LinqMaximalSubtreeNominator.cs source code in C# .NET

                        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 / Objects / ELinq / Visitors / LinqMaximalSubtreeNominator.cs / 1 / LinqMaximalSubtreeNominator.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....], [....]
//--------------------------------------------------------------------- 
using System.Linq.Expressions; 
using System.Collections.Generic;
using System.Diagnostics; 
namespace System.Data.Objects.ELinq
{
    /// 
    /// Goes from the bottom to top and nominates nodes where all the nodes 
    /// below the node return true from the shouldBeNominatedDelegate
    ///  
    internal sealed class LinqMaximalSubtreeNominator : ExpressionVisitor 
    {
        readonly HashSet _candidates; 
        readonly Func _shouldBeNominatedDelegate;
        bool _cannotBeNominated = false;

        // not creatable 
        private LinqMaximalSubtreeNominator(HashSet candidates, Func shouldBeNominatedDelegate)
        { 
            _candidates = candidates; 
            _shouldBeNominatedDelegate = shouldBeNominatedDelegate;
        } 

        internal static HashSet Nominate(Expression expression, HashSet candidates, Func shouldBeNominatedDelegate)
        {
            Debug.Assert(candidates != null, "Candidates hashset cannot be null"); 

            LinqMaximalSubtreeNominator nominator = new LinqMaximalSubtreeNominator(candidates, shouldBeNominatedDelegate); 
            nominator.Visit(expression); 
            return nominator._candidates;
        } 

        internal static HashSet FindMaximalSubtrees(Expression expression, Func shouldBeNominatedDelegate)
        {
            HashSet nominees = Nominate(expression, new HashSet(), shouldBeNominatedDelegate); 
            return MaximalSubtreeVisitor.FindMaximalSubtrees(nominees, expression);
        } 
 
        internal override Expression Visit(Expression exp)
        { 
            if (exp != null)
            {
                bool saveCannotBeNominated = _cannotBeNominated;
                _cannotBeNominated = false; 
                base.Visit(exp);
                if (!_cannotBeNominated) 
                { 
                    // everyone below me can be nominated, so
                    // see if this one can be also 
                    if (_shouldBeNominatedDelegate(exp))
                    {
                        _candidates.Add(exp);
                    } 
                    else
                    { 
                        _cannotBeNominated = true; 
                    }
                } 
                _cannotBeNominated |= saveCannotBeNominated;
            }
            return exp;
        } 

 
        ///  
        /// Visitor that identifies maximal subtrees given a set of nominees. It walks the tree top down
        /// and when it identifies a nominated node, adds it to the _subtree set and stops walking. 
        /// 
        private sealed class MaximalSubtreeVisitor : ExpressionVisitor
        {
            private readonly HashSet _subtrees; 
            private readonly HashSet _nominees;
 
            private MaximalSubtreeVisitor(HashSet nominees) 
            {
                _nominees = nominees; 
                _subtrees = new HashSet();
            }

            internal static HashSet FindMaximalSubtrees(HashSet nominees, Expression query) 
            {
                MaximalSubtreeVisitor visitor = new MaximalSubtreeVisitor(nominees); 
                visitor.Visit(query); 
                return visitor._subtrees;
            } 

            internal override Expression Visit(Expression exp)
            {
                if (exp != null && 
                    _nominees.Contains(exp))
                { 
                    _subtrees.Add(exp); 
                    return exp;
                } 
                return base.Visit(exp);
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....], [....]
//--------------------------------------------------------------------- 
using System.Linq.Expressions; 
using System.Collections.Generic;
using System.Diagnostics; 
namespace System.Data.Objects.ELinq
{
    /// 
    /// Goes from the bottom to top and nominates nodes where all the nodes 
    /// below the node return true from the shouldBeNominatedDelegate
    ///  
    internal sealed class LinqMaximalSubtreeNominator : ExpressionVisitor 
    {
        readonly HashSet _candidates; 
        readonly Func _shouldBeNominatedDelegate;
        bool _cannotBeNominated = false;

        // not creatable 
        private LinqMaximalSubtreeNominator(HashSet candidates, Func shouldBeNominatedDelegate)
        { 
            _candidates = candidates; 
            _shouldBeNominatedDelegate = shouldBeNominatedDelegate;
        } 

        internal static HashSet Nominate(Expression expression, HashSet candidates, Func shouldBeNominatedDelegate)
        {
            Debug.Assert(candidates != null, "Candidates hashset cannot be null"); 

            LinqMaximalSubtreeNominator nominator = new LinqMaximalSubtreeNominator(candidates, shouldBeNominatedDelegate); 
            nominator.Visit(expression); 
            return nominator._candidates;
        } 

        internal static HashSet FindMaximalSubtrees(Expression expression, Func shouldBeNominatedDelegate)
        {
            HashSet nominees = Nominate(expression, new HashSet(), shouldBeNominatedDelegate); 
            return MaximalSubtreeVisitor.FindMaximalSubtrees(nominees, expression);
        } 
 
        internal override Expression Visit(Expression exp)
        { 
            if (exp != null)
            {
                bool saveCannotBeNominated = _cannotBeNominated;
                _cannotBeNominated = false; 
                base.Visit(exp);
                if (!_cannotBeNominated) 
                { 
                    // everyone below me can be nominated, so
                    // see if this one can be also 
                    if (_shouldBeNominatedDelegate(exp))
                    {
                        _candidates.Add(exp);
                    } 
                    else
                    { 
                        _cannotBeNominated = true; 
                    }
                } 
                _cannotBeNominated |= saveCannotBeNominated;
            }
            return exp;
        } 

 
        ///  
        /// Visitor that identifies maximal subtrees given a set of nominees. It walks the tree top down
        /// and when it identifies a nominated node, adds it to the _subtree set and stops walking. 
        /// 
        private sealed class MaximalSubtreeVisitor : ExpressionVisitor
        {
            private readonly HashSet _subtrees; 
            private readonly HashSet _nominees;
 
            private MaximalSubtreeVisitor(HashSet nominees) 
            {
                _nominees = nominees; 
                _subtrees = new HashSet();
            }

            internal static HashSet FindMaximalSubtrees(HashSet nominees, Expression query) 
            {
                MaximalSubtreeVisitor visitor = new MaximalSubtreeVisitor(nominees); 
                visitor.Visit(query); 
                return visitor._subtrees;
            } 

            internal override Expression Visit(Expression exp)
            {
                if (exp != null && 
                    _nominees.Contains(exp))
                { 
                    _subtrees.Add(exp); 
                    return exp;
                } 
                return base.Visit(exp);
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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LinqMaximalSubtreeNominator.cs source code in C# .NET

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