Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Common / Utils / Boolean / Simplifier.cs / 1305376 / Simplifier.cs
//---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // // // @owner [....] // @backupOwner [....] //--------------------------------------------------------------------- using System; using System.Collections.Generic; using System.Text; using System.Diagnostics; namespace System.Data.Common.Utils.Boolean { // Simplifier visitor for Boolean expressions. Performs the following // simplifications bottom-up: // - Eliminate True and False (A Or False iff. A, A And True iff. A) // - Resolve tautology (A Or !A iff. True, True Or A iff. True) and // contradiction (A And !A iff. False, False And A iff. False) // - Flatten nested negations (!!A iff. A) // - Evaluate bound literals (!True iff. False, etc.) // - Flatten unary/empty And/Or expressions internal class Simplifier: BasicVisitor { internal static readonly Simplifier Instance = new Simplifier (); protected Simplifier() { } internal override BoolExpr VisitNot(NotExpr expression) { BoolExpr child = expression.Child.Accept(this); switch (child.ExprType) { case ExprType.Not: return ((NotExpr )child).Child; case ExprType.True: return FalseExpr .Value; case ExprType.False: return TrueExpr .Value; default: return base.VisitNot(expression); } } internal override BoolExpr VisitAnd(AndExpr expression) { return SimplifyTree(expression); } internal override BoolExpr VisitOr(OrExpr expression) { return SimplifyTree(expression); } private BoolExpr SimplifyTree(TreeExpr tree) { bool isAnd = ExprType.And == tree.ExprType; Debug.Assert(isAnd || ExprType.Or == tree.ExprType); // Get list of simplified children, flattening nested And/Or expressions List > simplifiedChildren = new List >(tree.Children.Count); foreach (BoolExpr child in tree.Children) { BoolExpr simplifiedChild = child.Accept(this); // And(And(A, B), C) iff. And(A, B, C) // Or(Or(A, B), C) iff. Or(A, B, C) if (simplifiedChild.ExprType == tree.ExprType) { simplifiedChildren.AddRange(((TreeExpr )simplifiedChild).Children); } else { simplifiedChildren.Add(simplifiedChild); } } // Track negated children separately to identify tautologies and contradictions Dictionary , bool> negatedChildren = new Dictionary , bool>(tree.Children.Count); List > otherChildren = new List >(tree.Children.Count); foreach (BoolExpr simplifiedChild in simplifiedChildren) { switch (simplifiedChild.ExprType) { case ExprType.Not: negatedChildren[((NotExpr )simplifiedChild).Child] = true; break; case ExprType.False: // False And A --> False if (isAnd) { return FalseExpr .Value; } // False || A --> A (omit False from child collections) break; case ExprType.True: // True Or A --> True if (!isAnd) { return TrueExpr .Value; } // True And A --> A (omit True from child collections) break; default: otherChildren.Add(simplifiedChild); break; } } List > children = new List >(); foreach (BoolExpr child in otherChildren) { if (negatedChildren.ContainsKey(child)) { // A && !A --> False, A || !A --> True if (isAnd) { return FalseExpr .Value; } else { return TrueExpr .Value; } } children.Add(child); } foreach (BoolExpr child in negatedChildren.Keys) { children.Add(child.MakeNegated()); } if (0 == children.Count) { // And() iff. True if (isAnd) { return TrueExpr .Value; } // Or() iff. False else { return FalseExpr .Value; } } else if (1 == children.Count) { // Or(A) iff. A, And(A) iff. A return children[0]; } else { // Construct simplified And/Or expression TreeExpr result; if (isAnd) { result = new AndExpr (children); } else { result = new OrExpr (children); } return result; } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. //---------------------------------------------------------------------- // // Copyright (c) Microsoft Corporation. All rights reserved. // // // @owner [....] // @backupOwner [....] //--------------------------------------------------------------------- using System; using System.Collections.Generic; using System.Text; using System.Diagnostics; namespace System.Data.Common.Utils.Boolean { // Simplifier visitor for Boolean expressions. Performs the following // simplifications bottom-up: // - Eliminate True and False (A Or False iff. A, A And True iff. A) // - Resolve tautology (A Or !A iff. True, True Or A iff. True) and // contradiction (A And !A iff. False, False And A iff. False) // - Flatten nested negations (!!A iff. A) // - Evaluate bound literals (!True iff. False, etc.) // - Flatten unary/empty And/Or expressions internal class Simplifier: BasicVisitor { internal static readonly Simplifier Instance = new Simplifier (); protected Simplifier() { } internal override BoolExpr VisitNot(NotExpr expression) { BoolExpr child = expression.Child.Accept(this); switch (child.ExprType) { case ExprType.Not: return ((NotExpr )child).Child; case ExprType.True: return FalseExpr .Value; case ExprType.False: return TrueExpr .Value; default: return base.VisitNot(expression); } } internal override BoolExpr VisitAnd(AndExpr expression) { return SimplifyTree(expression); } internal override BoolExpr VisitOr(OrExpr expression) { return SimplifyTree(expression); } private BoolExpr SimplifyTree(TreeExpr tree) { bool isAnd = ExprType.And == tree.ExprType; Debug.Assert(isAnd || ExprType.Or == tree.ExprType); // Get list of simplified children, flattening nested And/Or expressions List > simplifiedChildren = new List >(tree.Children.Count); foreach (BoolExpr child in tree.Children) { BoolExpr simplifiedChild = child.Accept(this); // And(And(A, B), C) iff. And(A, B, C) // Or(Or(A, B), C) iff. Or(A, B, C) if (simplifiedChild.ExprType == tree.ExprType) { simplifiedChildren.AddRange(((TreeExpr )simplifiedChild).Children); } else { simplifiedChildren.Add(simplifiedChild); } } // Track negated children separately to identify tautologies and contradictions Dictionary , bool> negatedChildren = new Dictionary , bool>(tree.Children.Count); List > otherChildren = new List >(tree.Children.Count); foreach (BoolExpr simplifiedChild in simplifiedChildren) { switch (simplifiedChild.ExprType) { case ExprType.Not: negatedChildren[((NotExpr )simplifiedChild).Child] = true; break; case ExprType.False: // False And A --> False if (isAnd) { return FalseExpr .Value; } // False || A --> A (omit False from child collections) break; case ExprType.True: // True Or A --> True if (!isAnd) { return TrueExpr .Value; } // True And A --> A (omit True from child collections) break; default: otherChildren.Add(simplifiedChild); break; } } List > children = new List >(); foreach (BoolExpr child in otherChildren) { if (negatedChildren.ContainsKey(child)) { // A && !A --> False, A || !A --> True if (isAnd) { return FalseExpr .Value; } else { return TrueExpr .Value; } } children.Add(child); } foreach (BoolExpr child in negatedChildren.Keys) { children.Add(child.MakeNegated()); } if (0 == children.Count) { // And() iff. True if (isAnd) { return TrueExpr .Value; } // Or() iff. False else { return FalseExpr .Value; } } else if (1 == children.Count) { // Or(A) iff. A, And(A) iff. A return children[0]; } else { // Construct simplified And/Or expression TreeExpr result; if (isAnd) { result = new AndExpr (children); } else { result = new OrExpr (children); } return result; } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- AccessDataSource.cs
- DataService.cs
- TableItemPattern.cs
- XmlSchemaComplexContentExtension.cs
- DbParameterCollectionHelper.cs
- QueuePathDialog.cs
- InvalidOleVariantTypeException.cs
- XmlTextWriter.cs
- SynchronizedDispatch.cs
- MessageLogger.cs
- SQLUtility.cs
- embossbitmapeffect.cs
- RecommendedAsConfigurableAttribute.cs
- SqlFactory.cs
- ExpressionPrefixAttribute.cs
- Stroke.cs
- StringBlob.cs
- BufferBuilder.cs
- TypefaceMetricsCache.cs
- OutputScopeManager.cs
- SubMenuStyle.cs
- BamlBinaryReader.cs
- ActivityStateRecord.cs
- Dictionary.cs
- RectConverter.cs
- DataReaderContainer.cs
- PreservationFileWriter.cs
- SafeTokenHandle.cs
- MailAddressCollection.cs
- WebConfigurationHostFileChange.cs
- Size.cs
- DocumentSignatureManager.cs
- Imaging.cs
- SoapHeaderAttribute.cs
- QuaternionRotation3D.cs
- SimplePropertyEntry.cs
- WebPartUtil.cs
- SubpageParagraph.cs
- RouteParser.cs
- RedistVersionInfo.cs
- log.cs
- HttpWebRequestElement.cs
- Assert.cs
- SynchronizedDispatch.cs
- MessageQueuePermissionEntryCollection.cs
- StrokeRenderer.cs
- RequestNavigateEventArgs.cs
- Rule.cs
- CustomValidator.cs
- FlowLayout.cs
- VirtualizedCellInfoCollection.cs
- SQLBoolean.cs
- TypeDescriptorContext.cs
- DefaultMemberAttribute.cs
- SoapDocumentServiceAttribute.cs
- smtpconnection.cs
- DependencyPropertyAttribute.cs
- ProfileGroupSettings.cs
- DataGridTable.cs
- Triangle.cs
- ActivationArguments.cs
- ReadOnlyCollectionBase.cs
- KeyGestureConverter.cs
- SchemaImporterExtensionsSection.cs
- InstanceDescriptor.cs
- BitmapFrame.cs
- ColorTranslator.cs
- WindowsAuthenticationEventArgs.cs
- KnownBoxes.cs
- Form.cs
- TypeElementCollection.cs
- OleDbRowUpdatingEvent.cs
- GroupPartitionExpr.cs
- UTF7Encoding.cs
- SvcMapFile.cs
- ConnectionStringSettings.cs
- XmlSchemaExternal.cs
- SvcMapFile.cs
- DeflateInput.cs
- TextTabProperties.cs
- ConnectionStringSettingsCollection.cs
- ClientScriptManager.cs
- FigureParagraph.cs
- TabletDevice.cs
- OleDbConnectionInternal.cs
- MeshGeometry3D.cs
- BinaryNode.cs
- OutputCacheProviderCollection.cs
- JsonByteArrayDataContract.cs
- RuntimeEnvironment.cs
- SafePipeHandle.cs
- TextElement.cs
- CodeTryCatchFinallyStatement.cs
- X509ScopedServiceCertificateElement.cs
- SQLConvert.cs
- WebServiceHostFactory.cs
- NetCodeGroup.cs
- Int64Animation.cs
- tooltip.cs
- ActivityCompletionCallbackWrapper.cs