On 03/14/2011 07:55 AM, ZY Zhou wrote:
Thank you Jussi,
But still this is not part of the standard, U+FFFD is a commonly used approach,
while the U+DC80..U+DCFF is also a common solution for
that(http://en.wikipedia.org/wiki/Utf8#Invalid_byte_sequences), different
approach
solve different problems.
I am surprised of some of your very affirmative statements (all along the
thread). None of the string processing libs I have met use the approach you
propose here, which is replacing invalid input by other invalid data (surrogate
values). On the other hand, the replacement character (0xFFFD) evoked by Jussi
(which I also proposed in a previous post) is a valid Unicode code point; same
for free user-avalable areas.
I think the current problem in D is that std.utf module is ill defined, it's not
designed to make developer's life easier. It just make the developers to ignore
the case that utf8 string can be invalid.
On the contrary, D perfectly deals with invalid input by signalling it to you
programmer. It is not ignored, which would be the worse approach. What to do
with invalid input belongs to your application's logic (as pointed by
Jonathan); you are demanding D standard libs to do your job at your place,
exactly the way you want it, using an incorrect approach.
Denis
--ZY Zhou
== Quote from Jussi Jumppanen (jus...@zeusedit.com)'s article
%u Wrote:
I agree with a), but not b), Can't find anything in unicode standard says
you can use the low surrogate like that
According to: http://www.cl.cam.ac.uk/~mgk25/
According to ISO 10646-1:2000, sections D.7 and 2.3c, a device
receiving UTF-8 shall interpret a "malformed sequence in the same way
that it interprets a character that is outside the adopted subset" and
"characters that are not within the adopted subset shall be indicated
to the user" by a receiving device. A quite commonly used approach in
UTF-8 decoders is to replace any malformed UTF-8 sequence by a
replacement character (U+FFFD), which looks a bit like an inverted
question mark, or a similar symbol.
Refer to this file for the above quote:
http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt
--
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