javaout typemap doesn't work for std::vector of pointers

Question

With vector of structures everything works fine

%include <std_vector.i>

%typemap(javaout) const S1& std::vector<S1>::get {
  //custom code
}

struct S1 {};
std::vector<S1> val;

%template(vector_s1) std::vector<S1>;

But doesn't work with vector of pointers

%include <std_vector.i>

%typemap(javaout) const S1*& std::vector<S1*>::get {
  //custom code
}

struct S1 {};
std::vector<S1*> val;

%template(vector_s1) std::vector<S1*>;

Samples were compiled with swig -java -c++ -module sample sample.i

SWIG version:

$ swig -version

SWIG Version 3.0.7

Compiled with i586-mingw32msvc-g++ [i586-pc-mingw32msvc]

Configured options: +pcre

Answer 1

If you have a look in the file swig/Lib/std/std_vector.i that provides language independent wrapper code for std::vector, you will find the following comment:

// ***
// This specialization should disappear or get simplified when
// a 'const SWIGTYPE*&' can be defined
// ***
template<class _Tp, class _Alloc >
class vector<_Tp*, _Alloc > { ...

So it appears that SWIG currently cannot handle the const S1*& in your above typemap definition.

Now, the file swig/Lib/java/std_vector.i that provides the java wrappers for std::vector is much less sophisticated and lacks the specialization for std::vector<T*>.

Adding such a specialization yourself should solve your problem:

file std_vector_pointer.i:

%include <std_vector.i>
namespace std {
template<class T> class vector<T*> {
  public:
    typedef size_t size_type;
    typedef T* value_type;
    typedef value_type const_reference;
    vector();
    vector(size_type n);
    size_type size() const;
    size_type capacity() const;
    void reserve(size_type n);
    %rename(isEmpty) empty;
    bool empty() const;
    void clear();
    %rename(add) push_back;
    void push_back(T* x);
    %extend {
        T* get(int i) throw (std::out_of_range) {
            int size = int(self->size());
            if (i>=0 && i<size)
                return (*self)[i];
            else
                throw std::out_of_range("vector index out of range");
        }
        void set(int i, T* val) throw (std::out_of_range) {
            int size = int(self->size());
            if (i>=0 && i<size)
                (*self)[i] = val;
            else
                throw std::out_of_range("vector index out of range");
        }
    }
};
}

Then the following should work for your above example:

%include "std_vector_pointer.i"

%typemap(javaout) S1* std::vector<S1*>::get {
  //custom code
}

struct S1 {};
std::vector<S1*> val;

%template(vector_s1) std::vector<S1*>;