[antlr-interest] Empty Quoted String Literal

[Bart Kiers]

Richard,

Note that I am a C# illiterate, but, isn't the C# literal:

@""""


only just a single quote? If so, then it is no wonder you're getting errors.
Parsing:

WhitespaceInSymbolsLexer lexer = new WhitespaceInSymbolsLexer(new
ANTLRStringStream("\""));


will also produce the error 'line 1:1 mismatched character '<EOF>' expecting
'"'' with me (of course) since a single quote is no valid token.

Regards,

Bart.



On Wed, Jul 27, 2011 at 11:14 PM, G. Richard Bellamy <rbellamy at pteradigm.com
> wrote:

> Bart,
>
> When I escape the quotes things work on my end as well - you'll note
> that I'm passing a set of non-escaped quotes... (C# Verbatim String), so
> you'll not be able to test this on your end (since Java doesn't have an
> equivalent to the Verbatim String).
>
> Thanks again.
>
> -rb
>
> On 7/27/2011 2:10 PM, Bart Kiers wrote:
> > Hi Richard,
> >
> > Both ANTLRWorks' debugger, and my Java test rig:
> >
> >     import org.antlr.runtime.*;
> >
> >     public class Main {
> >       public static void main(String[] args) throws Exception {
> >         WhitespaceInSymbolsLexer lexer = new
> >     WhitespaceInSymbolsLexer(new ANTLRStringStream("\"\""));
> >         WhitespaceInSymbolsParser parser = new
> >     WhitespaceInSymbolsParser(new CommonTokenStream(lexer));
> >         parser.compileUnit();
> >       }
> >     }
> >
> >
> > produce no errors when parsing "" (2 double quotes) as input:
> >
> >     bart at hades:~/Programming/ANTLR/Demos/WhitespaceInSymbols$ java -cp
> >     antlr-3.3.jar org.antlr.Tool WhitespaceInSymbols.g
> >     bart at hades:~/Programming/ANTLR/Demos/WhitespaceInSymbols$ javac
> >     -cp antlr-3.3.jar *.java
> >     bart at hades:~/Programming/ANTLR/Demos/WhitespaceInSymbols$ java -cp
> >     .:antlr-3.3.jar Main
> >     bart at hades:~/Programming/ANTLR/Demos/WhitespaceInSymbols$
> >
> >
> > Then there must be something going differently in the CSharp3 target
> > than in the Java target (note that I am not able to test the CSharp3
> > target here...).
> >
> > Regards,
> >
> > Bart.
> >
> >
> > On Wed, Jul 27, 2011 at 11:01 PM, G. Richard Bellamy
> > <rbellamy at pteradigm.com <mailto:rbellamy at pteradigm.com>> wrote:
> >
> >     Sam, Bart & Jim, I really appreciate your help on this.
> >
> >     Here's a more complete example, without the greedy confusion. I'm
> >     including the combined grammar and a test rig.
> >
> >     I get: CombinedLexer:line 1:2 mismatched character '<EOF>'
> >     expecting '"'
> >     just before a NullReferenceException.
> >
> >     GRAMMAR:
> >     ----------------------------
> >     grammar Combined;
> >
> >     options {
> >     language=CSharp3;
> >     TokenLabelType=CommonToken;
> >     output=AST;
> >     ASTLabelType=CommonTree;
> >     }
> >
> >     @lexer::namespace{StringLiteralLexerTest}
> >     @parser::namespace{StringLiteralLexerTest}
> >
> >     /*
> >     * Parser Rules
> >     */
> >
> >     public
> >     compileUnit
> >     : STRING
> >     ;
> >
> >     /*
> >     * Lexer Rules
> >     */
> >     STRING : '"' ('""' | ~'"')* '"';
> >
> >     TEST RIG:
> >     ------------------------------
> >     static void Main()
> >     {
> >     CombinedLexer lexer = new CombinedLexer(new
> ANTLRStringStream(@""""));
> >     //lexer.TraceDestination = new
> >     ConsoleTextWriter(typeof(CombinedLexer));
> >
> >     CommonTokenStream tokenStream = new CommonTokenStream(lexer);
> >
> >     CombinedParser parser = new CombinedParser(tokenStream);
> >     //parser.TraceDestination = new
> >     ConsoleTextWriter(typeof(CombinedParser));
> >
> >     CommonTree parseTree = parser.compileUnit().Tree;
> >     Console.WriteLine(parseTree.ToStringTree());
> >     }
> >
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