namespace HeuristicLab.Problems.ProgramSynthesis.Push.Expressions {
  using System;
  using System.Collections.Generic;

  using HeuristicLab.Common;
  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
  using HeuristicLab.Problems.ProgramSynthesis.Push.Data.Pool;

  using Interpreter;

  [Serializable]
  [StorableClass]
  public abstract class Expression : IDeepCloneable, IPooledObject {

    protected Expression() { }

    [StorableConstructor]
    protected Expression(bool deserializing) { }

    public bool IsProgram { get { return GetType() == typeof(PushProgram); } }

    public static readonly IReadOnlyCollection<Expression> EmptyContainer = new Expression[0];

    public abstract string StringRepresentation
    {
      get;
    }

    public abstract bool IsNoop(IInternalPushInterpreter interpreter);
    public abstract void Eval(IInternalPushInterpreter interpreter);

    public bool TryEval(IInternalPushInterpreter interpreter) {
      if (IsNoop(interpreter))
        return false;

      Eval(interpreter);
      return true;
    }

    public override string ToString() {
      return StringRepresentation;
    }

    public object Clone() {
      return Clone(new Cloner());
    }

    public virtual IDeepCloneable Clone(Cloner cloner) {
      return this;
    }

    void IPooledObject.Init() { }

    void IPooledObject.Reset() { }
  }
}