sqlparsing.find with backwards search doesn't match end of token list

Detail name	Value
Changelog Number	8071
Type	Bug
Status	Resolved
Affected Versions	EXASOL 6.0.0, Exasol 6.1.0, Exasol 6.2.0, Exasol 7.0.0-alpha1
Fix Versions	Exasol 7.0.0, Exasol 6.2.6
Resolution Date	2020-04-09

Description

The function sqlparsing.find (usually used in the context of preprocessor scripts) does not find a match that is at the end of the token list when searching backwards from the end.
Instead it finds the first match before the end.

Expected Behavior
The last token should be found.

Example

The following script demonstrates the problem. Instead of the matching the last token ('dual' at position 7) the token before ('from' at position 5) is found.

--/
create or replace lua script checkFindBackwardsAtEnd()
as
 tokens = sqlparsing.tokenize("select * from dual")
 results = sqlparsing.find(tokens, #tokens, false, true, sqlparsing.iswhitespaceorcomment, sqlparsing.isany)
 
 exa.output(table.concat(results, ','))
/

--> shows position 5 (from) instead of 7 (dual)
execute script checkFindBackwardsAtEnd() with output;