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RecordHandler.cs
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executable file
·144 lines (126 loc) · 5.02 KB
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#region License
// The PostgreSQL License
//
// Copyright (C) 2015 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 JetBrains.Annotations;
using Npgsql.BackendMessages;
namespace Npgsql.TypeHandlers
{
/// <summary>
/// Type handler for PostgreSQL record types.
/// </summary>
/// <remarks>
/// http://www.postgresql.org/docs/current/static/datatype-pseudo.html
///
/// Encoding (identical to composite):
/// A 32-bit integer with the number of columns, then for each column:
/// * An OID indicating the type of the column
/// * The length of the column(32-bit integer), or -1 if null
/// * The column data encoded as binary
/// </remarks>
[TypeMapping("record")]
internal class RecordHandler : ChunkingTypeHandler<object[]>
{
readonly TypeHandlerRegistry _registry;
NpgsqlBuffer _buf;
int _fieldIndex, _fieldCount, _fieldLen;
TypeHandler _fieldHandler;
object[] _value;
public RecordHandler(TypeHandlerRegistry registry)
{
_registry = registry;
}
#region Read
public override void PrepareRead(NpgsqlBuffer buf, int len, FieldDescription fieldDescription = null)
{
_buf = buf;
_fieldIndex = _fieldCount = - 1;
_fieldLen = -1;
}
public override bool Read([CanBeNull] out object[] result)
{
result = null;
if (_fieldIndex == -1)
{
if (_buf.ReadBytesLeft < 4) { return false; }
_fieldCount = _buf.ReadInt32();
_value = new object[_fieldCount];
_fieldIndex = 0;
}
for (; _fieldIndex < _fieldCount; _fieldIndex++)
{
// Not yet started reading the field.
// Read the type OID, then the length.
if (_fieldLen == -1)
{
if (_buf.ReadBytesLeft < 8) { return false; }
var typeOID = _buf.ReadInt32();
_fieldLen = _buf.ReadInt32();
if (_fieldLen == -1)
{
// Null field, simply skip it and leave at default
continue;
}
_fieldHandler = _registry[typeOID];
}
// Get the field's type handler and read the value
object fieldValue;
if (_fieldHandler is ISimpleTypeHandler)
{
var asSimpleReader = (ISimpleTypeHandler)_fieldHandler;
if (_buf.ReadBytesLeft < _fieldLen) { return false; }
fieldValue = asSimpleReader.ReadAsObject(_buf, _fieldLen);
}
else if (_fieldHandler is IChunkingTypeHandler)
{
var asChunkingReader = (IChunkingTypeHandler)_fieldHandler;
asChunkingReader.PrepareRead(_buf, _fieldLen);
if (!asChunkingReader.ReadAsObject(out fieldValue))
{
return false;
}
}
else throw PGUtil.ThrowIfReached();
_value[_fieldIndex] = fieldValue;
_fieldLen = -1;
}
result = _value;
_fieldHandler = null;
return true;
}
#endregion
#region Write (unsupported)
public override int ValidateAndGetLength(object value, ref LengthCache lengthCache, NpgsqlParameter parameter)
{
throw new NotSupportedException("Can't write record types");
}
public override void PrepareWrite(object value, NpgsqlBuffer buf, LengthCache lengthCache, NpgsqlParameter parameter)
{
throw new NotSupportedException("Can't write record types");
}
public override bool Write(ref DirectBuffer directBuf)
{
throw new NotSupportedException("Can't write record types");
}
#endregion
}
}