context: //
  // System.Data.Common.DbCommand
  //
  // Author:
  //   Tim Coleman (tim@timcoleman.com)
  //
  // Copyright (C) Tim Coleman, 2003
  //
  
  //
  // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  //
  // Permission is hereby granted, free of charge, to any person obtaining
  // a copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to
  // permit persons to whom the Software is furnished to do so, subject to
  // the following conditions:
  // 
  // The above copyright notice and this permission notice shall be
  // included in all copies or substantial portions of the Software.
  // 
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  //
  
  using System.ComponentModel;
  using System.Data;
  
  #if NET_4_5
  using System.Threading;
  using System.Threading.Tasks;
  #endif
  
  namespace System.Data.Common {
  	public abstract class DbCommand : Component, IDbCommand, IDisposable
  	{
  		protected DbCommand ()
  		{
  		}
  
  		#region Properties
  
  		[DefaultValue ("")]
  		[RefreshProperties (RefreshProperties.All)]
  		public abstract string CommandText { get; set; }
  
  		public abstract int CommandTimeout { get; set; }
  
  		[DefaultValue (CommandType.Text)]
  		[RefreshProperties (RefreshProperties.All)]
  		public abstract CommandType CommandType { get; set; }
  
  		[DefaultValue (null)]
  		[Browsable (false)]
  		[DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  		public DbConnection Connection {
  			get { return DbConnection; }
  			set { DbConnection = value; }
  		}
  
  		protected abstract DbConnection DbConnection { get; set; }
  		protected abstract DbParameterCollection DbParameterCollection { get; }
  		protected abstract DbTransaction DbTransaction { get; set; }
  
  		[EditorBrowsable (EditorBrowsableState.Never)]
  		[Browsable (false)]
  		[DefaultValue (true)]
  		[DesignOnly (true)]
  		public abstract bool DesignTimeVisible { get; set; }
  
  		IDbConnection IDbCommand.Connection {
  			get { return Connection; }
  			set { Connection = (DbConnection) value; }
  		}
  
  		IDataParameterCollection IDbCommand.Parameters {
  			get { return Parameters; }
  		}
  
  		IDbTransaction IDbCommand.Transaction {
  			get { return Transaction; }
  			set { Transaction = (DbTransaction) value; }
  		}
  
  		[Browsable (false)]
  		[DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  		public DbParameterCollection Parameters {
  			get { return DbParameterCollection; }
  		}
  
  		[Browsable (false)]
  		[DefaultValue (null)]
  		[DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  		public DbTransaction Transaction {
  			get { return DbTransaction; }
  			set { DbTransaction = value; }
  		}
  
  		[DefaultValue (UpdateRowSource.Both)]
  		public abstract UpdateRowSource UpdatedRowSource { get; set; }
  
  		#endregion // Properties
  
  		#region Methods
  
  		public abstract void Cancel ();
  		protected abstract DbParameter CreateDbParameter ();
  
  		public DbParameter CreateParameter ()
  		{
  			return CreateDbParameter ();
  		}
  
  		protected abstract DbDataReader ExecuteDbDataReader (CommandBehavior behavior);
  		public abstract int ExecuteNonQuery ();
  		
  		public DbDataReader ExecuteReader ()
  		{
  			return ExecuteDbDataReader (CommandBehavior.Default);
  		}
  
  		public DbDataReader ExecuteReader (CommandBehavior behavior)
  		{
                          return ExecuteDbDataReader (behavior);
  		}
  
  		public abstract object ExecuteScalar ();
  
  		IDbDataParameter IDbCommand.CreateParameter ()
  		{
  			return CreateParameter ();
  		}
  
  		IDataReader IDbCommand.ExecuteReader ()
  		{
  			return ExecuteReader ();
  		}
  
  		IDataReader IDbCommand.ExecuteReader (CommandBehavior behavior)
  		{
  			return ExecuteReader (behavior);
  		}
  
  		public abstract void Prepare ();
  		
  #if NET_4_5
  		protected virtual Task<DbDataReader> ExecuteDbDataReaderAsync (CommandBehavior behavior, CancellationToken cancellationToken)
  		{
  			if (cancellationToken.IsCancellationRequested) {
  				return TaskHelper.CreateCanceledTask<DbDataReader> ();
  			}
  			
  			try {
  				return Task.FromResult (ExecuteDbDataReader (behavior));
  			} catch (Exception e) {
  				return TaskHelper.CreateExceptionTask<DbDataReader> (e);
  			}
  		}
  		
  		public Task<int> ExecuteNonQueryAsync ()
  		{
  			return ExecuteNonQueryAsync (CancellationToken.None);
  		}
  		
  		public virtual Task<int> ExecuteNonQueryAsync (CancellationToken cancellationToken)
  		{
  			if (cancellationToken.IsCancellationRequested) {
  				return TaskHelper.CreateCanceledTask<int> ();
  			}
  			
  			try {
  				return Task.FromResult (ExecuteNonQuery ());
  			} catch (Exception e) {
  				return TaskHelper.CreateExceptionTask<int> (e);
  			}
  		}
  		
  		public Task<Object> ExecuteScalarAsync ()
  		{
  			return ExecuteScalarAsync (CancellationToken.None);
  		}
  		
  		public virtual Task<Object> ExecuteScalarAsync (CancellationToken cancellationToken)
  		{
  			if (cancellationToken.IsCancellationRequested) {
  				return TaskHelper.CreateCanceledTask<Object> ();
  			}
  			
  			try {
  				return Task.FromResult (ExecuteScalar ());
  			} catch (Exception e) {
  				return TaskHelper.CreateExceptionTask<Object> (e);
  			}
  		}
  		
  		public Task<DbDataReader> ExecuteReaderAsync ()
  		{
  			return ExecuteReaderAsync (CancellationToken.None);
  		}
  		
  		public Task<DbDataReader> ExecuteReaderAsync (CancellationToken cancellationToken)
  		{
  			if (cancellationToken.IsCancellationRequested) {
  				return TaskHelper.CreateCanceledTask<DbDataReader> ();
  			}
  			
  			try {
  				return Task.FromResult (ExecuteReader ());
  			} catch (Exception e) {
  				return TaskHelper.CreateExceptionTask<DbDataReader> (e);
  			}
  		}
  		
  		public Task<DbDataReader> ExecuteReaderAsync (CommandBehavior behavior)
  		{
  			return ExecuteReaderAsync (behavior, CancellationToken.None);
  		}
  		
  		public Task<DbDataReader> ExecuteReaderAsync (CommandBehavior behavior, CancellationToken cancellationToken)
  		{
  			if (cancellationToken.IsCancellationRequested) {
  				return TaskHelper.CreateCanceledTask<DbDataReader> ();
  			}
  			
  			try {
  				return Task.FromResult (ExecuteReader (behavior));
  			} catch (Exception e) {
  
gt: 				return TaskHelper.CreateExceptionTask<DbDataReader> (e);