[cfe-dev] Problems retrieving container type specializations in function prototypes from the clang AST

[Benjamin.Fabricius at leica-geosystems.com]

Hello everybody,

I have started to use libtooling to write some software that can parse a 
c++ header in order to generate automatic code used in a SDK. In order to 
do this I have implemented RecursiveASTVisitor and its virtual member 
function VisitFunctionDecl. In VisitFunctionDecl i collect all kinds of 
data from the Function prototype in order to expand the string templates 
in the code Id like to generate. When sorting through the parameter 
declarations I'm experiencing difficulties in uniquely identifying some of 
the class types. Whereas it is quite clear how to handle builtin types and 
enumerals I am struggling with class types. Heres an example of a 
prototype that i am visiting:

CallResult ExampleApiCall(std::vector<std::string> &outputVector);

Now I am interested in identifying the exact type of the LValue 
outputVector. What I have been able to do up until now is check if the 
desugared type pointer is a class type. This is straight forward. Once I 
know it is a class type such as in the above example I am interested in 
its unique class type. Up until now all i could manage to do retrieve the 
CXXRecordDecl from the type im looking at. Now I can find out the kind 
name and qualified name string of this class which is vector. So naively 
spoken i can string compare (which I dont want to really) the unqualified 
name with the string "vector" and I'd now that I am looking at a vector 
type. I am also interested in knowing what type of vector container this 
is though as I will generate different code depending on what is in the 
container. This, I have not been able to find out yet. How can I access 
the specified template parameter? One of the things I tried was 

const ClassTemplateSpecializationDecl *cltmplsdcl = 
desugaredType->getAs<ClassTemplateSpecializationDecl>();

but to no avail. Maybe Im barking up the completely wrong tree here, my 
experience with clang AST is very limited. I'd appreciate any help and 
ideas from the community. Thanks a lot!

Here's an excerpt of the code Im using right now in VisitFunctionDecl :

        // desugar the parameter qualifier type
        const QualType desugaredQualType = 
parmQualType.getCanonicalType().getTypePtr()->getPointeeType();
        // get the desugared type pointer
        const Type *desugaredType = desugaredQualType.getTypePtr();

        // handle class types
        if(desugaredType->isClassType()) {
            // get the class type
            const CXXRecordDecl *cxxrcdcl = 
desugaredType->getAsCXXRecordDecl();
            if(nullptr == cxxrcdcl
            ) {
                cout << "Could not cast class type to CXXRecordDecl" << 
endl;
                return hdt_CXXRecord_NA;
            }
            // some cxx record decl tests ---> this gets me the class type 
but not the template specification
            cout << "cxxrcdcl->getKindName(): " << cxxrcdcl->getKindName() 
<< endl;
            cout << "cxxrcdcl->getQualifiedNameAsString(): " << 
cxxrcdcl->getQualifiedNameAsString() << endl;
            return hdt_CXXRecord_NA;
        }

Cheers,

Benjamin Fabricius
Software Engineer

Leica Geosystems AG, part of Hexagon
Machine Control Division
Heinrich-Wild-Strasse
9435 Heerbrugg, Switzerland
Skype: b.fabricius
Phone: +41 71 727 3407
E-Mail: benjamin.fabricius at leica-geosystems.com
Website: http://www.leica-geosystems.com

Social Networks: 




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 906 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 1139 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment-0001.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 1089 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment-0002.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 1085 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment-0003.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 2844 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131017/12bfeee2/attachment-0004.gif>