124 lines
3.6 KiB
C#
124 lines
3.6 KiB
C#
// ---------------------------------------------------------------------------
|
|
// <copyright file="CursorEnumerator.cs" company="Microsoft">
|
|
// Copyright (c) Microsoft Corporation. All rights reserved.
|
|
// </copyright>
|
|
// ---------------------------------------------------------------------------
|
|
|
|
// ---------------------------------------------------------------------
|
|
// <summary>
|
|
// </summary>
|
|
// ---------------------------------------------------------------------
|
|
|
|
namespace Microsoft.Database.Isam
|
|
{
|
|
using System;
|
|
using System.Collections;
|
|
|
|
/// <summary>
|
|
/// Enumerates the records visible to a given cursor.
|
|
/// </summary>
|
|
public class CursorEnumerator : IEnumerator
|
|
{
|
|
/// <summary>
|
|
/// The cursor
|
|
/// </summary>
|
|
private Cursor cursor;
|
|
|
|
/// <summary>
|
|
/// The moved
|
|
/// </summary>
|
|
private bool moved = false;
|
|
|
|
/// <summary>
|
|
/// The current
|
|
/// </summary>
|
|
private bool current = false;
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="CursorEnumerator"/> class.
|
|
/// </summary>
|
|
/// <param name="cursor">The cursor.</param>
|
|
internal CursorEnumerator(Cursor cursor)
|
|
{
|
|
this.cursor = cursor;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the current element in the collection.
|
|
/// </summary>
|
|
/// <returns>The current element in the collection.</returns>
|
|
/// <exception cref="System.InvalidOperationException">
|
|
/// after last record in cursor
|
|
/// or
|
|
/// before first record in cursor
|
|
/// </exception>
|
|
/// <remarks>
|
|
/// This is the type safe version that may not work in other CLR
|
|
/// languages.
|
|
/// </remarks>
|
|
public FieldCollection Current
|
|
{
|
|
get
|
|
{
|
|
if (this.current == false)
|
|
{
|
|
if (this.moved == true)
|
|
{
|
|
throw new InvalidOperationException("after last record in cursor");
|
|
}
|
|
else
|
|
{
|
|
throw new InvalidOperationException("before first record in cursor");
|
|
}
|
|
}
|
|
|
|
return this.cursor.Fields;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the current element in the collection.
|
|
/// </summary>
|
|
/// <returns>The current element in the collection.</returns>
|
|
/// <remarks>
|
|
/// This is the standard version that will work with other CLR
|
|
/// languages.
|
|
/// </remarks>
|
|
object IEnumerator.Current
|
|
{
|
|
get
|
|
{
|
|
return this.Current;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Sets the enumerator to its initial position, which is before the first element in the collection.
|
|
/// </summary>
|
|
public void Reset()
|
|
{
|
|
this.cursor.MoveBeforeFirst();
|
|
this.moved = false;
|
|
this.current = false;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Advances the enumerator to the next element of the collection.
|
|
/// </summary>
|
|
/// <returns>
|
|
/// true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.
|
|
/// </returns>
|
|
public bool MoveNext()
|
|
{
|
|
if (this.moved == false)
|
|
{
|
|
this.Reset();
|
|
}
|
|
|
|
this.current = this.cursor.MoveNext();
|
|
this.moved = true;
|
|
return this.current;
|
|
}
|
|
}
|
|
}
|