/// <summary>
/// Recursively qualifies all <see cref="ProjectedSlot" />s and returns a new deeply qualified
/// <see
/// cref="CaseStatement" />
/// .
/// </summary>
internal CaseStatement DeepQualify(CqlBlock block)
{
// Go through the whenthens and else and make a new case statement with qualified slots as needed.
var result = new CaseStatement(m_memberPath);
foreach (var whenThen in m_clauses)
{
var newClause = whenThen.ReplaceWithQualifiedSlot(block);
result.m_clauses.Add(newClause);
}
if (m_elseValue != null)
{
result.m_elseValue = m_elseValue.DeepQualify(block);
}
result.m_simplified = m_simplified;
return result;
}
/// <summary>
/// Given the slot (<paramref name="foundSlot" />) and its corresponding case statement (
/// <paramref
/// name="thisCaseStatement" />
/// ),
/// generates the slotinfos for the cql block producing the case statement.
/// </summary>
private SlotInfo[] CreateSlotInfosForCaseStatement(
bool[] parentRequiredSlots,
int foundSlot,
CqlBlock childBlock,
CaseStatement thisCaseStatement,
IEnumerable<WithRelationship> withRelationships)
{
var numSlotsAddedByChildBlock = childBlock.Slots.Count - TotalSlots;
var slotInfos = new SlotInfo[TotalSlots + numSlotsAddedByChildBlock];
for (var slotNum = 0; slotNum < TotalSlots; slotNum++)
{
var isProjected = childBlock.IsProjected(slotNum);
var isRequiredByParent = parentRequiredSlots[slotNum];
var slot = childBlock.SlotValue(slotNum);
var outputMember = GetOutputMemberPath(slotNum);
if (slotNum == foundSlot)
{
// We need a case statement instead for this slot that we
// are handling right now
Debug.Assert(isRequiredByParent, "Case result not needed by parent");
// Get a case statement with all slots replaced by aliases slots
var newCaseStatement = thisCaseStatement.DeepQualify(childBlock);
slot = new CaseStatementProjectedSlot(newCaseStatement, withRelationships);
isProjected = true; // We are projecting this slot now
}
else if (isProjected && isRequiredByParent)
{
// We only alias something that is needed and is being projected by the child.
// It is a qualified slot into the child block.
slot = childBlock.QualifySlotWithBlockAlias(slotNum);
}
// For slots, if it is not required by the parent, we want to
// set the isRequiredByParent for this slot to be
// false. Furthermore, we do not want to introduce any "NULL
// AS something" at this stage for slots not being
// projected. So if the child does not project that slot, we
// declare it as not being required by the parent (if such a
// NULL was needed, it would have been pushed all the way
// down to a non-case block.
// Essentially, from a Case statement's parent perspective,
// it is saying "If you can produce a slot either by yourself
// or your children, please do. Otherwise, do not concoct anything"
var slotInfo = new SlotInfo(isRequiredByParent && isProjected, isProjected, slot, outputMember);
slotInfos[slotNum] = slotInfo;
}
for (var i = TotalSlots; i < TotalSlots + numSlotsAddedByChildBlock; i++)
{
var childAddedSlot = childBlock.QualifySlotWithBlockAlias(i);
slotInfos[i] = new SlotInfo(true, true, childAddedSlot, childBlock.MemberPath(i));
}
return slotInfos;
}
// for backward compatibility: add (WHEN True THEN Type) for non-scalar types
internal void AddTrivialCaseStatementsForConditionMembers()
{
for (var memberNum = 0; memberNum < _context.MemberMaps.ProjectedSlotMap.Count; memberNum++)
{
var memberPath = _context.MemberMaps.ProjectedSlotMap[memberNum];
if (!memberPath.IsScalarType()
&& !_caseStatements.ContainsKey(memberPath))
{
Constant typeConstant = new TypeConstant(memberPath.EdmType);
{
var caseStmt = new CaseStatement(memberPath);
caseStmt.AddWhenThen(BoolExpression.True, new ConstantProjectedSlot(typeConstant));
_caseStatements[memberPath] = caseStmt;
}
}
}
}
private void AddElseDefaultToCaseStatement(
MemberPath currentPath, CaseStatement caseStatement, List<Constant> domain,
CellTreeNode rightDomainQuery, Tile<FragmentQuery> unionCaseRewriting)
{
Debug.Assert(_context.ViewTarget == ViewTarget.UpdateView, "Used for update views only");
Constant defaultValue;
var hasDefaultValue = Domain.TryGetDefaultValueForMemberPath(currentPath, out defaultValue);
if (false == hasDefaultValue
|| false == domain.Contains(defaultValue))
{
Debug.Assert(unionCaseRewriting != null, "No union of rewritings for case statements");
var unionTree = TileToCellTree(unionCaseRewriting, _context);
var configurationNeedsDefault = _context.RightFragmentQP.Difference(
rightDomainQuery.RightFragmentQuery, unionTree.RightFragmentQuery);
if (_context.RightFragmentQP.IsSatisfiable(configurationNeedsDefault))
{
if (hasDefaultValue)
{
caseStatement.AddWhenThen(BoolExpression.True, new ConstantProjectedSlot(defaultValue));
}
else
{
configurationNeedsDefault.Condition.ExpensiveSimplify();
var builder = new StringBuilder();
builder.AppendLine(
Strings.ViewGen_No_Default_Value_For_Configuration(currentPath.PathToString(false /* for alias */)));
_errorLog.AddEntry(
new ErrorLog.Record(
ViewGenErrorCode.NoDefaultValue, builder.ToString(), _context.AllWrappersForExtent, String.Empty));
}
}
}
}
// Modifies _caseStatements and _topLevelWhereClause
private List<LeftCellWrapper> RemapFromVariables()
{
var usedCells = new List<LeftCellWrapper>();
// remap CellIdBooleans appearing in WHEN clauses and in topLevelWhereClause so the first used cell = 0, second = 1, etc.
// This ordering is exploited in CQL generation
var newNumber = 0;
var literalRemap = new Dictionary<BoolLiteral, BoolLiteral>(BoolLiteral.EqualityIdentifierComparer);
foreach (var leftCellWrapper in _context.AllWrappersForExtent)
{
if (_usedViews.Contains(leftCellWrapper.FragmentQuery))
{
usedCells.Add(leftCellWrapper);
var oldNumber = leftCellWrapper.OnlyInputCell.CellNumber;
if (newNumber != oldNumber)
{
literalRemap[new CellIdBoolean(_identifiers, oldNumber)] = new CellIdBoolean(_identifiers, newNumber);
}
newNumber++;
}
}
if (literalRemap.Count > 0)
{
// Remap _from literals in WHERE clause
_topLevelWhereClause = _topLevelWhereClause.RemapLiterals(literalRemap);
// Remap _from literals in case statements
var newCaseStatements = new Dictionary<MemberPath, CaseStatement>();
foreach (var entry in _caseStatements)
{
var newCaseStatement = new CaseStatement(entry.Key);
Debug.Assert(entry.Value.ElseValue == null);
foreach (var clause in entry.Value.Clauses)
{
newCaseStatement.AddWhenThen(clause.Condition.RemapLiterals(literalRemap), clause.Value);
}
newCaseStatements[entry.Key] = newCaseStatement;
}
_caseStatements = newCaseStatements;
}
return usedCells;
}
private void GenerateCaseStatements(
IEnumerable<MemberPath> members,
HashSet<FragmentQuery> outputUsedViews)
{
// Compute right domain query - non-simplified version of "basic view"
// It is used below to check whether we need a default value in a case statement
var usedCells = _context.AllWrappersForExtent.Where(w => _usedViews.Contains(w.FragmentQuery));
CellTreeNode rightDomainQuery = new OpCellTreeNode(
_context, CellTreeOpType.Union,
usedCells.Select(wrapper => new LeafCellTreeNode(_context, wrapper)).ToArray());
foreach (var currentPath in members)
{
// Add the types can member have, i.e., its type and its subtypes
var domain = GetDomain(currentPath).ToList();
var caseStatement = new CaseStatement(currentPath);
Tile<FragmentQuery> unionCaseRewriting = null;
// optimization for domain = {NULL, NOT_NULL}
// Create a single case: WHEN True THEN currentPath
// Reason: if the WHEN condition is not satisfied (say because of LOJ), then currentPath = NULL
var needCaseStatement =
!(domain.Count == 2 &&
domain.Contains(Constant.Null, Constant.EqualityComparer) &&
domain.Contains(Constant.NotNull, Constant.EqualityComparer));
{
// go over the domain
foreach (var domainValue in domain)
{
if (domainValue == Constant.Undefined
&& _context.ViewTarget == ViewTarget.QueryView)
{
// we cannot assume closed domain for query views;
// if obtaining undefined is possible, we need to account for that
caseStatement.AddWhenThen(
BoolExpression.False /* arbitrary condition */,
new ConstantProjectedSlot(Constant.Undefined));
continue;
}
TraceVerbose("CASE STATEMENT FOR {0}={1}", currentPath, domainValue);
// construct WHERE clause for this value
var memberConditionQuery = CreateMemberConditionQuery(currentPath, domainValue);
Tile<FragmentQuery> caseRewriting;
if (FindRewritingAndUsedViews(
memberConditionQuery.Attributes, memberConditionQuery.Condition, outputUsedViews, out caseRewriting))
{
if (_context.ViewTarget
== ViewTarget.UpdateView)
{
unionCaseRewriting = (unionCaseRewriting != null)
? _qp.Union(unionCaseRewriting, caseRewriting)
: caseRewriting;
}
if (needCaseStatement)
{
var isAlwaysTrue = AddRewritingToCaseStatement(caseRewriting, caseStatement, currentPath, domainValue);
if (isAlwaysTrue)
{
break;
}
}
}
else
{
if (!IsDefaultValue(domainValue, currentPath))
{
Debug.Assert(_context.ViewTarget == ViewTarget.UpdateView || !_config.IsValidationEnabled);
if (!ErrorPatternMatcher.FindMappingErrors(_context, _domainMap, _errorLog))
{
var builder = new StringBuilder();
var extentName = StringUtil.FormatInvariant("{0}", _extentPath);
var objectString = _context.ViewTarget == ViewTarget.QueryView
? Strings.ViewGen_Entities
: Strings.ViewGen_Tuples;
if (_context.ViewTarget
== ViewTarget.QueryView)
{
builder.AppendLine(Strings.Viewgen_CannotGenerateQueryViewUnderNoValidation(extentName));
}
else
{
builder.AppendLine(Strings.ViewGen_Cannot_Disambiguate_MultiConstant(objectString, extentName));
}
RewritingValidator.EntityConfigurationToUserString(
memberConditionQuery.Condition, builder, _context.ViewTarget == ViewTarget.UpdateView);
var record = new ErrorLog.Record(
ViewGenErrorCode.AmbiguousMultiConstants, builder.ToString(), _context.AllWrappersForExtent,
String.Empty);
_errorLog.AddEntry(record);
}
}
}
}
}
if (_errorLog.Count == 0)
{
// for update views, add WHEN True THEN defaultValue
// which will ultimately be translated into a (possibly implicit) ELSE clause
if (_context.ViewTarget == ViewTarget.UpdateView && needCaseStatement)
{
AddElseDefaultToCaseStatement(currentPath, caseStatement, domain, rightDomainQuery, unionCaseRewriting);
}
if (caseStatement.Clauses.Count > 0)
{
TraceVerbose("{0}", caseStatement.ToString());
_caseStatements[currentPath] = caseStatement;
}
}
}
}
// 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;
}
// <summary>
// Creates a slot for <paramref name="statement" />.
// </summary>
internal CaseStatementProjectedSlot(CaseStatement statement, IEnumerable<WithRelationship> withRelationships)
{
m_caseStatement = statement;
m_withRelationships = withRelationships;
}
// 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
var unrequiredSlotInfo = new SlotInfo(false, false, null, GetMemberPath(slotNum));
return(unrequiredSlotInfo);
}
// For a required slot, determine the child who is contributing to this value
var childDefiningSlot = -1;
CaseStatement caseForOuterJoins = null;
for (var childNum = 0; childNum < children.Count; childNum++)
{
var 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)
{
var 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;
}
}
var 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));
}
}
// 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.
var 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
var slotInfo = new SlotInfo(true, true, slot, memberPath, enforceNotNull);
return(slotInfo);
}
// <summary>
// Creates a slot for <paramref name="statement" />.
// </summary>
internal CaseStatementProjectedSlot(CaseStatement statement, IEnumerable <WithRelationship> withRelationships)
{
m_caseStatement = statement;
m_withRelationships = withRelationships;
}
