function A ( );
function B (var w, var x);
y = 5 + A;
z = 8 + B (A / 2, A);

grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"

Program:
	declarations+=FunctionDeclaration+
	assignments+=Assignment+
	;

FunctionDeclaration returns Variable:
	'function' name=ID ('(' ('var' var+=ID ('var' var+=ID)*)? ')')? ';' ;

FunctionReference:
	declaration=[Variable] ('(' (sequence+=Sequence (',' sequence+=Sequence)*)? ')')?
;

Assignment:
	name=ID '=' sequence+=Sequence ';'
	;

Sequence: Addition ( {Sequence.expressions+=current} expressions+=Addition)*;

Addition returns Expression: 
	Multiplication ( {Op.values+=current} operator=('+'|'-') values+=Multiplication)*;

Multiplication returns Expression: 
	Term ( {Op.values+=current} operator=('*'|'/') values+=Term)*;
	
Term returns Expression:
	Atom | Parens;
	
Atom: 
	value+=INT | (references += FunctionReference) ;

Parens returns Expression: 
	'(' Addition ')';
	

{Op.values+=current}

error(211): [fatal] rule rule__FunctionReference__Group__1__Impl has non-LL(*) decision due to recursive rule invocations reachable from alts 1,2.  Resolve by left-factoring or using syntactic predicates hereor using backtrack=true option.
warning(200): Decision can match input such as "'(' RULE_ID" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): Decision can match input such as "'(' '('..')'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input