// requires: caseForOuterJoins corresponds the slot "slotNum"
// effects: Adds a WhenThen corresponding to child to caseForOuterJoins.
private void AddCaseForOuterJoins(CaseStatement caseForOuterJoins, CqlBlock child, int slotNum, CqlIdentifiers identifiers)
{
// Determine the cells that the slot comes from
// and make an OR expression, e.g., WHEN _from0 or _from2 or ... THEN child[slotNum]
ProjectedSlot childSlot = child.SlotValue(slotNum);
ConstantProjectedSlot constantSlot = childSlot as ConstantProjectedSlot;
if (constantSlot != null && constantSlot.CellConstant.IsNull())
{
// NULL being generated by a child - don't need to project
return;
}
BoolExpression originBool = BoolExpression.False;
for (int i = 0; i < NumBoolSlots; i++)
{
int boolSlotNum = BoolIndexToSlot(i);
if (child.IsProjected(boolSlotNum))
{
// OR it to the expression
QualifiedCellIdBoolean boolExpr = new QualifiedCellIdBoolean(child, identifiers, i);
originBool = BoolExpression.CreateOr(originBool, BoolExpression.CreateLiteral(boolExpr, RightDomainMap));
}
}
// Qualify the slotNum with the child.CqlAlias for the THEN
QualifiedSlot slot = child.QualifySlotWithBlockAlias(slotNum);
caseForOuterJoins.AddWhenThen(originBool, slot);
}
// requires: children to be a list of nodes that are children of an
// Inner Join node. slotNum does not correspond to the key slot
// effects: Determines the child number from which the slot should be
// picked up.
private static int GetInnerJoinChildForSlot(List <CqlBlock> children, int slotNum)
{
// Picks the child with the non-constant slot first. If none, picks a non-null constant slot.
// If not een that, picks any one
int result = -1;
for (int i = 0; i < children.Count; i++)
{
CqlBlock child = children[i];
if (false == child.IsProjected(slotNum))
{
continue;
}
ProjectedSlot slot = child.SlotValue(slotNum);
ConstantProjectedSlot constantSlot = slot as ConstantProjectedSlot;
MemberProjectedSlot joinSlot = slot as MemberProjectedSlot;
if (joinSlot != null)
{ // Pick the non-constant slot
result = i;
}
else if (constantSlot != null && constantSlot.CellConstant.IsNull())
{
if (result == -1)
{ // In case, all are null
result = i;
}
}
else
{
// Just pick anything
result = i;
}
}
return(result);
}
protected override bool IsEqualTo(ProjectedSlot right)
{
ConstantProjectedSlot rightSlot = right as ConstantProjectedSlot;
if (rightSlot == null)
{
return(false);
}
return(Constant.EqualityComparer.Equals(m_constant, rightSlot.m_constant));
}
/// <summary>
/// Simplifies the <see cref="CaseStatement"/> so that unnecessary WHEN/THENs for nulls/undefined values are eliminated.
/// Also, adds an ELSE clause if possible.
/// </summary>
internal void Simplify()
{
if (m_simplified)
{
return;
}
List <CaseStatement.WhenThen> clauses = new List <CaseStatement.WhenThen>();
// remove all WHEN clauses where the value gets set to "undefined"
// We eliminate the last clause for now - we could determine the
// "most complicated" WHEN clause and eliminate it
bool eliminatedNullClauses = false;
foreach (WhenThen clause in m_clauses)
{
ConstantProjectedSlot constantSlot = clause.Value as ConstantProjectedSlot;
// If null or undefined, remove it
if (constantSlot != null && (constantSlot.CellConstant.IsNull() || constantSlot.CellConstant.IsUndefined()))
{
eliminatedNullClauses = true;
}
else
{
clauses.Add(clause);
if (clause.Condition.IsTrue)
{
// none of subsequent case statements will be evaluated - ignore them
break;
}
}
}
if (eliminatedNullClauses && clauses.Count == 0)
{
// There is nothing left -- we should add a null as the value
m_elseValue = new ConstantProjectedSlot(Constant.Null, m_memberPath);
}
// If we eliminated some undefined or null clauses, we do not want an else clause
if (clauses.Count > 0 && false == eliminatedNullClauses)
{
// turn the last WHEN clause into an ELSE
int lastIndex = clauses.Count - 1;
m_elseValue = clauses[lastIndex].Value;
clauses.RemoveAt(lastIndex);
}
m_clauses = clauses;
m_simplified = true;
}
private bool TryGetInstantiatedType(ProjectedSlot slot, out EdmType type)
{
type = null;
ConstantProjectedSlot constantSlot = slot as ConstantProjectedSlot;
if (constantSlot != null)
{
TypeConstant typeConstant = constantSlot.CellConstant as TypeConstant;
if (typeConstant != null)
{
type = typeConstant.EdmType;
return(true);
}
}
return(false);
}
private static void WithRelationshipsClauseAsCql(Action <WithRelationship> emitWithRelationship, IEnumerable <WithRelationship> withRelationships, ProjectedSlot slot)
{
if (withRelationships != null && withRelationships.Count() > 0)
{
ConstantProjectedSlot constantSlot = slot as ConstantProjectedSlot;
Debug.Assert(constantSlot != null, "WITH RELATIONSHIP clauses should be specified for type constant slots only.");
TypeConstant typeConstant = constantSlot.CellConstant as TypeConstant;
Debug.Assert(typeConstant != null, "WITH RELATIONSHIP clauses should be there for type constants only.");
EdmType fromType = typeConstant.EdmType;
foreach (WithRelationship withRelationship in withRelationships)
{
// Add With statement for the types that participate in the association.
if (withRelationship.FromEndEntityType.IsAssignableFrom(fromType))
{
emitWithRelationship(withRelationship);
}
}
}
}
internal override CqlBlock ToCqlBlock(bool[] requiredSlots, CqlIdentifiers identifiers, ref int blockAliasNum, ref List <WithRelationship> withRelationships)
{
// Get the projected slots and the boolean expressions
int totalSlots = requiredSlots.Length;
CellQuery cellQuery = LeftCellWrapper.RightCellQuery;
SlotInfo[] projectedSlots = new SlotInfo[totalSlots];
Debug.Assert(cellQuery.NumProjectedSlots + cellQuery.NumBoolVars == totalSlots,
"Wrong number of projected slots in node");
Debug.Assert(cellQuery.NumProjectedSlots == ProjectedSlotMap.Count,
"Different number of slots in cell query and what we have mappings for");
// Add the regular fields
for (int i = 0; i < cellQuery.NumProjectedSlots; i++)
{
ProjectedSlot slot = cellQuery.ProjectedSlotAt(i);
// If the slot is not null, we will project it
// For extents, we say that all requiredlots are the only the
// ones that are CLR non-null. Recall that "real" nulls are
// handled by having a CellConstant.Null in ConstantSlot
if (requiredSlots[i] && slot == null)
{
MemberPath memberPath = ProjectedSlotMap[i];
ConstantProjectedSlot defaultValue = new ConstantProjectedSlot(Domain.GetDefaultValueForMemberPath(memberPath, GetLeaves(), ViewgenContext.Config), memberPath);
cellQuery.FixMissingSlotAsDefaultConstant(i, defaultValue);
slot = defaultValue;
}
SlotInfo slotInfo = new SlotInfo(requiredSlots[i], slot != null,
slot, ProjectedSlotMap[i]);
projectedSlots[i] = slotInfo;
}
// Add the boolean fields
for (int boolNum = 0; boolNum < cellQuery.NumBoolVars; boolNum++)
{
BoolExpression expr = cellQuery.GetBoolVar(boolNum);
BooleanProjectedSlot boolSlot;
if (expr != null)
{
boolSlot = new BooleanProjectedSlot(expr, identifiers, boolNum);
}
else
{
boolSlot = new BooleanProjectedSlot(BoolExpression.False, identifiers, boolNum);
}
int slotIndex = BoolIndexToSlot(boolNum);
SlotInfo slotInfo = new SlotInfo(requiredSlots[slotIndex], expr != null,
boolSlot, null);
projectedSlots[slotIndex] = slotInfo;
}
// See if we are generating a query view and whether there are any colocated foreign keys for which
// we have to add With statements.
IEnumerable <SlotInfo> totalProjectedSlots = projectedSlots;
if ((cellQuery.Extent.EntityContainer.DataSpace == DataSpace.SSpace) &&
(this.m_cellWrapper.LeftExtent.BuiltInTypeKind == BuiltInTypeKind.EntitySet))
{
IEnumerable <StorageAssociationSetMapping> associationSetMaps =
this.ViewgenContext.EntityContainerMapping.GetRelationshipSetMappingsFor(this.m_cellWrapper.LeftExtent, cellQuery.Extent);
List <SlotInfo> foreignKeySlots = new List <SlotInfo>();
foreach (StorageAssociationSetMapping colocatedAssociationSetMap in associationSetMaps)
{
WithRelationship withRelationship;
if (TryGetWithRelationship(colocatedAssociationSetMap, this.m_cellWrapper.LeftExtent, cellQuery.SourceExtentMemberPath, ref foreignKeySlots, out withRelationship))
{
withRelationships.Add(withRelationship);
totalProjectedSlots = projectedSlots.Concat(foreignKeySlots);
}
}
}
ExtentCqlBlock result = new ExtentCqlBlock(cellQuery.Extent, cellQuery.SelectDistinctFlag, totalProjectedSlots.ToArray(),
cellQuery.WhereClause, identifiers, ++blockAliasNum);
return(result);
}
// effects: Generates a SlotInfo object for a slot of a join node. It
// uses the type of the join operation (opType), whether the slot is
// required by the parent or not (isRequiredSlot), the children of
// this node (children) and the number of the slotNum
private SlotInfo GetJoinSlotInfo(CellTreeOpType opType, bool isRequiredSlot,
List <CqlBlock> children, int slotNum, CqlIdentifiers identifiers)
{
if (false == isRequiredSlot)
{
// The slot will not be used. So we can set the projected slot to be null
SlotInfo unrequiredSlotInfo = new SlotInfo(false, false, null, GetMemberPath(slotNum));
return(unrequiredSlotInfo);
}
// For a required slot, determine the child who is contributing to this value
int childDefiningSlot = -1;
CaseStatement caseForOuterJoins = null;
for (int childNum = 0; childNum < children.Count; childNum++)
{
CqlBlock child = children[childNum];
if (false == child.IsProjected(slotNum))
{
continue;
}
// For keys, we can pick any child block. So the first
// one that we find is fine as well
if (IsKeySlot(slotNum))
{
childDefiningSlot = childNum;
break;
}
else if (opType == CellTreeOpType.IJ)
{
// For Inner Joins, most of the time, the entries will be
// the same in all the children. However, in some cases,
// we will end up with NULL in one child and an actual
// value in another -- we should pick up the actual value in that case
childDefiningSlot = GetInnerJoinChildForSlot(children, slotNum);
break;
}
else
{
// For LOJs, we generate a case statement if more than
// one child generates the value - until then we do not
// create the caseForOuterJoins object
if (childDefiningSlot != -1)
{
// We really need a case statement now
// We have the value being generated by another child
// We need to fetch the variable from the appropriate child
Debug.Assert(false == IsBoolSlot(slotNum), "Boolean slots cannot come from two children");
if (caseForOuterJoins == null)
{
MemberPath outputMember = GetMemberPath(slotNum);
caseForOuterJoins = new CaseStatement(outputMember);
// Add the child that we had not added in the first shot
AddCaseForOuterJoins(caseForOuterJoins, children[childDefiningSlot], slotNum, identifiers);
}
AddCaseForOuterJoins(caseForOuterJoins, child, slotNum, identifiers);
}
childDefiningSlot = childNum;
}
}
MemberPath memberPath = GetMemberPath(slotNum);
ProjectedSlot slot = null;
// Generate the slot value -- case statement slot, or a qualified slot or null or false.
// If case statement slot has nothing, treat it as null/empty.
if (caseForOuterJoins != null && (caseForOuterJoins.Clauses.Count > 0 || caseForOuterJoins.ElseValue != null))
{
caseForOuterJoins.Simplify();
slot = new CaseStatementProjectedSlot(caseForOuterJoins, null);
}
else if (childDefiningSlot >= 0)
{
slot = children[childDefiningSlot].QualifySlotWithBlockAlias(slotNum);
}
else
{
// need to produce output slot, but don't have a value
// output NULL for fields or False for bools
if (IsBoolSlot(slotNum))
{
slot = new BooleanProjectedSlot(BoolExpression.False, identifiers, SlotToBoolIndex(slotNum));
}
else
{
slot = new ConstantProjectedSlot(Domain.GetDefaultValueForMemberPath(memberPath, GetLeaves(), ViewgenContext.Config), memberPath);
}
}
// We need to ensure that _from variables are never null since
// view generation uses 2-valued boolean logic.
// They can become null in outer joins. We compensate for it by
// adding AND NOT NULL condition on boolean slots coming from outer joins.
bool enforceNotNull = IsBoolSlot(slotNum) &&
((opType == CellTreeOpType.LOJ && childDefiningSlot > 0) ||
opType == CellTreeOpType.FOJ);
// We set isProjected to be true since we have come up with some value for it
SlotInfo slotInfo = new SlotInfo(true, true, slot, memberPath, enforceNotNull);
return(slotInfo);
}
// returns true when the case statement is completed
private bool AddRewritingToCaseStatement(
Tile<FragmentQuery> rewriting, CaseStatement caseStatement, MemberPath currentPath, Constant domainValue)
{
var whenCondition = BoolExpression.True;
// check whether the rewriting is always true or always false
// if it's always true, we don't need any other WHEN clauses in the case statement
// if it's always false, we don't need to add this WHEN clause to the case statement
// given: domainQuery is satisfied. Check (domainQuery -> rewriting)
var isAlwaysTrue = _qp.IsContainedIn(CreateTile(_domainQuery), rewriting);
var isAlwaysFalse = _qp.IsDisjointFrom(CreateTile(_domainQuery), rewriting);
Debug.Assert(!(isAlwaysTrue && isAlwaysFalse));
if (isAlwaysFalse)
{
return false; // don't need an unsatisfiable WHEN clause
}
if (isAlwaysTrue)
{
Debug.Assert(caseStatement.Clauses.Count == 0);
}
ProjectedSlot projectedSlot;
if (domainValue.HasNotNull())
{
projectedSlot = new MemberProjectedSlot(currentPath);
}
else
{
projectedSlot = new ConstantProjectedSlot(domainValue);
}
if (!isAlwaysTrue)
{
whenCondition = TileToBoolExpr(rewriting);
}
else
{
whenCondition = BoolExpression.True;
}
caseStatement.AddWhenThen(whenCondition, projectedSlot);
return isAlwaysTrue;
}
internal void FixMissingSlotAsDefaultConstant(int slotNumber, ConstantProjectedSlot slot)
{
Debug.Assert(m_projectedSlots[slotNumber] == null, "Another attempt to plug in a default value");
m_projectedSlots[slotNumber] = slot;
}
internal void FixMissingSlotAsDefaultConstant(int slotNumber, ConstantProjectedSlot slot)
{
Debug.Assert(m_projectedSlots[slotNumber] == null, "Another attempt to plug in a default value");
m_projectedSlots[slotNumber] = slot;
}