This patch introduces basic support for terminal emulation. Basic means
commands that don't use paging and are not full screen applications like
vim or tmux. Some paging applications are working properly, such as as
`git log`. Other pagers work reasonably well as long as the help menu is
not accessed.
There is now a central Rgb color type which is shared by the renderer,
terminal emulation, and the pty parser.
The parser no longer owns a Handler. Instead, a mutable reference to a
Handler is provided whenever advancing the parser. This resolved some
potential ownership issues (eg parser owning the `Term` type would've
been unworkable).
This is the initial terminal stream parsing implementation for
Alacritty. There are currently several TODOs, FIXMEs, and unimplemented!
things scattered about still, but what's here is good enough to
correctly parse my zsh startup.
The `Parser` implementation is largely based on the suck-less _simple
terminal_ parser. Because this is Rust and Rust has a fantastic type
system, some improvements are possible. First, `Parser` is a struct, and
its data is stored internally instead of statically. Second, there's no
terminal updates hard-coded into the parser. Instead, `Parser` is
generic over a `Handler` type which has methods for all of the actions
supported by the parser. Because Parser is generic, it should be
possible (with proper inlining) to have equivalent performance to the
hard-coded version.
In addition to using _simple terminal_ as a reference, there's a doc in
Alacritty's repository `docs/ansicode.txt`, a summary of the ANSI
terminal protocol, which has been referenced extensively.
There's probably a large number escapes we don't handle, and that's ok.
There's a lot that aren't necessary for everyday terminal usage. If you
feel like something that's not supported should be, feel free to add it.
Please try not to become overzealous and adding support for sequences
only used by folks trapped in 1988.
Opens a pty, forks a child process, and execs the shell defined in
user's /etc/passwd file. Bytes from the pty are currently just written
to Alacritty's stdout as a sanity check that things are hooked up.
Thanks to `st` for some guidance on setting this up.
Joe Wilm