Re: Transitive Closure with XDb1

> Leandro said: You are 30 years late. Relational is declarative.

Below shows how to create the simple hierarchy "declaratively" via XDb1's API and loop thru parts of universe.

void Example003()
{
// Vars set by S_process_r

   int* pR_r = NULL; // Relation created    const kMsgSz = 1023; // Error message size    TCHAR msg_r[kMsgSz+1] = _T(""); // Error message

// Create universe

   S_process_r(_T("universe isa thing"), NULL, msg_r, kMsgSz, &pR_r);

// Create planets

   S_process_r(_T("planet isa thing"), NULL, msg_r, kMsgSz, &pR_r);
   S_process_r(_T("mars isa planet"), NULL, msg_r, kMsgSz, &pR_r);
   S_process_r(_T("venus isa planet"), NULL, msg_r, kMsgSz, &pR_r);

// Create persons

   S_process_r(_T("person isa thing"), NULL, msg_r, kMsgSz, &pR_r);
   S_process_r(_T("john isa person"), NULL, msg_r, kMsgSz, &pR_r);
   S_process_r(_T("mary isa person"), NULL, msg_r, kMsgSz, &pR_r);

// Create hierarchy

   S_process_r(_T("mars isPartOf universe"), NULL,msg_r,kMsgSz,&pR_r);
   S_process_r(_T("venus isPartOf universe"),NULL,msg_r,kMsgSz,&pR_r);
   S_process_r(_T("john isPartOf mars"), NULL, msg_r, kMsgSz, &pR_r);
   S_process_r(_T("mary isPartOf venus"), NULL, msg_r, kMsgSz, &pR_r);

// Get ptr to universe
// Note: one of several methods

   int* pUniverse = R_Dest(Str_getDefT(_T("universe")));

// Looping thru parts of universe
// Prints: mars, john, venus, mary

   #define maxTreeDepth 64
   int* pDescX_a[maxTreeDepth] = {T_R_PriRecip(pUniverse), NULL};    while (int i=T_Relative(pDescX_a, maxTreeDepth, rPart, TRUE)){

      TCHAR sName[kNmSz_g+1] = _T("");
      int* pT = R_Dest(pDescX_a[i]);
      T_Name_get(pT, sName, kNmSz_g);
      TRACE(_T("%s\n"), sName);