Add line breaks in the debug tap output

[j4james]

Summary of the Pull Request

When the debug tap converts control characters into visible glyphs, it
ends up losing the structure of the output, and that can sometimes make
things difficult to read. This PR attempts to alleviate that problem by
reinjecting an actual line break in the debug stream whenever an LF
control is received.

PR Checklist

• Closes Add an additional debug option to show a \n when \r is received #12312
• CLA signed.
• Tests added/passed
• Documentation updated.
• Schema updated.
• I've discussed this with core contributors already. Issue number
  where discussion took place: Add an additional debug option to show a \n when \r is received #12312

Validation Steps Performed

I've tested the updated debug tab with a number of different shells, and
also a couple of different apps. When there aren't many linefeeds in the
output, it's obviously not going to make much of a difference, but when
there are, I think it definitely improves the readability.

[j4james]

Some sample output so you can see the kind of difference it makes...

[lhecker]

I'm fine with this.

Although I'd generally prefer it if til::visualize_control_codes was decomposed, so that we can "recompose" it back into the two behaviors we need (namely newline preserving and not). Something like that:

namespace til
{
    constexpr wchar_t visualize_control_code(wchar_t ch) noexcept
    {
        if (ch < 0x20)
        {
            ch += 0x2400;
        }
        else if (ch == 0x20)
        {
            ch = 0x2423; // replace space with ␣
        }
        else if (ch == 0x7f)
        {
            ch = 0x2421; // replace del with ␡
        }
        return ch;
    }

    _TIL_INLINEPREFIX std::wstring visualize_control_codes(std::wstring str) noexcept
    {
        for (auto& ch : str)
        {
            ch = visualize_control_code(ch);
        }
        return str;
    }

    _TIL_INLINEPREFIX std::wstring visualize_control_codes_with_newlines(std::wstring_view str) noexcept
    {
        std::wstring out;
        out.reserve(str.size());

        wchar_t buffer[3]{ L'\0', L'\r', L'\n' };

        for (const auto& ch : str)
        {
            buffer[0] = visualize_control_code(ch);
            const auto length = buffer[0] != 0x240A ? 1 : 3;
            out.append(&buffer[0], length);
        }

        return out;
    }
}

(I haven't tested, nor commented it, but I think it should work. The main benefit is that it doesn't need to reshuffle the string so that it's only a single O(n) loop.)

[DHowett]

I agree, but also... this is an "under duress" debugging feature. It's going to impact performance, even if negligibly, but it is on a low-use surface. I'm cool with it.

I know you probably approved instead of blocking because you're aware of that already. :)

[lhecker]

I know you probably approved instead of blocking because you're aware of that already. :)

^ This. 🙂

[j4james]

Sorry. I guess this was a bit lazy of me, but I didn't want to mess with the existing code, and I figured the performance wasn't that important here.

[DHowett]

I agree, but also... this is an "under duress" debugging feature. It's going to impact performance, even if negligibly, but it is on a low-use surface. I'm cool with it.

I know you probably approved instead of blocking because you're aware of that already. :)

[ghost]

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[ghost]

🎉Windows Terminal v1.14.196 has been released which incorporates this pull request.:tada:

Handy links:

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[ghost]

🎉Windows Terminal Preview v1.15.200 has been released which incorporates this pull request.:tada:

Handy links:

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