Formula:
	statement=Statement
;

UnaryNumeric:
	unary_numeric_function=UNARY_NUMERIC_FUNCTION
	"(" expression=Expression ")"
;

BinaryNumeric:
	binary_numeric_function=BINARY_NUMERIC_FUNCTION
	"(" expressionl=Expression "," (INT | STRING) ")"
;

Statistical:
	statistical_function=STATISTICAL_FUNCTION
	"(" "["referenceIndicator=[Indicator]"]" ")"
 	//Constraint: only direct indicators should be used
;

Statement:
	expression=Expression | if_statement=If_statement
;

If_statement:
	"IF" expression=Expression "THEN" thenStatement=Statement
	(=>"ELSE" elseStatement=Statement)?
;

Expression:
	simpleExpressionl=Simple_expression ( ("=" | "<>" | "<" | "<=" | ">" | ">=" | "==") 
	simpleExpressionr=Simple_expression)?
;

Simple_expression:
	terml=Term ((("+" | "-") | "OR") termr=Term)*
;

Term:
	factorl=Factor ((("*" | "/") | "AND") factorr=Factor)*
;

Factor:
	basel=Base ("^" baser=Base)?
;

Base:
	( "(" expression=Expression ")" | "["referenceIndicator=[Indicator] "]" | 
	statistic=Statistical | unarynumeric=UnaryNumeric |
	binarynumeric=BinaryNumeric | BOOLEAN | STRING | INT | DOUBLE )
;

enum UNARY_NUMERIC_FUNCTION: absolute="abs" | int="int" ;
enum BINARY_NUMERIC_FUNCTION: roundup="roundUp" | rounddown="roundDown" | 
                              round="round" | count="count" | countif="countIf" ; 
enum STATISTICAL_FUNCTION: minimum="min" | maximum="max" |
                           sum="sum" | mean="avg" | mode="mode" | median="median";
terminal BOOLEAN : ("true"|"false");
terminal DOUBLE: INT "." INT;