serialization of hierarchical object/array/int/str to a flat object and back

flat_object.js

// serialization of hierarchical object/array/int/str to a flat object and back
// 
// useful to store an object in compressed column store
// so it will be compressed by type and not as blob.
// the resulting object values and keys can be escaped and converted to a sql query

//example:
// var xx=['test',{data:[1,2,"asd"]}]
// result=flat(xx)
//
// result:
// {
//  a0:'test',
//  a1_odata_a0:1,
//  a1_odata_a1:2,
//  a1_odata_a2:'asd'
// }
function flat(a,pf,ret)
{
 if(pf===undefined)pf='';
 if(ret===undefined)ret={};
 var pp=a instanceof Array?'a':'o';
 Object.keys(a).forEach(function(k)
 {
  var v=a[k];
  if(v instanceof Object)
   return flat(v,pf+pp+k+'_',ret)
  else
   ret[pf+pp+k]=v;
 });
 return ret;
}
exports.flat=flat;

//example:
// var fxx=
// {
//  a0:'test',
//  a1_odata_a0:1,
//  a1_odata_a1:2,
//  a1_odata_a2:'asd'
// }
// result=unflat(fxx)
//
// result:
// ['test',{data:[1,2,"asd"]}]

function unflat(a)
{
 var ret={};
 Object.keys(a).forEach(function(k)
 {
  var v=a[k]
  var splitedkey=k.split('_');
  var pt=ret;
  var prevkey='ret';
  for(i=0;i<splitedkey.length;i++)
  {
   var prefixedkey=splitedkey[i];
   var prevkeytype=prefixedkey[0];
   var currentkey=prevkeytype=='o'?prefixedkey.substring(1):parseInt(prefixedkey.substring(1));
   if(!(prevkey in pt)) pt[prevkey]=(prevkeytype=='o'?{}:[]);
   pt=pt[prevkey]
   prevkey=currentkey;
  }
  pt[prevkey]=v;
 })
 return ret.ret;
}
exports.unflat=unflat;