feat: Highlight in prqlc

[vanillajonathan]

This PR adds a command called highlight (under experimental) to prqlc which does syntax highlighting on the terminal.

Example:

prqlc experimental highlight example.prql

It works pretty good but single quotes becomes double quotes because that's what the lexer does.

I couldn't get the test to work because somehow it still includes the ANSI escape sequences even though the test sets the environment variable NO_COLOR and passes in the --color=never argument. It shows a diff between what is returned and what is expected that is identical.

-␛[32mfrom␛[39m foo
+␛[32mfrom␛[39m foo

Later maybe we can use this in prqlc compile too.

[max-sixty]

Very cool! I will look tomorrow more.

We could instead instead enable this by default for prqlc fmt...

[max-sixty]

I think this is great! Nice work!

Can you push a version with a test? If the color stuff breaks then I will take a look and try to fix; but we do need a test.

I added some notes — let's have the linewrap passing. The TODO you don't need to do now, but let's leave it in the code for the future.

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Something we could do is run this automatically on the output of prqlc fmt, rather than have this behind the experimental option. We could even add a --no-fmt option there which only does highlighting.

[max-sixty]

@vanillajonathan this is really nice, for example:

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I refactored some related code (maybe I should have done it in a separate PR, sorry to use yours...). Take a look at the changes and then hit the button if you're happy

[vanillajonathan]

Do want it to still reside under experimental?
Feel free to refactor it into fmt if you feel it makes more sense to have it there.
The codecov fails.

The changes look fine. I think you should merge it!

[max-sixty]

Do want it to still reside under experimental?
Feel free to refactor it into fmt if you feel it makes more sense to have it there.

Let's merge now as experimental and then we can refactor in into fmt later?

The codecov fails.

Yes, another advantage of merging with fmt is we'll get full test coverage given that's heavily tested... Doesn't need to stop us merging though

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I'll hit the button now. If you want to add a Changelog as a separate PR that would be nice, so people know about it