Code:
/ Dotnetfx_Win7_3.5.1 / Dotnetfx_Win7_3.5.1 / 3.5.1 / DEVDIV / depot / DevDiv / releases / Orcas / NetFXw7 / ndp / fx / src / DataEntity / System / Data / Common / Utils / Boolean / Simplifier.cs / 1 / 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
- ConnectionStringSettings.cs
- AnimationClockResource.cs
- ShaderEffect.cs
- CqlParserHelpers.cs
- UserValidatedEventArgs.cs
- HtmlInputText.cs
- Random.cs
- Pkcs7Recipient.cs
- Parsers.cs
- XmlObjectSerializerReadContext.cs
- DesignerActionPropertyItem.cs
- RolePrincipal.cs
- HttpRequestCacheValidator.cs
- SortKey.cs
- SequentialWorkflowHeaderFooter.cs
- SchemaDeclBase.cs
- TextContainerHelper.cs
- _TimerThread.cs
- PositiveTimeSpanValidatorAttribute.cs
- FactoryId.cs
- InteropBitmapSource.cs
- XamlTreeBuilderBamlRecordWriter.cs
- AnnotationService.cs
- DefaultWorkflowLoaderService.cs
- PackageRelationship.cs
- FlowLayoutSettings.cs
- HttpModuleAction.cs
- UserControlParser.cs
- HtmlInputReset.cs
- HtmlDocument.cs
- TransformedBitmap.cs
- CompModSwitches.cs
- GetPageNumberCompletedEventArgs.cs
- GPRECTF.cs
- _FtpDataStream.cs
- Group.cs
- OutputCacheSettingsSection.cs
- InkPresenterAutomationPeer.cs
- ConfigXmlWhitespace.cs
- Keywords.cs
- Membership.cs
- ElapsedEventArgs.cs
- DateTimeHelper.cs
- TextEndOfSegment.cs
- NoResizeHandleGlyph.cs
- CallContext.cs
- TdsParserSafeHandles.cs
- XmlQueryContext.cs
- input.cs
- SoapExtensionImporter.cs
- TextChangedEventArgs.cs
- ZoneMembershipCondition.cs
- WebConfigurationFileMap.cs
- PersistenceParticipant.cs
- XmlTextEncoder.cs
- DBCSCodePageEncoding.cs
- RawStylusSystemGestureInputReport.cs
- CustomPopupPlacement.cs
- X509Certificate.cs
- OdbcRowUpdatingEvent.cs
- ClientRequest.cs
- TypeEnumerableViewSchema.cs
- UriSectionData.cs
- VerificationAttribute.cs
- BitmapEffectDrawingContent.cs
- DrawListViewSubItemEventArgs.cs
- ArraySortHelper.cs
- Nullable.cs
- HScrollBar.cs
- complextypematerializer.cs
- CodeLabeledStatement.cs
- SafeMILHandleMemoryPressure.cs
- TitleStyle.cs
- DataGridViewRowHeightInfoNeededEventArgs.cs
- AsmxEndpointPickerExtension.cs
- URLAttribute.cs
- ToolBar.cs
- SetUserPreferenceRequest.cs
- HttpCachePolicy.cs
- WebBrowserBase.cs
- Int16AnimationUsingKeyFrames.cs
- ThicknessAnimationBase.cs
- DataGridViewHeaderCell.cs
- VectorCollection.cs
- CustomAttribute.cs
- AuthenticatingEventArgs.cs
- DBBindings.cs
- RSAPKCS1SignatureDeformatter.cs
- AsyncStreamReader.cs
- SHA384Managed.cs
- ModelVisual3D.cs
- CombinedTcpChannel.cs
- UrlPropertyAttribute.cs
- JapaneseCalendar.cs
- XsdBuilder.cs
- ActivationProxy.cs
- ColorConvertedBitmapExtension.cs
- WebPartEditVerb.cs
- ClientConfigurationHost.cs
- SystemTcpStatistics.cs