mcs/class/referencesource/System.Data/System/Data/SQLTypes/SqlCharStream.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="SqlStreamChars.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //  </copyright>
   5 // <owner current="true" primary="true">junfang</owner>
   6 // <owner current="true" primary="false">Microsoft</owner>
   7 // <owner current="true" primary="false">Microsoft</owner>
   8 //------------------------------------------------------------------------------
   9
  10 //**************************************************************************
  11 // @File: SqlStreamChars.cs
  12 //
  13 // Create by:   JunFang
  14 //
  15 // Description:
  16 //
  17 // Notes:
  18 //
  19 // History:
  20 //
  21 //   04/17/01  JunFang  Created.
  22 //
  23 // @EndHeader@
  24 //**************************************************************************
  25
  26 namespace System.Data.SqlTypes
  27         {
  28         using System;
  29         using System.IO;
  30         using System.Runtime.InteropServices;
  31         using System.Data.SqlTypes;
  32
  33         internal abstract class SqlStreamChars: System.Data.SqlTypes.INullable, IDisposable
  34                 {
  35                 public abstract bool IsNull { get; }
  36
  37                 public abstract bool CanRead { get; }
  38
  39                 public abstract bool CanSeek { get; }
  40
  41                 public abstract bool CanWrite { get; }
  42
  43                 public abstract long Length { get; }
  44
  45                 public abstract long Position { get; set; }
  46
  47                 // --------------------------------------------------------------
  48                 //        Public methods
  49                 // --------------------------------------------------------------
  50                 public abstract int Read (char[] buffer, int offset, int count);
  51
  52                 public abstract void Write (char[] buffer, int offset, int count);
  53
  54                 public abstract long Seek (long offset, SeekOrigin origin);
  55
  56                 public abstract void SetLength (long value);
  57
  58                 public abstract void Flush ();
  59
  60                 public virtual void Close(){
  61                         Dispose(true);
  62                 }
  63
  64                 void IDisposable.Dispose() {
  65             Dispose(true);
  66         }
  67
  68                 protected virtual void Dispose(bool disposing) {
  69                 }
  70
  71                 public virtual int ReadChar()
  72                         {
  73                         // Reads one char from the stream by calling Read(char[], int, int).
  74                         // Will return an char cast to an int or -1 on end of stream.
  75                         // The performance of the default implementation on Stream is bad,
  76                         // and any subclass with an internal buffer should override this method.
  77                         char[] oneCharArray = new char[1];
  78                         int r = Read(oneCharArray, 0, 1);
  79                         if (r==0)
  80                                 return -1;
  81                         return oneCharArray[0];
  82                         }
  83
  84                 public virtual void WriteChar(char value)
  85                         {
  86                         // Writes one char from the stream by calling Write(char[], int, int).
  87                         // The performance of the default implementation on Stream is bad,
  88                         // and any subclass with an internal buffer should override this method.
  89                         char[] oneCharArray = new char[1];
  90                         oneCharArray[0] = value;
  91                         Write(oneCharArray, 0, 1);
  92                         }
  93
  94
  95                 // Private class: the Null SqlStreamChars
  96                 private class NullSqlStreamChars : SqlStreamChars
  97                         {
  98                         // --------------------------------------------------------------
  99                         //        Constructor(s)
 100                         // --------------------------------------------------------------
 101
 102                         internal NullSqlStreamChars()
 103                                 {
 104                                 }
 105
 106
 107                         // --------------------------------------------------------------
 108                         //        Public properties
 109                         // --------------------------------------------------------------
 110
 111                         public override bool IsNull
 112                                 {
 113                                 get
 114                                         {
 115                                         return true;
 116                                         }
 117                                 }
 118
 119                         public override bool CanRead
 120                                 {
 121                                 get
 122                                         {
 123                                         return false;
 124                                         }
 125                                 }
 126
 127                         public override bool CanSeek
 128                                 {
 129                                 get
 130                                         {
 131                                         return false;
 132                                         }
 133                                 }
 134
 135                         public override bool CanWrite
 136                                 {
 137                                 get
 138                                         {
 139                                         return false;
 140                                         }
 141                                 }
 142
 143                         public override long Length
 144                                 {
 145                                 get
 146                                         {
 147                                         throw new SqlNullValueException();
 148                                         }
 149                                 }
 150
 151                         public override long Position
 152                                 {
 153                                 get
 154                                         {
 155                                         throw new SqlNullValueException();
 156                                         }
 157                                 set
 158                                         {
 159                                         throw new SqlNullValueException();
 160                                         }
 161                                 }
 162
 163                         // --------------------------------------------------------------
 164                         //        Public methods
 165                         // --------------------------------------------------------------
 166                         public override int Read (char[] buffer, int offset, int count)
 167                                 {
 168                                 throw new SqlNullValueException();
 169                                 }
 170
 171                         public override void Write (char[] buffer, int offset, int count)
 172                                 {
 173                                 throw new SqlNullValueException();
 174                                 }
 175
 176                         public override long Seek (long offset, SeekOrigin origin)
 177                                 {
 178                                 throw new SqlNullValueException();
 179                                 }
 180
 181                         public override void SetLength (long value)
 182                                 {
 183                                 throw new SqlNullValueException();
 184                                 }
 185
 186                         public override void Flush ()
 187                                 {
 188                                 throw new SqlNullValueException();
 189                                 }
 190
 191                         public override void Close ()
 192                                 {
 193                                 }
 194
 195                         } // class NullSqlStreamChars
 196
 197
 198                 // The Null instance
 199                 public static SqlStreamChars Null {
 200                     get {
 201                         return new NullSqlStreamChars();
 202                     }
 203                 }
 204
 205                 } // class SqlStreamChars
 206
 207         } // namespace System.Data.SqlTypes