Make Expr enum consistent with LogicalPlan by using structs for each variant

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
See the discussion at #2175 for background context, but the basic issue is that there are different styles between LogicalPlan and Expr.

LogicalPlan

Each variant in LogicalPlan wraps a struct. The structs typically have try_new methods with some validation logic.

pub enum LogicalPlan {
    Projection(Projection),
    Filter(Filter),
    ..
}

Expr

Expr has a mixed style. Some variants wrap structs and some do not.

pub enum Expr {
    Alias(Box<Expr>, String),
    Column(Column),
    Between {
        /// The value to compare
        expr: Box<Expr>,
        /// Whether the expression is negated
        negated: bool,
        /// The low end of the range
        low: Box<Expr>,
        /// The high end of the range
        high: Box<Expr>,
    },
    Like {
        negated: bool,
        expr: Box<Expr>,
        pattern: Box<Expr>,
        escape_char: Option<char>,
    },

Describe the solution you'd like
We would like each variant in Expr to wrap a struct (except perhaps for the very simple ones that contain one or two items) and add new and/or try_new methods to those structs as appropriate.

• Refactor Expr::Case to use a struct #3757
• BinaryExpr - Refactor Expr::BinaryExpr to use a struct #3835
• Like / ILike / SimilarTo - Refactor Expr::Like, Expr::ILike, Expr::SimilarTo to use a struct #3836
• GetIndexedField - Refactor Expr::GetIndexedField to use a struct #3860
• Between
• Cast - Refactor Expr::Cast to use a struct. #3931
• TryCast
• Sort
• ScalarFunction
• ScalarUDF
• AggregateFunction
• AggregateUDF
• WindowFunction
• InList
• Exists
• InSubquery
• PlaceHolder

Describe alternatives you've considered
Do nothing

Additional context
None

[jackwener]

I prepare to promote this task. I invite some contributor.
if anyone are interested in this issue. Please reply the part which you want to do.

[SkyFan2002]

I prepare to finish this task. I invite some contributor, if you are interested in this issue. Please reply the part which you want to do.

Hi, I am new to this project. Can I help with InList?

[jackwener]

Hi, I am new to this project. Can I help with InList?

It's OK, Thank you @SkyFan2002

[QuenKar]

Hello，I‘m a noob to this project and interested in Exists part.May I have a try?

[jackwener]

Hello，I‘m a noob to this project and interested in Exists part.May I have a try?

It's OK, Thank you @QuenKar

[gitccl]

Hi, I'd like to try InSubquery.

[jackwener]

Hi, I'd like to try InSubquery.

@gitccl welcome, thanks

[my-vegetable-has-exploded]

I'd like to try AggregateUDF. Thanks.

[jackwener]

Already finish it, thanks everyone!❤️

[alamb]

Pretty amazing @jackwener and everyone else who helped out here -- very nice