ydiff: side-by-side, character-level diffs in the terminal

joshuarli's ydiff fork

This is ydiff , distilled down to the very core.

It's been heavily modified and stripped down to a very specific feature subset:

• py3.6+
• assumes utf-8
• only read git unified diffs from stdin
• only side-by-side rendering

And, modified to be visually less noisy.

Screenshots

Here's what it looks like:

Compared to before (the automatic width detection failed lol):

Performance

I'm definitely not smart enough to port it to more performant languages, but I've made it quite fast:

$ git log --patch | pv > /tmp/sentry-git-log
... 17.4MiB/s ...
-rw-r--r-- 1 josh josh 573M Jun 27 00:00 /tmp/sentry-git-log

$ ./ymattw-ydiff.py --wrap --side-by-side --color=always --pager=cat \
    < /tmp/sentry-git-log | pv >/dev/null

... 761KiB/s ...

$ ./ydiff < /tmp/sentry-git-log | pv >/dev/null

... 1.37MiB/s ...

I've also optimized it to build as a relatively clean Cython binary, which runs a bit faster but more importantly is faster to start up:

$ ./ydiff-bin < /tmp/sentry-git-log | pv >/dev/null
... 1.60MiB/s ...

$ hyperfine --warmup 3 "./ydiff < tests/sentry/1/in.diff >/dev/null"
Benchmark #1: ./ydiff < tests/sentry/1/in.diff >/dev/null
  Time (mean ± σ):     115.3 ms ±   2.3 ms    [User: 53.1 ms, System: 43.4 ms]
  Range (min … max):   112.5 ms … 123.7 ms    24 runs

$ hyperfine --warmup 3 "./ydiff-bin < tests/sentry/1/in.diff >/dev/null"
Benchmark #1: ./ydiff-bin < tests/sentry/1/in.diff >/dev/null
  Time (mean ± σ):      35.8 ms ±   1.9 ms    [User: 26.3 ms, System: 7.8 ms]
  Range (min … max):    32.8 ms …  40.2 ms    74 runs

Installation

Just download this to anywhere on your PATH, then set the following git config:

git config --global pager.diff "ydiff | less"
git config --global pager.show "ydiff | less"
git config --global pager.log less
git config --global color.diff never

I also recommend setting LESS=FSXR . less will use those flags by default. You could alternatively put those in your git config.

Optionally, if you have a C compiler, you can compile the Cython binary with make ydiff-bin .