added automatic wrapping of command results and removed the manual wrappers from the demo code

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/BaseWorkspaceService.java

@@ -31,6 +31,10 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CopyOnWriteArrayList;
 import com.google.gson.JsonPrimitive;
+
+import io.usethesource.vallang.IMap;
+import io.usethesource.vallang.IValue;
+
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.eclipse.lsp4j.ClientCapabilities;
 import org.eclipse.lsp4j.DidChangeConfigurationParams;
@@ -44,6 +48,7 @@
 import org.eclipse.lsp4j.services.LanguageClient;
 import org.eclipse.lsp4j.services.LanguageClientAware;
 import org.eclipse.lsp4j.services.WorkspaceService;
+import org.rascalmpl.values.IRascalValueFactory;
 
 public class BaseWorkspaceService implements WorkspaceService, LanguageClientAware {
     public static final String RASCAL_LANGUAGE = "Rascal";
@@ -111,15 +116,36 @@ public void didChangeWorkspaceFolders(DidChangeWorkspaceFoldersParams params) {
     @Override
     public CompletableFuture<Object> executeCommand(ExecuteCommandParams params) {
         if (params.getCommand().startsWith(RASCAL_META_COMMAND) || params.getCommand().startsWith(RASCAL_COMMAND)) {
-            String languageName = ((JsonPrimitive) params.getArguments().get(0)).getAsString();
-            String command = ((JsonPrimitive) params.getArguments().get(1)).getAsString();
-            return documentService.executeCommand(languageName, command).thenApply(v -> v);
-        }
+            var languageName = ((JsonPrimitive) params.getArguments().get(0)).getAsString();
+            var command = ((JsonPrimitive) params.getArguments().get(1)).getAsString();
 
-        return CompletableFuture.supplyAsync(() -> params.getCommand() + " was ignored.");
+            return documentService.executeCommand(languageName, command).thenApply(v -> commandResultMap(v));
+        }
+        else {
+            return CompletableFuture.supplyAsync(() -> commandResultMap(IRascalValueFactory.getInstance().bool(false)));
+        }
     }
 
+    /**
+     * Command results are wrapped in an IMap such that on the client side of the LSP they end up
+     * as a JSON object `{'result' : <value> }`, and `<value>` can remain to be any
+     * value including primitive values like integers and strings.
+     */
+    private static IMap commandResultMap(IValue result) {
+        var vf = IRascalValueFactory.getInstance();
+
+        /* Check if the result is already wrapped in a singleton map `("result":x)`
+         * We do this for backward compatibility with the previous semantics where
+         * the wrapping had to be done manually in Rascal code to avoid failures in
+         * the JSON bridge w.r.t. to values of primitive types.
+         */
+        if (result.getType().isMap()) {
+            IMap m = (IMap) result;
+            if (m.size() == 1 && m.iterator().next().equals(vf.string("result"))) {
+                return m;
+            }
+        }
 
-
-
+        return vf.map().put(vf.string("result"), result);
+    }
 }

rascal-lsp/src/main/java/org/rascalmpl/vscode/lsp/rascal/RascalLanguageServices.java

@@ -278,15 +278,13 @@ public CompletableFuture<IList> parseCodeActions(String command) {
     public InterruptibleFuture<IValue> executeCommand(String command) {
         logger.debug("executeCommand({}...) (full command value in TRACE level)", () -> command.substring(0, Math.min(10, command.length())));
         logger.trace("Full command: {}", command);
-        var defaultMap = VF.mapWriter();
-        defaultMap.put(VF.string("result"), VF.bool(false));
 
         return InterruptibleFuture.flatten(parseCommand(command).thenApply(cons ->
             EvaluatorUtil.<IValue>runEvaluator(
                 "executeCommand",
                 semanticEvaluator,
                 ev -> ev.call("evaluateRascalCommand", cons),
-                defaultMap.done(),
+                VF.bool(false),
                 exec,
                 true,
                 client

rascal-lsp/src/main/rascal/demo/lang/pico/LanguageServer.rsc

@@ -168,13 +168,13 @@ list[DocumentEdit] getAtoBEdits(start[Program] input)
 @synopsis{Command handler for the renameAtoB command}
 value picoExecutionService(renameAtoB(start[Program] input)) {
     applyDocumentsEdits(getAtoBEdits(input));
-    return ("result": true);
+    return true;
 }
 
 @synopsis{Command handler for the removeDecl command}
 value picoExecutionService(removeDecl(start[Program] program, IdType toBeRemoved)) {
     applyDocumentsEdits([changed(program@\loc.top, [replace(toBeRemoved@\loc, "")])]);
-    return ("result": true);
+    return true;
 }
 
 @synopsis{The main function registers the Pico language with the IDE}

rascal-lsp/src/main/rascal/demo/lang/pico/OldStyleLanguageServer.rsc

@@ -151,13 +151,13 @@ list[DocumentEdit] getAtoBEdits(start[Program] input)
 @synopsis{Command handler for the renameAtoB command}
 value picoCommands(renameAtoB(start[Program] input)) {
     applyDocumentsEdits(getAtoBEdits(input));
-    return ("result": true);
+    return true;
 }
 
 @synopsis{Command handler for the removeDecl command}
 value picoCommands(removeDecl(start[Program] program, IdType toBeRemoved)) {
     applyDocumentsEdits([changed(program@\loc.top, [replace(toBeRemoved@\loc, "")])]);
-    return ("result": true);
+    return true;
 }
 
 @synopsis{The main function registers the Pico language with the IDE}

rascal-lsp/src/main/rascal/lang/rascal/lsp/Actions.rsc

@@ -131,7 +131,7 @@ default value evaluateRascalCommand(Command _) =  ("result" : false);
 
 value evaluateRascalCommand(visualImportGraphCommand(PathConfig pcfg)) {
     importGraph(pcfg);
-    return ("result" : true);
+    return true;
 }
 
 value evaluateRascalCommand(sortImportsAndExtends(Header h)) {
@@ -152,5 +152,5 @@ value evaluateRascalCommand(sortImportsAndExtends(Header h)) {
                 '<}>"[..-2];
 
     applyDocumentsEdits([changed(h@\loc.top, [replace(h.imports@\loc, newHeader)])]);
-    return ("result":true);
+    return true;
 }