Util/DelayedTextWriter.cs

   1 //
   2 // DelayedTextWriter.cs
   3 //
   4 // Copyright (C) 2005 Novell, Inc.
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a copy
   9 // of this software and associated documentation files (the "Software"), to deal
  10 // in the Software without restriction, including without limitation the rights
  11 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12 // copies of the Software, and to permit persons to whom the Software is
  13 // furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in all
  16 // copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24 // SOFTWARE.
  25 //
  26
  27 using System;
  28 using System.IO;
  29 using System.Text;
  30
  31 namespace Beagle.Util {
  32
  33         // This allows you to delay instantiating a TextWriter
  34         // (and thus e.g. opening a file) until the first
  35         // write.
  36         public class DelayedTextWriter : TextWriter {
  37
  38                 public delegate TextWriter Builder ();
  39
  40                 Builder builder;
  41                 TextWriter writer;
  42
  43                 public DelayedTextWriter (Builder builder)
  44                 {
  45                         this.builder = builder;
  46                 }
  47
  48                 public override Encoding Encoding {
  49                         get {
  50                                 lock (builder) {
  51                                         if (writer == null)
  52                                                 writer = builder ();
  53                                 }
  54
  55                                 return writer.Encoding;
  56                         }
  57                 }
  58
  59                 public override void Close ()
  60                 {
  61                         if (writer != null)
  62                                 writer.Close ();
  63                 }
  64
  65                 public override void Flush ()
  66                 {
  67                         if (writer != null)
  68                                 writer.Flush ();
  69                 }
  70
  71                 public override void Write (char value)
  72                 {
  73                         lock (builder) {
  74                                 if (writer == null)
  75                                         writer = builder ();
  76                         }
  77
  78                         writer.Write (value);
  79                 }
  80         }
  81 }