How can I visualize per-character differences in a unified diff file?

Question

Say I get a patch created with git format-patch. The file is basically a unified diff with some metadata. If I open the file in Vim, I can see which lines have

Answer 1

Given your references to Vim in the question, I'm not sure if this is the answer you want :) but Emacs can do this. Open the file containing the diff, make sure that you're in diff-mode (if the file is named foo.diff or foo.patch this happens automatically; otherwise type M-x diff-mode RET), go to the hunk you are interested in and hit C-c C-b for refine-hunk. Or step through the file one hunk at a time with M-n; that will do the refining automatically.

Answer 2

git diff --color-words="[^[:space:]]|([[:alnum:]]|UTF_8_GUARD)+"

The above regex (from Thomas Rast) does a decent job of separating diff fragments at the punctuation/character level (while not being as noisy as --word-diff-regex=.).

I posted a screenshot of the resulting output here.

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Update:

This article has some great suggestions. Specifically, the contrib/ tree of the git repo has a diff-highlight perl script that shows fine-grained highlights.

Quick start to use it:

$ curl https://git.kernel.org/cgit/git/git.git/plain/contrib/diff-highlight/diff-highlight > diff-highlight
$ chmod u+x diff-highlight
$ git diff --color=always HEAD~10 | diff-highlight | less -R

Answer 3

In git, you can merge without committing. Merge your patch first, then do:

git diff --word-diff-regex=.

Note the dot after the equals sign.

Answer 4

After a little research, I notice this question has come up twice recently on the main Vim mailing list. The NrrwRgn plugin was mentioned both times (make two narrow regions and diff them). Using NrrwRgn as described by Christian Brabandt feels more like a workaround than a solution, but maybe that's good enough.

I tried out NrrwRgn and it, together with :diffthis, was indeed useful for illustrating per-character differences within parts of a single file. But it took many keystrokes. My Vimscript is pretty rusty, but it could likely be scripted. Maybe NrrwRgn could be enhanced to provide the desired functionality.

Thoughts?

Answer 5

If you have nothing against installing NodeJS, there's a package called "diff-so-fancy" (https://github.com/so-fancy/diff-so-fancy), which is very easy to install and works perfectly:

npm install -g diff-so-fancy
git diff --color | diff-so-fancy | less -R

Edit: Just found out it's actually a wrapper for the official diff-highlight... At least it's easier to install for perlophobes like me and the GitHub page is nicely documented :)

Answer 6

Am not aware of per character difference tool, but there is a per word difference tool: wdiff.

refer examples Top 4 File Difference Tools on UNIX / Linux – Diff, Colordiff, Wdiff, Vimdiff.