The "principal" parser is the one and only today; in the future we hope to
have multiple parsers to execute fish script in parallel.
Having a globally accessible "principle" parser is suspicious; now we can
get rid of it.
The "principal" environment stack was the one that was associated with the
"principal" parser and would dispatch changes like to TZ, etc.
This was always very suspicious, as a global; now we can remove it.
Prior to this commit, there was a stack of ReaderDatas, each one has a
reference to a Parser (same Parser in each, for now). However, the current
ReaderData is globally accessible. Because it holds a Parser, effectively
anything can run fish script; this also prevents us from making the Parser
&mut.
Split these up. Create ReaderData, which holds the data portion of the
reader machinery, and then create Reader which holds a ReaderData and a
Parser. Now `reader_current_data()` can only return the data itself; it
cannot execute fish script.
This results in some other nice simplifications.
This is a start on untangling input. Prior to this, a ReaderData and an
Inputter would communicate with each other; this is natural in C++ but
difficult in Rust because the Reader would own an Inputter and therefore
the Inputter could not easily reference the Reader. This was previously
"resolved" via unsafe code.
Fix this by collapsing Inputter into Reader. Now they're the same object!
Migrate Inputter's logic into a trait, so we get some modularity, and then
directly implement the remaining input methods on ReaderData.
Add round options, but I think can also add floor, ceiling, etc. And
the default mode is trunc.
Closes#9117
Co-authored-by: Mahmoud Al-Qudsi <mqudsi@neosmart.net>
The special input functions self-insert, self-insert-not-first, and
and or used to be handled by inputter_t::readch, but they aren't
anymore with `commandline -f`.
I am unsure if these *would* have worked, I can't come up with a use.
So, for now, do nothing instead of panicking.
This would crash if you ran `commandline -f backward-jump`.
The C++ version would read a char (but badly), this doesn't anymore.
So, at least instead of crashing, just do nothing.
