ZeroOpNode.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Filter / ZeroOpNode.cs / 1 / ZeroOpNode.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
// [....] 
//----------------------------------------------------------------------------- 

namespace System.Data { 
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
 
    internal sealed class ZeroOpNode : ExpressionNode {
        internal readonly int op; 
 
        internal const int zop_True = 1;
        internal const int zop_False = 0; 
        internal const int zop_Null = -1;


        internal ZeroOpNode(int op) : base((DataTable)null) { 
            this.op = op;
            Debug.Assert(op == Operators.True || op == Operators.False || op == Operators.Null, "Invalid zero-op"); 
        } 

        internal override void Bind(DataTable table, List list) { 
        }

        internal override object Eval() {
            switch (op) { 
                case Operators.True:
                    return true; 
                case Operators.False: 
                    return false;
                case Operators.Null: 
                    return DBNull.Value;
                default:
                    Debug.Assert(op == Operators.True || op == Operators.False || op == Operators.Null, "Invalid zero-op");
                    return DBNull.Value; 
            }
        } 
 
        internal override object Eval(DataRow row, DataRowVersion version) {
            return Eval(); 
        }

        internal override object Eval(int[] recordNos) {
            return Eval(); 
        }
 
        internal override bool IsConstant() { 
            return true;
        } 

        internal override bool IsTableConstant() {
            return true;
        } 

        internal override bool HasLocalAggregate() { 
            return false; 
        }
 
        internal override bool HasRemoteAggregate() {
            return false;
        }
 
        internal override ExpressionNode Optimize() {
            return this; 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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