Fix: lex now throws error on unbalanced closing parentheses (issue #11982)

[dj-sourbrough]

• Fixes issue Incomplete parser of boolean expressions ending with bracket #11982

Description

Expressions with unbalanced parenthesis [excess closing ')' parenthesis] will throw an error instead of interpreting ')' as a string.

Solved he same way as closing braces '}' are handled.

User-Facing Changes

• Trailing closing parentheses ')' which do not match the number of opening parentheses '(' will lead to a parse error.
• From what I have found in the documentation this is the intended behavior, thus no documentation has been updated on my part

Tests + Formatting

• Two tests added in src/tests/test_parser.rs
• All previous tests are still passing
• cargo fmt, clippy and test have been run

Unable to get the following command run

• cargo run -- -c "use std testing; testing run-tests --path crates/nu-std" to run the tests for the standard library
  

[rgwood]

Wow, this is an awesome first PR thanks! LGTM (from reading the code and trying it out locally).

[fdncred]

Thanks @dj-sourbrough. The reason the use std testing part didn't work was because that has been removed from the nushell std-lib. There was a recent PR about this in the docs repo nushell/nushell.github.io#1284 that helps explain how to use it.

[dj-sourbrough]

After reading up in the docs on string interpolation (https://www.nushell.sh/book/working_with_strings.html#string-interpolation) I got interested to see how this fix would work in this case.

From my understanding parentheses need to be escaped for string interpolation, however trailing unclosed parentheses ')' are still treated as strings and not solved by my patch

Also, it is not possible to wrap an escaped parentheses block inside a regular parentheses block, ie ( (test) )

Would you like a new issue raised for this or #11982 should remain open?

[fdncred]

Typically I use (char lp) and (char rp) instead of trying to use \( and \), although I think the escaping should work too. But also you need to remember that parens are for evaluation like (2 + 2) evaluates to 4 (blah blah) doesn't evaluate to anything.

I think what's going on is that the parser sees ( but not \( and it's trying to eval it.

You could just create a new issue.