unidiff #

unidiff adds support for creating unified diff format
to jsdiff

The following snippet:

var unidiff = require('unidiff')

var diff = unidiff.diffLines(
'a quick\nbrown\nfox\njumped\nover\nthe\nlazy\ndog\n',
'a quick\nbrown\ncat\njumped\nat\nthe\nnot-so-lazy\nfox\n'
)
console.log(unidiff.formatLines(diff), {context: 2})

Produces this unified diff output:

--- a
+++ b
@@ -1,8 +1,8 @@
a quick
brown
-fox
+cat
jumped
-over
+at
the
-lazy
-dog
+not-so-lazy
+fox

This same output can be achieved more concisely using the diffAsText function:

console.log(require('unidiff').diffAsText(
'a quick\nbrown\nfox\njumped\nover\nthe\nlazy\ndog\n',
'a quick\nbrown\ncat\njumped\nat\nthe\nnot-so-lazy\nfox\n'
))

Both formatLines() and diffAsText() take a format options parameter with the
following options.

{
aname: file name for input a, defaults to 'a'
bname: file name for input b, defaults to 'b'
pre_context: write up to this many unmodified lines before each change
post_context: write up to this many unmodified lines after each change
context: default values for pre_context and post_context (specify both in one setting)
(context defaults to 3 when nothing is specified)
format: format of output text. currently only "unified" is supported
}

Differences From JSDiff ##

All js-diff functions are also availalbe in unidiff, with a couple minor changes:

* unidiff.diffLines() and unidiff.diffAsText() accept arrays of strings as well as strings with new lines for input.
* unidiff.diffLines() returns an empty array when there are no differences instead of an array with a single unmodified change.

Useful features to add to unidiff ##

* implement parsing of unified format to convert text output into patches.