LookupNode.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / Filter / LookupNode.cs / 3 / LookupNode.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
// [....] 
//----------------------------------------------------------------------------- 

namespace System.Data { 
    using System;
    using System.ComponentModel;
    using System.Collections.Generic;
    using System.Diagnostics; 

    internal sealed class LookupNode : ExpressionNode { 
        private readonly string relationName;    // can be null 
        private readonly string columnName;
 
        private DataColumn column;
        private DataRelation relation;

        internal LookupNode(DataTable table, string columnName, string relationName) : base(table) { 
            this.relationName = relationName;
            this.columnName = columnName; 
        } 

        internal override void Bind(DataTable table, List list) { 
            BindTable(table);
            column = null;  // clear for rebinding (if original binding was valid)
            relation = null;
 
            if (table == null)
                throw ExprException.ExpressionUnbound(this.ToString()); 
 
            // First find parent table
 
            DataRelationCollection relations;
            relations = table.ParentRelations;

            if (relationName == null) { 
                // must have one and only one relation
 
                if (relations.Count > 1) { 
                    throw ExprException.UnresolvedRelation(table.TableName, this.ToString());
                } 
                relation = relations[0];
            }
            else {
                relation = relations[relationName]; 
            }
            if (null == relation) { 
                throw ExprException.BindFailure(relationName);// WebData 112162: this operation is not clne specific, throw generic exception 
            }
            DataTable parentTable = relation.ParentTable; 

            Debug.Assert(relation != null, "Invalid relation: no parent table.");
            Debug.Assert(columnName != null, "All Lookup expressions have columnName set.");
 
            this.column = parentTable.Columns[columnName];
 
            if (column == null) 
                throw ExprException.UnboundName(columnName);
 
            // add column to the dependency list

            int i;
            for (i = 0; i < list.Count; i++) { 
                // walk the list, check if the current column already on the list
                DataColumn dataColumn = list[i]; 
                if (column == dataColumn) { 
                    break;
                } 
            }
            if (i >= list.Count) {
                list.Add(column);
            } 

            // 
            AggregateNode.Bind(relation, list); 
        }
 
        internal override object Eval() {
            throw ExprException.EvalNoContext();
        }
 
        internal override object Eval(DataRow row, DataRowVersion version) {
            if (column == null || relation == null) 
                throw ExprException.ExpressionUnbound(this.ToString()); 

            DataRow parent = row.GetParentRow(relation, version); 
            if (parent == null)
                return DBNull.Value;

            return parent[column, parent.HasVersion(version) ? version : DataRowVersion.Current]; // [....] : Bug 76154 
        }
 
        internal override object Eval(int[] recordNos) { 
            throw ExprException.ComputeNotAggregate(this.ToString());
        } 

        internal override bool IsConstant() {
            return false;
        } 

        internal override bool IsTableConstant() { 
            return false; 
        }
 
        internal override bool HasLocalAggregate() {
            return false;
        }
 
        internal override bool HasRemoteAggregate() {
            return false; 
        } 

        internal override bool DependsOn(DataColumn column) { 
            if (this.column == column) {
                return true;
            }
            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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LookupNode.cs source code in C# .NET

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