AST: generic operator support

[hemberger]

AST: generic operator support

[staabm]

if you plan to work on this please do it for one operator at first and post a rough prototype, so we can decide how to approach/go on from it

[staabm]

If we want to support SQL operators, would we need to duplicate all this logic from PHPStan? Even if we omit the parts that are irrelevant to SQL, this seems like it would be quite a lot of code duplication. Would it be reasonable to consider refactoring PHPStan to create a generic set of "type math" classes?

I think we could take different approaches. I am not sure the logic required is really 100% identical, therefore I guess it would make sense to build it in phpstan-dba itself.

I think we can/should directly base it on the SQL AST Nodes. the phpstan logic is based on nikic/php-parser AST nodes. we could transform the SQL AST Nodes into equivalent nikic/php-parser nodes and pass it into phpstan, but then I think the logic in phpstan would be to php-specific and in the end will not reflect the sql context/semantics we need.

summary: I think we should implement it our own for now and do it in a separate math class based on sql ast nodes

whether there is room for re-use can be decided after we implemented a rough prototype and we see similarities or not