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//---------------------------------------------------------------------
// <copyright file="CQLGenerator.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System.Data.Common;
using System.Data.Common.CommandTrees;
using System.Data.Common.Utils;
using System.Data.Mapping.ViewGeneration.Structures;
using System.Collections.Generic;
using System.Data.Mapping.ViewGeneration.CqlGeneration;
using System.Text;
using System.Diagnostics;
using System.Data.Metadata.Edm;
namespace System.Data.Mapping.ViewGeneration
{
/// <summary>
/// This class is responsible for generation of CQL after the cell merging process has been done.
/// </summary>
internal sealed class CqlGenerator : InternalBase
{
#region Constructor
/// <summary>
/// Given the generated <paramref name="view"/>, the <paramref name="caseStatements"/> for the multiconstant fields,
/// the <paramref name="projectedSlotMap"/> that maps different paths of the entityset (for which the view is being generated) to slot indexes in the view,
/// creates an object that is capable of generating the Cql for <paramref name="view"/>.
/// </summary>
internal CqlGenerator(CellTreeNode view,
Dictionary<MemberPath,
CaseStatement> caseStatements,
CqlIdentifiers identifiers,
MemberProjectionIndex projectedSlotMap,
int numCellsInView,
BoolExpression topLevelWhereClause,
StorageMappingItemCollection mappingItemCollection)
{
m_view = view;
m_caseStatements = caseStatements;
m_projectedSlotMap = projectedSlotMap;
m_numBools = numCellsInView; // We have that many booleans
m_topLevelWhereClause = topLevelWhereClause;
m_identifiers = identifiers;
m_mappingItemCollection = mappingItemCollection;
}
#endregion
#region Fields
/// <summary>
/// The generated view from the cells.
/// </summary>
private readonly CellTreeNode m_view;
/// <summary>
/// Case statements for the multiconstant fields.
/// </summary>
private readonly Dictionary<MemberPath, CaseStatement> m_caseStatements;
/// <summary>
/// Mapping from member paths to slot indexes.
/// </summary>
private MemberProjectionIndex m_projectedSlotMap;
/// <summary>
/// Number of booleans in the view, one per cell (from0, from1, etc...)
/// </summary>
private readonly int m_numBools;
/// <summary>
/// A counter used to generate aliases for blocks.
/// </summary>
private int m_currentBlockNum = 0;
private readonly BoolExpression m_topLevelWhereClause;
/// <summary>
/// Identifiers used in the Cql queries.
/// </summary>
private readonly CqlIdentifiers m_identifiers;
private readonly StorageMappingItemCollection m_mappingItemCollection;
#endregion
#region Properties
private int TotalSlots
{
get { return m_projectedSlotMap.Count + m_numBools; }
}
#endregion
#region CqlBlock generation methods for all node types
/// <summary>
/// Returns eSQL query that represents a query/update mapping view for the view information that was supplied in the constructor.
/// </summary>
internal string GenerateEsql()
{
// Generate a CqlBlock tree and then convert that to eSQL.
CqlBlock blockTree = GenerateCqlBlockTree();
// Create the string builder with 1K so that we don't have to
// keep growing it
StringBuilder builder = new StringBuilder(1024);
blockTree.AsEsql(builder, true, 1);
return builder.ToString();
}
/// <summary>
/// Returns Cqtl query that represents a query/update mapping view for the view information that was supplied in the constructor.
/// </summary>
internal DbQueryCommandTree GenerateCqt()
{
// Generate a CqlBlock tree and then convert that to CQT.
CqlBlock blockTree = GenerateCqlBlockTree();
DbExpression query = blockTree.AsCqt(true);
Debug.Assert(query != null, "Null CQT generated for query/update view.");
return DbQueryCommandTree.FromValidExpression(m_mappingItemCollection.Workspace, TargetPerspective.TargetPerspectiveDataSpace, query);
}
/// <summary>
/// Generates a <see cref="CqlBlock"/> tree that is capable of generating the actual Cql strings.
/// </summary>
private CqlBlock GenerateCqlBlockTree()
{
// Essentially, we create a block for each CellTreeNode in the
// tree and then we layer case statements on top of that view --
// one case statement for each multiconstant entry
// Dertmine the slots that are projected by the whole tree. Tell
// the children that they need to produce those slots somehow --
// if they don't have it, they can produce null
bool[] requiredSlots = GetRequiredSlots();
Debug.Assert(requiredSlots.Length == TotalSlots, "Wrong number of requiredSlots");
List<WithRelationship> withRelationships = new List<WithRelationship>();
CqlBlock viewBlock = m_view.ToCqlBlock(requiredSlots, m_identifiers, ref m_currentBlockNum, ref withRelationships);
// Handle case statements for multiconstant entries
// Right now, we have a simplication step that removes one of the
// entries and adds ELSE instead
foreach (CaseStatement statement in m_caseStatements.Values)
{
statement.Simplify();
}
// Generate the case statements and get the top level block which
// must correspond to the entity set
CqlBlock finalViewBlock = ConstructCaseBlocks(viewBlock, withRelationships);
return finalViewBlock;
}
private bool[] GetRequiredSlots()
{
bool[] requiredSlots = new bool[TotalSlots];
// union all slots that are required in case statements
foreach (CaseStatement caseStatement in m_caseStatements.Values)
{
GetRequiredSlotsForCaseMember(caseStatement.MemberPath, requiredSlots);
}
// For now, make sure that all booleans are required
// Reason: OUTER JOINs may introduce an extra CASE statement (in OpCellTreeNode.cs/GetJoinSlotInfo)
// if a member is projected in both inputs to the join.
// This case statement may use boolean variables that may not be marked as "required"
// The problem is that this decision is made _after_ CqlBlocks for children get produced (in OpCellTreeNode.cs/JoinToCqlBlock)
for (int i = TotalSlots - m_numBools; i < TotalSlots; i++)
{
requiredSlots[i] = true;
}
// Because of the above we don't need to harvest used booleans from the top-level WHERE clause
// m_topLevelWhereClause.GetRequiredSlots(m_projectedSlotMap, requiredSlots);
// Do we require the case statement member slot be produced by the inner queries?
foreach (CaseStatement caseStatement in m_caseStatements.Values)
{
bool notNeeded = !caseStatement.MemberPath.IsPartOfKey && // keys are required in inner queries for joins conditions
!caseStatement.DependsOnMemberValue; // if case statement returns its slot value as one of the options, then we need to produce it
if (notNeeded)
{
requiredSlots[m_projectedSlotMap.IndexOf(caseStatement.MemberPath)] = false;
}
}
return requiredSlots;
}
#endregion
#region Multiconstant CaseStatement methods
/// <summary>
/// Given the <paramref name="viewBlock"/> tree, generates the case statement blocks on top of it (using <see cref="m_caseStatements"/>) and returns the resulting tree.
/// One block per case statement is generated. Generated blocks are nested, with the <paramref name="viewBlock"/> is the innermost input.
/// </summary>
private CqlBlock ConstructCaseBlocks(CqlBlock viewBlock, IEnumerable<WithRelationship> withRelationships)
{
// Get the 0th slot only, i.e., the extent
bool[] topSlots = new bool[TotalSlots];
topSlots[0] = true;
// all booleans in the top-level WHERE clause are required and get bubbled up
// this makes some _fromX booleans be marked as 'required by parent'
m_topLevelWhereClause.GetRequiredSlots(m_projectedSlotMap, topSlots);
CqlBlock result = ConstructCaseBlocks(viewBlock, 0, topSlots, withRelationships);
return result;
}
/// <summary>
/// Given the <paramref name="viewBlock"/> tree generated by the cell merging process and the <paramref name="parentRequiredSlots"/>,
/// generates the block tree for the case statement at or past the startSlotNum, i.e., only for case statements that are beyond startSlotNum.
/// </summary>
private CqlBlock ConstructCaseBlocks(CqlBlock viewBlock, int startSlotNum, bool[] parentRequiredSlots, IEnumerable<WithRelationship> withRelationships)
{
int numMembers = m_projectedSlotMap.Count;
// Find the next slot for which we have a case statement, i.e.,
// which was in the multiconstants
int foundSlot = FindNextCaseStatementSlot(startSlotNum, parentRequiredSlots, numMembers);
if (foundSlot == -1)
{
// We have bottomed out - no more slots to generate cases for
// Just get the base view block
return viewBlock;
}
// Compute the requiredSlots for this member, i.e., what slots are needed to produce this member.
MemberPath thisMember = m_projectedSlotMap[foundSlot];
bool[] thisRequiredSlots = new bool[TotalSlots];
GetRequiredSlotsForCaseMember(thisMember, thisRequiredSlots);
Debug.Assert(thisRequiredSlots.Length == parentRequiredSlots.Length &&
thisRequiredSlots.Length == TotalSlots,
"Number of slots in array should not vary across blocks");
// Merge parent's requirements with this requirements
for (int i = 0; i < TotalSlots; i++)
{
// We do ask the children to generate the slot that we are
// producing if it is available
if (parentRequiredSlots[i])
{
thisRequiredSlots[i] = true;
}
}
// If current case statement depends on its slot value, then make sure the value is produced by the child block.
CaseStatement thisCaseStatement = m_caseStatements[thisMember];
thisRequiredSlots[foundSlot] = thisCaseStatement.DependsOnMemberValue;
// Recursively, determine the block tree for slots beyond foundSlot.
CqlBlock childBlock = ConstructCaseBlocks(viewBlock, foundSlot + 1, thisRequiredSlots, null);
// For each slot, create a SlotInfo object
SlotInfo[] slotInfos = CreateSlotInfosForCaseStatement(parentRequiredSlots, foundSlot, childBlock, thisCaseStatement, withRelationships);
m_currentBlockNum++;
// We have a where clause only at the top level
BoolExpression whereClause = startSlotNum == 0 ? m_topLevelWhereClause : BoolExpression.True;
if (startSlotNum == 0)
{
// only slot #0 is required by parent; reset all 'required by parent' booleans introduced above
for (int i = 1; i < slotInfos.Length; i++)
{
slotInfos[i].ResetIsRequiredByParent();
}
}
CaseCqlBlock result = new CaseCqlBlock(slotInfos, foundSlot, childBlock, whereClause, m_identifiers, m_currentBlockNum);
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)
{
int numSlotsAddedByChildBlock = childBlock.Slots.Count - TotalSlots;
SlotInfo[] slotInfos = new SlotInfo[TotalSlots + numSlotsAddedByChildBlock];
for (int slotNum = 0; slotNum < TotalSlots; slotNum++)
{
bool isProjected = childBlock.IsProjected(slotNum);
bool isRequiredByParent = parentRequiredSlots[slotNum];
ProjectedSlot slot = childBlock.SlotValue(slotNum);
MemberPath 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
CaseStatement 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"
SlotInfo slotInfo = new SlotInfo(isRequiredByParent && isProjected, isProjected, slot, outputMember);
slotInfos[slotNum] = slotInfo;
}
for (int i = TotalSlots; i < TotalSlots + numSlotsAddedByChildBlock; i++)
{
QualifiedSlot childAddedSlot = childBlock.QualifySlotWithBlockAlias(i);
slotInfos[i] = new SlotInfo(true, true, childAddedSlot, childBlock.MemberPath(i));
}
return slotInfos;
}
/// <summary>
/// Returns the next slot starting at <paramref name="startSlotNum"/> that is present in the <see cref="m_caseStatements"/>.
/// </summary>
private int FindNextCaseStatementSlot(int startSlotNum, bool[] parentRequiredSlots, int numMembers)
{
int foundSlot = -1;
// Simply go through the slots and check the m_caseStatements map
for (int slotNum = startSlotNum; slotNum < numMembers; slotNum++)
{
MemberPath member = m_projectedSlotMap[slotNum];
if (parentRequiredSlots[slotNum] && m_caseStatements.ContainsKey(member))
{
foundSlot = slotNum;
break;
}
}
return foundSlot;
}
/// <summary>
/// Returns an array of size <see cref="TotalSlots"/> which indicates the slots that are needed to constuct value at <paramref name="caseMemberPath"/>,
/// e.g., CPerson may need pid and name (say slots 2 and 5 - then bools[2] and bools[5] will be true.
/// </summary>
/// <param name="caseMemberPath">must be part of <see cref="m_caseStatements"/></param>
private void GetRequiredSlotsForCaseMember(MemberPath caseMemberPath, bool[] requiredSlots)
{
Debug.Assert(true == m_caseStatements.ContainsKey(caseMemberPath), "Constructing case for regular field?");
Debug.Assert(requiredSlots.Length == TotalSlots, "Invalid array size for populating required slots");
CaseStatement statement = m_caseStatements[caseMemberPath];
// Find the required slots from the when then clause conditions
// and values
bool requireThisSlot = false;
foreach (CaseStatement.WhenThen clause in statement.Clauses)
{
clause.Condition.GetRequiredSlots(m_projectedSlotMap, requiredSlots);
ProjectedSlot slot = clause.Value;
if (!(slot is ConstantProjectedSlot))
{
// If this slot is a scalar and a non-constant,
// we need the lower down blocks to generate it for us
requireThisSlot = true;
}
}
EdmType edmType = caseMemberPath.EdmType;
if (Helper.IsEntityType(edmType) || Helper.IsComplexType(edmType))
{
foreach (EdmType instantiatedType in statement.InstantiatedTypes)
{
foreach (EdmMember childMember in Helper.GetAllStructuralMembers(instantiatedType) )
{
int slotNum = GetSlotIndex(caseMemberPath, childMember);
requiredSlots[slotNum] = true;
}
}
}
else if (caseMemberPath.IsScalarType())
{
// A scalar does not need anything per se to be constructed
// unless it is referring to a field in the tree below, i.e., the THEN
// slot is not a constant slot
if (requireThisSlot)
{
int caseMemberSlotNum = m_projectedSlotMap.IndexOf(caseMemberPath);
requiredSlots[caseMemberSlotNum] = true;
}
}
else if (Helper.IsAssociationType(edmType))
{
// For an association, get the indices of the ends, e.g.,
// CProduct and CCategory in CProductCategory1
// Need just it's ends
AssociationSet associationSet = (AssociationSet)caseMemberPath.Extent;
AssociationType associationType = associationSet.ElementType;
foreach (AssociationEndMember endMember in associationType.AssociationEndMembers)
{
int slotNum = GetSlotIndex(caseMemberPath, endMember);
requiredSlots[slotNum] = true;
}
}
else
{
// For a reference, all we need are the keys
RefType refType = edmType as RefType;
Debug.Assert(refType != null, "What other non scalars do we have? Relation end must be a reference type");
EntityTypeBase refElementType = refType.ElementType;
// Go through all the members of elementType and get the key properties
EntitySet entitySet = MetadataHelper.GetEntitySetAtEnd((AssociationSet)caseMemberPath.Extent,
(AssociationEndMember)caseMemberPath.LeafEdmMember);
foreach (EdmMember entityMember in refElementType.KeyMembers)
{
int slotNum = GetSlotIndex(caseMemberPath, entityMember);
requiredSlots[slotNum] = true;
}
}
}
#endregion
#region Helper methods
/// <summary>
/// Given the <paramref name="slotNum"/>, returns the output member path that this slot contributes/corresponds to in the extent view.
/// If the slot corresponds to one of the boolean variables, returns null.
/// </summary>
private MemberPath GetOutputMemberPath(int slotNum)
{
return m_projectedSlotMap.GetMemberPath(slotNum, TotalSlots - m_projectedSlotMap.Count);
}
/// <summary>
/// Returns the slot index for the following member path: <paramref name="member"/>.<paramref name="child"/>, e.g., CPerson1.pid
/// </summary>
private int GetSlotIndex(MemberPath member, EdmMember child)
{
MemberPath fullMember = new MemberPath(member, child);
int index = m_projectedSlotMap.IndexOf(fullMember);
Debug.Assert(index != -1, "Couldn't locate " + fullMember.ToString() + " in m_projectedSlotMap");
return index;
}
#endregion
#region String methods
internal override void ToCompactString(StringBuilder builder)
{
builder.Append("View: ");
m_view.ToCompactString(builder);
builder.Append("ProjectedSlotMap: ");
m_projectedSlotMap.ToCompactString(builder);
builder.Append("Case statements: ");
foreach (MemberPath member in m_caseStatements.Keys)
{
CaseStatement statement = m_caseStatements[member];
statement.ToCompactString(builder);
builder.AppendLine();
}
}
#endregion
}
}
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