Transitive Closure with XDb1

Mars is part of Universe.
John is part of Mars.
Venus is part of Universe.
Mary is part of Venus.

The code also loops thru persons, planets and moves John to Venus and Mary to Mars.

void Example003()
{

// Create universe and classify as a thing

      int* pUniverse = T_create();
      T_relate(&pUniverse, rCls, &pThing_g);
      T_Name_relate(&pUniverse, _T("universe"));



   // Create planet and classify as a thing


      int* pPlanet = T_create();
      T_relate(&pPlanet, rCls, &pThing_g);
      T_Name_relate(&pPlanet, _T("planet"));



   // Create mars and classify as a planet


      int* pMars = T_create();
      T_relate(&pMars, rCls, &pThing_g);
      T_Name_relate(&pMars, _T("mars"));



   // Create venus and classify as a planet


      int* pVenus = T_create();
      T_relate(&pVenus, rCls, &pThing_g);
      T_Name_relate(&pVenus, _T("venus"));



   // Create person and classify as a thing


      int* pPerson = T_create();
      T_relate(&pPerson, rCls, &pThing_g);
      T_Name_relate(&pPerson, _T("person"));



   // Create john and classify as a person


      int* pJohn = T_create();
      T_relate(&pJohn, rCls, &pPerson);
      T_Name_relate(&pJohn, _T("john"));



   // Create mary and classify as a person


      int* pMary = T_create();
      T_relate(&pMary, rCls, &pPerson);
      T_Name_relate(&pMary, _T("mary"));

// Create universe hierarchy
// Note: rPart/rAsm are reciprocal relators

      T_relate(&pMars, rAsm, &pUniverse);   // or (&pUniverse, rPart, &pMars)
      T_relate(&pVenus, rAsm, &pUniverse);  // or (&pUniverse, rPart, &pVenus)
      T_relate(&pJohn, rAsm, &pMars);       // or (&pMars, rPart, &pJohn)
      T_relate(&pMary, rAsm, &pVenus);      // or (&pVenus, rPart, &pMary)
      

// Demo transitive closure by
// 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)){
         // Print name of thing
            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);
      }

// Print names of persons: john and mary
// Loop thru person's relations

      int* pR = pPerson;
      while (*(++pR)){
         // If relation is to an instance
            if (rInst == R_Type_get(pR)){
               // Print name of instance
                  TCHAR sName[kNmSz_g+1] = _T("");
                  int* pInst = R_Dest(pR);
                  T_Name_get(pInst, sName, kNmSz_g);
                  TRACE(_T("%s\n"), sName);
            }
      }

// Print names of planets: mars and venu
// Loop thru planet's relations

      pR = pPlanet;
      while (*(++pR)){
         // If relation is to an instance
            if (rInst == R_Type_get(pR)){
               // Print name of instance
                  TCHAR sName[kNmSz_g+1] = _T("");
                  int* pInst = R_Dest(pR);
                  T_Name_get(pInst, sName, kNmSz_g);
                  TRACE(_T("%s\n"), sName);
            }
      }



   // Move john from mars to venus


      // Get mar's relation to john
         pR = T_R_For(pMars, pJohn);

      // Move relation to venus
         R_move(pR, &pVenus);




   // Move mary from venus to mars


      // Get venus's relation to mary
         pR = T_R_For(pVenus, pMary);

      // Move relation to mars
         R_move(pR, &pMars);

For more info, see www.xdb1.com/Example/Ex003.asp Received on Tue May 11 2004 - 21:18:10 CEST