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HstoreHandler.cs
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executable file
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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 System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Text;
using JetBrains.Annotations;
using Npgsql.BackendMessages;
using NpgsqlTypes;
namespace Npgsql.TypeHandlers
{
[TypeMapping("hstore", NpgsqlDbType.Hstore)]
class HstoreHandler : ChunkingTypeHandler<IDictionary<string, string>>, IChunkingTypeHandler<string>
{
NpgsqlBuffer _buf;
NpgsqlParameter _parameter;
LengthCache _lengthCache;
FieldDescription _fieldDescription;
IDictionary<string, string> _value;
IEnumerator<KeyValuePair<string, string>> _enumerator;
string _key;
int _numElements;
State _state;
/// <summary>
/// The text handler to which we delegate encoding/decoding of the actual strings
/// </summary>
readonly TextHandler _textHandler;
public HstoreHandler()
{
_textHandler = new TextHandler();
}
#region Write
public override int ValidateAndGetLength(object value, ref LengthCache lengthCache, NpgsqlParameter parameter = null)
{
if (lengthCache == null) {
lengthCache = new LengthCache(1);
}
if (lengthCache.IsPopulated) {
return lengthCache.Get();
}
var asDict = value as IDictionary<string, string>;
if (asDict != null)
{
// Leave empty slot for the entire hstore length, and go ahead an populate the individual string slots
var pos = lengthCache.Position;
lengthCache.Set(0);
var totalLen = 4; // Number of key-value pairs
foreach (var kv in asDict)
{
totalLen += 8; // Key length + value length
if (kv.Key == null) {
throw new FormatException("HSTORE doesn't support null keys");
}
totalLen += lengthCache.Set(Encoding.UTF8.GetByteCount(kv.Key));
if (kv.Value != null) {
totalLen += lengthCache.Set(Encoding.UTF8.GetByteCount(kv.Value));
}
}
return lengthCache.Lengths[pos] = totalLen;
}
throw CreateConversionException(value.GetType());
}
public override void PrepareWrite(object value, NpgsqlBuffer buf, LengthCache lengthCache, NpgsqlParameter parameter)
{
_buf = buf;
_lengthCache = lengthCache;
_parameter = parameter;
_state = State.Count;
var asDict = value as IDictionary<string, string>;
if (asDict != null) {
_value = asDict;
return;
}
throw PGUtil.ThrowIfReached();
}
public override bool Write(ref DirectBuffer directBuf)
{
switch (_state)
{
case State.Count:
if (_buf.WriteSpaceLeft < 4) { return false; }
_buf.WriteInt32(_value.Count);
if (_value.Count == 0)
{
CleanupState();
return true;
}
_enumerator = _value.GetEnumerator();
_enumerator.MoveNext();
goto case State.KeyLen;
case State.KeyLen:
_state = State.KeyLen;
if (_buf.WriteSpaceLeft < 4) { return false; }
var keyLen = _lengthCache.Get();
_buf.WriteInt32(keyLen);
_textHandler.PrepareWrite(_enumerator.Current.Key, _buf, _lengthCache, _parameter);
goto case State.KeyData;
case State.KeyData:
_state = State.KeyData;
if (!_textHandler.Write(ref directBuf)) { return false; }
goto case State.ValueLen;
case State.ValueLen:
_state = State.ValueLen;
if (_buf.WriteSpaceLeft < 4) { return false; }
if (_enumerator.Current.Value == null)
{
_buf.WriteInt32(-1);
if (!_enumerator.MoveNext()) {
CleanupState();
return true;
}
goto case State.KeyLen;
}
var valueLen = _lengthCache.Get();
_buf.WriteInt32(valueLen);
_textHandler.PrepareWrite(_enumerator.Current.Value, _buf, _lengthCache, _parameter);
goto case State.ValueData;
case State.ValueData:
_state = State.ValueData;
if (!_textHandler.Write(ref directBuf)) { return false; }
if (!_enumerator.MoveNext())
{
CleanupState();
return true;
}
goto case State.KeyLen;
default:
throw PGUtil.ThrowIfReached();
}
}
#endregion
#region Read
public override void PrepareRead(NpgsqlBuffer buf, int len, FieldDescription fieldDescription)
{
_buf = buf;
_fieldDescription = fieldDescription;
_state = State.Count;
}
public override bool Read([CanBeNull] out IDictionary<string, string> result)
{
result = null;
switch (_state)
{
case State.Count:
if (_buf.ReadBytesLeft < 4) { return false; }
_numElements = _buf.ReadInt32();
_value = new Dictionary<string, string>(_numElements);
if (_numElements == 0)
{
CleanupState();
return true;
}
goto case State.KeyLen;
case State.KeyLen:
_state = State.KeyLen;
if (_buf.ReadBytesLeft < 4) { return false; }
var keyLen = _buf.ReadInt32();
Contract.Assume(keyLen != -1);
_textHandler.PrepareRead(_buf, _fieldDescription, keyLen);
goto case State.KeyData;
case State.KeyData:
_state = State.KeyData;
if (!_textHandler.Read(out _key)) { return false; }
goto case State.ValueLen;
case State.ValueLen:
_state = State.ValueLen;
if (_buf.ReadBytesLeft < 4) { return false; }
var valueLen = _buf.ReadInt32();
if (valueLen == -1)
{
_value[_key] = null;
if (--_numElements == 0)
{
result = _value;
CleanupState();
return true;
}
goto case State.KeyLen;
}
_textHandler.PrepareRead(_buf, _fieldDescription, valueLen);
goto case State.ValueData;
case State.ValueData:
_state = State.ValueData;
string value;
if (!_textHandler.Read(out value)) { return false; }
_value[_key] = value;
if (--_numElements == 0)
{
result = _value;
CleanupState();
return true;
}
goto case State.KeyLen;
default:
throw PGUtil.ThrowIfReached();
}
}
public bool Read([CanBeNull] out string result)
{
IDictionary<string, string> dict;
if (!((IChunkingTypeHandler<IDictionary<string, string>>) this).Read(out dict))
{
result = null;
return false;
}
var sb = new StringBuilder();
var i = dict.Count;
foreach (var kv in dict)
{
sb.Append('"');
sb.Append(kv.Key);
sb.Append(@"""=>");
if (kv.Value == null)
{
sb.Append("NULL");
}
else
{
sb.Append('"');
sb.Append(kv.Value);
sb.Append('"');
}
if (--i > 0) {
sb.Append(',');
}
}
result = sb.ToString();
return true;
}
#endregion
void CleanupState()
{
_buf = null;
_value = null;
_parameter = null;
_fieldDescription = null;
_enumerator = null;
_key = null;
}
enum State { Count, KeyLen, KeyData, ValueLen, ValueData }
}
}