[cfe-dev] Get number of unique operators and operands for calculation of Halstead metrics

[manavender reddy]

Thanks guys :)

On Mon, Aug 16, 2010 at 9:23 AM, Ted Kremenek <kremenek at apple.com> wrote:

> Hi Manavender,
>
> I don't know if your metrics actually require a CFG, or just can be done
> with a walk on the AST.
>
> Assuming you are starting with a FunctionDecl*, it is possible to query the
> FunctionDecl for its body (getBody()).  That value will be a Stmt*.  After
> that, you can walk the AST using a variety of schemes.  To "pattern match" a
> Stmt* against a particular AST kind (i.e., a subclass of Stmt), do:
>
>  if (CallExpr *CE = dyn_cast<CallExpr>(S))
>  ...
>
> There are plenty of examples like this in the Clang codebase.  Specific
> Stmt/Expr classes will have accessors to their subexpressions, but there is
> also a generic iterator interface in Stmt (child_begin(), child_end()) which
> allows you to recursively walk the AST.  We also have various visitor
> classes that you can use, e.g. StmtVisitor, RecursiveASTVisitor, which also
> have example uses in the codebase.
>
> Using the CFG is a bit tricker.  The CFG consists of basic blocks, which
> you can iterate through.  Each CFGBlock contains an ordered set of
> statements, and those statements can be traversed just like you would
> traverse an AST.  The main catch is that CFGBlocks have a notion of
> "block-level expression", which are the Stmt* that appear in the ordered set
> (not all subexpressions appear in the set).  Those block-level expressions
> may appear as subexpressions of later block-level expressions, but they are
> ordered in the CFGBlock to represent control-flow dependencies.
>
> Ted
>
> On Aug 15, 2010, at 1:27 PM, manavender reddy wrote:
>
> > Hi all,
> >
> > Can anyone help me with this. How can i find number of unique operators
> and operands in a function. Here's what i am doing.
> > I first got an CFG of the function and then i am going through each
> block. I am stuck after that, i dont know how to parse each Stmt/Expr in a
> block to get operators and operands ?
> >
> >
> > Thanks
> > Manavender
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
>
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