indexer/Content.cs

   1
   2 using System;
   3 using System.Collections;
   4 using System.IO;
   5 using System.Reflection;
   6
   7 namespace Dewey {
   8
   9     abstract public class Content {
  10
  11         static Hashtable registry = new Hashtable();
  12
  13         static public void Register(Type handler) {
  14             if (! handler.IsSubclassOf(typeof(Content))) {
  15                 // throw exception: type not subclass of Content
  16             }
  17
  18             Content dummy = (Content)Activator.CreateInstance(handler);
  19             foreach (String mime_type in dummy.HandledMimeTypes()) {
  20                 if (registry.Contains(mime_type)) {
  21                     // throw exception: duplicated mime type
  22                 }
  23                 registry[mime_type] = handler;
  24             }
  25         }
  26
  27         static public Content Extract(String mime_type, Stream stream) {
  28             Content content = null;
  29             if (registry.Contains(mime_type)) {
  30                 Type handler = registry[mime_type] as Type;
  31                 content = Activator.CreateInstance(handler) as Content;
  32
  33                 if (! content.Read(stream))
  34                     return null;
  35             }
  36             return content;
  37         }
  38
  39         //////////////////////////////
  40
  41         Hashtable metadata = new Hashtable();
  42         String body;
  43
  44         public Content() { }
  45
  46         abstract public String[] HandledMimeTypes();
  47         abstract public bool Read(Stream content_stream);
  48
  49         protected void SetMetadata(String key, String value) {
  50             metadata[key.ToLower()] = value;
  51         }
  52
  53         protected void SetBody(String _body) {
  54             if (body != null) {
  55                 // FIXME: complain that you can't set the body twice
  56             }
  57             body = _body;
  58         }
  59
  60         public ICollection MetadataKeys {
  61             get { return metadata.Keys; }
  62         }
  63
  64         public String this[String key] {
  65             get { return metadata[key.ToLower()] as String; }
  66         }
  67
  68         public String Body {
  69             get { return body; }
  70         }
  71
  72     }
  73
  74 }