Experimenting with some low hanging fruit in the code that parses and imports modules for the sake of DSL loading time in VScode

src/org/rascalmpl/semantics/dynamic/Import.java

@@ -538,7 +538,12 @@ public ITree visitTreeAppl(ITree tree)  {
            IListWriter w = vf.listWriter();
            IList args = TreeAdapter.getArgs(tree);
            for (IValue arg : args) {
-             w.append(arg.accept(this));
+            if (TreeAdapter.isContextFree(tree)) {
+              w.append(arg.accept(this));
+            }
+            else {
+              w.append(arg);
+            }
            }
            args = w.done();
 
@@ -686,7 +691,12 @@ public ITree visitTreeAppl(ITree tree)  {
     	IListWriter w = vf.listWriter();
       IList args = TreeAdapter.getArgs(tree);
       for (IValue arg : args) {
-        w.append(arg.accept(this));
+        if (!TreeAdapter.isLayout((ITree) arg)) {
+          w.append(arg.accept(this));
+        }
+        else {
+          w.append(arg);
+        }
       }
       args = w.done();
 
@@ -772,7 +782,12 @@ public ITree visitTreeAppl(ITree tree)  {
             IListWriter w = vf.listWriter();
             IList args = TreeAdapter.getArgs(tree);
             for (IValue elem : args) {
-              w.append(elem.accept(this));
+              if (!TreeAdapter.isLayout((ITree) elem)) {
+                w.append(elem.accept(this));
+              }
+              else {
+                w.append(elem);
+              }
             }
             args = w.done();
 

src/org/rascalmpl/values/parsetrees/ProductionAdapter.java

@@ -84,7 +84,8 @@ public static IList getASTSymbols(IConstructor tree) {
 	}
 
 	public static boolean isContextFree(IConstructor tree) {
-		return SymbolAdapter.isSort(getType(tree));
+		IConstructor t = getType(tree);
+		return SymbolAdapter.isSort(t) || SymbolAdapter.isParameterizedSort(t);
 	}
 
 	public static boolean isLayout(IConstructor tree) {

src/org/rascalmpl/values/parsetrees/SymbolAdapter.java

@@ -194,6 +194,7 @@ public static String getLabel(IConstructor tree) {
 	}
 
 	public static boolean isParameterizedSort(IConstructor tree) {
+		tree = delabel(tree);
 		return tree.getConstructorType() == Symbol_ParameterizedSort;
 	}
 

src/org/rascalmpl/values/parsetrees/TreeAdapter.java

@@ -18,7 +18,10 @@
 import java.io.Writer;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Map;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
 
 import org.fusesource.jansi.Ansi;
 import org.fusesource.jansi.Ansi.Attribute;
@@ -369,6 +372,21 @@ public static IList getListASTArgs(ITree tree) {
 		}
 		return writer.done();
 	}
+
+	public static Stream<ITree> streamListASTArgs(ITree tree) {
+		if (!isList(tree)) {
+			throw new ImplementationError("This is not a context-free list production: " + tree);
+		}
+
+		IList children = getArgs(tree);
+		int jump = isSeparatedList(tree) ? getSeparatorCount(tree) - 1 : 2;
+
+		return IntStream.range(0, children.size())
+			.filter(i -> i % jump == 0)
+			.mapToObj(children::get)
+			.map(t -> (ITree) t)
+			;
+	}
 
 	public static int getSeparatorCount(ITree tree) {
 		IConstructor nt = ProductionAdapter.getType(getProduction(tree));
@@ -412,6 +430,25 @@ public static IList getASTArgs(ITree tree) {
 		return writer.done();
 	}
 
+	public static Stream<ITree> streamASTArgs(ITree tree) {
+		if (SymbolAdapter.isStartSort(TreeAdapter.getType(tree))) {
+			return Stream.of((ITree) getArgs(tree).get(1));
+		}
+
+		if (isLexical(tree)) {
+			throw new ImplementationError("This is not a context-free production: " + tree);
+		}
+
+		IList children = getArgs(tree);
+
+		return IntStream.range(0, children.size())
+			.filter(i -> i % 2 == 0)
+			.mapToObj(children::get)
+			.map(t -> (ITree) t)
+			.filter(t -> !isLiteral(t) && !isCILiteral(t))
+			;
+	}
+
 	public static boolean isCILiteral(ITree tree) {
 		return isAppl(tree) && ProductionAdapter.isCILiteral(getProduction(tree));
 	}