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Simplify evaluate_function codes by adding macros #349

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panarch opened this issue Sep 14, 2021 · 1 comment
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Simplify evaluate_function codes by adding macros #349

panarch opened this issue Sep 14, 2021 · 1 comment
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@vbbono

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@panarch
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panarch commented Sep 14, 2021

This issue is to simplify Nullable enum control flow using declarative macro.

gluesql/src/executor/evaluate/mod.rs

Lines 175 to 191 in de73106

async fn evaluate_function<'a, T: 'static + Debug>(
storage: &'a dyn GStore<T>,
context: Option<Rc<FilterContext<'a>>>,
aggregated: Option<Rc<HashMap<&'a Aggregate, Value>>>,
func: &'a Function,
) -> Result<Evaluated<'a>> {
let eval = |expr| {
let context = context.as_ref().map(Rc::clone);
let aggregated = aggregated.as_ref().map(Rc::clone);
evaluate(storage, context, aggregated, expr)
};
enum Nullable<T> {
Value(T),
Null,
}

When Nullable::Null comes, it always returns Ok(Evaluated::from(Value::Null)).
However, that result is also kind of success Ok. It cannot be handled by try operator ?.
It would be good to use macro until rfcs/3058-try-trait-v2.html comes to Rust stable.

e.g.

gluesql/src/executor/evaluate/mod.rs

Lines 225 to 229 in de73106

Function::Lower(expr) => match eval_to_str(expr).await? {
Nullable::Value(v) => Ok(Value::Str(v.to_lowercase())),
Nullable::Null => Ok(Value::Null),
}
.map(Evaluated::from),

We can change the above like this,

Function::Lower(expr) => {
    let v = eval_to_str!(expr).to_lowercase();

    Ok(Evaluated::from(Value::Str(v)))
}

It is expected for us not to handle Nullable enum explicitly.
@vbbono
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vbbono commented Sep 14, 2021

Thanks! Assign to me :D

@vbbono vbbono mentioned this issue Oct 4, 2021
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@panarch panarch closed this as completed Oct 16, 2021
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