[xsd-users] Non intrusive data structures

[Boris Kolpackov]

Hi Barrie,

Barrie Kovish <barrie.kovish at singularsoftware.com> writes:

> I'm using the XSD tree mapping. I'd like to be able to move 
> elements around the XML document without changing the address 
> of the elements.  For example suppose I have
> 
> <Dealer id="A">
>     <Car id="1">
>         <Color>
>             Red
>         <Color>
>     </Car>
>     <Car id="2">
>         <Color>
>             Blue
>         <Color>
>     </Car>
> </Dealer>
> 
> <Dealer id="B" >
>     <Car id="3">
>         <Color>
>             Red
>         <Color>
>     </Car>
>     <Car id="4">
>         <Color>
>             Blue
>         <Color>
>     </Car>
> </Dealer>
>   
> In code I want to keep a list of pointers to all Red cars. But if I 
> move car id 1 from dealer A to dealer B the address of the XSD data 
> structure will change. Is there a way to generate XSD classes which 
> save the Car elements as pointers?

If you are using the beta for the upcoming 3.3.0 release[1], then you 
can detach a sub-tree from the object model and then re-attach it at
a different point, all without reallocations and thus without changing
the sub-tree's memory location. Here is the relevant part from the
NEWS file:

  New option, --generate-detach, triggers the generation of detach 
  functions for required elements and attributes. For optional and 
  sequence cardinalities the detach functions are now provided by the 
  respective containers even without this option. These functions, for 
  example, allow one to move sub-trees in the object model either within
  the same tree or between different trees without copying. For more 
  information, refer to Section 2.8 "Mapping for Local Elements and 
  Attributes" in the C++/Tree Mapping User Manual.

[The C++/Tree Mapping User Manual is in the package's documentation/
 directory; the online version is still for 3.2.0.]

[1] http://www.codesynthesis.com/products/xsd/download.xhtml

Boris