IF (A == B) THEN 
  (...)
ELSE IF (A == C) THEN 
  (...)
ELSE
  IF (C == E) THEN 
    (...)
  ELSE IF (C == F) THEN 
    (...)
  ELSE
    (...)
  ENDIF  
  (...)
ENDIF

error(211): ../org.xtext.example.iftest/src-gen/org/xtext/example/iftest/parser/antlr/internal/InternalIfTest.g:1009:3: [fatal] rule ruleCondition has non-LL(*) decision due to recursive rule invocations reachable from alts 1,2.  Resolve by left-factoring or using syntactic predicates or using backtrack=true option.

Condition hidden(WS):
	{Condition}
	'IF' '('if=Expression')' 'THEN'
		(cond+=Condition)*
	(('ELSE' 'IF') '('elseif=Expression')' 'THEN'
		(cond+=Condition)*)*	
	(=> 'ELSE'
		(cond+=Condition)*)?	
	'ENDIF'	
;

IF (A == B) THEN 
  (...)
ELSE IF (A == C) THEN 
  (...)
ELSE
  IF (C == E) THEN 
    (...)
  ELSE IF (C == F) THEN 
    (...)
  ELSE
    (...)
  ENDIF  
  (...)
ENDIF

IF (....) THEN
ELSE
  IF (....) THEN
  ENDIF
ENDIF

IF (....) THEN
ELSE IF (....) THEN
ENDIF

Model:
	cs+=IfStatement*;
	
	
Literal:
	value=INT
;

IfStatement:
	{Condition}
	'IF' '('if+=Literal')' 'THEN' BEGIN
		expr+=Expression+
	END
	('ELSE' 'IF'  '('if+=Literal')' 'THEN' BEGIN expr+=Expression+ END)*
	( 'ELSE' BEGIN expr+=Expression+ END)?
	'ENDIF'	
;

Expression:
    IfStatement | Literal;

terminal BEGIN: 'synthetic:BEGIN';
terminal END: 'synthetic:END';