Support as a restricted refinement variable

Author: RajShivu

liquidjava-verifier/src/main/antlr4/rj/grammar/RJ.g4

@@ -36,6 +36,7 @@ operand:
 literalExpression:
 		'(' literalExpression ')'	#litGroup
 	|	literal						#lit
+	|   RESULT                      #result
 	| 	ID 							#var
 	|	ID '.' functionCall			#targetInvocation
 	|	functionCall				#invocation
@@ -91,8 +92,9 @@ ARITHOP : '+'|'*'|'/'|'%';//|'-';
 BOOL    : 'true' | 'false';
 ID_UPPER: ([A-Z][a-zA-Z0-9]*);
 OBJECT_TYPE:
-		  (([a-zA-Z][a-zA-Z0-9]+) ('.' [a-zA-Z][a-zA-Z0-9]*)+);
-ID     	: '#'*('$')? [a-zA-Z_] [a-zA-Z0-9_#]* ;
+		  (([a-zA-Z][a-zA-Z0-9]+) ('.' [a-zA-Z][a-zA-Z0-9]*)+);	  
+RESULT  : '$result';		  
+ID     	: '#'*[a-zA-Z_][a-zA-Z0-9_#]*;
 STRING  : '"'(~["])*'"';
 INT     : 	(([0-9]+) |	([0-9]+('_'[0-9]+)*));
 REAL   	: (([0-9]+('.'[0-9]+)?) | '.'[0-9]+);

liquidjava-verifier/src/main/java/liquidjava/rj_language/visitors/CreateASTVisitor.java

@@ -49,6 +49,7 @@
 import rj.grammar.RJParser.PredLogicContext;
 import rj.grammar.RJParser.PredNegateContext;
 import rj.grammar.RJParser.ProgContext;
+import rj.grammar.RJParser.ResultContext;
 import rj.grammar.RJParser.StartContext;
 import rj.grammar.RJParser.StartPredContext;
 import rj.grammar.RJParser.TargetInvocationContext;
@@ -159,9 +160,18 @@ else if (rc instanceof VarContext) {
         } else if (rc instanceof TargetInvocationContext) {
             // TODO Finish Invocation with Target (a.len())
             return null;
-        } else {
+        }
+        // else {
+        // return create(((InvocationContext) rc).functionCall());
+        // }
+        else if (rc instanceof ResultContext) {
+            return new Var("$result");
+        } else if (rc instanceof InvocationContext) {
             return create(((InvocationContext) rc).functionCall());
+        } else {
+            throw new IllegalStateException("Unknown literalExpression: " + rc.getClass());
         }
+
     }
 
     private Expression functionCallCreate(FunctionCallContext rc) throws LJError {