[cfe-dev] Matching method defined outside a class declaration

[Jesper Eskilson]

On 09/17/2013 02:50 PM, Manuel Klimek wrote:
> On Tue, Sep 17, 2013 at 2:24 PM, Jesper Eskilson 
> <jesper.eskilson at iar.com <mailto:jesper.eskilson at iar.com>> wrote:
>
>
>     Hello,
>
>     I'm trying to write an AST matcher rule which is able to match
>     method definitions. Given the following C++ source code:
>
>         class B
>         {
>           void foo();
>           void bar() {
>             int a_local_variable_in_bar;
>           }
>         };
>
>         void B::foo()
>         {
>           int a_local_variable_in_foo;
>         }
>
>         B b
>
>         int main()
>         {
>         }
>
>
>     I would like a matcher which can tell me where instances of B are
>     created and also give me the definitions of its methods (in this
>     case "foo" and "bar").
>
>           StatementMatcher m = constructExpr(
>               hasType(
>                   recordDecl(isSameOrDerivedFrom("B"),
>         hasMethod(methodDecl(isDefinition()).bind("method")))));
>
>
>     But it will only give me the definition of "bar", and not the
>     defintion of "foo" which is declared outside the class.
>
>
> This is because hasMethod will not give you anything outside of the 
> class definition. The reason is that you often don't see out-of-class 
> method definitions of when you have a class definition.
>
> If you already know the name of the class (as you specify it in your 
> matcher), why do you want to write this matcher in the first place? 
> You'll not be able to match all constructor calls and method 
> definitions in general, as classes may be instantiated in a 
> translation unit where not all method definitions are visible.
>
> If you have more details on what you're actually trying to do (on a 
> higher level) we might be able to help more...
>
>     If I cannot do this with matchers, is there a way to get to the
>     definition of "foo" given the declaration of the class B?
>
>
> No, as you might see the class definition in a header where foo is not 
> visible. Usually you'll want to go the other way - find all method 
> definitions of class "B".
>

I have a bunch of class instantiations in a large codebase which look 
like this

A a1("banana", new B1);
A a2("apple", new B2);
A a3("ananas", new B2);

B1, B2, B3, all inherit from B which defines a method "foo" (outside the 
declaration of B). This definition may or may not be overridden in B1/B2/B3.

I want to be able to generate output on the form:

banana:
     void foo() { /* this is the foo implementation in class B1 */ }
apple:
     void foo() { /* this is the foo implementation in class B2 */ }
ananas:
     void foo() { /* this is the foo implementation in class B3 */ }

I was thinking about first matching out all the different definitions of 
foo, and then in a separate matcher match the construction expressions 
of a1-a3, but I'm not sure of the best way to "share" information 
between matchers.

-- 
*Jesper Eskilson* /Development Engineer/
IAR Systems AB
Box 23051, Strandbodgatan 1
SE-750 23 Uppsala, SWEDEN
E-mail: jesper.eskilson at iar.com <mailto:jesper.eskilson at iar.com> 
Website: www.iar.com
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