Why custom Dialect doesn't work properly about sqlparser-rs

[universalmind303]

@groobyming I ran into a similar issue here #1227.

If you want your dialect to "extend" an existing dialect, you can implement the dialect function

impl Dialect for MyDialect {
    fn dialect(&self) -> std::any::TypeId {
        std::any::TypeId::of::<HiveDialect>()
    }

This'll allow the parser to treat it as that dialect whenever there is a check for dialect_of!.

IMO, more logic needs to move out of the dialect_of! macro, and into the Dialect trait, but considering there are 100+ uses of dialect_of in the parser, it may not be practical to add every one of those checks to Dialect.

[groobyming]

@alamb Hi, could you please take a look at this issue? I didn't find any more instructions about this custom Dialect

[alamb]

I am not sure what is going on @groobyming -- your description certainly sounds like a bug.

Maybe there is code in the parser that is special casing HiveDialect rather than using a trait method:

https://github.com/search?q=repo%3Asqlparser-rs%2Fsqlparser-rs%20HiveDialect&type=code

[groobyming]

@alamb Thanks, when I added the following code in src/dialect/tokenizer.rs, it worked for me, but I still don't know why it works

test success：

So if I want to extend my own dialect, do I need to modify the source code and then package it for release?

[alamb]

So if I want to extend my own dialect, do I need to modify the source code and then package it for release?

that is one alternative

Another is to change the code so that rather than testing dilaect_of!(...) it would do something like self.supports_numeric_prefix() and adding fn supports_numeric_prefix to the the Dialect trait

[groobyming]

@alamb Thanks for the feedback! I'll create a PR to address this issue.
PR addressing: #1188

[alamb]

Thanks @groobyming -- I will try and take a look at the outstanding sqlparser PRs next week sometime. I don't think I'll have a chance to do so this week

[groobyming]

@alamb OK，Thanks