[antlr-interest] org.antlr.runtime.tree.RewriteEmptyStreamException

[David Maier]

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?


BTW: Further information about the project is available here: http://community.ingres.com/wiki/Ingres_Migration_Tool_Set_Idiom_MySQL


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:   david.maier at ingres.com

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