You've defined GENERIC_ID as a fragment.
Fragments can only be part of another lexer rule, they are not stand-alone
token-producing lexer rules. Henxe the missing token exception.
Also:
> I cant
>understand why it would break the recognition of "XML" when its before
>the attribute call.
So far as I know, there is no impact of order in which the lexer and parser
rules appear in the .g file.
-- Graham
--------------------------------
At 10/13/2009 10:46 AM, Evan Metheny wrote:
>Alright I am currently trying to learn ANTLR via the definitive guide
>book. My current questions regards the following XML Grammar. What I
>am trying to do is; re-write the grammar from the XMLLexer.g example
>to be a parser and lexer grammar, I am doing this as an exercise to
>try to understand ANTLR.
>
>When debugging under ANTLR Works 1.3 i get a missing token exception
>on GENERIC_ID within the "attribute" parser rule. I tried problem
>solving by changing it to a non-fragment lexer rule and to a parser
>rule, but this causes the beginning XML declaration to break. I cant
>understand why it would break the recognition of "XML" when its before
>the attribute call.
>
>Any help would be much appreciated for me to understand this situation better.
>
>
>XML.g:
>-----------------------------------------------------------------
>
>grammar XML;
>
>options {
>backtrack = true;
>}
>
>document
> : xmldecl WS? doctype
> ;
>
>doctype
> :
> '<!DOCTYPE' WS? GENERIC_ID
>
> WS?
> (
> ( 'SYSTEM' WS? VALUE
> | 'PUBLIC' WS? VALUE WS? VALUE
> )
> ( WS )?
> )?
> ( INTERNAL_DTD
>
> )?
> '>'
> ;
>
>INTERNAL_DTD : '[' (options {greedy=false;} : .)* ']' ;
>
>pi :
> '<?' GENERIC_ID WS?
>
> ( attribute WS? )* '?>'
> ;
>
>xmldecl :
> '<?' ('x'|'X') ('m'|'M') ('l'|'L') WS?
>
> attribute '?>'
> ;
>
>
>element
> : ( start_tag
> (element
> | PCDATA
>
> | cdata
>
> | comment
>
> | pi
> )*
> end_tag
> | emptyelement
> )
> ;
>
>start_tag
> : '<' WS? GENERIC_ID WS?
>
> ( attribute WS? )* '>'
> ;
>
>emptyelement
> : '<' WS? GENERIC_ID WS?
>
> ( attribute WS? )* '/>'
> ;
>
>attribute
> : GENERIC_ID WS? '=' WS? VALUE
>
> ;
>
>end_tag
> : '</' WS? GENERIC_ID WS? '>'
>
> ;
>
>comment
> : '<!--' (options {greedy=false;} : .)* '-->'
> ;
>
>cdata
> : '<![CDATA[' (options {greedy=false;} : .)* ']]>'
> ;
>
>
>
>fragment GENERIC_ID
> : ( LETTER | '_' | ':')
> ( options {greedy=true;} :
> LETTER | '0'..'9' | '.' | '-' | '_' | ':' )*
> ;
>
>fragment LETTER
> : 'a'..'z'
> | 'A'..'Z'
> ;
>
>
> WS :
> ( ' '
> | '\t'
> | ( '\n'
> | '\r\n'
> | '\r'
> )
> )+
> ;
>
>fragment PCDATA : (~'<')+ ;
>
>fragment VALUE :
> ( '\"' (~'\"')* '\"'
> | '\'' (~'\'')* '\''
> )
> ;
>
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