source: trunk/sources/HeuristicLab.SequentialEngine/3.3/SequentialEngine.cs @ 2664

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2008 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Text;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.SequentialEngine {
  /// <summary>
  /// Represents an engine that executes its steps sequentially, also if they could be executed 
  /// in parallel.
  /// </summary>
  [EmptyStorableClass]
  [Creatable("Engines")]
  [Item("Sequential Engine", "Engine for sequential execution of algorithms.")]
  public class SequentialEngine : Engine {
    private IOperator currentOperator;

    /// <summary>
    /// Aborts the engine execution.
    /// </summary>
    /// <remarks>Calls <see cref="EngineBase.Abort"/> of base class <see cref="EngineBase"/> and
    /// <see cref="IOperator.Abort"/> of the current <see cref="IOperator"/>.</remarks>
    public override void Stop() {
      base.Stop();
      if (currentOperator != null)
        currentOperator.Abort();
    }

    /// <summary>
    /// Deals with the next operation, if it is an <see cref="AtomicOperation"/> it is executed,
    /// if it is a <see cref="CompositeOperation"/> its single operations are pushed on the execution stack.
    /// </summary>
    /// <remarks>If an error occurs during the execution the operation is aborted and the operation
    /// is pushed on the stack again.<br/>
    /// If the execution was successful <see cref="EngineBase.OnOperationExecuted"/> is called.</remarks>
    protected override void ProcessNextOperator() {
      currentOperator = null;
      ExecutionContext context = ExecutionStack.Pop();
      ExecutionContextCollection next = null;
      try {
        currentOperator = context.Operator;
        next = context.Operator.Execute(context);
        currentOperator = null;
      }
      catch (Exception ex) {
        ExecutionStack.Push(context);
        Stop();
        OnExceptionOccurred(ex);
      }
      if (next != null) {
        for (int i = next.Count - 1; i >= 0; i--)
          ExecutionStack.Push(next[i]);
      }
      if (context.Operator.Breakpoint)
        Stop();
    }
  }
}