/// <summary>
/// Resets this enumerator.
/// </summary>
public override void Reset()
{
if( _Surrogate != null ) { _Surrogate.Dispose(); _Surrogate = null; }
_Schema = null;
_CurrentRecord = null;
}
internal void Reset()
{
_WeakReference = null;
_State = KMaps.MetaState.Empty; // By default...
_Map = null;
_Record = null; // Do not dispose, might be in use elsewhere...
}
/// <summary>
/// Advances this enumerator to return the next element from the database.
/// <para>In this implementation these elements are not maintained in an in-memory structure, but rather are retrieved
/// and maintained in the CurrentRecord property just until the next invocation of MoveNext().
/// </summary>
/// <returns>True if the next element has been obtained, false if there are no more elements available.</returns>
public override bool MoveNext()
{
// First iteration...
if( _Surrogate == null ) {
_Surrogate = new KSurrogate( this.Command, iterable: true );
_Schema = _Surrogate._Schema;
}
// If we have finished, cleaning it up...
if( !_Surrogate._DataReader.Read() ) {
DEBUG.IndentLine( "\n-- MoveNext: null" ); DEBUG.Unindent();
_Surrogate.Dispose(); _Surrogate = null;
return false;
}
// Else, generating the record...
_CurrentRecord = new KRecord( _Schema ); for( int i = 0; i < _Schema.Count; i++ ) {
object value = _Surrogate._DataReader.IsDBNull( i ) ? null : _Surrogate._DataReader.GetValue( i );
_CurrentRecord[i] = value;
}
DEBUG.IndentLine( "\n-- MoveNext: {0}", CurrentRecord.ToString() ); DEBUG.Unindent();
return true;
}
// --------------------------------------------------
internal static KMetaEntity First( IKMap map, KRecord find )
{
if( map == null ) throw new ArgumentNullException( "map", "Map cannot be null." );
if( find == null ) throw new ArgumentNullException( "find", "KRecord cannot be null." );
if( find.Count == 0 ) throw new ArgumentException( "Find record contains no columns." );
lock( _SyncRoot ) {
foreach( var meta in _MetaEntities ) {
if( meta.Host == null ) continue;
if( meta.Record == null ) continue;
if( meta.Map != map ) continue;
if( !find.EquivalentTo( meta.Record, strict: false ) ) continue;
return meta;
}
}
return null;
}
