[antlr-interest] Antlr syntax reference

[Steven D. Vormwald]

Sam Kuper wrote:
> Dear all,
>
> I am looking for an exhaustive guide to Antlr 3.0.1 syntax (I am using 
> AntlrWorks 1.1.7); I'll explain why. My grammar so far looks like this:
>
> grammar DCP;
> options {
>     language=Python;
> }
> dcp     : DOCUMENT* EOF;
> DOCUMENT    : HEADERS;
> HEADERS    : YEAR_HEADER MONTH_HEADER ;
> YEAR_HEADER    : '*Y 18\n';
> MONTH_HEADER    : '*M October\n';
>
> Notice that in this grammar, I have used \n to denote new lines. But 
> although I have not declared what \n is, Antlr's lexical analyser 
> recognises that it denotes a newline; in other words, \n is a 
> pre-defined token in Antlr grammar. I'm guessing there are others, and 
> I want to be conscious of them as I work, but I have so far been 
> unable to find a document that lists all the pre-defined tokens in 
> Antlr's grammar. Presumably one exists somewhere. If you know where, 
> please could you tell me?
>
> Many thanks,
>
> Sam
I could be wrong about this, but I believe ANTLR recognizes the same 
character escapes in strings that java does:

'\n' is newline
'\r' is carriage return
'\t' is tab
'\uXXXX' is the unicode character at codepoint XXXX (in hex)
'\\' is backslash

and so on.  From http://www.antlr.org/wiki/display/ANTLR3/Grammars 
(Lexer Rules section), you can see examples of the '\t' and '\uXXXX' 
being used.  I don't think this is a rule, as much as a convention for 
inserting "special" characters in strings.

Steven Vormwald