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MetadataLibraryObject.cs

//
// MetadataLibraryObject.cs: Provides a representation of an ASF Metadata
// Library object which can be read from and written to disk.
//
// Author:
//   Brian Nickel (brian.nickel@gmail.com)
//
// Copyright (C) 2006-2007 Brian Nickel
// 
// This library is free software; you can redistribute it and/or modify
// it  under the terms of the GNU Lesser General Public License version
// 2.1 as published by the Free Software Foundation.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
// USA
//

using System;
using System.Collections.Generic;

namespace TagLib.Asf {
      /// <summary>
      ///    This class extends <see cref="Object" /> to provide a
      ///    representation of an ASF Metadata Library object which can be
      ///    read from and written to disk.
      /// </summary>
00034       public class MetadataLibraryObject : Object,
            IEnumerable<DescriptionRecord>
      {
            #region Private Fields
            
            /// <summary>
            ///    Contains the description records.
            /// </summary>
00042             private List<DescriptionRecord> records =
                  new List<DescriptionRecord> ();
            
            #endregion
            
            
            
            #region Constructors
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="MetadataLibraryObject" /> by reading the contents
            ///    from a specified position in a specified file.
            /// </summary>
            /// <param name="file">
            ///    A <see cref="Asf.File" /> object containing the file from
            ///    which the contents of the new instance are to be read.
            /// </param>
            /// <param name="position">
            ///    A <see cref="long" /> value specify at what position to
            ///    read the object.
            /// </param>
            /// <exception cref="ArgumentNullException">
            ///    <paramref name="file" /> is <see langword="null" />.
            /// </exception>
            /// <exception cref="ArgumentOutOfRangeException">
            ///    <paramref name="position" /> is less than zero or greater
            ///    than the size of the file.
            /// </exception>
            /// <exception cref="CorruptFileException">
            ///    The object read from disk does not have the correct GUID
            ///    or smaller than the minimum size.
            /// </exception>
00075             public MetadataLibraryObject (Asf.File file, long position)
                  : base (file, position)
            {
                  if (!Guid.Equals (Asf.Guid.AsfMetadataLibraryObject))
                        throw new CorruptFileException (
                              "Object GUID incorrect.");
                  
                  if (OriginalSize < 26)
                        throw new CorruptFileException (
                              "Object size too small.");
                  
                  ushort count = file.ReadWord ();
                  
                  for (ushort i = 0; i < count; i ++) {
                        DescriptionRecord rec = new DescriptionRecord (
                              file);
                        AddRecord (rec);
                  }
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="MetadataLibraryObject" /> with no contents.
            /// </summary>
00099             public MetadataLibraryObject ()
                  : base (Asf.Guid.AsfMetadataLibraryObject)
            {
            }
            
            #endregion
            
            
            
            #region Public Properties
            
            /// <summary>
            ///    Gets whether or not the current instance is empty.
            /// </summary>
            /// <value>
            ///    <see langword="true" /> if the current instance doesn't
            ///    contain any <see cref="DescriptionRecord" /> objects.
            ///    Otherwise <see langword="false" />.
            /// </value>
00118             public bool IsEmpty {
                  get {return records.Count == 0;}
            }
            
            #endregion
            
            
            
            #region Public Methods
            
            /// <summary>
            ///    Renders the current instance as a raw ASF object.
            /// </summary>
            /// <returns>
            ///    A <see cref="ByteVector" /> object containing the
            ///    rendered version of the current instance.
            /// </returns>
00135             public override ByteVector Render ()
            {
                  ByteVector output = new ByteVector ();
                  ushort count = 0;
                  
                  foreach (DescriptionRecord rec in records) {
                        count ++;
                        output.Add (rec.Render ());
                  }
                  
                  return Render (RenderWord (count) + output);
            }
            
            /// <summary>
            ///    Removes all records with a given language, stream, and
            ///    name from the current instance.
            /// </summary>
            /// <param name="languageListIndex">
            ///    A <see cref="ushort" /> value containing the language
            ///    list index of the records to be removed.
            /// </param>
            /// <param name="streamNumber">
            ///    A <see cref="ushort" /> value containing the stream
            ///    number of the records to be removed.
            /// </param>
            /// <param name="name">
            ///    A <see cref="string" /> object containing the name of the
            ///    records to be removed.
            /// </param>
00164             public void RemoveRecords (ushort languageListIndex,
                                       ushort streamNumber,
                                       string name)
            {
                  for (int i = records.Count - 1; i >= 0; i --) {
                        DescriptionRecord rec = records [i];
                        if (rec.LanguageListIndex == languageListIndex &&
                              rec.StreamNumber == streamNumber &&
                              rec.Name == name)
                              records.RemoveAt (i);
                  }
            }
            
            /// <summary>
            ///    Gets all records with a given language, stream, and any
            ///    of a collection of names from the current instance.
            /// </summary>
            /// <param name="languageListIndex">
            ///    A <see cref="ushort" /> value containing the language
            ///    list index of the records to be retrieved.
            /// </param>
            /// <param name="streamNumber">
            ///    A <see cref="ushort" /> value containing the stream
            ///    number of the records to be retrieved.
            /// </param>
            /// <param name="names">
            ///    A <see cref="string[]" /> containing the names of the
            ///    records to be retrieved.
            /// </param>
            /// <returns>
            ///    A <see cref="T:System.Collections.Generic.IEnumerable`1" /> object enumerating
            ///    through the <see cref="DescriptionRecord" /> objects
            ///    retrieved from the current instance.
            /// </returns>
00198             public IEnumerable<DescriptionRecord> GetRecords (ushort languageListIndex,
                                                              ushort streamNumber,
                                                              params string [] names)
            {
                  foreach (DescriptionRecord rec in records) {
                        if (rec.LanguageListIndex != languageListIndex ||
                              rec.StreamNumber != streamNumber)
                              continue;
                        
                        foreach (string name in names)
                              if (rec.Name == name)
                                    yield return rec;
                  }
            }
            
            /// <summary>
            ///    Adds a record to the current instance.
            /// </summary>
            /// <param name="record">
            ///    A <see cref="DescriptionRecord" /> object to add to the
            ///    current instance.
            /// </param>
00220             public void AddRecord (DescriptionRecord record)
            {
                  records.Add (record);
            }
            
            /// <summary>
            ///    Sets the a collection of records for a given language,
            ///    stream, and name, removing the existing matching records.
            /// </summary>
            /// <param name="languageListIndex">
            ///    A <see cref="ushort" /> value containing the language
            ///    list index of the records to be added.
            /// </param>
            /// <param name="streamNumber">
            ///    A <see cref="ushort" /> value containing the stream
            ///    number of the records to be added.
            /// </param>
            /// <param name="name">
            ///    A <see cref="string" /> object containing the name of the
            ///    records to be added.
            /// </param>
            /// <param name="records">
            ///    A <see cref="DescriptionRecord[]" /> containing records
            ///    to add to the new instance.
            /// </param>
            /// <remarks>
            ///    All added entries in <paramref name="records" /> should
            ///    match <paramref name="languageListIndex" />, <paramref
            ///    name="streamNumber" /> and <paramref name="name" /> but
            ///    it is not verified by the method. The records will be
            ///    added with their own values and not those provided in
            ///    this method, which are used for removing existing values
            ///    and determining where to position the new object.
            /// </remarks>
00254             public void SetRecords (ushort languageListIndex,
                                    ushort streamNumber, string name,
                                    params DescriptionRecord [] records)
            {
                  int position = this.records.Count;
                  for (int i = this.records.Count - 1; i >= 0; i --) {
                        DescriptionRecord rec = this.records [i];
                        if (rec.LanguageListIndex == languageListIndex &&
                              rec.StreamNumber == streamNumber &&
                              rec.Name == name) {
                              this.records.RemoveAt (i);
                              position = i;
                        }
                  }
                  this.records.InsertRange (position, records);
            }
            
            #endregion
            
            
            
#region IEnumerable
            
            /// <summary>
            ///    Gets an enumerator for enumerating through the
            ///    description records.
            /// </summary>
            /// <returns>
            ///    A <see cref="T:System.Collections.IEnumerator`1" /> for
            ///    enumerating through the description records.
            /// </returns>
00285             public IEnumerator<DescriptionRecord> GetEnumerator ()
            {
                  return records.GetEnumerator ();
            }
            
            System.Collections.IEnumerator
                  System.Collections.IEnumerable.GetEnumerator ()
            {
                  return records.GetEnumerator ();
            }
            
#endregion
      }
}

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