// PhysSequence::computeHistoryAttributes
//
// Helper function to compute the attribute for the history buffer based
// on the items projected from the child and the computed history items.
// Also, adds the attribute information the the map table.
//
void
PhysSequence::computeHistoryAttributes(Generator *generator,
MapTable *localMapTable,
Attributes **attrs,
const ValueIdSet &historyIds) const
{
// Get a local handle on some of the generator objects.
//
CollHeap *wHeap = generator->wHeap();
// Populate the attribute vector with the flattened list of sequence
// functions and/or sequence function arguments that must be in the
// history row. Add convert nodes for the items that are not sequence
// functions to force them to be moved into the history row.
//
if(NOT historyIds.isEmpty())
{
Int32 i = 0;
ValueId valId;
for (valId = historyIds.init();
historyIds.next(valId);
historyIds.advance(valId))
{
// If this is not a sequence function, then insert a convert
// node.
//
if(!valId.getItemExpr()->isASequenceFunction())
{
// Get a handle on the original expression and erase
// the value ID.
//
ItemExpr *origExpr = valId.getItemExpr();
origExpr->setValueId(NULL_VALUE_ID);
origExpr->markAsUnBound();
// Construct the cast expression with the original expression
// as the child -- must have undone the child value ID to
// avoid recursion later.
//
ItemExpr *castExpr = new(wHeap)
Cast(origExpr, &(valId.getType()));
// Replace the expression for the original value ID and the
// synthesize the types and value ID for the new expression.
//
valId.replaceItemExpr(castExpr);
castExpr->synthTypeAndValueId(TRUE);
}
attrs[i++] = (generator->addMapInfoToThis(localMapTable, valId, 0))->getAttr();
}
}
} // PhysSequence::computeHistoryAttributes
