These aren't currently rendered, but the parser and model now support
recognizing expanded underline sequences:
```
CSI 24 m -> No underline
CSI 4 m -> Single underline
CSI 21 m -> Double underline
CSI 60 m -> Curly underline
CSI 61 m -> Dotted underline
CSI 62 m -> Dashed underline
CSI 58 ; 2 ; R ; G ; B m -> set underline color to specified true color RGB
CSI 58 ; 5 ; I m -> set underline color to palette index I (0-255)
CSI 59 -> restore underline color to default
```
The Curly, Dotted and Dashed CSI codes are a wezterm assignment in the
SGR space. This is by no means official; I just picked some numbers
that were not used based on the xterm ctrl sequences.
The color assignment codes 58 and 59 are prior art from Kitty.
refs: https://github.com/wez/wezterm/issues/415
This corrects an issue where the mode byte of the DCS sequence was
discarded from the DcsHook, making it impossible to know what sequence
is being activated.
So far this hasn't come up as these sequences are relatively rare,
but in looking at sixel parsing I noticed the error.
Change build.rs codegen to const_fns. This makes vtparse more friendly for buck
build.
Note const_fn functions still have limitation on the current stable (1.41)
rustc (ex. native "match" or "if" cannot be used in const_fn). So I used some
tricks to get it compile.
These are used in the default Fedora 31 bash profile, so it seems
worth handling even if they are a bit amgiguously defined.
Closes: https://github.com/wez/wezterm/issues/86
I've noticed this off and on for a while, and thought it was something
fishy with my shell dotfiles.
Tracing through I found that the final byte in the "Face with head
bandage" emoji 🤕 U+1F915 was being interpreted as the MW control
code and causing the vt parser to jump out of the OSC state.
The solution for this is to hook up proper UTF-8 processing in the
same way that it is applied in the ground state.
Since we don't have enough bits to introduce new state values (we're
pretty tightly packed in the 16 bits available), I've introduced a
memory of the state to which the utf8 parser needs to return once
a complete sequence is detected.
This enables using large OSC buffers in a form that we can publish
to crates.io without blocking on an external crate. Large OSC
buffers are important both for some tunnelling use cases and for
eg: iTerm2 image protocol handling.
