Antlr4: rule 'program' contains a closure with at least one alternative that can match an empty string

[PUSRISTEK]

Here is my simple grammar

`grammar ilp;

program
: statements+ EOF
;

statements
: var_declaration*
| 'tampilkan' Lparen identifier Rparen Semicolon
;

var_declaration
: primitive_type identifier Semicolon
| primitive_type identifier '=' expression Semicolon
| primitive_type identifier '[' expression ']' Semicolon
;

expression
: Num
| string
| Decimal
;

primitive_type
: 'angka32'
| 'bita'
| 'angka64'
| 'desimal'
| 'karakter'
| 'kalimat'
| 'logika'
| 'komposisi'
;

identifier
: Id
;

string
: '"' (~'"'|'"')* '"'
;

Semicolon
: ';'
;

Lparen
: '('
;

Rparen
: ')'
;

Comma
: ','
;

Id
: Letter(Letter|Digit)*
;

Num
: Digit
;

Decimal
: '-'?[0-9]+('.'[0-9]+)?
;

fragment
Digit
: [0-9]+
;

Letter
: [a-zA-Z]
;

WS
: [ trnu000C]+ -> skip ;

LINE_COMMENT
: '//' ~[rn]* -> skip
;`

but its give me error. why?
what should i do?

[KvanTTT]

You should not use empty alternatives such as var_declaration* in rule

statements
: var_declaration*
| 'tampilkan' Lparen identifier Rparen Semicolon
;

Replace it with var_declaration+ or rewrite rules.
Please, use stackoverflow.com for questinons.

[PUSRISTEK]

KVANTTT thankyou so much you save my life :')
if i have quetion i will email you. its work now :)
i generate for c#

[jimidle]

You have specified your 'string' rule as a parser rule, but it should be a
lexer rule. Fix that, then see if you still get the error

On Sun, Apr 10, 2016 at 5:11 PM, Techno Camp [email protected]
wrote:

Here is my simple grammar

`grammar ilp;

program
: statements+ EOF
;

statements
: var_declaration*
| 'tampilkan' Lparen identifier Rparen Semicolon
;

var_declaration
: primitive_type identifier Semicolon
| primitive_type identifier '=' expression Semicolon

| primitive_type identifier '[' expression ']' Semicolon

;

expression
: Num
| string
| Decimal
;

primitive_type
: 'angka32'
| 'bita'
| 'angka64'
| 'desimal'
| 'karakter'
| 'kalimat'

| 'logika'
| 'komposisi'
;

identifier
: Id
;

string
: '"' (~'"'|'"')* '"'
;

Semicolon
: ';'
;

Lparen
: '('
;

Rparen
: ')'
;

Comma
: ','
;

Id
: Letter(Letter|Digit)*
;

Num
: Digit
;

Decimal
: '-'?[0-9]+('.'[0-9]+)?
;

fragment
Digit
: [0-9]+
;

Letter
: [a-zA-Z]
;

WS
: [ trnu000C]+ -> skip ;

LINE_COMMENT
: '//' ~[rn]* -> skip
;`

but its give me error. why?
what should i do?

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