ripgrep began it's life with docopt for argument parsing. Then it moved
to Clap and stayed there for a number of years. Clap has served ripgrep
well, and it probably could continue to serve ripgrep well, but I ended
up deciding to move off of it.
Why?
The first time I had the thought of moving off of Clap was during the
2->3->4 transition. I thought the 3.x and 4.x releases were great, but
for me, it ended up moving a little too quickly. Since the release of
4.x was telegraphed around when 3.x came out, I decided to just hold off
and wait to migrate to 4.x instead of doing a 3.x migration followed
shortly by another 4.x migration. Of course, I just never ended up doing
the migration at all. I never got around to it and there just wasn't a
compelling reason for me to upgrade. While I never investigated it, I
saw an upgrade as a non-trivial amount of work in part because I didn't
encapsulate the usage of Clap enough.
The above is just what got me started thinking about it. It wasn't
enough to get me to move off of it on its own. What ended up pushing me
over the edge was a combination of factors:
* As mentioned above, I didn't want to run on the migration treadmill.
This has proven to not be much of an issue, but at the time of the
2->3->4 releases, I didn't know how long Clap 4.x would be out before a
5.x would come out.
* The release of lexopt[1] caught my eye. IMO, that crate demonstrates
exactly how something new can arrive on the scene and just thoroughly
solve a problem minimalistically. It has the docs, the reasoning, the
simple API, the tests and good judgment. It gets all the weird corner
cases right that Clap also gets right (and is part of why I was
originally attracted to Clap).
* I have an overall desire to reduce the size of my dependency tree. In
part because a smaller dependency tree tends to correlate with better
compile times, but also in part because it reduces my reliance and trust
on others. It lets me be the "master" of ripgrep's destiny by reducing
the amount of behavior that is the result of someone else's decision
(whether good or bad).
* I perceived that Clap solves a more general problem than what I
actually need solved. Despite the vast number of flags that ripgrep has,
its requirements are actually pretty simple. We just need simple
switches and flags that support one value. No multi-value flags. No
sub-commands. And probably a lot of other functionality that Clap has
that makes it so flexible for so many different use cases. (I'm being
hand wavy on the last point.)
With all that said, perhaps most importantly, the future of ripgrep
possibly demands a more flexible CLI argument parser. In today's world,
I would really like, for example, flags like `--type` and `--type-not`
to be able to accumulate their repeated values into a single sequence
while respecting the order they appear on the CLI. For example, prior
to this migration, `rg regex-automata -Tlock -ttoml` would not return
results in `Cargo.lock` in this repository because the `-Tlock` always
took priority even though `-ttoml` appeared after it. But with this
migration, `-ttoml` now correctly overrides `-Tlock`. We would like to
do similar things for `-g/--glob` and `--iglob` and potentially even
now introduce a `-G/--glob-not` flag instead of requiring users to use
`!` to negate a glob. (Which I had done originally to work-around this
problem.) And some day, I'd like to add some kind of boolean matching to
ripgrep perhaps similar to how `git grep` does it. (Although I haven't
thought too carefully on a design yet.) In order to do that, I perceive
it would be difficult to implement correctly in Clap.
I believe that this last point is possible to implement correctly in
Clap 2.x, although it is awkward to do so. I have not looked closely
enough at the Clap 4.x API to know whether it's still possible there. In
any case, these were enough reasons to move off of Clap and own more of
the argument parsing process myself.
This did require a few things:
* I had to write my own logic for how arguments are combined into one
single state object. Of course, I wanted this. This was part of the
upside. But it's still code I didn't have to write for Clap.
* I had to write my own shell completion generator.
* I had to write my own `-h/--help` output generator.
* I also had to write my own man page generator. Well, I had to do this
with Clap 2.x too, although my understanding is that Clap 4.x supports
this. With that said, without having tried it, my guess is that I
probably wouldn't have liked the output it generated because I
ultimately had to write most of the roff by hand myself to get the man
page I wanted. (This also had the benefit of dropping the build
dependency on asciidoc/asciidoctor.)
While this is definitely a fair bit of extra work, it overall only cost
me a couple days. IMO, that's a good trade off given that this code is
unlikely to change again in any substantial way. And it should also
allow for more flexible semantics going forward.
Fixes#884, Fixes#1648, Fixes#1701, Fixes#1814, Fixes#1966
[1]: https://docs.rs/lexopt/0.3.0/lexopt/index.html
Like a previous commit did for the grep-cli crate, this does some
polishing to the grep-printer crate. We aren't able to achieve as much
as we did with grep-cli, but we at least eliminate all rust-analyzer
lints and group imports in the way I've been doing recently.
Next we'll start doing some more invasive changes.
This commit hacks in a bug fix for handling look-around across multiple
lines. The main problem is that by the time the matching lines are sent
to the printer, the surrounding context---which some look-behind or
look-ahead might have matched---could have been dropped if it wasn't
part of the set of matching lines. Therefore, when the printer re-runs
the regex engine in some cases (to do replacements, color matches, etc
etc), it won't be guaranteed to see the same matches that the searcher
found.
Overall, this is a giant clusterfuck and suggests that the way I divided
the abstraction boundary between the printer and the searcher is just
wrong. It's likely that the searcher needs to handle more of the work of
matching and pass that info on to the printer. The tricky part is that
this additional work isn't always needed. Ultimately, this means a
serious re-design of the interface between searching and printing. Sigh.
The way this fix works is to smuggle the underlying buffer used by the
searcher through into the printer. Since these bugs only impact
multi-line search (otherwise, searches are only limited to matches
across a single line), and since multi-line search always requires
having the entire file contents in a single contiguous slice (memory
mapped or on the heap), it follows that the buffer we pass through when
we need it is, in fact, the entire haystack. So this commit refactors
the printer's regex searching to use that buffer instead of the intended
bundle of bytes containing just the relevant matching portions of that
same buffer.
There is one last little hiccup: PCRE2 doesn't seem to have a way to
specify an ending position for a search. So when we re-run the search to
find matches, we can't say, "but don't search past here." Since the
buffer is likely to contain the entire file, we really cannot do
anything here other than specify a fixed upper bound on the number of
bytes to search. So if look-ahead goes more than N bytes beyond the
match, this code will break by simply being unable to find the match. In
practice, this is probably pretty rare. I believe that if we did a
better fix for this bug by fixing the interfaces, then we'd probably try
to have PCRE2 find the pertinent matches up front so that it never needs
to re-discover them.
Fixes#1412
In the case where after-context is requested with a match count limit,
we need to be careful not to reset the state tracking the remaining
context lines.
Fixes#1380, Closes#1642
The top-level listing was just getting a bit too long for my taste. So
put all of the code in one directory and shrink the large top-level mess
to a small top-level mess.
NOTE: This commit only contains renames. The subsequent commit will
actually make ripgrep build again. We do it this way with the naive hope
that this will make it easier for git history to track the renames.
Sigh.
