Allow whitespaces in functions of value expressions

[rlaiola]

Reference issue

None.

What does this implement/fix?

This PR aims at providing a more flexible way to write queries based on the SQL standard and RDBMS implementations such as MySQL, PostgreSQL and MS SQL Server. In summary, it is possible to have whitespaces between a function name and its opening parenthesis "(".

Note: To run the tests refer to http://dbis-uibk.github.io/relax/calc/local/uibk/local/0

Test 1: concat expression (could be any function in a value expression)

pi concat (a, b, c)->k (R)

or

SELECT concat (a, b, c) AS k
FROM R

• Before:

• After:

How to test this PR?

Test it live at https://rlaiola.github.io/relax/calc/local/uibk/local/0. For automated tests visit https://rlaiola.github.io/relax/test.html

References

• https://www.w3schools.com/sql/func_mysql_concat.asp
• https://onecompiler.com/postgresql
• https://www.w3schools.com/sql/func_sqlserver_concat.asp