Add a mechanism for extending the file type resolution in JuK using FileRefs.

This is generally much better thought out than the current method of creating
FileRefs using the native mime system and also allows for extension to additional
file formats.


git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@437382 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

fileref.cpp

@@ -39,8 +39,11 @@ public:
   }
 
   File *file;
+  static List<const FileTypeResolver *> fileTypeResolvers;
 };
 
+List<const FileRef::FileTypeResolver *> FileRef::FileRefPrivate::fileTypeResolvers;
+
 ////////////////////////////////////////////////////////////////////////////////
 // public members
 ////////////////////////////////////////////////////////////////////////////////
@@ -92,6 +95,11 @@ bool FileRef::save()
   return d->file->save();
 }
 
+void FileRef::addFileTypeResolver(const FileTypeResolver *resolver) // static
+{
+  FileRefPrivate::fileTypeResolvers.prepend(resolver);
+}
+
 bool FileRef::isNull() const
 {
   return !d->file || !d->file->isValid();

fileref.h

@@ -43,32 +43,61 @@ namespace TagLib {
    * across file types.
    *
    * Also note that it is probably a good idea to plug this into your mime
-   * type system rather than using the constructor that accepts a file name.
+   * type system rather than using the constructor that accepts a file name using
+   * the FileTypeResolver.
    *
-   * For example in KDE this could be done with:
-   *
-   * \code
-   *
-   * TagLib::FileRef createFileRef( const QString &fileName )
-   * {
-   *   KMimeType::Ptr result = KMimeType::findByPath( fileName, 0, true );
-   *
-   *   if( result->name() == "audio/x-mp3" )
-   *     return FileRef( new MPEG::File( QFile::encodeName( fileName ).data() ) );
-   *
-   *   if( result->name() == "application/ogg" )
-   *     return FileRef( new Vorbis::File( QFile::encodeName( fileName ).data() ) );
-   *
-   *   return FileRef( 0 );
-   * }
-   *
-   * \endcode
+   * \see FileTypeResolver
+   * \see addFileTypeResolver()
    */
 
   class FileRef
   {
   public:
 
+  //! A class for pluggable file type resolution.
+
+  /*!
+   * This class is used to add extend TagLib's very basic file name based file
+   * type resolution.
+   *
+   * This can be accomplished with:
+   *
+   * \code
+   *
+   * class MyFileTypeResolver : FileTypeResolver
+   * {
+   *   TagLib::File *createFile(const char *fileName)
+   *   {
+   *     if(someCheckForAnMP3File(fileName))
+   *       return new TagLib::MPEG::File(fileName);
+   *     return 0;
+   *   }
+   * }
+   *
+   * FileRef::addFileTypeResolver(new MyFileTypeResolver);
+   *
+   * \endcode
+   *
+   * Naturally a less contrived example would be slightly more complex.  This
+   * can be used to plug in mime-type detection systems or to add new file types
+   * to TagLib.
+   */
+
+    class FileTypeResolver
+    {
+    public:
+      /*!
+       * This method must be overriden to provide an additional file type
+       * resolver.  If the resolver is able to determine the file type it should
+       * return a valid File object; if not it should return 0.
+       *
+       * \note The created file is then owned by the FileRef and should not be
+       * deleted.  Deletion will happen automatically when the FileRef passes
+       * out of scope.
+       */
+      virtual File *createFile(const char *fileName) = 0;
+    };
+
     FileRef();
 
     /*!
@@ -139,6 +168,14 @@ namespace TagLib {
      */
     bool save();
 
+    /*!
+     * Adds a FileTypeResolver to the list of those used by TagLib.  Each
+     * additional FileTypeResolver is added to the front of a list of resolvers
+     * that are tried.  If the FileTypeResolver returns zero the next resolver
+     * is tried.
+     */
+    static void addFileTypeResolver(const FileTypeResolver *resolver);
+
     /*!
      * Returns true if the file (and as such other pointers) are null.
      */

tests/toolkit-test.cpp

@@ -233,11 +233,11 @@ void testList()
   List<int> l1;
   List<int> l2;
   List<int> l3;
-  l1.append(1);
   l1.append(2);
   l2.append(3);
   l2.append(4);
   l1.append(l2);
+  l1.prepend(1);
   l3.append(1);
   l3.append(2);
   l3.append(3);

toolkit/tlist.h

@@ -120,6 +120,9 @@ namespace TagLib {
      */
     List<T> &append(const List<T> &l);
 
+    List<T> &prepend(const T &item);
+    List<T> &prepend(const List<T> &l);
+
     /*!
      * Clears the list.  If auto deletion is enabled and this list contains a
      * pointer type the members are also deleted.

toolkit/tlist.tcc

@@ -164,6 +164,22 @@ List<T> &List<T>::append(const List<T> &l)
   return *this;
 }
 
+template <class T>
+List<T> &List<T>::prepend(const T &item)
+{
+  detach();
+  d->list.push_front(item);
+  return *this;
+}
+
+template <class T>
+List<T> &List<T>::prepend(const List<T> &l)
+{
+  detach();
+  d->list.insert(d->list.begin(), l.begin(), l.end());
+  return *this;
+}
+
 template <class T>
 void List<T>::clear()
 {