ANTLR4: matching token with same rule but with different position in the grammar - antlr

Question

I have the following statement I wish to parse:
in(name,(Silver,Gold))
in: is a function.
name: is a ID.
(Silver, Gold): is string array with elements 'Silver', and 'Gold'.
The parser is always confused as ID and string array elements have the same rule. Using quotes or double quotes for string will help, but this is not the case here.
Also, predicates didn't help much.
The grammar:
grammar Rql;
statement
: EOF
| query EOF
;
query
: function
;
function
: FUNCTION_IN OPAR id COMMA OPAR array CPAR CPAR
;
array
: VALUE (COMMA VALUE)*
;
FUNCTION_IN: 'in';
id
: {in(}? ID
;
ID
: [a-zA-Z_] [a-zA-Z_0-9]*
;
VALUE
: STRING
| INT
| FLOAT
;
OPAR : '(';
CPAR : ')';
COMMA : ',';
INT
: [0-9]+
;
FLOAT
: [0-9]+ '.' [0-9]*
| '.' [0-9]+
;
SPACE
: [ \t\r\n] -> skip
;
STRING
: [a-zA-Z_] [a-zA-Z_0-9]*
;
OTHER
: .
;

Answer 1

The idea is to change the type of the token under some condition. Here seeing an ID for the first time in a line sets a switch to true. The next time an ID is matched, the lexer will execute the if and set the type to ID_VALUE. I wanted to reset the switch while entering the rule function, but it doesn't work :
function
#init {QuestionLexer.id_seen = false; System.out.println("id_seen has been reset" + QuestionLexer.id_seen);}
: FUNCTION_IN OPAR ID COMMA OPAR array CPAR CPAR
ID=name1 seen ? false
ID=Silver seen ? true
...
ID=Platinum seen ? true
[#0,0:1='in',<'in'>,1:0]
[#1,2:2='(',<'('>,1:2]
[#2,3:7='name1',<ID>,1:3]
[#3,8:8=',',<','>,1:8]
[#4,9:9='(',<'('>,1:9]
[#5,10:15='Silver',<10>,1:10]
...
[#12,27:31='name2',<10>,2:3]
...
[#20,52:51='<EOF>',<EOF>,3:0]
Question last update 1336
id_seen has been reset false
id_seen has been reset false
line 2:3 mismatched input 'name2' expecting ID
.
That's why I reset it in the FUNCTION_IN rule.
Grammar Question.g4 :
grammar Question;
#lexer::members {
static boolean id_seen = false;
}
tokens { ID_VALUE }
question
#init {System.out.println("Question last update 1352");}
: function+ EOF
;
function
: FUNCTION_IN OPAR ID COMMA OPAR array CPAR CPAR
;
array
: value (COMMA value)*
;
value
: ID_VALUE
| INT
| FLOAT
;
FUNCTION_IN: 'in' {id_seen = false;} ;
ID : [a-zA-Z_] [a-zA-Z_0-9]*
{System.out.println("ID=" + getText() + " seen ? " + id_seen);
if (id_seen) setType(QuestionParser.ID_VALUE); id_seen = true; } ;
OPAR : '(';
CPAR : ')';
COMMA : ',';
INT
: [0-9]+
;
FLOAT
: [0-9]+ '.' [0-9]*
| '.' [0-9]+
;
SPACE
: [ \t\r\n] -> skip
;
OTHER
: .
;
File t.text :
in(name1,(Silver,Gold))
in(name2,(Copper,Platinum))
Execution with ANTLR 4.6 :
$ grun Question question -tokens -diagnostics t.text
ID=name1 seen ? false
ID=Silver seen ? true
ID=Gold seen ? true
ID=name2 seen ? false
ID=Copper seen ? true
ID=Platinum seen ? true
[#0,0:1='in',<'in'>,1:0]
[#1,2:2='(',<'('>,1:2]
[#2,3:7='name1',<ID>,1:3]
[#3,8:8=',',<','>,1:8]
[#4,9:9='(',<'('>,1:9]
[#5,10:15='Silver',<10>,1:10]
[#6,16:16=',',<','>,1:16]
[#7,17:20='Gold',<10>,1:17]
[#8,21:21=')',<')'>,1:21]
[#9,22:22=')',<')'>,1:22]
[#10,24:25='in',<'in'>,2:0]
[#11,26:26='(',<'('>,2:2]
[#12,27:31='name2',<ID>,2:3]
[#13,32:32=',',<','>,2:8]
[#14,33:33='(',<'('>,2:9]
[#15,34:39='Copper',<10>,2:10]
[#16,40:40=',',<','>,2:16]
[#17,41:48='Platinum',<10>,2:17]
[#18,49:49=')',<')'>,2:25]
[#19,50:50=')',<')'>,2:26]
[#20,52:51='<EOF>',<EOF>,3:0]
Question last update 1352
Type <10> is ID_VALUE as can be seen in the .tokens file
$ cat Question.tokens
FUNCTION_IN=1
...
OTHER=9
ID_VALUE=10
'in'=1