[xsde-users] Parsing - Getting Super Data

[Boris Kolpackov]

Hi Mark,

Mark Easton <mark63 at azurebell.co.nz> writes:

> I have a site which is made up of areas. I.e. SO have a site type 
> and an area type.
> 
> <site>
> 	<id>1</id>
> 	<name>Auckland</name>
> 	<area>
> 		<id>1</id>
> 		<name>Onehunga</name>
> 	</area>
> </site>
> 
> 
> So in my areapimpl class how do I access the id from sitepimpl (ie I
> need the site_id for my area record)? 

There is no built-in mechanism for this kind of access since the data 
normally flows from inner parsers to the outer ones. The recommended
way to handle this is to propagate the information from inner parsers
to the point where you have all the parts necessary to process it. In
your case, to handle area you need the area data itself as well as
the site id. The place where all this information can be made 
conveniently available is the site_pimpl::area() callback. Here is
an outline of the site_pimpl class:

// In the type map, map XML Schema type for area to this struct.
// 
//
struct area_data
{
  int id;
  string name;
};


struct site_pimpl: size_pskel
{

  virtual void id (int v)
  {
    site_id = v;
  }

  virtual void area (const area_data& ad)
  {
    // ad and site_id contain all the information we need.
  }

private:
  int site_id;
};

struct area_pimpl: area_pskel
{
  
  virtual void id (int v)
  {
    ad.id = v;
  }

  virtual void name (const string& s)
  {
    ad.name = s;
  }
  
  virtual area_data post_area ()
  {
    return ad;
  }

private:
  area_data ad;
};

Another alternative which is not as clean but can be useful if you
can't afford to copy, say, the name string to a temporary struct
is to arrange a connection between site_pimpl and area_pimpl:


struct site_pimpl: size_pskel
{
  virtual void id (int v)
  {
    site_id = v;
  }

  int site_id;
};

struct area_pimpl: area_pskel
{  
  area_pimpl (site_pimpl& s)
    : site_p (s)
  {
  }

  virtual void id (int v)
  {
    // site_p.site_id conatins site id
  }

  virtual void name (const string& s)
  {
    // site_p.site_id conatins site id
  }
 
private:
  site_pimpl& site_p;
};

Boris