/// <summary>
/// Creates an Equal comparison of a nullable property (db column) to a nullable parameter (lambda param)
/// that adds the necessary "is null" checks to support a filter like "e.TenantId = tenantId".
/// Results in sql: (e.TenantID is null and @tenantID is null) or (e.TenantID is not null and e.TenantID = @tenantID)
/// which will support parmeter values that are "null" or a specific value and will correctly filter on columns that
/// are "null" or a specific value.
/// </summary>
/// <param name="propExpression"></param>
/// <param name="paramExpression"></param>
/// <returns></returns>
private DbExpression CreateEqualComparisonOfNullablePropToNullableParam(DbExpression propExpression, DbExpression paramExpression)
{
var condition1 = propExpression.IsNull().And(paramExpression.IsNull());
var condition2 = propExpression.IsNull().Not().And(propExpression.Equal(paramExpression));
return(condition1.Or(condition2));
}
private static DbExpression GeneratePredicate(
ConditionPropertyMapping condition,
DbExpression row)
{
DbExpression columnRef = FunctionImportMappingComposable.GenerateColumnRef(row, condition.Column);
if (!condition.IsNull.HasValue)
{
return((DbExpression)columnRef.Equal((DbExpression)columnRef.ResultType.Constant(condition.Value)));
}
if (!condition.IsNull.Value)
{
return((DbExpression)columnRef.IsNull().Not());
}
return((DbExpression)columnRef.IsNull());
}
internal static CqtExpression StripNull(LinqExpression sourceExpression,
DbExpression inputExpression, DbExpression outputExpression, bool useDatabaseNullSemantics)
{
if (sourceExpression.IsNullConstant())
{
return(DbExpressionBuilder.Constant(string.Empty));
}
if (sourceExpression.NodeType == ExpressionType.Constant)
{
return(outputExpression);
}
if (useDatabaseNullSemantics)
{
return(outputExpression);
}
// converts evaluated null values to empty string, nullable primitive properties etc.
var castNullToEmptyString = DbExpressionBuilder.Case(
new[] { inputExpression.IsNull() },
new[] { DbExpressionBuilder.Constant(string.Empty) },
outputExpression);
return(castNullToEmptyString);
}
internal DbExpression AsCqt(DbExpression row)
{
DbExpression left = this.m_slotValue.AsCqt(row, this.m_outputMember);
if (this.m_enforceNotNull)
{
left = (DbExpression)left.And((DbExpression)left.IsNull().Not());
}
return(left);
}
/// <summary>
/// Generates CQT representation of the slot.
/// </summary>
internal DbExpression AsCqt(DbExpression row)
{
DbExpression cqt = m_slotValue.AsCqt(row, m_outputMember);
if (m_enforceNotNull)
{
cqt = cqt.And(cqt.IsNull().Not());
}
return(cqt);
}
// Effects: given a "clause" in the form of a property/value pair, produces an equality expression. If the
// value is null, creates an IsNull expression
// Requires: all arguments are set
private DbExpression GenerateEqualityExpression(DbExpressionBinding target, EdmProperty property, PropagatorResult value)
{
Debug.Assert(null != target && null != property && null != value);
DbExpression propertyExpression = GeneratePropertyExpression(target, property);
DbExpression valueExpression = GenerateValueExpression(property, value);
if (valueExpression.ExpressionKind == DbExpressionKind.Null)
{
return(propertyExpression.IsNull());
}
return(propertyExpression.Equal(valueExpression));
}
private DbExpression GeneratePredicate(StorageConditionPropertyMapping condition, DbExpression row)
{
Debug.Assert(condition.EdmProperty == null, "C-side conditions are not supported in function mappings.");
DbExpression columnRef = GenerateColumnRef(row, condition.ColumnProperty);
if (condition.IsNull.HasValue)
{
return(condition.IsNull.Value ? (DbExpression)columnRef.IsNull() : (DbExpression)columnRef.IsNull().Not());
}
else
{
return(columnRef.Equal(columnRef.ResultType.Constant(condition.Value)));
}
}
private DbExpression GenerateEqualityExpression(
DbExpressionBinding target,
EdmProperty property,
PropagatorResult value)
{
DbExpression propertyExpression = UpdateCompiler.GeneratePropertyExpression(target, property);
DbExpression valueExpression = this.GenerateValueExpression(property, value);
if (valueExpression.ExpressionKind == DbExpressionKind.Null)
{
return((DbExpression)propertyExpression.IsNull());
}
return((DbExpression)propertyExpression.Equal(valueExpression));
}
private DbExpression RewriteRow(DbExpression expression, RowType rowType)
{
var lambdaExpression = expression as DbLambdaExpression;
DbNewInstanceExpression newRow;
if (lambdaExpression != null)
{
// NOTE: We rely on the fact that today span cannot be done over queries containing DbLambdaExpressions
// created by users, because user-created expressions cannot be used for querying in O-space.
// If that were to change, pushing span beyond a LambdaExpression could cause variable name
// collisions between the variable names used in the Lambda and the names generated by the
// RelationshipNavigationVisitor.
newRow = lambdaExpression.Lambda.Body as DbNewInstanceExpression;
}
else
{
newRow = expression as DbNewInstanceExpression;
}
Dictionary <int, DbExpression> unmodifiedColumns = null;
Dictionary <int, DbExpression> spannedColumns = null;
for (var idx = 0; idx < rowType.Properties.Count; idx++)
{
// Retrieve the property that represents the current column
var columnProp = rowType.Properties[idx];
// Construct an expression that defines the current column.
DbExpression columnExpr = null;
if (newRow != null)
{
// For a row-constructing NewInstance expression, the corresponding argument can simply be used
columnExpr = newRow.Arguments[idx];
}
else
{
// For all other expressions the property corresponding to the column name must be retrieved
// from the row-typed expression
columnExpr = expression.Property(columnProp.Name);
}
var spannedColumn = Rewrite(columnExpr);
if (!ReferenceEquals(spannedColumn, columnExpr))
{
// If so, then update the dictionary of column index to span information
if (null == spannedColumns)
{
spannedColumns = new Dictionary <int, DbExpression>();
}
spannedColumns[idx] = spannedColumn;
}
else
{
// Otherwise, update the dictionary of column index to unmodified expression
if (null == unmodifiedColumns)
{
unmodifiedColumns = new Dictionary <int, DbExpression>();
}
unmodifiedColumns[idx] = columnExpr;
}
}
// A new expression need only be built if at least one column was spanned
if (null == spannedColumns)
{
// No columns were spanned, indicate that the original expression should remain.
return(expression);
}
else
{
// At least one column was spanned, so build a new row constructor that defines the new row, including spanned columns.
var columnArguments = new List <DbExpression>(rowType.Properties.Count);
var properties = new List <EdmProperty>(rowType.Properties.Count);
for (var idx = 0; idx < rowType.Properties.Count; idx++)
{
var columnProp = rowType.Properties[idx];
DbExpression columnDef = null;
if (!spannedColumns.TryGetValue(idx, out columnDef))
{
columnDef = unmodifiedColumns[idx];
}
columnArguments.Add(columnDef);
properties.Add(new EdmProperty(columnProp.Name, columnDef.ResultType));
}
// Copy over any eLinq initializer metadata (if present, or null if not).
// Note that this initializer metadata does not strictly match the new row type
// that includes spanned columns, but will be correct once the object materializer
// has interpreted the query results to produce the correct value for each column.
var rewrittenRow = new RowType(properties, rowType.InitializerMetadata);
var rewrittenRowTypeUsage = TypeUsage.Create(rewrittenRow);
DbExpression rewritten = rewrittenRowTypeUsage.New(columnArguments);
// SQLBUDT #554182: If we insert a new projection we should make sure to
// not interfere with the nullability of the input.
// In particular, if the input row is null and we construct a new row as a projection over its columns
// we would get a row consisting of nulls, instead of a null row.
// Thus, given an input X, we rewrite it as: if (X is null) then NULL else rewritten.
if (newRow == null)
{
DbExpression condition = expression.IsNull();
DbExpression nullExpression = rewrittenRowTypeUsage.Null();
rewritten = DbExpressionBuilder.Case(
new List <DbExpression>(new[] { condition }),
new List <DbExpression>(new[] { nullExpression }),
rewritten);
}
// Add an entry to the spanned row type => original row type map for the new row type.
AddSpannedRowType(rewrittenRow, expression.ResultType);
if (lambdaExpression != null &&
newRow != null)
{
rewritten = DbLambda.Create(rewritten, lambdaExpression.Lambda.Variables).Invoke(lambdaExpression.Arguments);
}
return(rewritten);
}
}
// Generate an equality expression where the values of the left and right operands are completely unknown
private DbExpression ImplementEqualityUnknownArguments(DbExpression left, DbExpression right, EqualsPattern pattern)
{
switch (pattern)
{
case EqualsPattern.Store: // left EQ right
return left.Equal(right);
case EqualsPattern.PositiveNullEqualityNonComposable: // for Joins
return left.Equal(right).Or(left.IsNull().And(right.IsNull()));
case EqualsPattern.PositiveNullEqualityComposable:
{
var bothNotNull = left.Equal(right);
var bothNull = left.IsNull().And(right.IsNull());
if (!_funcletizer.RootContext.ContextOptions.UseCSharpNullComparisonBehavior)
{
return bothNotNull.Or(bothNull); // same as EqualsPattern.PositiveNullEqualityNonComposable
}
// add more logic to avoid undefined result for true clr semantics, ensuring composability
// (left EQ right AND NOT (left IS NULL OR right IS NULL)) OR (left IS NULL AND right IS NULL)
var anyOneIsNull = left.IsNull().Or(right.IsNull());
return (bothNotNull.And(anyOneIsNull.Not())).Or(bothNull);
}
default:
Debug.Fail("unexpected pattern");
return null;
}
}
// Generate an equality expression with one unknown operator and
private DbExpression ImplementEqualityConstantAndUnknown(
DbConstantExpression constant, DbExpression unknown, EqualsPattern pattern)
{
switch (pattern)
{
case EqualsPattern.Store:
case EqualsPattern.PositiveNullEqualityNonComposable: // for Joins
return constant.Equal(unknown); // either both are non-null, or one is null and the predicate result is undefined
case EqualsPattern.PositiveNullEqualityComposable:
if (!_funcletizer.RootContext.ContextOptions.UseCSharpNullComparisonBehavior)
{
return constant.Equal(unknown); // same as EqualsPattern.PositiveNullEqualityNonComposable
}
return constant.Equal(unknown).And(unknown.IsNull().Not());
// add more logic to avoid undefined result for true clr semantics
default:
Debug.Fail("unknown pattern");
return null;
}
}
// For comparisons, where the left and right side are nullable or not nullable,
// here are the (compositionally safe) null equality predicates:
// -- x NOT NULL, y NULL
// x = y AND NOT (y IS NULL)
// -- x NULL, y NULL
// (x = y AND (NOT (x IS NULL OR y IS NULL))) OR (x IS NULL AND y IS NULL)
// -- x NOT NULL, y NOT NULL
// x = y
// -- x NULL, y NOT NULL
// x = y AND NOT (x IS NULL)
private DbExpression ImplementEquality(DbExpression left, DbExpression right, EqualsPattern pattern)
{
switch (left.ExpressionKind)
{
case DbExpressionKind.Constant:
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant: // constant EQ constant
return left.Equal(right);
case DbExpressionKind.Null: // null EQ constant --> false
return DbExpressionBuilder.False;
default:
return ImplementEqualityConstantAndUnknown((DbConstantExpression)left, right, pattern);
}
case DbExpressionKind.Null:
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant: // null EQ constant --> false
return DbExpressionBuilder.False;
case DbExpressionKind.Null: // null EQ null --> true
return DbExpressionBuilder.True;
default: // null EQ right --> right IS NULL
return right.IsNull();
}
default: // unknown
switch (right.ExpressionKind)
{
case DbExpressionKind.Constant:
return ImplementEqualityConstantAndUnknown((DbConstantExpression)right, left, pattern);
case DbExpressionKind.Null: // left EQ null --> left IS NULL
return left.IsNull();
default:
return ImplementEqualityUnknownArguments(left, right, pattern);
}
}
}
// <summary>
// Creates an implementation of IsNull. Throws exception when operand type is not supported.
// </summary>
private static DbExpression CreateIsNullExpression(DbExpression operand, Type operandClrType)
{
VerifyTypeSupportedForComparison(operandClrType, operand.ResultType, null);
return operand.IsNull();
}
internal static CqtExpression StripNull(LinqExpression sourceExpression,
DbExpression inputExpression, DbExpression outputExpression)
{
if (sourceExpression.IsNullConstant())
{
return DbExpressionBuilder.Constant(string.Empty);
}
if (sourceExpression.NodeType == ExpressionType.Constant)
{
return outputExpression;
}
// converts evaluated null values to empty string, nullable primitive properties etc.
var castNullToEmptyString = DbExpressionBuilder.Case(
new[] { inputExpression.IsNull() },
new[] { DbExpressionBuilder.Constant(string.Empty) },
outputExpression);
return castNullToEmptyString;
}
private DbExpression RewriteRow(DbExpression expression, RowType rowType)
{
DbLambdaExpression lambdaExpression = expression as DbLambdaExpression;
DbNewInstanceExpression instanceExpression = lambdaExpression == null ? expression as DbNewInstanceExpression : lambdaExpression.Lambda.Body as DbNewInstanceExpression;
Dictionary <int, DbExpression> dictionary1 = (Dictionary <int, DbExpression>)null;
Dictionary <int, DbExpression> dictionary2 = (Dictionary <int, DbExpression>)null;
for (int index = 0; index < rowType.Properties.Count; ++index)
{
EdmProperty property = rowType.Properties[index];
DbExpression expression1 = instanceExpression == null ? (DbExpression)expression.Property(property.Name) : instanceExpression.Arguments[index];
DbExpression dbExpression = this.Rewrite(expression1);
if (!object.ReferenceEquals((object)dbExpression, (object)expression1))
{
if (dictionary2 == null)
{
dictionary2 = new Dictionary <int, DbExpression>();
}
dictionary2[index] = dbExpression;
}
else
{
if (dictionary1 == null)
{
dictionary1 = new Dictionary <int, DbExpression>();
}
dictionary1[index] = expression1;
}
}
if (dictionary2 == null)
{
return(expression);
}
List <DbExpression> dbExpressionList = new List <DbExpression>(rowType.Properties.Count);
List <EdmProperty> edmPropertyList = new List <EdmProperty>(rowType.Properties.Count);
for (int key = 0; key < rowType.Properties.Count; ++key)
{
EdmProperty property = rowType.Properties[key];
DbExpression dbExpression = (DbExpression)null;
if (!dictionary2.TryGetValue(key, out dbExpression))
{
dbExpression = dictionary1[key];
}
dbExpressionList.Add(dbExpression);
edmPropertyList.Add(new EdmProperty(property.Name, dbExpression.ResultType));
}
RowType spannedType = new RowType((IEnumerable <EdmProperty>)edmPropertyList, rowType.InitializerMetadata);
TypeUsage typeUsage = TypeUsage.Create((EdmType)spannedType);
DbExpression dbExpression1 = (DbExpression)typeUsage.New((IEnumerable <DbExpression>)dbExpressionList);
if (instanceExpression == null)
{
dbExpression1 = (DbExpression)DbExpressionBuilder.Case((IEnumerable <DbExpression>) new List <DbExpression>((IEnumerable <DbExpression>) new DbExpression[1]
{
(DbExpression)expression.IsNull()
}), (IEnumerable <DbExpression>) new List <DbExpression>((IEnumerable <DbExpression>) new DbExpression[1]
{
(DbExpression)typeUsage.Null()
}), dbExpression1);
}
this.AddSpannedRowType(spannedType, expression.ResultType);
if (lambdaExpression != null && instanceExpression != null)
{
dbExpression1 = (DbExpression)DbLambda.Create(dbExpression1, (IEnumerable <DbVariableReferenceExpression>)lambdaExpression.Lambda.Variables).Invoke((IEnumerable <DbExpression>)lambdaExpression.Arguments);
}
return(dbExpression1);
}
private DbExpression RewriteRow(DbExpression expression, RowType rowType)
{
var lambdaExpression = expression as DbLambdaExpression;
DbNewInstanceExpression newRow;
if (lambdaExpression != null)
{
// NOTE: We rely on the fact that today span cannot be done over queries containing DbLambdaExpressions
// created by users, because user-created expressions cannot be used for querying in O-space.
// If that were to change, pushing span beyond a LambdaExpression could cause variable name
// collisions between the variable names used in the Lambda and the names generated by the
// RelationshipNavigationVisitor.
newRow = lambdaExpression.Lambda.Body as DbNewInstanceExpression;
}
else
{
newRow = expression as DbNewInstanceExpression;
}
Dictionary<int, DbExpression> unmodifiedColumns = null;
Dictionary<int, DbExpression> spannedColumns = null;
for (var idx = 0; idx < rowType.Properties.Count; idx++)
{
// Retrieve the property that represents the current column
var columnProp = rowType.Properties[idx];
// Construct an expression that defines the current column.
DbExpression columnExpr = null;
if (newRow != null)
{
// For a row-constructing NewInstance expression, the corresponding argument can simply be used
columnExpr = newRow.Arguments[idx];
}
else
{
// For all other expressions the property corresponding to the column name must be retrieved
// from the row-typed expression
columnExpr = expression.Property(columnProp.Name);
}
var spannedColumn = Rewrite(columnExpr);
if (!ReferenceEquals(spannedColumn, columnExpr))
{
// If so, then update the dictionary of column index to span information
if (null == spannedColumns)
{
spannedColumns = new Dictionary<int, DbExpression>();
}
spannedColumns[idx] = spannedColumn;
}
else
{
// Otherwise, update the dictionary of column index to unmodified expression
if (null == unmodifiedColumns)
{
unmodifiedColumns = new Dictionary<int, DbExpression>();
}
unmodifiedColumns[idx] = columnExpr;
}
}
// A new expression need only be built if at least one column was spanned
if (null == spannedColumns)
{
// No columns were spanned, indicate that the original expression should remain.
return expression;
}
else
{
// At least one column was spanned, so build a new row constructor that defines the new row, including spanned columns.
var columnArguments = new List<DbExpression>(rowType.Properties.Count);
var properties = new List<EdmProperty>(rowType.Properties.Count);
for (var idx = 0; idx < rowType.Properties.Count; idx++)
{
var columnProp = rowType.Properties[idx];
DbExpression columnDef = null;
if (!spannedColumns.TryGetValue(idx, out columnDef))
{
columnDef = unmodifiedColumns[idx];
}
columnArguments.Add(columnDef);
properties.Add(new EdmProperty(columnProp.Name, columnDef.ResultType));
}
// Copy over any eLinq initializer metadata (if present, or null if not).
// Note that this initializer metadata does not strictly match the new row type
// that includes spanned columns, but will be correct once the object materializer
// has interpreted the query results to produce the correct value for each colum.
var rewrittenRow = new RowType(properties, rowType.InitializerMetadata);
var rewrittenRowTypeUsage = TypeUsage.Create(rewrittenRow);
DbExpression rewritten = rewrittenRowTypeUsage.New(columnArguments);
// SQLBUDT #554182: If we insert a new projection we should should make sure to
// not interfere with the nullability of the input.
// In particular, if the input row is null and we construct a new row as a projection over its columns
// we would get a row consisting of nulls, instead of a null row.
// Thus, given an input X, we rewritte it as: if (X is null) then NULL else rewritten.
if (newRow == null)
{
DbExpression condition = expression.IsNull();
DbExpression nullExpression = rewrittenRowTypeUsage.Null();
rewritten = DbExpressionBuilder.Case(
new List<DbExpression>(new[] { condition }),
new List<DbExpression>(new[] { nullExpression }),
rewritten);
}
// Add an entry to the spanned row type => original row type map for the new row type.
AddSpannedRowType(rewrittenRow, expression.ResultType);
if (lambdaExpression != null
&& newRow != null)
{
rewritten = DbLambda.Create(rewritten, lambdaExpression.Lambda.Variables).Invoke(lambdaExpression.Arguments);
}
return rewritten;
}
}
