Hi again,
thanks for your quick reply Andrew. But shouldn't the following rule be enough to make ANTRL aware of that it can be void: sp_decls: (sp_decl ';')* -> (sp_decl)*; I mean that the Kleene operator (*) means to also match the empty word, right? So I think the following is true for rules named 'a', 'b' and 'c': (1) My variant a : b; b : c*; with c* := /*empty*/ | c+ and if I resolve it then 'a' means: a: /*empty*/ | c+ (2) Your variant a: b?; b: c*; with b?:= /*empty*/ | b b:= /*empty*/ | c+ and so a:= /*empty*/ | /*empty*/ | c+ := /*empty*/ | c+ So you can see that both should mean the same. So is it a kind of ANTLR issue that I would have to use the (?) operator here? Regards, David -- David Maier Senior Software Engineer Ingres Germany GmbH Weimarer Straße 1a D-98693 Ilmenau PHONE: +49.3677.6785-59 FAX: +49.3677.6785-23 MAIL: [email protected] This transmission is confidential and intended solely for the use of the recipient named above. It may contain confidential, proprietary, or legally privileged information. If you are not the intended recipient, you are hereby notified that any unauthorized review, use, disclosure or distribution is strictly prohibited. If you have received this transmission in error, please contact the sender by reply e-mail and delete the original transmission and all copies from your system. -----Ursprüngliche Nachricht----- Von: [email protected] im Auftrag von Andrew Haley Gesendet: Mi 07.07.2010 18:22 An: [email protected] Betreff: Re: [antlr-interest]org.antlr.runtime.tree.RewriteEmptyStreamException On 07/07/2010 05:19 PM, David Maier wrote: > Hello, > > > I am getting the following error message as Output of a tree generating > grammar which I am currently writing. > > Exception in thread "main" > org.antlr.runtime.tree.RewriteEmptyStreamException: rule sp_decls > at > org.antlr.runtime.tree.RewriteRuleElementStream._next(RewriteRuleElementStream.java:158) > at > org.antlr.runtime.tree.RewriteRuleElementStream.nextTree(RewriteRuleElementStream.java:145) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.sp_block_content(MySQLASTGenParser.java:10730) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.sp_unlabeled_block(MySQLASTGenParser.java:9691) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.sp_proc_stmt(MySQLASTGenParser.java:8577) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.sp_tail(MySQLASTGenParser.java:1691) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.no_definer_tail(MySQLASTGenParser.java:1541) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.view_or_trigger_or_sp_or_event(MySQLASTGenParser.java:1401) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.create(MySQLASTGenParser.java:1260) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.stmt(MySQLASTGenParser.java:1186) > at > com.ingres.antlr.idiom.mysql.MySQLASTGenParser.prog(MySQLASTGenParser.java:1117) > at __Test__.main(__Test__.java:16) > > So the last rules are looking as the following: > > sp_unlabeled_block: > > sp_block_content > > ; > > sp_block_content: > BEGIN_SYM > > sp_decls > sp_proc_stmts > END -> sp_decls sp_proc_stmts //To ignore the BEGIN and END > ; > > sp_decls: (sp_decl ';')* -> (sp_decl)*; > > sp_decl: > DECLARE_SYM sp_decl_idents > > type > (sp_opt_default)? -> ^(TN_DECLARE ^(TN_PARAMS sp_decl_idents > type) ^(TN_TODO sp_opt_default)?) > > > | DECLARE_SYM ident CURSOR_SYM FOR_SYM sp_cursor_stmt -> > ^(TN_DECLARE ^(TN_NAME ident) ^(TN_SELECT sp_cursor_stmt)) > > ; > > > There is a TN_CODE token type which I want to use as the root node of the > subtree which will then have this TN_DECLARE nodes as child nodes. So I only > did rewrite the rules 'between' TN_CODE and TN_DECLARE to remove unnecessary > information like the ';' or the BEGIN and END keywords. > > So I guess that the error occurs because my test input does not have a > DECLARE section, but this is OK because of the rule 'sp_decls: (sp_decl > ';')* -> (sp_decl)*; > ' which says that there could be even no one (*=0 or multiple). So has > anybody an answer what is causing the issue and how to solve it? sp_decls might be void. Try sp_block_content: BEGIN_SYM sp_decls sp_proc_stmts END -> sp_decls? sp_proc_stmts //To ignore the BEGIN and END ; List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
