ATL / WTL / STL

Re: My codecvt (a.k.a. facet) never gets called.

28-Jun-09 23:37

From what I can tell, the C++ stream system presumes that files are sequences of bytes, not characters - even when you use wide streams - the 'wide' part of wide stream (AFAICT) indicates how the stream object interacts with C++, not the underlying file or whatever. Thus, your codecvt facet has to take in characters.

By changing the declaration of your codecvt facet to that shown below, I was able to get breakpoints in the replacement facet being set.

class utf16_codecvt : public std::codecvt<char16_t, char, std::mbstate_t>
{
   typedef std::codecvt<char16_t, char, std::mbstate_t> Base;
   typedef char16_t ElemT;
   typedef char ByteT;
   virtual result __CLR_OR_THIS_CALL do_in(std::mbstate_t& s,
      const ByteT *_First1, const ByteT *_Last1, const ByteT *& _Mid1,
      ElemT*_First2, ElemT* _Last2, ElemT *& _Mid2) const
   {	// convert bytes [_First1, _Last1) to [_First2, _Last)
      return Base::do_in(s, _First1, _Last1, _Mid1, _First2, _Last2, _Mid2);
   }

   virtual result __CLR_OR_THIS_CALL do_out(std::mbstate_t& s,
      const ElemT*_First1, const ElemT*_Last1, const ElemT*& _Mid1,
      ByteT*_First2, ByteT*_Last2, ByteT*& _Mid2) const
   {	// convert [_First1, _Last1) to bytes [_First2, _Last)
      return Base::do_out(s, _First1, _Last1, _Mid1, _First2, _Last2, _Mid2);
   }

   virtual result __CLR_OR_THIS_CALL do_unshift(std::mbstate_t& s,
      ByteT*_First2, ByteT*_Last2, ByteT*&_Mid2) const
   {	// generate bytes to return to default shift state
      return Base::do_unshift(s, _First2, _Last2, _Mid2);
   }

   virtual int __CLR_OR_THIS_CALL do_length(const std::mbstate_t& s, const ByteT*_First1,
      const ByteT*_Last1, size_t _Count) const
   {	// return min(_Count, converted length of bytes [_First1, _Last1))
      return Base::do_length(s, _First1, _Last1, _Count);
   }
};

So, your replacement facet will have to know it needs two bytes read for every character (and vice versa, obviously). The best reference for that sort of information is probably Standard C++ IOStreams and Locales by Angelika Langer and Klaus Kreft[^] - but even then, locales and facets are heavy going in C++ Frown | :-(

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

John R. Shaw29-Jun-09 2:43

John R. Shaw

29-Jun-09 2:43

Thanks, Stuart

That worked great; I expected the problem was something like that. Something else I discovered was that the second template parameter has to be ‘char’ or it will not work. That is ‘unsigned char’ will not even work as the second parameter.

I need to dig up a copy of the standard to see if this is compliant and makes since, because having template parameters that can only be of a single integral type is illogical.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: My codecvt (a.k.a. facet) never gets called.

Stuart Dootson29-Jun-09 3:16

Possible to have a two-way Associative Arrays

29-Jun-09 3:16

John R. Shaw wrote:
Something else I discovered was that the second template parameter has to be ‘char’ or it will not work. That is ‘unsigned char’ will not even work as the second parameter.

I need to dig up a copy of the standard to see if this is compliant and makes since, because having template parameters that can only be of a single integral type is illogical.

I think there are two pertinent ideas here - firstly, files are streams of bytes (that's the basic concept underlying file streams in C++), which is why they always convert to/from bytes. Secondly, codecvt facets can be used on their own, without streams.

So, say you'd read in a file converting from a byte stream to (say) UCS-2. Then you want to write the UTF-32 equivalent to a file. You could use a codecvt facet that could convert from UCS-2 to UTF-32. The example code in the codecvt::in documentation on MSDN[^] shows this sort of scenario.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

ComplexLifeForm25-Jun-09 2:30

ComplexLifeForm

25-Jun-09 2:30

Hi,

I am looking for a possibility to have a two way associative array. What I mean is that I would like to have an array say

My2WayArray<int, string=""> _twoWayArray;

and I can do the following

_twoWayArray["user1"] = 123;
_twoWayArray["user2"] = 456;

and

_twoWayArray[123] = "user1";
_twoWayArray[456] = "user2";

this way I will be able to lookup a user if the integer (used as user id) is specified and integer id if user name is provided.

I don't want to use it anywhere, it is just out of curiosity.

While I am posting this question I am trying to figure it out at my end.

Thanks and Regards
Smile | :)

Andy Moore25-Jun-09 6:09

Andy Moore

25-Jun-09 6:09

Look at boost::bimap.

http://www.boost.org/doc/libs/1_39_0/libs/bimap/doc/html/index.html[^]

Pax Domini sit semper vobiscum

Stuart Dootson25-Jun-09 6:10

25-Jun-09 6:10

Bah - you beat me to it by a matter of seconds Smile | :)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Stuart Dootson25-Jun-09 6:09

25-Jun-09 6:09

Like this[^]? Smile | :)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Kevin McFarlane4-Jul-09 6:01

Kevin McFarlane

4-Jul-09 6:01

It's a pity they don't have something like this in the .NET collection classes. And it doesn't seem to exist in the third party libraries either. Frown | :(

Kevin

Stuart Dootson4-Jul-09 7:49

4-Jul-09 7:49

Probably be quite difficult to port the approach used in Boost - one of the first comments I saw in the bimap headers was:

// Bimap Core, use mpl magic to find the desired bimap type

Once you're using the words 'mpl' (== C++ template metaprogramming library) and 'magic' together, there's little to no hope of translating the code directly to another language. I suspect some form of code generator would be the best bet (I seem to remember a container generator being written by someone before C# got generics - that would be similar).

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

How to Implement RPC in windows XP

ComplexLifeForm25-Jun-09 7:01

ComplexLifeForm

25-Jun-09 7:01

Thank you Andy and Stuart for the reply.

I was looking for boost bi-map type functionality.

Regards
Smile | :)

suthakar5618-Jun-09 18:45

18-Jun-09 18:45

Hi,

I need to implement the RPC in windows XP based system and I created an IDL file which contains the RPC calls and i created stub files. While compiling with server and client application it shows "You need a Windows NT Version 4.0 or Later to run this stub".But i am using Microsoft Visual C++ 6.0. Can anyone help to solve this problem?

Thanks,

S.Suthakar

Stuart Dootson18-Jun-09 22:05

18-Jun-09 22:05

You probably need to set WINVER[^] to reflect you're using Windows XP, rather than Windows 98, which was the current version of Windows when VC6 came out.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

led mike19-Jun-09 5:25

led mike

19-Jun-09 5:25

What Stuart said and depending on what you are using you might need to have an updated Platform SDK[^] from the original VC6

suthakar5619-Jun-09 5:38

19-Jun-09 5:38

I am using original version. The auto generated code only shows the error(defined in #).if i remove that then it is compiled.

led mike19-Jun-09 5:53

led mike

19-Jun-09 5:53

suthakar56 wrote:
I am using original version. The auto generated code only shows the error(defined in #).if i remove that then it is compiled.

I have no new information. Follow the advice previously given by myself and Stuart.

Stuart Dootson19-Jun-09 12:46

19-Jun-09 12:46

Good point - I forgot that one. So long since I used VC6....since I moved to VS2003, I've always used a Visual Studio newer than my standard target (Windows 2000 - we've not managed to make the giant leap to XP or Vista at the company I work for).

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

suthakar5619-Jun-09 22:30

19-Jun-09 22:30

Hi,

I compiled the idl file and it creates server and client (ie client_c.c and server_s.c) stub files.Client stub file is working properly in application.But In server stub file Interface definition is not implemented(generated code).(I created idl file project type is ATL COM AppWizard and server type as Service).

Regrads,
Suthakar

Stuart Dootson20-Jun-09 14:09

20-Jun-09 14:09

suthakar56 wrote:
But In server stub file Interface definition is not implemented

What do you mean by 'not implemented'?

I just tried a quick sample of IDL, which I processed with midl /server stub /client stub a.idl - seemed to have the correct server marshalling code.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

suthakar5621-Jun-09 17:53

21-Jun-09 17:53

I just compiled .idl by vc++ editer itself.It creates the client and server stub files.I want to know that whether i should compile .idl file using midl compiler only or the the first is enough.
Not implemented -->The function(idl) definition is implemented in server stub file (in my sample code).But original code it was not there.

Stuart Dootson21-Jun-09 20:07

21-Jun-09 20:07

suthakar56 wrote:
I just compiled .idl by vc++ editer itself.It creates the client and server stub files.I want to know that whether i should compile .idl file using midl compiler only or the the first is enough.

VC++ uses MIDL. That's fine.

suthakar56 wrote:
Not implemented -->The function(idl) definition is implemented in server stub file (in my sample code).But original code it was not there.

Can you explain what you mean by 'But original code it was not there'

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

suthakar5621-Jun-09 20:20