[incubator-kie-drools-5909] [new-parser] Accumulate parsed incorrectl…

drools-drl/drools-drl-parser-tests/src/test/java/org/drools/drl/parser/antlr4/MiscDRLParserTest.java

@@ -5122,4 +5122,24 @@ void javaKeywordsInPackage(String keyword) {
 
         assertThat(pkg.getRules().get(0).getName()).isEqualTo("R");
     }
+
+    @Test
+    void accumulateEmptyChunks() {
+        String text = "rule R\n" +
+                "when\n" +
+                "        $totalAmount : Number() from accumulate( Cheese( $price : price ),\n" +
+                "                                                 init( ),\n" +
+                "                                                 action( ),\n" +
+                "                                                 result( null ) );\n" +
+                "then\n" +
+                "end";
+        RuleDescr rule = parseAndGetFirstRuleDescr(text);
+
+        final PatternDescr outPattern = (PatternDescr) rule.getLhs().getDescrs().get( 0 );
+        final AccumulateDescr accumulateDescr = (AccumulateDescr) outPattern.getSource();
+        assertThat(accumulateDescr.getInitCode()).isEmpty();
+        assertThat(accumulateDescr.getActionCode()).isEmpty();
+        assertThat(accumulateDescr.getReverseCode()).isNull();
+        assertThat(accumulateDescr.getResultCode()).isEqualTo( "null");
+    }
 }

drools-drl/drools-drl-parser/src/main/antlr4/org/drools/drl/parser/antlr4/DRLParser.g4

@@ -340,7 +340,7 @@ fromAccumulate := ACCUMULATE LEFT_PAREN lhsAnd (COMMA|SEMICOLON)
                         ) RIGHT_PAREN
 */
 fromAccumulate : (DRL_ACCUMULATE|DRL_ACC) LPAREN lhsAndDef (COMMA|SEMI)
-                   ( DRL_INIT LPAREN initBlockStatements=chunk RPAREN COMMA? DRL_ACTION LPAREN actionBlockStatements=chunk RPAREN COMMA? ( DRL_REVERSE LPAREN reverseBlockStatements=chunk RPAREN COMMA?)? DRL_RESULT LPAREN expression RPAREN
+                   ( DRL_INIT LPAREN initBlockStatements=chunk? RPAREN COMMA? DRL_ACTION LPAREN actionBlockStatements=chunk? RPAREN COMMA? ( DRL_REVERSE LPAREN reverseBlockStatements=chunk? RPAREN COMMA?)? DRL_RESULT LPAREN resultBlockStatements=chunk RPAREN
                    | accumulateFunction
                    )
                  RPAREN (SEMI)?

drools-drl/drools-drl-parser/src/main/java/org/drools/drl/parser/antlr4/Antlr4ParserStringUtils.java

@@ -38,6 +38,9 @@ private Antlr4ParserStringUtils() {
      * Get text from ParserRuleContext's CharStream without trimming whitespace
      */
     public static String getTextPreservingWhitespace(ParserRuleContext ctx) {
+        if (ctx == null) {
+            return "";
+        }
         // Using raw CharStream
         int startIndex = ctx.start.getStartIndex();
         int stopIndex = ctx.stop.getStopIndex();

drools-drl/drools-drl-parser/src/main/java/org/drools/drl/parser/antlr4/DRLVisitorImpl.java

@@ -798,7 +798,7 @@ public AccumulateDescr visitFromAccumulate(DRLParser.FromAccumulateContext ctx)
             if (ctx.DRL_REVERSE() != null) {
                 accumulateDescr.setReverseCode(getTextPreservingWhitespace(ctx.reverseBlockStatements));
             }
-            accumulateDescr.setResultCode(getTextPreservingWhitespace(ctx.expression()));
+            accumulateDescr.setResultCode(getTextPreservingWhitespace(ctx.resultBlockStatements));
         } else {
             // accumulate function
             accumulateDescr.addFunction(visitAccumulateFunction(ctx.accumulateFunction()));