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using System;
using System.Collections.Generic;
using System.Text;
namespace System.Data.Linq.SqlClient {
internal class SqlRowNumberChecker {
Visitor rowNumberVisitor;
internal SqlRowNumberChecker() {
this.rowNumberVisitor = new Visitor();
}
internal bool HasRowNumber(SqlNode node) {
this.rowNumberVisitor.Visit(node);
return rowNumberVisitor.HasRowNumber;
}
internal bool HasRowNumber(SqlRow row) {
foreach (SqlColumn column in row.Columns) {
if (this.HasRowNumber(column)) {
return true;
}
}
return false;
}
internal SqlColumn RowNumberColumn {
get {
return rowNumberVisitor.HasRowNumber ? rowNumberVisitor.CurrentColumn : null;
}
}
private class Visitor: SqlVisitor {
bool hasRowNumber = false;
public bool HasRowNumber {
get { return hasRowNumber; }
}
public SqlColumn CurrentColumn { private set; get; }
internal override SqlRowNumber VisitRowNumber(SqlRowNumber rowNumber) {
this.hasRowNumber = true;
return rowNumber;
}
// shortcuts
internal override SqlExpression VisitScalarSubSelect(SqlSubSelect ss) {
return ss;
}
internal override SqlExpression VisitSubSelect(SqlSubSelect ss) {
return ss;
}
internal override SqlRow VisitRow(SqlRow row)
{
for (int i = 0, n = row.Columns.Count; i < n; i++) {
row.Columns[i].Expression = this.VisitExpression(row.Columns[i].Expression);
if (this.hasRowNumber) {
this.CurrentColumn = row.Columns[i];
break;
}
}
return row;
}
internal override SqlSelect VisitSelect(SqlSelect select) {
this.Visit(select.Row);
this.Visit(select.Where);
return select;
}
}
}
}
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