On 2006-09-19, Tommy Pettersson <[EMAIL PROTECTED]> wrote:
> On Mon, Sep 18, 2006 at 04:08:28PM +0000, Tuomo Valkonen wrote:
>> * UTF-16 is, of course, a rather different case than just a change in
>> encoding. The way I'd go about it, is to make the current patch type
>> polymorphic to input in arbitrary character types, if it isn't already,
>> and add skeleton support for plugging in and specifying different patch
>> type for files of arbitrary formats. (So, one day, support could be
>> written for structural formats to have structural instead of line-based
>> patches, and so on.)
>
> I think this could be a worthwhile task, although not so easy.
> If darcs could handle MS Word documents and other "industrial"
> file formats, it would become a "real" RCS in one more sense of
> the word real. And it would probably boost the development of
> new patch types, which would be interesting.
>
> One complication is the diff algorithm. It forms hunks, and
> would form the UTF-16 hunks and many of the eventual plug-in
> structural format hunks. It needs to be polymorphic as well, or
> worse...
Of course the diff algorithm should be polymorphic to various character
types/strings (FastPackedString8, FastPackedString16, etc.?), but I
don't see that as a problem. I have my doubts that the diff algorithm is
even applicable to many structural formats, so I wouldn't worry about it.
Not that I would familiar with it, or have given any thought to what kind
of patches different structural formats would have.
> My number one wish for new patch type, once I finally get time
> to finish the replace-with-space patch type, is be a hunk-move
> patch type
I'd like that.
> It would be nice if the user didn't have to ask for a specific
> diff algorithm on each record.
>
> ...
>
> Hand-coding a UTF-16 hunk would be easier, but there's still the
> problem of how to do it in the diff algorithm and the "select
> changes" dialogue, unless there should simply be _either_
> Raw8-bit or UTF-16, which wouldn't be so nice, I think.
I was thinking of something along the lines of 'darcs add
--format=text16 file.txt', 'darcs add --format=xml file.xml',
and so on, with this information stored somewhere. Then _only_
LineBasedPatch16 or XMLPatch or whatever ever get used on that
file. Different patch types (in the sense of the 'data' directive)
do not interact. Something like:
data RepoPatch = Move ...
| ...
| FileChange FileName Dynamic
class FilePatch a where
commute :: a -> a -> ...
...
data FPSType a => LineBasedPatch a = HunkLP ...
| MergerLP ...
...
instance FPSType a => FilePatch (LineBasedPatch a) where
...
(I wish Dynamic wasn't needed...)
--
Tuomo
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