/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="cmd">The command this instance will be associated with.</param>
protected EnumerableExecutor(IEnumerableCommand cmd)
{
if (cmd == null) throw new ArgumentNullException("command", "Command cannot be null.");
if (cmd.IsDisposed) throw new ObjectDisposedException(cmd.ToString());
if (cmd.Link.IsDisposed) throw new ObjectDisposedException("Link '{0}' of command '{1}' is disposed.".FormatWith(cmd.Link, cmd));
_Command = cmd;
}
/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="cmd">The command this instance will be associated with.</param>
protected EnumerableExecutor(IEnumerableCommand cmd)
{
if (cmd == null)
{
throw new ArgumentNullException("command", "Command cannot be null.");
}
if (cmd.IsDisposed)
{
throw new ObjectDisposedException(cmd.ToString());
}
if (cmd.Link.IsDisposed)
{
throw new ObjectDisposedException("Link '{0}' of command '{1}' is disposed.".FormatWith(cmd.Link, cmd));
}
_Command = cmd;
}
/// <summary>
/// Executes the command if it has not been executed yet in this instance. Returns true
/// if a new record is available, or false otherwise.
/// </summary>
public bool MoveNext()
{
// Always needed...
_CurrentRecord = null;
_Current = null;
try
{
// First execution...
if (!_Started)
{
if (IsDisposed)
{
throw new ObjectDisposedException(this.ToString());
}
if (_Command.IsDisposed)
{
throw new ObjectDisposedException(_Command.ToString());
}
if (_Command.Link.IsDisposed)
{
throw new ObjectDisposedException(_Command.Link.ToString());
}
if (!Command.CanBeExecuted)
{
throw new CannotExecuteException(
"State of command '{0}' is not ready for execution.".FormatWith(Command));
}
_Started = true;
_TakeOnGoing = false;
_TakeRemaining = -1;
_Schema = OnReaderStart();
if (_Schema == null)
{
throw new InvalidOperationException("Schema resulting from execution of '{0}' is null.".FormatWith(this));
}
if (_Schema.Count == 0)
{
throw new EmptyException("Schema resulting of execution from '{0}' is empty.".FormatWith(this));
}
// Emulation of skip/take if needed...
var cmd = _Command as IQueryCommand; if (cmd != null)
{
int skip = cmd.GetSkipValue();
int take = cmd.GetTakeValue();
bool valid = cmd.IsValidForNativeSkipTake();
if (!valid && skip > 0)
{
for (int i = 0; i < skip; i++)
{
if (OnReaderNext() == null)
{
Reset(); return(false);
}
}
}
if (!valid && take > 0)
{
_TakeOnGoing = true;
_TakeRemaining = take;
}
}
}
// Current iteration...
if (_TakeOnGoing)
{
if (_TakeRemaining > 0)
{
_CurrentRecord = OnReaderNext();
_TakeRemaining--;
}
else
{
_CurrentRecord = null;
}
}
else
{
_CurrentRecord = OnReaderNext();
}
// Finalizing...
if (_CurrentRecord == null)
{
Reset(); return(false);
}
else
{
_Current = _Converter == null ? _CurrentRecord : _Converter(_CurrentRecord);
return(true);
}
}
catch
{
OnDispose(disposing: true);
throw;
}
}