packed array?

Design:
 Arr[0] [1] [2] [3] ... [N]  => len(Array)=N+1
Count=N 1st 2nd 3rd ... Nth
Get(-1) (0) (1) (2) ...(N-1) => for (i=0;i<p->Get(-1);i++)  p->Get(i) [...];
Count=N 1st 2nd 3rd ... Nth     Appears like a normal array.

======================================================
CvBuildingInfo::getPrereqOrBonuses()
======================================================
// returns array length when called with -1
int CvBuildingInfo::getPrereqOrBonuses(int i) const
{
    FAssertMsg(i < GC.getNUM_BUILDING_PREREQ_OR_BONUSES(), "Index out of bounds");
    if (m_piPrereqOrBonuses)
    {
        int size = m_piPrereqOrBonuses[0];
        if (i == -1)    return size;
        if (i < size)   return m_piPrereqOrBonuses[i+1];
        return -1;
    }
    return -1;
}

======================================================
CvBuildingInfo::getCheckSum()
======================================================
    if (m_piPrereqOrBonuses)    CheckSumI(iSum, m_piPrereqOrBonuses[0]+1, m_piPrereqOrBonuses);


======================================================
CvBuildingInfo::read()
======================================================
    if (pXML->TryMoveToXmlFirstChild(L"PrereqBonuses"))
    {
        iNumChildren = pXML->GetXmlChildrenNumber();
        FAssertMsg((iNumChildren <= GC.getNUM_BUILDING_PREREQ_OR_BONUSES()),"Too many Prereq Or Bonuses for the building.");
        int *tmp = new int[iNumChildren];
        int iTotal = 0;
        if (0 < iNumChildren)
        {
            if (pXML->GetChildXmlVal(szTextVal))
            {
                for (j=0; j<iNumChildren; j++)
                {
                    int eInfo = pXML->GetInfoClass(szTextVal);
                    if (eInfo != -1)    tmp[iTotal++] = eInfo;
                    if (!pXML->GetNextXmlVal(szTextVal))    break;
                }
                if (iTotal != 0)
                {
                    m_piPrereqOrBonuses = new int[iTotal+1];
                    m_piPrereqOrBonuses[0] = iTotal;
                    for (j=0; j<iTotal; j++)    m_piPrereqOrBonuses[j+1] = tmp[j];
                }
                pXML->MoveToXmlParent();
            }
        }
        else    SAFE_DELETE_ARRAY(m_piPrereqOrBonuses);
        pXML->MoveToXmlParent();
    }
    else    SAFE_DELETE_ARRAY(m_piPrereqOrBonuses);

======================================================
CvBuildingInfo::CopyNonDefaults()
======================================================
    int iTotalTheirs = pClassInfo->getPrereqOrBonuses(-1);
    if (iTotalTheirs != -1)
    {
        int iTotalOurs = 0;
        if (m_piPrereqOrBonuses)    iTotalOurs = m_piPrereqOrBonuses[0];
        int* tmp = new int[iTotalTheirs+iTotalOurs+1];
        tmp[0] = iTotalTheirs+iTotalOurs;
        for (int j=0; j<iTotalTheirs; j++)
            tmp[j+1] = pClassInfo->getPrereqOrBonuses(j);
        for (int j=0; j<iTotalOurs; j++)
            tmp[j+iTotalTheirs+1] = m_piPrereqOrBonuses[j+1];
        m_piPrereqOrBonuses = tmp;
    }

======================================================
Take Two
======================================================
// Macro for concatenating two packed arrays in CopyNonDefaults()
#define PACKED_ARRAY_COPYNONDEFAULTS(theirFn, ourArr) if (theirFn(-1) != -1) {      \
    int theirSize = theirFn(-1), ourSize = 0; if (ourArr)   ourSize = ourArr[0];    \
    int* tmp = new int[theirSize+ourSize+1]; tmp[0] = theirSize+ourSize;            \
    for (int i=0; i<theirSize; i++) tmp[i+1] = theirFn(i);                          \
    for (int i=0; i<ourSize; i++)   tmp[i+theirSize+1] = ourArr[i+1]; ourArr = tmp; }

void CvBuildingInfo::copyNonDefaults(CvBuildingInfo* pClassInfo, CvXMLLoadUtility* pXML)
{ [...]
    PACKED_ARRAY_COPYNONDEFAULTS(pClassInfo->getPrereqAndTechs, m_piPrereqAndTechs);

    if (getPrereqAndBonus() == NO_BONUS) m_iPrereqAndBonus = pClassInfo->getPrereqAndBonus();
    PACKED_ARRAY_COPYNONDEFAULTS(pClassInfo->getPrereqOrBonuses, m_piPrereqOrBonuses);
[...] }


======================================================
CvCity::CanConstructInternal()
This modification applies in four other places:
    CvGameTextMgr::buildBuildingRequiresString(),
    CvPlayer::recalculateResourceConsumption(),
    CvPlayerAI::AI_bonusTrade(), and
    CvPlayerAI::AI_baseBonusVal().
======================================================
            for (iI = 0; iI < kBuilding.getPrereqOrBonuses(-1); iI++) // was "iI < GC.getNUM_BUILDING_PREREQ_OR_BONUSES()"
            {
                if (kBuilding.getPrereqOrBonuses(iI) != NO_BONUS)
                {
                    bRequiresBonus = true;

                    if (hasBonus((BonusTypes)kBuilding.getPrereqOrBonuses(iI)))
                    {
                        bNeedsBonus = false;
                    }
                }
            }