Replace ansi_term

[dbrgn]

ansi_term is not actively maintained anymore (see https://rustsec.org/advisories/RUSTSEC-2021-0139). Replace it with a suitable alternative.

I looked at termcolor, owo-colors and yansi, and ended up picking yansi:

• It is very simple
• It does not do terminal color support checking (we already do that in tealdeer)
• Its color enum type is almost identical to the one from ansi_term, so migrating is easy
• It's developed by Sergio Benitez (of Rocket fame)

The only change from a config API point of view is that "purple" is now renamed to "magenta", but "purple" still works.

(Based on #287, merge that one first!)

[dbrgn]

Note: We could replace the custom enable_colors logic with Paint::disable(), but we'd have to test that it doesn't have unintended interactions with our tests (due to global state).

[niklasmohrin]

Beyond tests: Does the disable functionality not have any performance impact? All methods that actually produce bytes from a Paint have to load from an atomic boolean before deciding how to paint :thinking: Let's measure before merging

[dbrgn]

Yes, that's true. I suspect there's no significant impact on real-world use cases like rendering a tldr page. I'm fairly sure the overhead will be insignificant compared to the I/O we're doing. However, I'll try to measure it.

[dbrgn]

[main] $ cargo build --release
[main] $ mv target/release/tldr tldr-ansi-term
[main] $ git switch replace-ansi-term
[replace-ansi-term] $ cargo build --release
[replace-ansi-term] $ mv target/release/tldr tldr-yansi

...and then:

If you run the benchmark multiple times, you get varying results. I'd say that the change is not significant. (I didn't expect it to be.)

[niklasmohrin]

Okay, I also reproduced these performance results :+1:

[niklasmohrin]

I wish they had Cargo features to remove a) the wrapping and b) the enable/disable stuff because I don't want to think about that :D

[niklasmohrin]

About using disable: I think I had some thoughts about OutputManager some time back to better separate concerns with IO, but never came to implement / design it to the end

[dbrgn]

I wish they had Cargo features to remove a) the wrapping and b) the enable/disable stuff because I don't want to think about that :D

Feel free to open an issue on the yansi issue tracker 🙂