[il-antlr-interest: 25650] Re: [antlr-interest] How to handle Quoted Strings?

Jim Idle Mon, 07 Sep 2009 17:58:02 -0700

Title: How to handle Quoted Strings?

Weiler-Thiessen, David, SASKATOON, Engineering wrote:

Hi

I am having trouble adding Lexer/Parser rules to a grammar that will deal with quoted strings.

A phrase I would like to parse is:

create register FAULT_CODE initial value '301'

I am having trouble with the quoted string '301'. When I build my AST, I would like to have just the inner value, 301 passed, but when I tried to get the text in my tree grammar, I get the full token with quotes, i.e. '301'.

This is a portion of my Parser/Lexer grammar where I am trying to define this.

stringValue
: SINGLE_QUOTE! (~SINGLE_QUOTE|BACK_SLASH SINGLE_QUOTE)* SINGLE_QUOTE!
;

Don't deal with it in the parser, use a lexer rule for single quotes, then either use the trick below or just set the text of the token ( $text = $text.substring( ... etc) to remove the quotes. It is returning the quotes in your tree parser because you are asking for the text of the subtree, which includes the SINGLE_QUOTE tokens.

STRING_LITERAL
@init
{
    int    theStart = $start;
}
        : '\''
            {
                // Start the token text here, when we don't want the opening '
                //
                theStart = getCharIndex();

            }

             ~'\''*
            { $start = theStart; emit(); }
            '\''
         ;

Jim
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[il-antlr-interest: 25650] Re: [antlr-interest] How to handle Quoted Strings?

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