Support for 3-way comparison (Submitted by Carsten Pfeiffer)

[Google Code Exporter]

(From the mailing list)

Hi,

currently, daisydiff only supports comparing one revision of a file with another
revision. One revision will be regarded as the "old" version, the other as the
"new" version. Content overwritten by the new version will be displayed in
red, strike-through, the new content is displayed in green.

This works well if the history of a file is linear and the file cannot be edited
concurrently by multiple persons. With revision control systems, you typically
have three versions to compare:
- the revision that was checked out (ancestor)
- the revision with the local changes
- the current remote revision in the revision control system

In this case, the changes to be displayed are always against the ancestor, so
there may be "old" and "new" changes created by the local revision, as well as
"old" and "new" changes created by the current remote revision. These together
can lead to "conflicting" changes.

Attached is an initial (working) patch for daisydiff to support this scenario.
3-way comparison is already supported by org.eclipse.compare, only daisdiff
needed some additional things. I implemented this against daisydiff 1.1, but
ported it to trunk.

Some constraints with the current version:
- 3-way comparison is currently only available by API (i.e. HTMLDiffer.diff() --
should probably also be added to the Differ interface at least)
- conflicting changes are reported as new and old changes, although most of the
code for conflict detection and formatting is already there

I'd appreciate any feedback.

Cheers,
Carsten

Original issue reported on code.google.com by [e-mail] on 16 Aug 2010 at 1:15

Attachments:

• 3way.patch

[Google Code Exporter]

We're using the three-way diff internally for almost a year now and it works 
pretty well.

It also doesn't affect the behavior of the two-wa diff, so I just committed it 
to trunk.

Original comment by [e-mail] on 17 Jun 2011 at 3:10

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[Google Code Exporter]

Committed in subversion r153. Re-open if you encounter any issues

Original comment by [e-mail] on 13 Sep 2011 at 9:00

• Changed state: Fixed
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