Correctly detect empty string literals ('') in SQL source

[mitya57]

In our project we had a query with the following line:

AND LOWER(REGEXP_REPLACE(company_name,'\W','','g')) = LOWER(REGEXP_REPLACE(:companyName,'\W','','g'))

aiosql did not detect the empty string literal '' properly. So it treated the closing ' as an opening quote, and then it treated ')) = LOWER(REGEXP_REPLACE(:companyName,' as a string literal. Because of this, :companyName was not substituted in it.

[nackjicholson]

@mitya57 Nice catch. I'll try to check this out sometime. Looks like all current tests work, but might want to add one that covers the case you hit here

[nackjicholson]

@mitya57 I added a new test based on your example. Thank you for providing an example of the use case, and thank you for your contribution!