opencxx-users

[Opencxx-users] template keyword cause parse error

[Alexander V. <al...@se...>]

  Hello!

We are using OpenC++ in our project for some intellectual C++ code
preprocessing.
Recently, I've found that OpenC++ (2.8) can not parse following code:

class X
{
public:
  template <typename T> int g() { return 123; }
};

template <typename T> class A
{
public:
  X x;
  X& getx() { return x; }
  void f() { getx().g<T>(); }
};

int main()
{
  A<int> a;
  a.f();
}

It says:
[alex@lorien ~]$ ./occ -c 1.cpp
1.cpp: In member function `void A<T>::f()':
1.cpp:12: error: parse error before `;' token

The 12th line corresponds to getx().g<T>()

Is this a correct code? I have 4 compilers on my machine (gcc 3.3.5,
gcc 3.4.3, gcc 4.0.0 snapshot, Intel C/C++ 8.1). All of them
compile this code cleanly.

I will be glad to provide any additional information about my
problem or opencxx configuration.

May be there is also some CVS, SVN or other "bleeding-edge" source that
I can try?

With best regards,
   Alexander.

Re: [Opencxx-users] template keyword cause parse error

[Stefan S. <se...@sy...>]

Alexander Vodomerov wrote:

> Recently, I've found that OpenC++ (2.8) can not parse following code:
> 
> class X
> {
> public:
>   template <typename T> int g() { return 123; }
> };
> 
> template <typename T> class A
> {
> public:
>   X x;
>   X& getx() { return x; }
>   void f() { getx().g<T>(); }
> };
> 
> int main()
> {
>   A<int> a;
>   a.f();
> }
> 
> It says:
> [alex@lorien ~]$ ./occ -c 1.cpp
> 1.cpp: In member function `void A<T>::f()':
> 1.cpp:12: error: parse error before `;' token
> 
> The 12th line corresponds to getx().g<T>()
> 
> Is this a correct code? I have 4 compilers on my machine (gcc 3.3.5,
> gcc 3.4.3, gcc 4.0.0 snapshot, Intel C/C++ 8.1). All of them
> compile this code cleanly.

The OpenC++ parser is indeed not powerful enough to understand that line.
The reason is that to be able to decide whether '<' is a relational operator
or the start of a template parameter spec, it has to figure out what 'g'
is. That requires symbol lookup, which OpenC++ doesn't do during parsing.

Regards,
		Stefan

Re: [Opencxx-users] template keyword cause parse error

[J D. <ja...@ja...>]

has anyone thought about integrating boosts spirit/wave with openc++
wave is a fully ansi compliant preprocessor as far as i understand
Ive been thinking about adding metaobjects to a modified wave 
preprocessor, openc++ just doesnt have a powerfull enough parser


Stefan Seefeld wrote:

> Alexander Vodomerov wrote:
>
>> Recently, I've found that OpenC++ (2.8) can not parse following code:
>>
>> class X
>> {
>> public:
>>   template <typename T> int g() { return 123; }
>> };
>>
>> template <typename T> class A
>> {
>> public:
>>   X x;
>>   X& getx() { return x; }
>>   void f() { getx().g<T>(); }
>> };
>>
>> int main()
>> {
>>   A<int> a;
>>   a.f();
>> }
>>
>> It says:
>> [alex@lorien ~]$ ./occ -c 1.cpp
>> 1.cpp: In member function `void A<T>::f()':
>> 1.cpp:12: error: parse error before `;' token
>>
>> The 12th line corresponds to getx().g<T>()
>>
>> Is this a correct code? I have 4 compilers on my machine (gcc 3.3.5,
>> gcc 3.4.3, gcc 4.0.0 snapshot, Intel C/C++ 8.1). All of them
>> compile this code cleanly.
>
>
> The OpenC++ parser is indeed not powerful enough to understand that line.
> The reason is that to be able to decide whether '<' is a relational 
> operator
> or the start of a template parameter spec, it has to figure out what 'g'
> is. That requires symbol lookup, which OpenC++ doesn't do during parsing.
>
> Regards,
>         Stefan
>
>
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Re: [Opencxx-users] template keyword cause parse error

[Stefan S. <se...@sy...>]

J Duncan wrote:
> has anyone thought about integrating boosts spirit/wave with openc++
> wave is a fully ansi compliant preprocessor as far as i understand

No, but the author of wave expressed interest in adding wave support
to synopsis, which is somewhat based on OpenC++ (note that synopsis
currently uses ucpp as preprocessor library).

> Ive been thinking about adding metaobjects to a modified wave 
> preprocessor, openc++ just doesnt have a powerfull enough parser

I'm not sure what you mean. We are talking about parsing C++ here,
not preprocessing, right ? And while OpenC++ doesn't support some
important aspects of C++ parsing, wave doesn't either (if only
because that is not its scope).
You still need symbol lookup, overload resolution, template
instantiation, etc., etc.

Regards,
		Stefan

Re: [Opencxx-users] template keyword cause parse error

[Grzegorz J. <ja...@ac...>]

>> has anyone thought about integrating boosts spirit/wave with openc++
>> wave is a fully ansi compliant preprocessor as far as i understand
> 
> No, but the author of wave expressed interest in adding wave support
> to synopsis, which is somewhat based on OpenC++ (note that synopsis
> currently uses ucpp as preprocessor library).

Word of caution: Synopsis is has much more restrictive license than 
OpenC++, think twice before investing your time.

BR
Grzegorz

Re: [Opencxx-users] template keyword cause parse error

[Grzegorz J. <ja...@ac...>]

Hello,

J Duncan wrote:
> has anyone thought about integrating boosts spirit/wave with openc++
> wave is a fully ansi compliant preprocessor as far as i understand

Curently preprocessing is out of the scope of OpenC++. OpenC++ works on 
preprocessed stream. It uses external preprocessor, so feel free to use 
Wave (or more precisely Wave CLI wrapper) as the preprocessor for 
OpenC++ if you like.

Another story is that some time ago there were proposals to incorporate 
preprocessing into OpenC++ flow to enable deparsing without expansion of 
preprocessor constructs. Wave would fit this space well, but there are 
nontrivial problems with interposing preprocessor structure over the 
AST. The initiative is on hold now, if you want to go in this direction 
I can provide help with orientation in OpenC++ architecture.

> Ive been thinking about adding metaobjects to a modified wave 
> preprocessor, openc++ just doesnt have a powerfull enough parser

Sorry, I don't understand your point here. In what aspects is OpenC++ 
preprocessor too weak? What kind of metaobjects would you like to add? Why?

Best regards
Grzegorz

> 
> 
> Stefan Seefeld wrote:
> 
>> Alexander Vodomerov wrote:
>>
>>> Recently, I've found that OpenC++ (2.8) can not parse following code:
>>>
>>> class X
>>> {
>>> public:
>>>   template <typename T> int g() { return 123; }
>>> };
>>>
>>> template <typename T> class A
>>> {
>>> public:
>>>   X x;
>>>   X& getx() { return x; }
>>>   void f() { getx().g<T>(); }
>>> };
>>>
>>> int main()
>>> {
>>>   A<int> a;
>>>   a.f();
>>> }
>>>
>>> It says:
>>> [alex@lorien ~]$ ./occ -c 1.cpp
>>> 1.cpp: In member function `void A<T>::f()':
>>> 1.cpp:12: error: parse error before `;' token
>>>
>>> The 12th line corresponds to getx().g<T>()
>>>
>>> Is this a correct code? I have 4 compilers on my machine (gcc 3.3.5,
>>> gcc 3.4.3, gcc 4.0.0 snapshot, Intel C/C++ 8.1). All of them
>>> compile this code cleanly.
>>
>>
>>
>> The OpenC++ parser is indeed not powerful enough to understand that line.
>> The reason is that to be able to decide whether '<' is a relational 
>> operator
>> or the start of a template parameter spec, it has to figure out what 'g'
>> is. That requires symbol lookup, which OpenC++ doesn't do during parsing.
>>
>> Regards,
>>         Stefan
>>
>>
>> -------------------------------------------------------
>> SF email is sponsored by - The IT Product Guide
>> Read honest & candid reviews on hundreds of IT Products from real users.
>> Discover which products truly live up to the hype. Start reading now.
>> http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
>> _______________________________________________
>> Opencxx-users mailing list
>> Ope...@li...
>> https://lists.sourceforge.net/lists/listinfo/opencxx-users
>>
> 
> 
> 
> -------------------------------------------------------
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> Read honest & candid reviews on hundreds of IT Products from real users.
> Discover which products truly live up to the hype. Start reading now.
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> Opencxx-users mailing list
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