Node for parenthesized expressions

[HiPhish]

Hello,

maintainer of HiPhish/rainbow-delimiters.nvim here; I have a problem matching and properly highlighting parenthesized expressions. The problem is that all the parentheses of an expression are on the same level as their siblings. Consider the following query:

SELECT ((((1))));

It's a weird query, but at least in SQLite it is valid. The tree looks like this:

  (select
    (keyword_select)
    (select_expression
      (term
        value: "("
        value: "("
        value: "("
        value: "("
        value: (literal)
        value: ")"
        value: ")"
        value: ")"
        value: ")")))

All the parentheses are on the same level, it is impossible to build up a tree of "containers" to determine the proper nesting. I propose a sort of parenthesized_expression node (or whatever name you consider more appropriate). With that node the term would have only one value:

  (select
    (keyword_select)
    (select_expression
      (term
    	value: (parenthesized_expression
    	  "("
    	  (parenthesized_expression
    	    "("
    	    (parenthesized_expression
    	      "("
    	      (parenthesized_expression
    	        "("
                (literal)
    	        ")")
    	      ")")
    	    ")")
    	  ")"))))

Let's take another example:

SELECT 1 + (2);

The original tree:

  (select
    (keyword_select)
    (select_expression
      (term
        value: (binary_expression
          left: (literal)
          operator: "+"
          right: "("
          right: (literal)
          right: ")"))))

How many right nodes can a binary expression reasonably have? Here is what it would look like with parenthesized_expression:

(select
  (keyword_select)
  (select_expression
    (term
      value: (binary_expression
        left: (literal)
        operator: "+"
        right: (parenthesized_expression
          "("
          (literal)
          ")")))))

[matthias-Q]

I agree. I think our AST is sometimes way to "flat". I will take a look later today.

[matthias-Q]

Closed by #275

Please tell me if that change is sufficient.

[HiPhish]

Looks great, thank you!