;
+    }
+
     public void write(JsonWriter out, IValue value) throws IOException {
         value.accept(new IValueVisitor<Void, IOException>() {
 
@@ -262,7 +268,7 @@ public Void visitSourceLocation(ISourceLocation o) throws IOException {
                 }
                 else {
                     if (!o.hasOffsetLength()) {
-                        if ("file".equals(o.getScheme())) {
+                        if (fileLocationsAsPathOnly && "file".equals(o.getScheme())) {
                             out.value(o.getPath());
                         }
                         else {

src/org/rascalmpl/shell/RascalShell.java

@@ -14,8 +14,8 @@
 package org.rascalmpl.shell;
 
 import java.io.IOException;
-import java.io.Writer;
 import java.io.PrintWriter;
+import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 
@@ -38,9 +38,6 @@ public static void main(String[] args) throws IOException {
         for (; i < args.length; i++) {
             if (args[i].equals("--remoteIDEServicesPort")) {
                 ideServicesPort = Integer.parseInt(args[++i]);
-            } else if (args[i].equals("--vfsPort")) {
-                System.err.println("Ignored parameter --vfsPort and its argument");
-                i++; // skip the argument
             } else if (args[i].startsWith("--")) {
                 // Currently unknown named argument, skipping over this
                 System.err.println("Ignored parameter " + args[i]);

src/org/rascalmpl/uri/IExternalResolverRegistry.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2018-2026, NWO-I CWI and Swat.engineering
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.rascalmpl.uri;
+
+public interface IExternalResolverRegistry extends ISourceLocationInputOutput, ILogicalSourceLocationResolver, ISourceLocationWatcher {
+    @Override
+    default String scheme() {
+        throw new UnsupportedOperationException("'scheme' is not supported for external resolvers");
+    }
+
+    @Override
+    default String authority() {
+        throw new UnsupportedOperationException("`authority` is not supported for external resolvers");
+    }
+}

src/org/rascalmpl/uri/ISourceLocationInput.java

@@ -33,10 +33,10 @@ default long created(ISourceLocation uri) throws IOException {
 	/** In bytes !only for internal use! */
 	long size(ISourceLocation uri)  throws IOException; 
 	boolean isDirectory(ISourceLocation uri);  
-	boolean isFile(ISourceLocation uri) ;
+	boolean isFile(ISourceLocation uri);
 	boolean isReadable(ISourceLocation uri) throws IOException;
 
-	String[] list(ISourceLocation uri)  throws IOException;
+	String[] list(ISourceLocation uri) throws IOException;
 	String scheme();
 	boolean supportsHost();
 	default boolean supportsReadableFileChannel() {

src/org/rascalmpl/uri/ISourceLocationWatcher.java

@@ -44,7 +44,6 @@ public interface ISourceLocationWatcher {
 	 */
 	boolean supportsRecursiveWatch();
 
-
 	public interface ISourceLocationChanged {
 		ISourceLocation getLocation();
 		ISourceLocationChangeType getChangeType();
@@ -63,9 +62,28 @@ default boolean isChanged() {
 	}
 
 	public enum ISourceLocationChangeType {
-		CREATED(),
-		DELETED(),
-		MODIFIED()
+		CREATED(2),
+		DELETED(3),
+		MODIFIED(1);
+
+		private final int value;
+
+		public int getValue() {
+			return value;
+		}
+
+		ISourceLocationChangeType(int value) {
+			this.value = value;
+		}
+
+		public static ISourceLocationChangeType fromValue(int value) {
+			switch (value) {
+				case 2: return CREATED;
+				case 3: return DELETED;
+				case 1: return MODIFIED;
+				default: throw new IllegalArgumentException("Unknown ISourceLocationChangeType value " + value);
+			}
+		}
 	}
 
 	static ISourceLocationChanged created(ISourceLocation loc) {

src/org/rascalmpl/uri/URIResolverRegistry.java

@@ -44,6 +44,7 @@
 import org.rascalmpl.unicode.UnicodeOutputStreamWriter;
 import org.rascalmpl.uri.ISourceLocationWatcher.ISourceLocationChanged;
 import org.rascalmpl.uri.classloaders.IClassloaderLocationResolver;
+import org.rascalmpl.uri.remote.RemoteExternalResolverRegistry;
 import org.rascalmpl.uri.watch.WatchRegistry;
 import org.rascalmpl.values.IRascalValueFactory;
 import org.rascalmpl.values.ValueFactoryFactory;
@@ -65,12 +66,7 @@ public class URIResolverRegistry {
 	private final Map<String, Map<String, ILogicalSourceLocationResolver>> logicalResolvers = new ConcurrentHashMap<>();
 	private final Map<String, IClassloaderLocationResolver> classloaderResolvers = new ConcurrentHashMap<>();
 
-	// we allow the user to define (using -Drascal.fallbackResolver=fully.qualified.classname) a single class that will handle
-	// scheme's not statically registered. That class should implement at least one of these interfaces
-	private volatile @Nullable ISourceLocationInput fallbackInputResolver;
-	private volatile @Nullable ISourceLocationOutput fallbackOutputResolver;
-	private volatile @Nullable ILogicalSourceLocationResolver fallbackLogicalResolver;
-	private volatile @Nullable IClassloaderLocationResolver fallbackClassloaderResolver;
+	private volatile @Nullable IExternalResolverRegistry externalRegistry;
 
 	private static class InstanceHolder {
 		static URIResolverRegistry sInstance = new URIResolverRegistry();
@@ -116,14 +112,38 @@ private void loadServices() {
 		try {
 			Enumeration<URL> resources = getClass().getClassLoader().getResources(RESOLVERS_CONFIG);
 			Collections.list(resources).forEach(f -> loadServices(f));
-			var fallbackResolverClassName = System.getProperty("rascal.fallbackResolver");
-			if (fallbackResolverClassName != null) {
-				loadFallback(fallbackResolverClassName);
-			}
 		}
 		catch (IOException e) {
 			throw new Error("WARNING: Could not load URIResolverRegistry extensions from " + RESOLVERS_CONFIG, e);
 		}
+
+		var remoteResolverRegistryPort = getRemoteResolverRegistryPort();
+        if (remoteResolverRegistryPort != null) {
+			synchronized (this) {
+				if (this.externalRegistry == null) {
+					registerRemoteResolverRegistry(new RemoteExternalResolverRegistry(remoteResolverRegistryPort));
+				}
+			}
+        }
+	}
+
+	public static Integer getRemoteResolverRegistryPort() {
+		var remoteResolverRegistryPortProperty = System.getProperty("rascal.remoteResolverRegistryPort");
+		if (remoteResolverRegistryPortProperty != null) {
+			try {
+				return Integer.parseInt(remoteResolverRegistryPortProperty);
+			} catch (NumberFormatException e) {
+				System.err.println("WARNING: Invalid remoteResolverRegistryPort environment variable: " + remoteResolverRegistryPortProperty + " is not parseable as integer");
+			}
+		}
+		return null;
+	}
+
+	public synchronized void registerRemoteResolverRegistry(RemoteExternalResolverRegistry registry) {
+		synchronized (this) {
+			this.externalRegistry = registry;
+			watchers.setExternalRegistry(registry);
+		}
 	}
 
 	public Set<String> getRegisteredInputSchemes() {
@@ -153,46 +173,6 @@ private Object constructService(String name) throws ClassNotFoundException, Inst
 		}
 	}
 
-	private void loadFallback(String fallbackClass) {
-		try {
-			Object instance = constructService(fallbackClass);
-			boolean ok = false;
-			if (instance instanceof ILogicalSourceLocationResolver) {
-				fallbackLogicalResolver = (ILogicalSourceLocationResolver) instance;
-				ok = true;
-			}
-
-			if (instance instanceof ISourceLocationInput) {
-				fallbackInputResolver = (ISourceLocationInput) instance;
-				ok = true;
-			}
-
-			if (instance instanceof ISourceLocationOutput) {
-				fallbackOutputResolver = (ISourceLocationOutput) instance;
-				ok = true;
-			}
-
-			if (instance instanceof IClassloaderLocationResolver) {
-				fallbackClassloaderResolver = (IClassloaderLocationResolver) instance;
-				ok = true;
-			}
-
-			if (instance instanceof ISourceLocationWatcher) {
-				watchers.setFallback((ISourceLocationWatcher) instance);
-			}
-			if (!ok) {
-				System.err.println("WARNING: could not load fallback resolver " + fallbackClass
-					+ " because it does not implement ISourceLocationInput or ISourceLocationOutput or ILogicalSourceLocationResolver");
-			}
-		}
-		catch (ClassNotFoundException | InstantiationException | IllegalAccessException | ClassCastException
-			| IllegalArgumentException | InvocationTargetException | SecurityException  e) {
-			System.err.println("WARNING: could not load resolver due to " + e.getMessage());
-			e.printStackTrace();
-		}
-
-	}
-
 	private void loadServices(URL nextElement) {
 		try {
 			for (String name : readConfigFile(nextElement)) {
@@ -402,9 +382,9 @@ private ISourceLocation physicalLocation(ISourceLocation loc) throws IOException
 			loc = resolveAndFixOffsets(loc, resolver, map.values());
 		}
 
-		if (fallbackLogicalResolver != null) {
-			var fallbackResult = resolveAndFixOffsets(loc == null ? original : loc, fallbackLogicalResolver, Collections.emptyList());
-			return fallbackResult == null ? loc : fallbackResult;
+		if (externalRegistry != null) {
+			var externalResult = resolveAndFixOffsets(loc == null ? original : loc, externalRegistry, Collections.emptyList());
+			return externalResult == null ? loc : externalResult;
 		}
 		return loc;
 	}
@@ -464,7 +444,7 @@ private ISourceLocationInput getInputResolver(String scheme) {
 					return result;
 				}
 			}
-			return fallbackInputResolver;
+			return externalRegistry;
 		}
 		return result;
 	}
@@ -480,7 +460,6 @@ private IClassloaderLocationResolver getClassloaderResolver(String scheme) {
 					return result;
 				}
 			}
-			return fallbackClassloaderResolver;
 		}
 		return result;
 	}
@@ -496,7 +475,7 @@ private ISourceLocationOutput getOutputResolver(String scheme) {
 					return result;
 				}
 			}
-			return fallbackOutputResolver;
+			return externalRegistry;
 		}
 		return result;
 	}
@@ -1118,7 +1097,7 @@ public boolean hasLogicalResolver(ISourceLocation loc) {
 	}
 
 	public boolean hasNativelyWatchableResolver(ISourceLocation loc) {
-		return watchers.hasNativeSupport(loc.getScheme()) || watchers.hasNativeSupport(safeResolve(loc).getScheme()) || watchers.hasFallback();
+		return watchers.hasNativeSupport(loc.getScheme()) || watchers.hasNativeSupport(safeResolve(loc).getScheme()) || watchers.hasExternalRegistry();
 	}
 
 	public FileAttributes stat(ISourceLocation loc) throws IOException {