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I have two structs (from a third party lib actually) in my swig .i file that follow this form:

typedef struct MY_STRUCT {
  void*       pParameter;
  unsigned long pLen;
} MY_STRUCT;
%extend MY_STRUCT
{
    MY_STRUCT()
    {
        MY_STRUCT *m= new MY_STRUCT();
        m->pParameter = NULL;
        m->pLen = 0;
        return m;
    }
}

typedef struct ANOTHER_STRUCT {
    char * another;
    unsigned long len;
} ANOTHER_STRUCT;
%extend ANOTHER_STRUCT
{
    ANOTHER_STRUCT()
    {
        ANOTHER_STRUCT *p= new ANOTHER_STRUCT();
        p->another = NULL;
        p->len = 0;
        return p;
    }
    unsigned long __len__()
    {
        return sizeof(ANOTHER_STRUCT);
    }
}

The pParameter in MY_STRUCT is a void * because it can be a char * or a pointer to a struct (such as ANOTHER_STRUCT). Handling just the char * mapping is simple using %typemap(in) void* = char*;, but any attempt to use a struct fails. Here's what I'd like to see in Python:

s = MY_STRUCT()
another = ANOTHER_STRUCT()
s.pParameter = another # this should pass the struct pointer
s.pParameter = "some string" # or a char pointer if this is provided

Is this possible? If not, do I need to declare some helper functions to assign the pointer values?

4

1 回答 1

2

您可以使用 SWIG 执行此操作。不过，您最终将编写一个相当大if的文件来选择如何处理 Python 输入，具体取决于您要处理的类型数量。这是您需要的两个类型图的完整示例：

%module test

%typemap(in) void* pParameter (int res=0, void *other_struct=NULL) %{
  int len;
  res = SWIG_ConvertPtr($input, &other_struct, $descriptor(struct ANOTHER_STRUCT*), 0);
  if (SWIG_IsOK(res)) {
    fprintf(stderr, "struct\n");
    $1 = reinterpret_cast< ANOTHER_STRUCT * >(argp1);
    len = sizeof(ANOTHER_STRUCT);
  }
  else if (PyString_Check($input)) {
    $1 = PyString_AsString($input);
    len = strlen((const char*)$1);
    fprintf(stderr, "string\n");
  }
  //else if (...) {
  //}
  else {
    SWIG_exception_fail(SWIG_TypeError, "some more details, see special typemap variables docs for ideas");
  }
%}

%typemap(memberin) void* pParameter %{
  $1 = $input; //fobar $self
  $self->pLen = len;
%}

%inline %{
typedef struct MY_STRUCT {
  void*       pParameter;
  unsigned long pLen;
} MY_STRUCT;

typedef struct ANOTHER_STRUCT {
} ANOTHER_STRUCT;
%}

%extend MY_STRUCT
{
    MY_STRUCT()
    {
        MY_STRUCT *m= new MY_STRUCT;
        m->pParameter = NULL;
        m->pLen = 0;
        return m;
    }
}

在这里，intypemap 接受一个 PyObject 并计算出如何处理它。它还将长度保存到局部变量中。

类型映射使用它来适当memberin地设置和长度。void*

您可能要考虑制作pLen不可变的（请参阅：）%immutable，以便人们不能随意更改该指针。您还需要仔细考虑此类类型映射的内存所有权语义，以避免泄漏或双重释放。

于 2013-08-10T22:20:16.280 回答