Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Common / Utils / Boolean / Visitor.cs / 1305376 / Visitor.cs
//---------------------------------------------------------------------- //// Copyright (c) Microsoft Corporation. All rights reserved. // // // @owner [....] // @backupOwner [....] //--------------------------------------------------------------------- using System; using System.Collections.Generic; using System.Text; using System.Globalization; using System.Collections.ObjectModel; using System.Diagnostics; using System.Linq; namespace System.Data.Common.Utils.Boolean { ////// Abstract visitor class. All Boolean expression nodes know how to /// 'accept' a visitor, and delegate to the appropriate visitor method. /// For instance, AndExpr invokes Visitor.VisitAnd. /// ///Type of leaf term identifiers in expression. ///Return type for visit methods. internal abstract class Visitor{ internal abstract T_Return VisitTrue(TrueExpr expression); internal abstract T_Return VisitFalse(FalseExpr expression); internal abstract T_Return VisitTerm(TermExpr expression); internal abstract T_Return VisitNot(NotExpr expression); internal abstract T_Return VisitAnd(AndExpr expression); internal abstract T_Return VisitOr(OrExpr expression); } /// /// Basic visitor which reproduces the given expression tree. /// ///Type of leaf term identifiers in expression. internal abstract class BasicVisitor: Visitor > { internal override BoolExpr VisitFalse(FalseExpr expression) { return expression; } internal override BoolExpr VisitTrue(TrueExpr expression) { return expression; } internal override BoolExpr VisitTerm(TermExpr expression) { return expression; } internal override BoolExpr VisitNot(NotExpr expression) { return new NotExpr (expression.Child.Accept(this)); } internal override BoolExpr VisitAnd(AndExpr expression) { return new AndExpr (AcceptChildren(expression.Children)); } internal override BoolExpr VisitOr(OrExpr expression) { return new OrExpr (AcceptChildren(expression.Children)); } private IEnumerable > AcceptChildren(IEnumerable > children) { foreach (BoolExpr child in children) { yield return child.Accept(this); } } } internal class TermCounter : Visitor { static readonly TermCounter s_instance = new TermCounter (); internal static int CountTerms(BoolExpr expression) { Debug.Assert(null != expression); return expression.Accept(s_instance); } internal override int VisitTrue(TrueExpr expression) { return 0; } internal override int VisitFalse(FalseExpr expression) { return 0; } internal override int VisitTerm(TermExpr expression) { return 1; } internal override int VisitNot(NotExpr expression) { return expression.Child.Accept(this); } internal override int VisitAnd(AndExpr expression) { return VisitTree(expression); } internal override int VisitOr(OrExpr expression) { return VisitTree(expression); } private int VisitTree(TreeExpr expression) { int sum = 0; foreach (var child in expression.Children) { sum += child.Accept(this); } return sum; } } /// /// A Visitor class that returns all the leaves in a boolean expression /// ///Type of leaf term identifiers in expression. internal class LeafVisitor: Visitor { readonly List > _terms; private LeafVisitor() { _terms = new List >(); } internal static List > GetTerms(BoolExpr expression) { Debug.Assert(null != expression, "expression must be given"); LeafVisitor visitor = new LeafVisitor (); expression.Accept(visitor); return visitor._terms; } internal static IEnumerable GetLeaves(BoolExpr expression) { return GetTerms(expression).Select(term => term.Identifier); } internal override bool VisitTrue(TrueExpr expression) { return true; } internal override bool VisitFalse(FalseExpr expression) { return true; } internal override bool VisitTerm(TermExpr expression) { _terms.Add(expression); return true; } internal override bool VisitNot(NotExpr expression) { return expression.Child.Accept(this); } internal override bool VisitAnd(AndExpr expression) { return VisitTree(expression); } internal override bool VisitOr(OrExpr expression) { return VisitTree(expression); } private bool VisitTree(TreeExpr expression) { foreach (BoolExpr child in expression.Children) { child.Accept(this); } return true; } } /// /// Rewrites the terms in a Boolean expression tree. /// ///Term type for leaf nodes of input ///Term type for leaf nodes of output internal class BooleanExpressionTermRewriter: Visitor > { private readonly Func , BoolExpr > _translator; /// /// Initialize a new translator /// /// Translator delegate; must not be null internal BooleanExpressionTermRewriter(Func, BoolExpr > translator) { Debug.Assert(null != translator); _translator = translator; } internal override BoolExpr VisitFalse(FalseExpr expression) { return FalseExpr .Value; } internal override BoolExpr VisitTrue(TrueExpr expression) { return TrueExpr .Value; } internal override BoolExpr VisitNot(NotExpr expression) { return new NotExpr (expression.Child.Accept(this)); } internal override BoolExpr VisitTerm(TermExpr expression) { return _translator(expression); } internal override BoolExpr VisitAnd(AndExpr expression) { return new AndExpr (VisitChildren(expression)); } internal override BoolExpr VisitOr(OrExpr expression) { return new OrExpr (VisitChildren(expression)); } private IEnumerable > VisitChildren(TreeExpr expression) { foreach (BoolExpr child in expression.Children) { yield return child.Accept(this); } } } /// /// Converts a BoolExpr to a Vertex within a solver. /// internal class ToDecisionDiagramConverter: Visitor { private readonly ConversionContext _context; private ToDecisionDiagramConverter(ConversionContext context) { Debug.Assert(null != context, "must provide a context"); _context = context; } internal static Vertex TranslateToRobdd(BoolExpr expr, ConversionContext context) { Debug.Assert(null != expr, "must provide an expression"); ToDecisionDiagramConverter converter = new ToDecisionDiagramConverter (context); return expr.Accept(converter); } internal override Vertex VisitTrue(TrueExpr expression) { return Vertex.One; } internal override Vertex VisitFalse(FalseExpr expression) { return Vertex.Zero; } internal override Vertex VisitTerm(TermExpr expression) { return _context.TranslateTermToVertex(expression); } internal override Vertex VisitNot(NotExpr expression) { return _context.Solver.Not(expression.Child.Accept(this)); } internal override Vertex VisitAnd(AndExpr expression) { return _context.Solver.And(expression.Children.Select(child => child.Accept(this))); } internal override Vertex VisitOr(OrExpr expression) { return _context.Solver.Or(expression.Children.Select(child => child.Accept(this))); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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