LookupNode.cs

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using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
 
namespace System.Data;
 
internal sealed class LookupNode : ExpressionNode
{
    private readonly string _relationName;
 
    private readonly string _columnName;
 
    private DataColumn _column;
 
    private DataRelation _relation;
 
    internal LookupNode(DataTable table, string columnName, string relationName)
        : base(table)
    {
        _relationName = relationName;
        _columnName = columnName;
    }
 
    internal override void Bind(DataTable table, List<DataColumn> list)
    {
        BindTable(table);
        _column = null;
        _relation = null;
        if (table == null)
        {
            throw ExprException.ExpressionUnbound(ToString());
        }
        DataRelationCollection parentRelations = table.ParentRelations;
        if (_relationName == null)
        {
            if (parentRelations.Count > 1)
            {
                throw ExprException.UnresolvedRelation(table.TableName, ToString());
            }
            _relation = parentRelations[0];
        }
        else
        {
            _relation = parentRelations[_relationName];
        }
        if (_relation == null)
        {
            throw ExprException.BindFailure(_relationName);
        }
        DataTable parentTable = _relation.ParentTable;
        _column = parentTable.Columns[_columnName];
        if (_column == null)
        {
            throw ExprException.UnboundName(_columnName);
        }
        int i;
        for (i = 0; i < list.Count; i++)
        {
            DataColumn dataColumn = list[i];
            if (_column == dataColumn)
            {
                break;
            }
        }
        if (i >= list.Count)
        {
            list.Add(_column);
        }
        AggregateNode.Bind(_relation, list);
    }
 
    [RequiresUnreferencedCode("Members from serialized types may be trimmed if not referenced directly.")]
    internal override object Eval()
    {
        throw ExprException.EvalNoContext();
    }
 
    [RequiresUnreferencedCode("Members from serialized types may be trimmed if not referenced directly.")]
    internal override object Eval(DataRow row, DataRowVersion version)
    {
        if (_column == null || _relation == null)
        {
            throw ExprException.ExpressionUnbound(ToString());
        }
        DataRow parentRow = row.GetParentRow(_relation, version);
        if (parentRow == null)
        {
            return DBNull.Value;
        }
        return parentRow[_column, parentRow.HasVersion(version) ? version : DataRowVersion.Current];
    }
 
    [RequiresUnreferencedCode("Members from serialized types may be trimmed if not referenced directly.")]
    internal override object Eval(int[] recordNos)
    {
        throw ExprException.ComputeNotAggregate(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 (_column == column)
        {
            return true;
        }
        return false;
    }
 
    internal override ExpressionNode Optimize()
    {
        return this;
    }
}