Code:
/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / Orcas / SP / ndp / fx / src / DLinq / Dlinq / SqlClient / Query / SqlExpressionNullability.cs / 1 / SqlExpressionNullability.cs
using System; using System.Collections; using System.Collections.Generic; using System.Data; using System.Reflection; using System.Text; using System.Linq; using System.Linq.Expressions; using System.Data.Linq; using System.Data.Linq.Provider; using System.Diagnostics.CodeAnalysis; namespace System.Data.Linq.SqlClient { internal static class SqlExpressionNullability { ////// Determines whether the given expression may return a null result. /// /// The expression to check. ///null means that it couldn't be determined [SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity", Justification="These issues are related to our use of if-then and case statements for node types, which adds to the complexity count however when reviewed they are easy to navigate and understand.")] internal static bool? CanBeNull(SqlExpression expr) { switch (expr.NodeType) { case SqlNodeType.ExprSet: SqlExprSet exprSet = (SqlExprSet)expr; return CanBeNull(exprSet.Expressions); case SqlNodeType.SimpleCase: SqlSimpleCase sc = (SqlSimpleCase)expr; return CanBeNull(sc.Whens.Select(w => w.Value)); case SqlNodeType.Column: SqlColumn col = (SqlColumn)expr; if (col.MetaMember != null) { return col.MetaMember.CanBeNull; } else if (col.Expression != null) { return CanBeNull(col.Expression); } return null; // Don't know. case SqlNodeType.ColumnRef: SqlColumnRef cref = (SqlColumnRef)expr; return CanBeNull(cref.Column); case SqlNodeType.Value: return ((SqlValue)expr).Value == null; case SqlNodeType.New: case SqlNodeType.Multiset: case SqlNodeType.Grouping: case SqlNodeType.ObjectType: case SqlNodeType.DiscriminatedType: case SqlNodeType.IsNotNull: // IsNull\IsNotNull always return true or false and can never return NULL. case SqlNodeType.IsNull: case SqlNodeType.Exists: return false; case SqlNodeType.Add: case SqlNodeType.Sub: case SqlNodeType.Mul: case SqlNodeType.Div: case SqlNodeType.Mod: case SqlNodeType.BitAnd: case SqlNodeType.BitOr: case SqlNodeType.BitXor: case SqlNodeType.Concat: { SqlBinary bop = (SqlBinary)expr; bool? left = CanBeNull(bop.Left); bool? right = CanBeNull(bop.Right); return (left != false) || (right != false); } case SqlNodeType.Negate: case SqlNodeType.BitNot: { SqlUnary uop = (SqlUnary)expr; return CanBeNull(uop.Operand); } case SqlNodeType.Lift: { SqlLift lift = (SqlLift)expr; return CanBeNull(lift.Expression); } case SqlNodeType.OuterJoinedValue: return true; default: return null; // Don't know. } } ////// Used to determine nullability for a collection of expressions. /// * If at least one of the expressions is nullable, the collection is nullable. /// * If no expressions are nullable, but at least one is 'don't know', the collection is 'don't know'. /// * Otherwise all expressions are non-nullable and the nullability is false. /// private static bool? CanBeNull(IEnumerableexprs) { bool hasAtleastOneUnknown = false; foreach(SqlExpression e in exprs) { bool? nullability = CanBeNull(e); // Even one expression that could return null means the // collection can return null. if (nullability == true) return true; // If there is one or more 'unknown' and no definitely nullable // results then the collection nullability is 'unknown'. if (nullability == null) hasAtleastOneUnknown = true; } if (hasAtleastOneUnknown) return null; return false; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved. using System; using System.Collections; using System.Collections.Generic; using System.Data; using System.Reflection; using System.Text; using System.Linq; using System.Linq.Expressions; using System.Data.Linq; using System.Data.Linq.Provider; using System.Diagnostics.CodeAnalysis; namespace System.Data.Linq.SqlClient { internal static class SqlExpressionNullability { /// /// Determines whether the given expression may return a null result. /// /// The expression to check. ///null means that it couldn't be determined [SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity", Justification="These issues are related to our use of if-then and case statements for node types, which adds to the complexity count however when reviewed they are easy to navigate and understand.")] internal static bool? CanBeNull(SqlExpression expr) { switch (expr.NodeType) { case SqlNodeType.ExprSet: SqlExprSet exprSet = (SqlExprSet)expr; return CanBeNull(exprSet.Expressions); case SqlNodeType.SimpleCase: SqlSimpleCase sc = (SqlSimpleCase)expr; return CanBeNull(sc.Whens.Select(w => w.Value)); case SqlNodeType.Column: SqlColumn col = (SqlColumn)expr; if (col.MetaMember != null) { return col.MetaMember.CanBeNull; } else if (col.Expression != null) { return CanBeNull(col.Expression); } return null; // Don't know. case SqlNodeType.ColumnRef: SqlColumnRef cref = (SqlColumnRef)expr; return CanBeNull(cref.Column); case SqlNodeType.Value: return ((SqlValue)expr).Value == null; case SqlNodeType.New: case SqlNodeType.Multiset: case SqlNodeType.Grouping: case SqlNodeType.ObjectType: case SqlNodeType.DiscriminatedType: case SqlNodeType.IsNotNull: // IsNull\IsNotNull always return true or false and can never return NULL. case SqlNodeType.IsNull: case SqlNodeType.Exists: return false; case SqlNodeType.Add: case SqlNodeType.Sub: case SqlNodeType.Mul: case SqlNodeType.Div: case SqlNodeType.Mod: case SqlNodeType.BitAnd: case SqlNodeType.BitOr: case SqlNodeType.BitXor: case SqlNodeType.Concat: { SqlBinary bop = (SqlBinary)expr; bool? left = CanBeNull(bop.Left); bool? right = CanBeNull(bop.Right); return (left != false) || (right != false); } case SqlNodeType.Negate: case SqlNodeType.BitNot: { SqlUnary uop = (SqlUnary)expr; return CanBeNull(uop.Operand); } case SqlNodeType.Lift: { SqlLift lift = (SqlLift)expr; return CanBeNull(lift.Expression); } case SqlNodeType.OuterJoinedValue: return true; default: return null; // Don't know. } } ////// Used to determine nullability for a collection of expressions. /// * If at least one of the expressions is nullable, the collection is nullable. /// * If no expressions are nullable, but at least one is 'don't know', the collection is 'don't know'. /// * Otherwise all expressions are non-nullable and the nullability is false. /// private static bool? CanBeNull(IEnumerableexprs) { bool hasAtleastOneUnknown = false; foreach(SqlExpression e in exprs) { bool? nullability = CanBeNull(e); // Even one expression that could return null means the // collection can return null. if (nullability == true) return true; // If there is one or more 'unknown' and no definitely nullable // results then the collection nullability is 'unknown'. if (nullability == null) hasAtleastOneUnknown = true; } if (hasAtleastOneUnknown) return null; return false; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- WebServiceHost.cs
- DomainConstraint.cs
- RuleSettings.cs
- DataRow.cs
- TrackingRecord.cs
- PolicyFactory.cs
- Boolean.cs
- MinimizableAttributeTypeConverter.cs
- TimelineGroup.cs
- HiddenFieldPageStatePersister.cs
- DbConnectionHelper.cs
- WindowsFormsHost.cs
- PageParser.cs
- CollectionView.cs
- PatternMatcher.cs
- PeerCollaboration.cs
- WeakReference.cs
- AutoSizeComboBox.cs
- DynamicRenderer.cs
- ApplicationContext.cs
- elementinformation.cs
- ConcurrentBag.cs
- DebuggerAttributes.cs
- DataControlButton.cs
- RemotingHelper.cs
- Selection.cs
- Mutex.cs
- DataGridColumnEventArgs.cs
- SymmetricCryptoHandle.cs
- TraceListener.cs
- DataBoundControl.cs
- X509InitiatorCertificateServiceElement.cs
- DataGridViewRowsAddedEventArgs.cs
- CompositeCollection.cs
- RadioButtonStandardAdapter.cs
- NavigationPropertyEmitter.cs
- TextSchema.cs
- XmlSchemaSimpleContentExtension.cs
- Msec.cs
- ConfigXmlSignificantWhitespace.cs
- ResolveNameEventArgs.cs
- SrgsElement.cs
- Sequence.cs
- AspCompat.cs
- PlanCompilerUtil.cs
- TransformerConfigurationWizardBase.cs
- UniqueConstraint.cs
- MetadataArtifactLoaderComposite.cs
- CompilerTypeWithParams.cs
- StateMachine.cs
- RecognizedWordUnit.cs
- References.cs
- Variable.cs
- ListViewInsertionMark.cs
- ImageCodecInfo.cs
- DoubleIndependentAnimationStorage.cs
- RepeaterItemEventArgs.cs
- SqlReferenceCollection.cs
- ColorInterpolationModeValidation.cs
- COM2PropertyPageUITypeConverter.cs
- Marshal.cs
- DefaultTextStore.cs
- SecurityPolicySection.cs
- UserPreferenceChangedEventArgs.cs
- SQLRoleProvider.cs
- ParameterModifier.cs
- RequestDescription.cs
- TriState.cs
- ScrollEventArgs.cs
- Adorner.cs
- VoiceChangeEventArgs.cs
- TextTabProperties.cs
- SMSvcHost.cs
- CategoryGridEntry.cs
- VectorAnimationBase.cs
- FloatUtil.cs
- CodeObjectCreateExpression.cs
- TemporaryBitmapFile.cs
- OperatorExpressions.cs
- PathGeometry.cs
- SafeNativeMethods.cs
- CodeSubDirectoriesCollection.cs
- ProvideValueServiceProvider.cs
- DataGridViewSortCompareEventArgs.cs
- MexTcpBindingCollectionElement.cs
- RecommendedAsConfigurableAttribute.cs
- ChtmlMobileTextWriter.cs
- TitleStyle.cs
- DatatypeImplementation.cs
- SystemEvents.cs
- ImageSource.cs
- CombinedGeometry.cs
- StringKeyFrameCollection.cs
- compensatingcollection.cs
- ExpressionBinding.cs
- HttpPostProtocolReflector.cs
- METAHEADER.cs
- TextStore.cs
- StaticExtension.cs
- MailHeaderInfo.cs