[cfe-dev] CXCursor API questions

Stefan Seefeld seefeld at sympatico.ca
Sun Jan 9 19:36:52 PST 2011


I'm trying to traverse a translation unit by means of CLang's CXCursor 
API (libclang), and I have run into a couple of questions. Consider the 
following code:

class Translator
   void translate()
&Translator::visit, this);


   static void visit(CXCursor cursor, CXCursor parent, CXClientData data)
     CXCursor lex_parent = clang_getCursorLexicalParent(cursor);

     return CXChildVisit_Continue;

I.e., I'm attempting to translate the AST clang generates into my own 
representation using a "Translator" object, but have some difficulties 
since the arguments the above "Translator::visit" callback is being 
called with don't seem to correspond to the CLang documentation:

1) The documentation suggests that 'parent' should correspond to the 
parent cursor of 'cursor'. However, I find that 'parent' and 
'lex_parent' don't (ever !) compare equal. Shouldn't they ?

2) The documentation suggests that the parent cursor of a global 
declaration is the translation unit. However, in case where 'cursor' 
corresponds in fact to global declarations in my source file, 
'lex_parent' is an 'unexposed' cursor (and isn't equal to 'parent', 
which always is the translation unit). What is wrong ? (And, how can I 
distinguish declarations in my source files from builtin declarations, 
such as __builtin_va_list ?)

3) I notice a strange ordering of during the cursor traversal: It starts 
with some builtin items (such as __builtin_va_list), followed by my own 
declarations, followed by other builtin items (macros such as 
__clang__). Shouldn't my own declarations come last ?

Am I doing something wrong, or have I run into libclang bugs ?

And finally:

How can I translate a cursor into a file location ? I see how to 
generate a CXSourceLocation, but that is an opaque type. What function 
should I use to query the (filename, linenum, column) triplet ?

Any help is much appreciated !



       ...ich hab' noch einen Koffer in Berlin...

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