Performance Improvements

[miles-to-go]

Thanks again for this great readline library. One issue I noticed is that there was some slowness, which is especially noticeable when pasting text on slower terminals such as the GNOME Terminal.

I spent a little time trying to improve this; below are descriptions of each commit. If this PR is accepted and you are open to it, I will try to implement additional improvements in the future.

• minimize allocs in line.go: Change core line buffer operations to not allocate in the default case (only if more space is needed)
• preallocate capacity for slices: Pre-allocate the slices to a known capacity in matchBind
• add DisplayLine test cases: Write a unit test for DisplayLine
• combine DisplayLine prints: Update DisplayLine to make a single fmt.Print call
• bracketed paste: Support bracketed paste mode so that pastes do not cause a display refresh - this is the main performance improvement for pastes just because it skips the refresh, but the other commits should make the library feel a little more responsive as well

[maxlandon]

Hello !

Thanks a lot for this PR, it is really appreciated!

At first glance, most commits will be merged.

I just need to check the one combining all DisplayLine calls in a single fmt.Print, because I'm pretty sure there is a reason why I did not do it in the first place.
Did you notice any chance occurring because of these modifications ?

I'm quite busy at work right now but I will soon merge this. Feel free to open new PRs with other improvements, these are always welcome !

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 33.03%. Comparing base (d3ac1d6) to head (0637db4).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
emacs.go	0.00%	11 Missing ⚠️
readline.go	0.00%	3 Missing ⚠️
internal/keymap/dispatch.go	0.00%	1 Missing ⚠️
internal/strutil/key.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #87      +/-   ##
==========================================
- Coverage   33.04%   33.03%   -0.01%     
==========================================
  Files          57       57              
  Lines        9110     9109       -1     
==========================================
- Hits         3010     3009       -1     
  Misses       6062     6062              
  Partials       38       38              

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[miles-to-go]

I have not noticed any changes so far with the fmt.Printf change in DisplayLine, but I can try testing specific cases if needed. Also happy to remove that commit for now if it makes it easier to review. Thanks for the quick response!

[maxlandon]

No need to remove this commits.
I will try writing a few tests around the prompt engine: it's been a while it should have some.

Will tackle this in a week. Try your luck if you want !