Hi,
I got to identify integer, decimal and EOD tokens (End of Description, like
we have in Copybook)
the following is the grammar
*
grammar* TestDecimal;
*
options* {
language = Java;
}
@lexer::members
{
*private* boolean isNotEOD()
{
*return* (((*char*)input.LA(2)!= *'\f'*) && ((*char*)input.LA(2)!= *'\t'*)
&&((*char*)input.LA(2)!= *'\r'*) && ((*char*)input.LA(2)!= *'\n'*) &&((*char
*)input.LA(2)!= *' '*) && (input.LA(2)!= -1));
}
}
@members
{
*public* static void main(*String* args[]) *throws* *Exception* {
ANTLRStringStream input = *new* ANTLRStringStream(args[0]);
Lexer lexer = *null*;
lexer = *new* TestDecimalLexer(input);
CommonTokenStream tokens = *null*;
tokens = *new* CommonTokenStream(lexer);
*for*(Object obj: tokens.getTokens())
System.out.println(obj);
TestDecimalParser parser = *new* TestDecimalParser (tokens);
parser.document();
}
}
document : *INT* *WS*? *INT* *WS*? *EOD*;
*
INT* : *DIGIT*+ ;
*
Decimal_* : *INT* *DOT* *INT;*
*
EOD* : '.' (*SS*+ | *EOF*);
*
fragment* *DOT* : {isNotEOD()}? => '.';
*
fragment* *DIGIT* : ('0'..'9');
*
fragment* *SS* : (' ' | '\t' | '\f' | '\r' | '\n');
*
WS* : *SS*+;
}
I got the input "01 00. " and got following error:
line 1:5 rule DOT failed predicate: {isNotEOD()}?
[EMAIL PROTECTED],0:1='01',<4>,1:0]
[EMAIL PROTECTED],2:2=' ',<5>,1:2]
[EMAIL PROTECTED],5:6='. ',<6>,1:5]
line 1:5 missing INT at '. '
If I replace the Decimal_ token definition with syntatic predicates like
below, it works fine.
**
*Decimal_* : (*INT*) => *INT* {_type=INT;}| (*INT* *DOT*) => *INT* *DOT* *
INT*;
why it is not able to identify the input correctly with out syntatic
predicates?
Why it fails to identify "00. " as INT EOD.
Is there any way to resolve this without syntatic/sematic predicates. I
would like to resolve this issue with just production rules.
Thanks in advance.
Regards,
Mani
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