From 1797178f64c1af8f058f665acd854e895d3dad9e Mon Sep 17 00:00:00 2001
From: Amin Borjian <borjianamin98@outlook.com>
Date: Thu, 6 Feb 2020 11:27:55 +0330
Subject: [PATCH] Fix Bug: Support loop on a node with nullable variables

---
 pom.xml                                               | 2 +-
 src/main/java/ir/ac/sbu/parser/LLParserGenerator.java | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pom.xml b/pom.xml
index 7c5546f..35b8370 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>ir.ac.sbu</groupId>
     <artifactId>PGen</artifactId>
-    <version>2.1</version>
+    <version>2.1.1</version>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
diff --git a/src/main/java/ir/ac/sbu/parser/LLParserGenerator.java b/src/main/java/ir/ac/sbu/parser/LLParserGenerator.java
index 2782ef3..04f3ddb 100644
--- a/src/main/java/ir/ac/sbu/parser/LLParserGenerator.java
+++ b/src/main/java/ir/ac/sbu/parser/LLParserGenerator.java
@@ -394,13 +394,15 @@ private Set<String> calculateFirstSet(Map<Integer, Set<String>> firstSets, Set<I
         calculate first set
         if there is an edge from N1 to N2 with token (or variable) C:
         first{N1} += first{C} + (first{N2} | if C is a variable and C is nullable)
+        if C is nullable and N1 == N2 (C is a loop), then first{N1} += first{C}
          */
         for (EdgeModel edgeModel : nodeModel.getAdjacent()) {
             if (edgeModel.isGraph()) {
                 Set<String> firstSetOfGraph = calculateFirstSet(firstSets, visited,
                         variableGraph.get(edgeModel.getToken()).getStart());
                 firstOfCurrentNode.addAll(firstSetOfGraph);
-                if (nullableVariables.contains(edgeModel.getToken())) {
+                if (nullableVariables.contains(edgeModel.getToken()) &&
+                        edgeModel.getEnd().getId() != nodeModel.getId()) {
                     Set<String> firstSetOfRestOfGraph = calculateFirstSet(firstSets, visited,
                             edgeModel.getEnd());
                     firstOfCurrentNode.addAll(firstSetOfRestOfGraph);