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DataRowMessage.cs
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121 lines (103 loc) · 4.03 KB
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#region License
// The PostgreSQL License
//
// Copyright (C) 2016 The Npgsql Development Team
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#endregion
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Npgsql.TypeHandlers;
namespace Npgsql.BackendMessages
{
abstract class DataRowMessage : IBackendMessage
{
public BackendMessageCode Code => BackendMessageCode.DataRow;
protected internal ReadBuffer Buffer { get; protected set; }
/// <summary>
/// The number of columns in the current row
/// </summary>
internal int NumColumns;
/// <summary>
/// The index of the column that we're on, i.e. that has already been parsed, is
/// is memory and can be retrieved. Initialized to -1
/// </summary>
internal int Column;
/// <summary>
/// For streaming types (e.g. bytea, text), holds the current byte position within the column.
/// Does not include the length prefix.
/// </summary>
internal int PosInColumn;
/// <summary>
/// For streaming types (e.g. bytea), holds the byte length of the column.
/// Does not include the length prefix.
/// </summary>
internal int ColumnLen;
internal bool IsColumnNull => ColumnLen == -1;
internal abstract DataRowMessage Load(ReadBuffer buf);
/// <summary>
/// Places our position at the beginning of the given column, after the 4-byte length.
/// The length is available in ColumnLen.
/// </summary>
internal abstract void SeekToColumn(int column);
internal abstract Task SeekToColumnAsync(int column, CancellationToken cancellationToken);
internal abstract void SeekInColumn(int posInColumn);
/// <summary>
/// Returns a stream for the current column.
/// </summary>
internal abstract Stream GetStream();
/// <summary>
/// Consumes the current row, allowing the reader to read in the next one.
/// </summary>
internal abstract void Consume();
/// <summary>
/// Consumes the current row asynchronously, allowing the reader to read in the next one.
/// </summary>
internal abstract Task ConsumeAsync(CancellationToken token);
internal void SeekToColumnStart(int column)
{
SeekToColumn(column);
if (PosInColumn != 0) {
SeekInColumn(0);
}
}
#region Checks
// ReSharper disable once UnusedParameter.Global
protected void CheckColumnIndex(int column)
{
if (column < 0 || column >= NumColumns)
{
throw new IndexOutOfRangeException("Column index out of range");
}
}
internal void CheckNotNull()
{
if (IsColumnNull)
{
throw new InvalidCastException("Column is null");
}
}
#endregion
}
}