CODEWITHSUNDEEP
swig
c12
c12

Reputation: 9827

Custom SWIG Wrapping to Handle Nested C Structures

I have the below C struct that has a couple nested structures that have proven to be difficult to deal with using my knowledge of SWIG. Everything below is easily wrapped by SWIG execept for saddr (C socket address) and mac[6] (C array representing a MAC address). Since SWIG gives me the pointer value (SWIGTYPE_p_unsigned_char and SWIGTYPE_p_sockaddr), I would like to somehow call a helper C function to convert the pointer to a char*. I have the helper function, but I don't know the best way to plug this into SWIG. Is there any way to configure the getMac() and getSaddr() to call the helper function?

C Structure Trying To Wrap:

%rename (Details) details_t_;
    typedef struct details_t_ {
        uint16_t                      code;
        char                          *name;              
        **sockaddr                      *saddr;**             
        uint32_t                      saddr_len;
        uint8_t                       flag;       
        ios_boolean                   is_child;             
        **unsigned char                 mac[6];**            
    } details_t;

Generated Java Code:

  public void setMac(SWIGTYPE_p_unsigned_char value) {
    TestJNI.Details_mac_set(swigCPtr, this, SWIGTYPE_p_unsigned_char.getCPtr(value));
  }

  public SWIGTYPE_p_unsigned_char getMac() {
    long cPtr = TestJNI.Details_mac_get(swigCPtr, this);
    return (cPtr == 0) ? null : new SWIGTYPE_p_unsigned_char(cPtr, false);
  }

public void setSaddr(SWIGTYPE_p_sockaddr value) {
    TestJNI.Details_saddr_set(swigCPtr, this, SWIGTYPE_p_sockaddr.getCPtr(value));
  }

  public SWIGTYPE_p_sockaddr getSaddr() {
    long cPtr = TestJNI.Details_saddr_get(swigCPtr, this);
    return (cPtr == 0) ? null : new SWIGTYPE_p_sockaddr(cPtr, false);
  }

Proposed SWIG.i Changes:

 %module Test
          %rename (realId) details_t_::mac;
            %typemap(javacode) struct details_t_ %{
              public String getMac() {
                return Test.getMacAddressAsString(this); 
               //this is a pointer to details_t_ struct
              }

            %};
                %rename (Details) details_t_;
                    typedef struct details_t_ {
                        uint16_t                      code;
                        char                          *name;              
                        **sockaddr                      *saddr;**             
                        uint32_t                      saddr_len;
                        uint8_t                       flag;       
                        ios_boolean                   is_child;             
                        **unsigned char                 mac[6];**            
                    } details_t;

Upvotes: 2

Views: 1368

Answers (1)

Flexo - Save the data dump
Flexo - Save the data dump

Reputation: 88711

You can do this with a javacode typemap, e.g.:

%module test

%rename (realId) Sample::id;
%typemap(javacode) struct Sample %{
  public byte getId() {
    return 100-getRealId(); // Transform the real call
  }

  public void setId(byte value) {
    setRealId(value+100);
  }
%};


struct Sample {
  char id;
};

Renames the generated getId() and setId(), but provides a Java get/set which can be written in terms of the SWIG generated (but renamed) one. You might want to make the SWIG generated ones private though.

Upvotes: 1

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