Parser fix: stop some unnecessary SystemDefn nodes being created in the parse tree.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@8789 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/parser/PrismParser.java

@@ -1279,7 +1279,7 @@ public class PrismParser implements PrismParserConstants {
       sys2 = SystemParallel();
                                                                                                                                par.addOperand(sys2);
     }
-                if (par==null) {
+                if (par==null || par.getNumOperands() == 1) {
                         {if (true) return sys1;}
                 }
                 else {
@@ -1310,7 +1310,7 @@ public class PrismParser implements PrismParserConstants {
       sys2 = SystemFullParallel();
                                                                                                                                              par.addOperand(sys2);
     }
-                if (par==null) {
+                if (par==null || par.getNumOperands() == 1) {
                         {if (true) return sys1;}
                 }
                 else {

prism/src/parser/PrismParser.jj

@@ -911,7 +911,7 @@ SystemDefn SystemFullParallel() :
 	sys1 = SystemInterleaved()
 	( { par = new SystemFullParallel(); par.addOperand(sys1); } ( LOOKAHEAD(<OR> <OR>) <OR> <OR> sys2 = SystemParallel() { par.addOperand(sys2); } )* )
 	{
-		if (par==null) {
+		if (par==null || par.getNumOperands() == 1) {
 			return sys1;
 		}
 		else {
@@ -934,7 +934,7 @@ SystemDefn SystemInterleaved() :
 	sys1 = SystemParallel()
 	( { par = new SystemInterleaved(); par.addOperand(sys1); } ( LOOKAHEAD(<OR> <OR> <OR>) <OR> <OR> <OR>  sys2 = SystemFullParallel() { par.addOperand(sys2); } )* )
 	{
-		if (par==null) {
+		if (par==null || par.getNumOperands() == 1) {
 			return sys1;
 		}
 		else {