mcs/class/Npgsql/Npgsql/NpgsqlAsciiRow.cs

   1 // created on 13/6/2002 at 21:06
   2
   3 // Npgsql.NpgsqlAsciiRow.cs
   4 //
   5 // Author:
   6 //      Francisco Jr. (fxjrlists@yahoo.com.br)
   7 //
   8 //      Copyright (C) 2002 The Npgsql Development Team
   9 //      npgsql-general@gborg.postgresql.org
  10 //      http://gborg.postgresql.org/project/npgsql/projdisplay.php
  11 //
  12 // This library is free software; you can redistribute it and/or
  13 // modify it under the terms of the GNU Lesser General Public
  14 // License as published by the Free Software Foundation; either
  15 // version 2.1 of the License, or (at your option) any later version.
  16 //
  17 // This library is distributed in the hope that it will be useful,
  18 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 // Lesser General Public License for more details.
  21 //
  22 // You should have received a copy of the GNU Lesser General Public
  23 // License along with this library; if not, write to the Free Software
  24 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  25
  26 using System;
  27 using System.Collections;
  28 using System.IO;
  29 using System.Text;
  30 using System.Net;
  31 using NpgsqlTypes;
  32
  33
  34 namespace Npgsql
  35 {
  36
  37         /// <summary>
  38         /// This class represents the AsciiRow message sent from PostgreSQL
  39         /// server.
  40         /// </summary>
  41         ///
  42         internal sealed class NpgsqlAsciiRow
  43         {
  44                 // Logging related values
  45     private static readonly String CLASSNAME = "NpgsqlAsciiRow";
  46
  47                 private ArrayList                                                       data;
  48                 private Byte[]                                                          null_map_array;
  49                 private Int16                                                                   num_fields;
  50                 private readonly Int16  READ_BUFFER_SIZE = 300; //[FIXME] Is this enough??
  51                 private NpgsqlRowDescription row_desc;
  52                 private Hashtable                                                       oid_to_name_mapping;
  53
  54                 public NpgsqlAsciiRow(NpgsqlRowDescription rowDesc, Hashtable oidToNameMapping)
  55                 {
  56                         NpgsqlEventLog.LogMsg("Entering " + CLASSNAME + ".NpgsqlAsciiRow()", LogLevel.Debug);
  57
  58                         data = new ArrayList();
  59                         row_desc = rowDesc;
  60                         null_map_array = new Byte[(row_desc.NumFields + 7)/8];
  61                         oid_to_name_mapping = oidToNameMapping;
  62                         //num_fields = numFields;
  63
  64
  65                 }
  66
  67
  68                 public void ReadFromStream(Stream inputStream, Encoding encoding)
  69                 {
  70                         NpgsqlEventLog.LogMsg("Entering " + CLASSNAME + ".ReadFromStream()", LogLevel.Debug);
  71
  72                         Byte[] input_buffer = new Byte[READ_BUFFER_SIZE];
  73
  74                         Array.Clear(null_map_array, 0, null_map_array.Length);
  75
  76                         // Read the null fields bitmap.
  77                         PGUtil.CheckedStreamRead(inputStream, null_map_array, 0, null_map_array.Length );
  78
  79                         // Get the data.
  80                         for (Int16 field_count = 0; field_count < row_desc.NumFields; field_count++)
  81                         {
  82
  83                                 // Check if this field isn't null
  84                                 if (IsNull(field_count))
  85                                 {
  86                                         // Field is null just keep next field.
  87
  88                                         //[FIXME] See this[] method.
  89                                         data.Add(null);
  90                                         continue;
  91                                 }
  92
  93                                 // Read the first data of the first row.
  94
  95                                 PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, 4);
  96
  97                                 Int32 field_value_size = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(input_buffer, 0));
  98
  99                                 Int32 bytes_left = field_value_size - 4;
 100
 101                                 StringBuilder result = new StringBuilder();
 102
 103                                 while (bytes_left > READ_BUFFER_SIZE)
 104                                 {
 105                                         // Now, read just the field value.
 106                                         PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, READ_BUFFER_SIZE);
 107
 108                                         // Read the bytes as string.
 109                                         result.Append(new String(encoding.GetChars(input_buffer, 0, READ_BUFFER_SIZE)));
 110
 111                                         bytes_left -= READ_BUFFER_SIZE;
 112                                 }
 113
 114                                 // Now, read just the field value.
 115                                 PGUtil.CheckedStreamRead(inputStream, input_buffer, 0, bytes_left);
 116
 117                                 // Read the bytes as string.
 118                                 result.Append(new String(encoding.GetChars(input_buffer, 0, bytes_left)));
 119
 120
 121                                 // Add them to the AsciiRow data.
 122                                 data.Add(NpgsqlTypesHelper.ConvertBackendStringToSystemType(oid_to_name_mapping, result.ToString(), row_desc[field_count].type_oid, row_desc[field_count].type_modifier));
 123
 124                         }
 125
 126                 }
 127
 128
 129                 public Boolean IsNull(Int32 index)
 130                 {
 131                         // [FIXME] Check more optimized way of doing this.
 132                         // Should this be public or internal?
 133
 134                         // Check valid index range.
 135                         if ((index < 0) || (index >= row_desc.NumFields))
 136                                         throw new ArgumentOutOfRangeException("index");
 137
 138                         // Check if the value (index) of the field is null
 139
 140                         // Get the byte that holds the bit index position.
 141                         Byte test_byte = null_map_array[index/8];
 142
 143                         // Now, check if index bit is set.
 144                         // To this, get its position in the byte, shift to
 145                         // MSB and test it with the byte 10000000.
 146         return (((test_byte << (index%8)) & 0x80) == 0);
 147                 }
 148
 149
 150                 public Object this[Int32 index]
 151                 {
 152                         get
 153                         {
 154
 155                                 if ((index < 0) || (index >= row_desc.NumFields))
 156                                         throw new ArgumentOutOfRangeException("this[] index value");
 157                                 // [FIXME] Should return null or something else
 158                                 // more meaningful?
 159
 160                                 //[FIXME] This code assumes that the data arraylist has the null and non null values
 161                                 // in order, but just the non-null values are added.
 162                                 // It is necessary to map the index value with the elements in the array list.
 163                                 // For now, the workaround is to insert the null values in the array list.
 164                                 // But this is a hack. :)
 165
 166                                 //return (IsNull(index) ? null : data[index]);
 167                                 return data[index];
 168
 169
 170
 171                         }
 172                 }
 173         }
 174
 175 }