removed unnecessary parenthesis from rendered output

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/JavaCodeUtils.java

@@ -9,6 +9,7 @@
 package org.eclipse.xtext.xtext.generator.parser.antlr;
 
 import org.eclipse.xtext.JavaCode;
+import org.eclipse.xtext.xtext.generator.parser.antlr.hoisting.guards.Guard;
 
 /**
  * @author overflow - Initial contribution and API
@@ -18,4 +19,19 @@ public class JavaCodeUtils {
 		String source = code.getSource();
 		return source.substring(2, source.length() - 2);
 	}
+	
+	static public String formatCodeForGrammar(String code) {
+		return "$$ " + code + " $$";
+	}
+	
+	static public String formatPredicateForGrammar(String predicate) {
+		return formatCodeForGrammar(
+				// remove parentheses
+				predicate.substring(1, predicate.length() - 1)
+			);
+	}
+	
+	static public String formatGuardForGrammar(Guard guard) {
+		return formatPredicateForGrammar(guard.render());
+	}
 }

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/HoistingProcessor.java

@@ -39,6 +39,7 @@ import org.eclipse.xtext.util.Tuples;
 
 import static org.eclipse.xtext.GrammarUtil.*;
 
+import org.eclipse.xtext.xtext.generator.parser.antlr.JavaCodeUtils;
 import org.eclipse.xtext.xtext.generator.parser.antlr.hoisting.exceptions.NestedPrefixAlternativesException;
 import org.eclipse.xtext.xtext.generator.parser.antlr.hoisting.exceptions.OptionalCardinalityWithoutContextException;
 import org.eclipse.xtext.xtext.generator.parser.antlr.hoisting.exceptions.TokenAnalysisAbortedException;
@@ -116,7 +117,7 @@ public class HoistingProcessor {
 
 	private AbstractElement getNopElement() {
 		JavaCode virtualJavaCodeForAction = XtextFactory.eINSTANCE.createJavaCode();
-		virtualJavaCodeForAction.setSource("$$ /* nop */ $$");
+		virtualJavaCodeForAction.setSource(JavaCodeUtils.formatCodeForGrammar("/* nop */"));
 		
 		JavaAction virtualNopJavaAction = XtextFactory.eINSTANCE.createJavaAction();
 		virtualNopJavaAction.setCode(virtualJavaCodeForAction);
@@ -145,7 +146,7 @@ public class HoistingProcessor {
 				
 				if (!guard.isTrivial()) {
 					JavaCode virtualJavaCodeForPredicate = XtextFactory.eINSTANCE.createJavaCode();
-					virtualJavaCodeForPredicate.setSource("$$ " + guard.render() + " $$");
+					virtualJavaCodeForPredicate.setSource(JavaCodeUtils.formatGuardForGrammar(guard));
 				
 					renderedVirtualPredicate = XtextFactory.eINSTANCE.createGatedSemanticPredicate();
 					renderedVirtualPredicate.setCode(virtualJavaCodeForPredicate);
@@ -234,9 +235,11 @@ public class HoistingProcessor {
 									.collect(Collectors.toList())
 							)
 							.map(TokenSequenceGuard::new)
+							.map(TokenGuard::reduce)
 							.collect(Collectors.toList())
 						)
-						.map(AlternativeTokenSequenceGuard::new),
+						.map(AlternativeTokenSequenceGuard::new)
+						.map(TokenGuard::reduce),
 					guards.stream(),
 					(TokenGuard tokenGuard, MergedPathGuard pathGuard) -> Tuples.pair(tokenGuard, pathGuard)
 				).map(p -> new PathGuard(p.getFirst(), p.getSecond()))

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/AlternativeTokenSequenceGuard.java

@@ -16,30 +16,31 @@ import java.util.stream.Collectors;
  * @author overflow - Initial contribution and API
  */
 public class AlternativeTokenSequenceGuard implements TokenGuard {
-	private Collection<? extends TokenSequenceGuard> alternatives;
+	private Collection<? extends TokenGuard> alternatives;
 	
-	public AlternativeTokenSequenceGuard(Collection<? extends TokenSequenceGuard> alternatives) {
+	public AlternativeTokenSequenceGuard(Collection<? extends TokenGuard> alternatives) {
 		this.alternatives = alternatives;
 	}
 	
+	public TokenGuard reduce() {
+		if (alternatives.size() == 1) {
+			return alternatives.stream().findAny().get();
+		} else {
+			return this;
+		}
+	}
+	
 	@Override
 	public String render() {
-		boolean addParentheses = alternatives.size() != 1;
-		String result = "";
-		
-		if (addParentheses) {
-			result += "(";
+		if (alternatives.size() != 1) {
+			return "(" + 
+					alternatives.stream()
+						.map(TokenGuard::render)
+						.collect(Collectors.joining(" && ")) + 
+					")";
+		} else {
+			return alternatives.stream().findAny().get().render();
 		}
-		
-		result += alternatives.stream()
-				.map(TokenGuard::render)
-				.collect(Collectors.joining(" && "));
-
-		if (addParentheses) {
-			result += ")";
-		}
-		
-		return result;
 	}
 	
 	@Override

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/MergedPathGuard.java

@@ -31,7 +31,7 @@ public class MergedPathGuard implements HoistingGuard {
 		pathGuards.addAll(mergedPathGuard.pathGuards);
 	}
 	
-	HoistingGuard simplify() {
+	HoistingGuard reduce() {
 		if (pathGuards.size() == 1) {
 			return pathGuards.get(0);
 		} else {
@@ -49,13 +49,15 @@ public class MergedPathGuard implements HoistingGuard {
 		if (pathGuards.size() == 1) {
 			return pathGuards.get(0).render();
 		} else {
-			return "(" + 
-					pathGuards.stream()
-						.map(Guard::render)
-						.collect(Collectors.joining(" || ")) +
-					")";
+			return "(" + renderWithoutParentheses() + ")";
 		}
 	}
+	
+	String renderWithoutParentheses() {
+		return pathGuards.stream()
+				.map(Guard::render)
+				.collect(Collectors.joining(" || "));
+	}
 
 	@Override
 	public boolean hasTerminal() {

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/PathGuard.java

@@ -42,7 +42,24 @@ public class PathGuard implements HoistingGuard {
 	@Override
 	public String render() {
 		// parentheses needed since tokenGuard is never empty
-		return "(" + tokenGuard.render() + " || " + hoistngGuard.render() + ")";
+		String result = "(";
+		
+		if (tokenGuard instanceof TokenSequenceGuard) {
+			result += ((TokenSequenceGuard) tokenGuard).renderWithoutParenthesis();
+		} else {
+			result += tokenGuard.render();
+		}
+		
+		result += " || ";
+		
+		if (hoistngGuard instanceof MergedPathGuard) {
+			result += ((MergedPathGuard) hoistngGuard).renderWithoutParentheses();
+		} else {
+			result += hoistngGuard.render();
+		}
+		
+		result += ")";
+		return result;
 	}
 	
 	public static List<PathGuard> collapse(List<PathGuard> paths) {
@@ -57,7 +74,7 @@ public class PathGuard implements HoistingGuard {
 			
 			// TODO: allow merged paths
 			if (guard instanceof MergedPathGuard) {
-				guard = ((MergedPathGuard) guard).simplify();
+				guard = ((MergedPathGuard) guard).reduce();
 			}
 			
 			if (guard instanceof AlternativesGuard) {

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/SingleTokenGuard.java

@@ -19,6 +19,11 @@ public class SingleTokenGuard implements TokenGuard {
 	public SingleTokenGuard(Token token) {
 		this.token = token;
 	}
+	
+	@Override
+	public TokenGuard reduce() {
+		return this;
+	}
 
 	@Override
 	public String render() {

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/TokenGuard.java

@@ -16,4 +16,6 @@ public interface TokenGuard extends Guard {
 	default boolean isTrivial() {
 		return false;
 	}
+	
+	TokenGuard reduce();
 }

org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/parser/antlr/hoisting/guards/TokenSequenceGuard.java

@@ -22,6 +22,15 @@ public class TokenSequenceGuard implements TokenGuard {
 		this.sequence = sequence;
 	}
 
+	@Override
+	public TokenGuard reduce() {
+		if (sequence.size() == 1) {
+			return sequence.stream().findAny().get();
+		} else {
+			return this;
+		}
+	}
+	
 	@Override
 	public String render() {
 		boolean addParentheses = sequence.size() != 1;
@@ -31,9 +40,7 @@ public class TokenSequenceGuard implements TokenGuard {
 			result += "(";
 		}
 		
-		result += sequence.stream()
-				.map(TokenGuard::render)
-				.collect(Collectors.joining(" || "));
+		result += renderWithoutParenthesis();
 
 		if (addParentheses) {
 			result += ")";
@@ -42,6 +49,12 @@ public class TokenSequenceGuard implements TokenGuard {
 		return result;
 	}
 	
+	public String renderWithoutParenthesis() {
+		return sequence.stream()
+				.map(TokenGuard::render)
+				.collect(Collectors.joining(" || "));
+	}
+	
 	@Override
 	public String toString() {
 		return "TokenSequenceGuard (\n" +