Decision can match input such as "{'A'..'Z', '_', 'a'..'z'}" using multiple alternatives: 1, 3 - antlr3

Question

I am a startbie for this antlr 3.5. I understood that left recursion is accepted in ant;r 4.0 and not in 3.5, I am getting ambigious error warning for my grammar .
I am just verifying my email using this grammar, can some one fix this grammar
grammar HelloWorld;
options
{
// antlr will generate java lexer and parser
language = Java;
// generated parser should create abstract syntax tree
output = AST;
backtrack = true;
}
//as the generated lexer will reside in com.nuwaza.aqua.antlr
//package, we have to add package declaration on top of it
#lexer::header {
package com.nuwaza.aqua.antlr;
}
//as the generated parser will reside in org.meri.antlr_step_by_step.parsers
//package, we have to add package declaration on top of it
#parser::header {
package com.nuwaza.aqua.antlr;
}
// ***************** parser rules:
//our grammar accepts only salutation followed by an end symbol
expression : EmailId At Domain Dot Web EOF;
// ***************** lexer rules:
//the grammar must contain at least one lexer rule
EmailId: (Domain)+;
At : '#';
Domain:(Identifier)+;
Dot: DotOperator;
Web:(Identifier)+|(DotOperator)+|(Identifier)+;
/*Space
:
(
' '
| '\t'
| '\r'
| '\n'
| '\u000C'
)
{
skip();
}
;*/
Identifier
:
(
'a'..'z'
| 'A'..'Z'
| '_'
)
(
'a'..'z'
| 'A'..'Z'
| '_'
| Digit
)*
;
fragment
Digit
:
'0'..'9'
;
fragment DotOperator:'.';

Answer 1

I assume that your problem is in your rule: Identifier. If I were you, I would do something like:
Identifier : ID (ID |Digit)*;
fragment ID : ('a'..'z' | 'A'..'Z' | '_');
I hope this would help you. ;)

Answer 2

I am having two different grammar file and i am trying to use combined grammar for different abstraction.
My code is as follows
HelloWorldParser.g
parser grammar HelloWorldParser;
options
{
// antlr will generate java lexer and parser
language = Java;
// generated parser should create abstract syntax tree
output = AST;
}
//as the generated parser will reside in org.meri.antlr_step_by_step.parsers
//package, we have to add package declaration on top of it
// ***************** parser rules:
//our grammar accepts only salutation followed by an end symbol
expression1
:
Hello World EOF;
and HelloWorldLexer.g
lexer grammar HelloWorldLexer;
//as the generated lexer will reside in com.nuwaza.aqua.antlr
//package, we have to add package declaration on top of it
//as the generated parser will reside in org.meri.antlr_step_by_step.parsers
//package, we have to add package declaration on top of it
// ***************** lexer rules:
Hello: 'Hello';
World: 'World';
My combined grammar is
Test.g
grammar Test;
options
{
// antlr will generate java lexer and parser
language = Java;
// generated parser should create abstract syntax tree
output = AST;
}
import HelloWorldLexer, HelloWorldParser;
#lexer::header {
package com.nuwaza.aqua.antlr;
}
#parser::header {
package com.nuwaza.aqua.antlr;
}
// ***************** parser rules:
//our grammar accepts only salutation followed by an end symbol
expression:expression1;
My LexerParserGenerator is :
package com.nuwaza.aqua.antlr.generator;
import org.antlr.Tool;
public class LexerParserGenerator {
private static final String OUTPUT_DIRECTORY_KEY = "-o";
public static void main(String[] args) {
//provide the grammar ( .g file) residing path
String grammarPath = "./src/main/resources/grammar/Test.g";
//Specify the path with which grammar has to be generated.
String outputPath = "./src/main/java/com/nuwaza/aqua/antlr/";
Tool tool = new Tool(new String[] { grammarPath, OUTPUT_DIRECTORY_KEY,
outputPath });
tool.process();
}
}