痛饮 - 生成包装来传递结构数组 [英] Swig - generate wrapper to pass an array of struct

问题描述

我刚刚发现了关于％适用指令（<一个href=\"http://stackoverflow.com/questions/14134598/how-to-pass-double-from-c-sharp-to-c-using-swig?rq=1\">see这里实例）。不幸的是，我不能使它与结构工作：

I have just found out about the %apply directive (see here for instance). Unfortunately I can't make it work with structs:

%module packer_cs
%include "carrays.i"
%{
    #include "packer.h" 
%}
%include "typemaps.i"
%include "arrays_csharp.i"
%apply image_t INPUT[] { image_t *images }
%include "packer.h"

其结果是：

swig -csharp -outdir bin\csharp packer\packer.i
Warning 453: Can't apply (image_t INPUT[]). No typemaps are defined.

我无法找到任何关于这一警告的任何文件。它看起来像我必须定义一个定制的类型映射，但是我不知道从哪里开始。我长大pretty厌倦了这种缺乏文档和pretty绝望的一天写我的包装成功的：（

I can't find any documentation whatsoever about this warning. It looks like I have to define a custom typemap, but I have no idea where to start. I'm growing pretty tired of this lack of documentation, and pretty desperate of one day succeeding in writing my wrapper :(

随着我的<一个href=\"http://stackoverflow.com/questions/24434869/compile-a-c-library-with-visual-studio-2010\">two <一href=\"http://stackoverflow.com/questions/24436262/linker-errors-in-c-program-lnk2019-and-lnk1120\">$p$pvious文章中，我仍然在C＃中使用C库有问题。

Following my two previous posts, I still have problems using a C library in C#.

要回顾一下：我有一个C库，和我想要编写使用痛饮一个C＃包装

To recap: I have a C library, and I'm trying to write a C# wrapper using Swig.

在h文件中，该方法被声明这样：

In the .h file, the method is declared such:

int pack(image_t *images, int nb_images, parameters_t params);

其实， *图片总是通过一个数组。如果我只是产生这样痛饮文件，在C＃中的文件，该函数需要一个实例：

Actually the *images is always passed an array. If I just generate swig files like this, in the C# files, the function expects a single instance:

  public static int pack(image_t images, int nb_images, parameters_t arg2) {
    int ret = packer_csPINVOKE.pack(image_t.getCPtr(images), nb_images, parameters_t.getCPtr(arg2));
    if (packer_csPINVOKE.SWIGPendingException.Pending) throw packer_csPINVOKE.SWIGPendingException.Retrieve();
    return ret;
  }

所以，下面的此评论，我已经修改了我的.i文件，例如：

So, following this comment, I have modified my .i file such :

%module packer_cs
%include <carrays.i>
%{
    #include "packer.h" 
%}
%include "packer.h"
%array_functions(image_t, image_t_array);

现在我可以使用 new_image_t_array 和 image_t_array_setitem 方法建立自己的打假阵列，但是当我跑我测试程序，它抛出一个 System.AccessViolationException （它试图读取或写入受保护的内存）在包方法调用（C＃程序）：

Now I can build my "fake" array using the new_image_t_array and image_t_array_setitem methods, but when I run my test program, it throws a System.AccessViolationException (it's trying to "read or write protected memory") on the pack method call (C# program):

// the "images" variable is a List<image_t>
var images_array = packer_cs.new_image_t_array(images.Count);
for (var i = 0; i < images.Count; i++)
{
    packer_cs.image_t_array_setitem(images_array, i, images[i]);
}

// this throws the exception
var result = packer_cs.pack(images_array, images.Count, param);

其实，异常是在 INT RET = packer_csPINVOKE.pack抛出（image_t.getCPtr（图像），nb_images，parameters_t.getCPtr（ARG2））; 行由痛饮生成的C＃文件。

Actually, the exception is thrown at the int ret = packer_csPINVOKE.pack(image_t.getCPtr(images), nb_images, parameters_t.getCPtr(arg2)); line in the C# file generated by Swig.

任何想法，为什么发生这种情况？正如我在其他职位说，我什么都不知道的C / C ++，指针的东西，所以它可能是显而易见的......

Any idea as to why this is happening ? As I said in my other posts, I know nothing about C/C++, pointers and stuff, so it may be obvious...

谢谢！

推荐答案

我不知道，如果它很重要，不能测试，但你的。我可能要导出包的array_functions后功能：

I don't know if it matters, can't test, but Your .i might have to export the pack function after the array_functions:

%module packer_cs
%include <carrays.i>
%{
    #include "packer.h" 
%}
%array_functions(image_t, image_t_array);
%include "packer.h"

此外，没有强迫你声明完全相同的签名。你也许可以有这样的事情：

Also, nothing forces you to declare the exact same signature. You can probably have something like this:

%module packer_cs
%include <carrays.i>
%{
    #include "packer.h" 
%}

// export image_t and parameters_t, then: 
int pack(image_t images[], int nb_images, parameters_t params);

该包装code将调用包的C版本，给它的数组，这是确定的，因为函数需要一个指向image_t和C知道如何与数组指针的作品。

The wrapper code will call the C version of pack, giving it the array, this is ok because the function takes a pointer to image_t and C knows how to works with array as pointer.

更新：由于上述没有帮助，我把在看 arrays_csharp.i ：调用 CSHARP_ARRAYS 和 CSHARP_ARRAYS_FIXED 宏观上所有的基本类型，并附带SWIG阵列的例子的。我调用了适用尽管如此所以它可能是％适用不会自动执行此操作。事实上，它看起来像这两个宏是的的typemaps，所以我认为这是值得一试：

Update: Since the above didn't help, I took at look at arrays_csharp.i: it calls CSHARP_ARRAYS and CSHARP_ARRAYS_FIXED macro on all basic types, and the .i of the arrays example that is included with SWIG calls the apply nonetheless so it may be that %apply does not do this automatically. In fact, it looks like these two macros are the typemaps, so I think it is worth a try:

%module packer_cs
%include "carrays.i"
%{
    #include "packer.h" 
%}
%include "typemaps.i"
%include "arrays_csharp.i"
CSHARP_ARRAYS(image_t, image_t)
CSHARP_ARRAYS_FIXED(image_t, image_t)
%apply image_t INPUT[] { image_t *images }
%include "packer.h"

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