Add compatibility with fish shell

[tjkirch]

Implementation notes:

• mcfly.fish is based on the bash/zsh implementations, with the key bindings function inspired by fzf.
  • Key bindings are added by running mcfly_key_bindings after sourcing the file, rather than automatically, in case the user doesn't like the default ones.
• The shebang is /usr/bin/env fish because I believe fish shell path is less likely to be consistent than bash/zsh.
• To simplify, usage with fish doesn't need a MCFLY_HISTORY file, because we can get the last command easily during a fish postexec function. It's pointed at /dev/null, and temporary file cleanup is skipped.
• A new HistoryFormat enum, defaulting to the current format Plain, lets us specify fish-format history so we can import/load.
• A new HistoryCommand struct is used to represent each command in the history file, since it's no longer necessarily one line per entry.
• The format of search -o files was extended to allow sending more commands back to the shell, in particular a 'delete' command for fish, which needs to handle history deletion itself rather than through file edits.

Possible future improvements:

• There's talk of changing fish's history format in fish 3.2. This could be handled with a new FishJson variant of HistoryFormat (named as appropriate, based on the format fish selects) and a MCFLY_HISTORY_FORMAT environment variable that the user can set to select it.
• Use zsh extended timestamp as the when in HistoryCommand, if available.
• Inspect zsh history file to see if extended timestamps are used, rather than requiring an argument, so that when the file is rewritten (when erasing lines) it doesn't lose extended timestamps. (Note: upon exit, zsh rewrites the file again, restoring extended timestamps, so it's not the end of the world.)

Testing done:

• Tested add/search, importing history, and deleting history with bash 5.0.17, zsh 5.8, fish 2.7.1, and fish 3.1.2.

Fixes cantino/mcfly#89.

[tjkirch]

^ This push rebases on master, per https://github.com/cantino/mcfly/pull/95#discussion_r461765585

[tjkirch]

^ This push addresses https://github.com/cantino/mcfly/pull/95#discussion_r461769704 by splitting HistoryFormat::Plain into Bash and Zsh, with extended_history only in Zsh. (This might also help to handle bash's HISTTIMEFORMAT in the future, similar to zsh's extended history.) It defaults to bash because that's probably most common, but the mcfly.*sh files all specify their format now.

[scott2b]

While this brings up McFly history in fish for me with ctrl^R, I am unable to get it to actually execute anything. Hitting either Tab or Return simply exits from McFly as if I had hit Esc.

[tjkirch]

While this brings up McFly history in fish for me with ctrl^R, I am unable to get it to actually execute anything. Hitting either Tab or Return simply exits from McFly as if I had hit Esc.

@scott2b What version of fish are you running?

It might help to comment out the removal of the temp file in mcfly.fish, then try again, and paste the content of that file here. Then we can see if the problem is inside mcfly or in mcfly.fish.

[scott2b]

I am using fish 3.1.2

My mcfly.output.... files consistently look like:

run
somecommand

Where somecommand is something that would have come from my history.

[scott2b]

Oh, but there's one file that is different. It is named mcfly.XXXXXXXX.g83UFnZd, note the missing .output. part of the name.

And the contents look more like a full history (it's about 10000 lines). E.g. a sample:

: 1592274472:0;mv 05* 05.Week05
: 1592274492:0;mv 06* 06.Week06
: 1592274504:0;mv 07* 07.Week07
: 1592274534:0;git add Lectures/02.Week02
: 1592274540:0;git add Lectures/03.Week03
: 1592274546:0;git add Lectures/04.Week04
: 1592274550:0;git add Lectures/05.Week05

[tjkirch]

My mcfly.output.... files consistently look like:

run
somecommand

Where somecommand is something that would have come from my history.

@scott2b That's the format of the McFly temp files before the change in this PR that makes them work with fish. Are you sure you built and installed McFly with the change from this PR, and put it in your PATH? The change isn't merged yet.

[scott2b]

I manually copied mcfly.fish into my fish functions directory and am sourcing that file and calling the binding function in my config.fish file.

Are you saying I should do a full install of mcfly from this branch?

[tjkirch]

I manually copied mcfly.fish into my fish functions directory and am sourcing that file and calling the binding function in my config.fish file.

Are you saying I should do a full install of mcfly from this branch?

Yeah, the Rust code changed too, so you have to build from this branch and use that McFly binary.

[scott2b]

Ok. My bad. I did not realize that. I should have dug deeper into the PR. Thank you for your time. I'll give that a shot.

[scott2b]

That was it! This is really great. Thank you so much @tjkirch

[tjkirch]

^ This push addresses @cantino's concerns by rebasing on master, then removing the MCFLY_PATH modifications in mcfly.bash (so there are no longer any changes in that file) and incorporates the path check from the bash/zsh files into mcfly.fish. Retested fish 2, fish 3, and bash OK.

[cantino]

Thanks @tjkirch! Sorry for the delay and thank you for your contribution!

[zicklag]

Yay! Thank you. Works in my fish shell. :smiley:

[cantino]

@tjkirch, I've been sometimes seeing commandline in my zsh output:

[tjkirch]

@tjkirch, I've been sometimes seeing commandline in my zsh output:

Interesting, I haven't seen that. I can't think of anything in the code that would insert "commandline" literally. I have a few thoughts:

• If you hit enter again when that happens, does it set the command line to the remainder of the line, allowing you to hit enter a second time to run it? I'm not super familiar with fish internals around command execution, but it seems like it's just getting here and dying rather than running it and setting the command line string. (If you fake this scenario by just typing commandline "echo hi" it should be about the same; two enter presses will echo hi.)
• Related: do you only see that when using 'tab' to edit the command line, but never with 'enter' to execute the command line?
• What version of fish?
• If you're using fish 3.1.1, there was a fix related to 'eval' in 3.1.2, and while I don't think it's related, it'd be interesting to see if you still have the issue in 3.1.2, or if you can't upgrade, if you still have it after removing the 'eval' from mcfly.fish.
• It'd be helpful to see the mcfly_output file from a run where that happened, so we can make sure it had the expected commandline and mode lines. Maybe set mcfly.fish to not delete the file temporarily?

[cantino]

So I think this was user error on my part. I haven't seen it again. Thanks @tjkirch!