Mapping C structure to an XML element

问题:

Suppose I have a structure in C or C++, such as:

struct ConfigurableElement {
   int ID;
   char* strName;
   long prop1;
   long prop2;
   ...
};

I would like to load/save it to/from the following XML element:

 <ConfigurableElement ID="1" strName="namedElem" prop1="2" prop2="3" ... />

Such a mapping can be trivially done in Java/C# or any other language with run-time reflection for the matter. Can it be done in any non-tedious way in C++ with macros/template trickery?

Bonus points for handling nested structures/unions.

回答1:

The technique you want is called serialization. You may want to read these articles:

http://www.codeproject.com/KB/cpp/xmlserialization.aspx

http://www.codesynthesis.com/products/xsd/ <=== Very close to what you want!

http://www.artima.com/cppsource/xml_data_binding.html

http://www.ibm.com/developerworks/xml/library/x-serial.html

http://www.firstobject.com/xml-serialization-in-c++.htm

EDIT:

There is another option for you: Xmlize provided by Ultimatepp:

http://www.ultimatepp.org/reference$Xmlize.html

http://www.ultimatepp.org/reference$Xmlize$en-us.html

http://www.ultimatepp.org/reference$XmlizeCustomValue$en-us.html

http://www.ultimatepp.org/reference$Xmlize_std$en-us.html

http://www.ultimatepp.org/reference$XML$en-us.html

回答2:

Tips and tricks always exists. Take a look at Metaresc library https://github.com/alexanderchuranov/Metaresc

It provides interface for types declaration that will also generate meta-data for the type. Based on meta-data you can easily serialize/deserialize objects of any complexity. Out of the box you can serialize/deserialize XML, JSON, XDR, Lisp-like notation, C-init notation.

Here is a simple example:

#include <stdio.h>
#include <stdlib.h>

#include "metaresc.h"

TYPEDEF_STRUCT (host_t,
                (char *, host),
                int port,
                );

TYPEDEF_STRUCT (config_t,
                (host_t, local),
                (host_t, remote),
                (char *, name),
                );

int main (int argc, char * argv[])
{
  config_t config = {
    .local = {
      .host = "localhost",
      .port = 8080,
    },
    .remote = {
      .host = "google.com",
      .port = 80,
    },
    .name = "service",
  };

  char * str = MR_SAVE_XML (config_t, &config);
  if (str)
    {
      printf ("%s\n", str);
      free (str);
    }
  return (EXIT_SUCCESS);
}

This program will output

$ ./config
<?xml version="1.0"?>
<config>
  <local>
    <host>localhost</host>
    <port>8080</port>
  </local>
  <remote>
    <host>google.com</host>
    <port>80</port>
  </remote>
  <name>service</name>
</config>

Library works fine for latest gcc and clang.