Hi,
On Wed, 5 Aug 2009, Sverre Rabbelier wrote:
> On Wed, Aug 5, 2009 at 08:45, Daniel Barkalow<barkalow@xxxxxxxxxxxx>
> wrote:
> > Someday, I want to have a diff output format that makes these things
> > clear somehow. I think it would be not-too-hard to get the diff code
> > to determine that an addition matches or almost matches a deletion (or
> > some unchanged code), and provide library access to this information,
> > but representing it to humans (and getting patch to still work) is
> > hard.
>
> I started on this a while ago (as part of some post-GSoC git-stats
> work), but I had a hard time finding a good rule to determine whether an
> added hunk is similar enough to a deleted hunk elsewhere. Perhaps a
> variant of Levenshtein can be used to determine how different two hunks
> are; I tried diffing the two hunks and then looking at the ration
> between the size of the diff and the size of the original hunk, but as
> said that didn't really work out.
I think that there are two complications:
- how to present it in a format that helps the human to understand, yet is
well-defined enough to be used as a machine-readable edit script (I
really do not think that it can be well-designed if it only fulfills one
of the two purposes). I could imagine something like this:
diff --git a/remote-curl.c b/remote-curl.c
partial copy from transport.c +394,130
#ifndef NO_CURL
static int curl_transport_push(struct transport *transport, int refspec_nr, const char **refspec, int flags)
{
[...]
}
#endif
@@ -1,4 +1,6
+#include "cache.h"
+#include "transport.h"
+#include "refs.h"
+
#ifndef NO_CURL
static int curl_transport_push(struct transport *transport, int refspec_nr, const char **refspec, int flags)
- how to determine efficiently where to spend a lot of time to determine
what could be similar enough.
For example, the diff would still look pretty unreadable if you determined
that there was a code move which involved a reindentation, so I am not at
all sure if it is worth to try hard to detect that that was a move after
all.
Ciao,
Dscho
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