private DbExpression RewriteCollection(DbExpression expression)
{
DbExpression dbExpression = expression;
DbProjectExpression projectExpression = (DbProjectExpression)null;
if (DbExpressionKind.Project == expression.ExpressionKind)
{
projectExpression = (DbProjectExpression)expression;
dbExpression = projectExpression.Input.Expression;
}
ObjectSpanRewriter.NavigationInfo navInfo = (ObjectSpanRewriter.NavigationInfo)null;
if (this.RelationshipSpan)
{
dbExpression = ObjectSpanRewriter.RelationshipNavigationVisitor.FindNavigationExpression(dbExpression, this._aliasGenerator, out navInfo);
}
if (navInfo != null)
{
this.EnterNavigationCollection(navInfo);
}
else
{
this.EnterCollection();
}
DbExpression body = expression;
if (projectExpression != null)
{
DbExpression projection = this.Rewrite(projectExpression.Projection);
if (!object.ReferenceEquals((object)projectExpression.Projection, (object)projection))
{
body = (DbExpression)dbExpression.BindAs(projectExpression.Input.VariableName).Project(projection);
}
}
else
{
DbExpressionBinding input = dbExpression.BindAs(this._aliasGenerator.Next());
DbExpression variable = (DbExpression)input.Variable;
DbExpression projection = this.Rewrite(variable);
if (!object.ReferenceEquals((object)variable, (object)projection))
{
body = (DbExpression)input.Project(projection);
}
}
this.ExitCollection();
if (navInfo != null && navInfo.InUse)
{
body = (DbExpression)DbExpressionBuilder.Lambda(body, (IEnumerable <DbVariableReferenceExpression>) new List <DbVariableReferenceExpression>(1)
{
navInfo.SourceVariable
}).Invoke((IEnumerable <DbExpression>) new List <DbExpression>(1)
{
navInfo.Source
});
}
return(body);
}
/// <summary>
/// Logicaly, <see cref="DbSkipExpression"/> translates to:
/// SELECT Y.x1, Y.x2, ..., Y.xn
/// FROM (
/// SELECT X.x1, X.x2, ..., X.xn,
/// FROM input AS X
/// EXCEPT
/// SELECT TOP(count) Z.x1, Z.x2, ..., Z.xn
/// FROM input AS Z
/// ORDER BY sk1, sk2, ...
/// ) AS Y
/// ORDER BY sk1, sk2, ...
///
/// Here, input refers to the input of the <see cref="DbSkipExpression"/>, and count to the count property of the <see cref="DbSkipExpression"/>.
/// The implementation of EXCEPT is non-duplicate eliminating, and does equality comparison only over the
/// equality comparable columns of the input.
///
/// This corresponds to the following expression tree:
///
/// SORT
/// |
/// NON-DISTINCT EXCEPT (specially translated, <see cref="TransformIntersectOrExcept(DbExpression left, DbExpression right, DbExpressionKind expressionKind, IList<DbPropertyExpression> sortExpressionsOverLeft, string sortExpressionsBindingVariableName)"/>
/// |
/// | - Left: clone of input
/// | - Right:
/// |
/// Limit
/// |
/// | - Limit: Count
/// | - Input
/// |
/// Sort
/// |
/// input
///
/// </summary>
/// <param name="e"></param>
/// <returns></returns>
public override DbExpression Visit(DbSkipExpression e)
{
//Build the right input of the except
DbExpression rightInput = VisitExpressionBinding(e.Input).Sort(VisitSortOrder(e.SortOrder)).Limit(VisitExpression(e.Count));
//Build the left input for the except
DbExpression leftInput = VisitExpression(e.Input.Expression); //Another copy of the input
IList <DbSortClause> sortOrder = VisitSortOrder(e.SortOrder); //Another copy of the sort order
// Create a list of the sort expressions to be used for translating except
IList <DbPropertyExpression> sortExpressions = new List <DbPropertyExpression>(e.SortOrder.Count);
foreach (DbSortClause sortClause in sortOrder)
{
//We only care about property expressions, not about constants
if (sortClause.Expression.ExpressionKind == DbExpressionKind.Property)
{
sortExpressions.Add((DbPropertyExpression)sortClause.Expression);
}
}
DbExpression exceptExpression = TransformIntersectOrExcept(leftInput, rightInput, DbExpressionKind.Skip, sortExpressions, e.Input.VariableName);
DbExpression result = exceptExpression.BindAs(e.Input.VariableName).Sort(sortOrder);
return(result);
}
public override DbExpression Visit(DbProjectExpression expression)
{
// Only allowed cases:
// SELECT Deref(x) FROM <expression> AS x
// SELECT x FROM <expression> as x
DbExpression testExpr = expression.Projection;
if (DbExpressionKind.Deref == testExpr.ExpressionKind)
{
testExpr = ((DbDerefExpression)testExpr).Argument;
}
if (DbExpressionKind.VariableReference == testExpr.ExpressionKind)
{
DbVariableReferenceExpression varRef = (DbVariableReferenceExpression)testExpr;
if (varRef.VariableName.Equals(expression.Input.VariableName, StringComparison.Ordinal))
{
DbExpression found = Find(expression.Input.Expression);
if (!object.ReferenceEquals(found, expression.Input.Expression))
{
return(found.BindAs(expression.Input.VariableName).Project(expression.Projection));
}
}
}
return(expression);
}
public override DbExpression Visit(DbSkipExpression expression)
{
Check.NotNull <DbSkipExpression>(expression, nameof(expression));
DbExpression input = this.Find(expression.Input.Expression);
if (!object.ReferenceEquals((object)input, (object)expression.Input.Expression))
{
return((DbExpression)input.BindAs(expression.Input.VariableName).Skip((IEnumerable <DbSortClause>)expression.SortOrder, expression.Count));
}
return((DbExpression)expression);
}
public override DbExpression Visit(DbFilterExpression expression)
{
Check.NotNull <DbFilterExpression>(expression, nameof(expression));
DbExpression input = this.Find(expression.Input.Expression);
if (!object.ReferenceEquals((object)input, (object)expression.Input.Expression))
{
return((DbExpression)input.BindAs(expression.Input.VariableName).Filter(expression.Predicate));
}
return((DbExpression)expression);
}
internal virtual DbExpression OfType(TypeUsage type)
{
// s.OfType<T> is normally translated to s.Filter(e => e is T).Project(e => e as T)
DbExpressionBinding rootBinding = _root.BindAs(_aliasGenerator.Next());
DbExpression filter = this.Filter(rootBinding.Filter(rootBinding.Variable.IsOf(type)));
OrderByLifterBase filterLifter = GetLifter(filter, _aliasGenerator);
DbExpressionBinding filterBinding = filter.BindAs(_aliasGenerator.Next());
DbExpression project = filterLifter.Project(filterBinding.Project(filterBinding.Variable.TreatAs(type)));
return(project);
}
private DbExpression GenerateStructuralTypeResultMappingView(
DbExpression storeFunctionInvoke,
out DiscriminatorMap discriminatorMap)
{
discriminatorMap = (DiscriminatorMap)null;
DbExpression dbExpression = storeFunctionInvoke;
DbExpression queryView;
if (this.m_structuralTypeMappings.Count == 1)
{
Tuple <StructuralType, List <ConditionPropertyMapping>, List <PropertyMapping> > structuralTypeMapping = this.m_structuralTypeMappings[0];
StructuralType structuralType = structuralTypeMapping.Item1;
List <ConditionPropertyMapping> conditions = structuralTypeMapping.Item2;
List <PropertyMapping> propertyMappings = structuralTypeMapping.Item3;
if (conditions.Count > 0)
{
dbExpression = (DbExpression)dbExpression.Where((Func <DbExpression, DbExpression>)(row => FunctionImportMappingComposable.GenerateStructuralTypeConditionsPredicate(conditions, row)));
}
DbExpressionBinding input = dbExpression.BindAs("row");
DbExpression structuralTypeMappingView = FunctionImportMappingComposable.GenerateStructuralTypeMappingView(structuralType, propertyMappings, (DbExpression)input.Variable);
queryView = (DbExpression)input.Project(structuralTypeMappingView);
}
else
{
DbExpressionBinding binding = dbExpression.BindAs("row");
List <DbExpression> list = this.m_structuralTypeMappings.Select <Tuple <StructuralType, List <ConditionPropertyMapping>, List <PropertyMapping> >, DbExpression>((Func <Tuple <StructuralType, List <ConditionPropertyMapping>, List <PropertyMapping> >, DbExpression>)(m => FunctionImportMappingComposable.GenerateStructuralTypeConditionsPredicate(m.Item2, (DbExpression)binding.Variable))).ToList <DbExpression>();
binding = binding.Filter(Helpers.BuildBalancedTreeInPlace <DbExpression>((IList <DbExpression>)list.ToArray(), (Func <DbExpression, DbExpression, DbExpression>)((prev, next) => (DbExpression)prev.Or(next)))).BindAs("row");
List <DbExpression> source = new List <DbExpression>(this.m_structuralTypeMappings.Count);
foreach (Tuple <StructuralType, List <ConditionPropertyMapping>, List <PropertyMapping> > structuralTypeMapping in this.m_structuralTypeMappings)
{
StructuralType structuralType = structuralTypeMapping.Item1;
List <PropertyMapping> propertyMappings = structuralTypeMapping.Item3;
source.Add(FunctionImportMappingComposable.GenerateStructuralTypeMappingView(structuralType, propertyMappings, (DbExpression)binding.Variable));
}
DbExpression projection = (DbExpression)DbExpressionBuilder.Case(list.Take <DbExpression>(this.m_structuralTypeMappings.Count - 1), source.Take <DbExpression>(this.m_structuralTypeMappings.Count - 1), source[this.m_structuralTypeMappings.Count - 1]);
queryView = (DbExpression)binding.Project(projection);
DiscriminatorMap.TryCreateDiscriminatorMap(this.FunctionImport.EntitySet, queryView, out discriminatorMap);
}
return(queryView);
}
public override DbExpression Visit(DbSkipExpression expression)
{
DbExpression found = Find(expression.Input.Expression);
if (!object.ReferenceEquals(found, expression.Input.Expression))
{
return(found.BindAs(expression.Input.VariableName).Skip(expression.SortOrder, expression.Count));
}
else
{
return(expression);
}
}
// For Distinct, Limit, OfType there is no need to override the base visitor behavior.
public override DbExpression Visit(DbFilterExpression expression)
{
// Only consider the Filter input
DbExpression found = Find(expression.Input.Expression);
if (!object.ReferenceEquals(found, expression.Input.Expression))
{
return(found.BindAs(expression.Input.VariableName).Filter(expression.Predicate));
}
else
{
return(expression);
}
}
public override DbExpression Visit(DbProjectExpression expression)
{
Check.NotNull <DbProjectExpression>(expression, nameof(expression));
DbExpression projection = expression.Projection;
if (DbExpressionKind.Deref == projection.ExpressionKind)
{
projection = ((DbUnaryExpression)projection).Argument;
}
if (DbExpressionKind.VariableReference == projection.ExpressionKind && ((DbVariableReferenceExpression)projection).VariableName.Equals(expression.Input.VariableName, StringComparison.Ordinal))
{
DbExpression input = this.Find(expression.Input.Expression);
if (!object.ReferenceEquals((object)input, (object)expression.Input.Expression))
{
return((DbExpression)input.BindAs(expression.Input.VariableName).Project(expression.Projection));
}
}
return((DbExpression)expression);
}
private DbExpression RewriteCollection(DbExpression expression, CollectionType collectionType)
{
DbExpression target = expression;
// If the collection expression is a project expression, get a strongly typed reference to it for later use.
DbProjectExpression project = null;
if (DbExpressionKind.Project == expression.ExpressionKind)
{
project = (DbProjectExpression)expression;
target = project.Input.Expression;
}
// If Relationship span is enabled and the source of this collection is (directly or indirectly)
// a RelationshipNavigation operation, it may be possible to optimize the relationship span rewrite
// for the Entities produced by the navigation.
NavigationInfo navInfo = null;
if (this.RelationshipSpan)
{
// Attempt to find a RelationshipNavigationExpression in the collection-defining expression
target = RelationshipNavigationVisitor.FindNavigationExpression(target, _aliasGenerator, out navInfo);
}
// If a relationship navigation expression defines this collection, make the Ref that is the navigation source
// and the source association end available for possible use when the projection over the collection is rewritten.
if (navInfo != null)
{
this.EnterNavigationCollection(navInfo);
}
else
{
// Otherwise, add a null navigation info instance to the stack to indicate that relationship navigation
// cannot be optimized for the entities produced by this collection expression (if it is a collection of entities).
this.EnterCollection();
}
// If the expression is already a DbProjectExpression then simply visit the projection,
// instead of introducing another projection over the existing one.
DbExpression result = expression;
if (project != null)
{
DbExpression newProjection = this.Rewrite(project.Projection);
if (!object.ReferenceEquals(project.Projection, newProjection))
{
result = target.BindAs(project.Input.VariableName).Project(newProjection);
}
}
else
{
// This is not a recognized special case, so simply add the span projection over the original
// collection-producing expression, if it is required.
DbExpressionBinding collectionBinding = target.BindAs(_aliasGenerator.Next());
DbExpression projection = collectionBinding.Variable;
DbExpression spannedProjection = this.Rewrite(projection);
if (!object.ReferenceEquals(projection, spannedProjection))
{
result = collectionBinding.Project(spannedProjection);
}
}
// Remove any navigation information from scope, if it was added
this.ExitCollection();
// If a navigation expression defines this collection and its navigation information was used to
// short-circuit relationship span rewrites, then enclose the entire rewritten expression in a
// Lambda binding that brings the source Ref of the navigation operation into scope. This ref is
// refered to by VariableReferenceExpressions in the original navigation expression as well as any
// short-circuited relationship span columns in the rewritten expression.
if (navInfo != null && navInfo.InUse)
{
// Create a Lambda function that binds the original navigation source expression under the variable name
// used in the navigation expression and the relationship span columns, and which has its Lambda body
// defined by the rewritten collection expression.
List <DbVariableReferenceExpression> formals = new List <DbVariableReferenceExpression>(1);
formals.Add(navInfo.SourceVariable);
List <DbExpression> args = new List <DbExpression>(1);
args.Add(navInfo.Source);
result = DbExpressionBuilder.Invoke(DbExpressionBuilder.Lambda(result, formals), args);
}
// Return the (possibly rewritten) collection expression.
return(result);
}
protected DbSkipExpression RebindSkip(DbExpression input, DbSkipExpression skip, DbExpression k)
{
DbExpressionBinding inputBinding = input.BindAs(skip.Input.VariableName);
return(inputBinding.Skip(skip.SortOrder, k));
}
protected DbSkipExpression ApplySortOrderToSkip(DbExpression input, DbSortExpression sort, DbExpression k)
{
DbExpressionBinding inputBinding = input.BindAs(sort.Input.VariableName);
return(inputBinding.Skip(sort.SortOrder, k));
}
protected DbSortExpression ApplySkipOrderToSort(DbExpression input, DbSkipExpression sortSpec)
{
DbExpressionBinding inputBinding = input.BindAs(sortSpec.Input.VariableName);
return(inputBinding.Sort(sortSpec.SortOrder));
}
protected DbSortExpression RebindSort(DbExpression input, DbSortExpression sort)
{
DbExpressionBinding inputBinding = input.BindAs(sort.Input.VariableName);
return(inputBinding.Sort(sort.SortOrder));
}
protected DbFilterExpression RebindFilter(DbExpression input, DbFilterExpression filter)
{
DbExpressionBinding inputBinding = input.BindAs(filter.Input.VariableName);
return inputBinding.Filter(filter.Predicate);
}
protected DbProjectExpression RebindProject(DbExpression input, DbProjectExpression project)
{
DbExpressionBinding inputBinding = input.BindAs(project.Input.VariableName);
return(inputBinding.Project(project.Projection));
}
// Utility translator method for lambda expressions. Given a lambda expression and its translated
// inputs, translates the lambda expression, assuming the input is a collection
private DbExpression TranslateLambda(
LambdaExpression lambda, DbExpression input, string bindingName, out DbExpressionBinding binding)
{
input = NormalizeSetSource(input);
// create binding context for this lambda expression
binding = input.BindAs(bindingName);
return TranslateLambda(lambda, binding.Variable);
}
protected DbSkipExpression RebindSkip(DbExpression input, DbSkipExpression skip, DbExpression k)
{
DbExpressionBinding inputBinding = input.BindAs(skip.Input.VariableName);
return inputBinding.Skip(skip.SortOrder, k);
}
private DbExpression GenerateStructuralTypeResultMappingView(DbExpression storeFunctionInvoke, IList <EdmSchemaError> errors, out DiscriminatorMap discriminatorMap)
{
Debug.Assert(m_structuralTypeMappings != null && m_structuralTypeMappings.Count > 0, "m_structuralTypeMappings != null && m_structuralTypeMappings.Count > 0");
discriminatorMap = null;
// Process explicit structural type mappings. The mapping is based on the direct call of the store function
// wrapped into a projection constructing the mapped structural types.
DbExpression queryExpression = storeFunctionInvoke;
if (m_structuralTypeMappings.Count == 1)
{
var mapping = m_structuralTypeMappings[0];
var type = mapping.Item1;
var conditions = mapping.Item2;
var propertyMappings = mapping.Item3;
if (conditions.Count > 0)
{
queryExpression = queryExpression.Where((row) => GenerateStructuralTypeConditionsPredicate(conditions, row));
}
var binding = queryExpression.BindAs("row");
var entityTypeMappingView = GenerateStructuralTypeMappingView(type, propertyMappings, binding.Variable, errors);
if (entityTypeMappingView == null)
{
return(null);
}
queryExpression = binding.Project(entityTypeMappingView);
}
else
{
var binding = queryExpression.BindAs("row");
// Make sure type projection is performed over a closed set where each row is guaranteed to produce a known type.
// To do this, filter the store function output using the type conditions.
Debug.Assert(m_structuralTypeMappings.All(m => m.Item2.Count > 0), "In multi-type mapping each type must have conditions.");
List <DbExpression> structuralTypePredicates = m_structuralTypeMappings.Select(m => GenerateStructuralTypeConditionsPredicate(m.Item2, binding.Variable)).ToList();
queryExpression = binding.Filter(Helpers.BuildBalancedTreeInPlace(
structuralTypePredicates.ToArray(), // clone, otherwise BuildBalancedTreeInPlace will change it
(prev, next) => prev.Or(next)));
binding = queryExpression.BindAs("row");
List <DbExpression> structuralTypeMappingViews = new List <DbExpression>(m_structuralTypeMappings.Count);
foreach (var mapping in m_structuralTypeMappings)
{
var type = mapping.Item1;
var propertyMappings = mapping.Item3;
var structuralTypeMappingView = GenerateStructuralTypeMappingView(type, propertyMappings, binding.Variable, errors);
if (structuralTypeMappingView == null)
{
continue;
}
else
{
structuralTypeMappingViews.Add(structuralTypeMappingView);
}
}
Debug.Assert(structuralTypeMappingViews.Count == structuralTypePredicates.Count, "structuralTypeMappingViews.Count == structuralTypePredicates.Count");
if (structuralTypeMappingViews.Count != m_structuralTypeMappings.Count)
{
Debug.Assert(errors.Count > 0, "errors.Count > 0");
return(null);
}
// Because we are projecting over the closed set, we can convert the last WHEN THEN into ELSE.
DbExpression typeConstructors = DbExpressionBuilder.Case(
structuralTypePredicates.Take(m_structuralTypeMappings.Count - 1),
structuralTypeMappingViews.Take(m_structuralTypeMappings.Count - 1),
structuralTypeMappingViews[m_structuralTypeMappings.Count - 1]);
queryExpression = binding.Project(typeConstructors);
if (DiscriminatorMap.TryCreateDiscriminatorMap(this.FunctionImport.EntitySet, queryExpression, out discriminatorMap))
{
Debug.Assert(discriminatorMap != null, "discriminatorMap == null after it has been created");
}
}
return(queryExpression);
}
protected DbSortExpression ApplySkipOrderToSort(DbExpression input, DbSkipExpression sortSpec)
{
DbExpressionBinding inputBinding = input.BindAs(sortSpec.Input.VariableName);
return inputBinding.Sort(sortSpec.SortOrder);
}
protected DbSortExpression RebindSort(DbExpression input, DbSortExpression sort)
{
DbExpressionBinding inputBinding = input.BindAs(sort.Input.VariableName);
return inputBinding.Sort(sort.SortOrder);
}
protected DbFilterExpression RebindFilter(DbExpression input, DbFilterExpression filter)
{
DbExpressionBinding inputBinding = input.BindAs(filter.Input.VariableName);
return(inputBinding.Filter(filter.Predicate));
}
protected DbSkipExpression ApplySortOrderToSkip(DbExpression input, DbSortExpression sort, DbExpression k)
{
DbExpressionBinding inputBinding = input.BindAs(sort.Input.VariableName);
return inputBinding.Skip(sort.SortOrder, k);
}
protected DbProjectExpression RebindProject(DbExpression input, DbProjectExpression project)
{
DbExpressionBinding inputBinding = input.BindAs(project.Input.VariableName);
return inputBinding.Project(project.Projection);
}