source: addons/HeuristicLab.PushGP/HeuristicLab.Problems.ProgramSynthesis.Base/Erc/ConstantsErcValue.cs

namespace HeuristicLab.Problems.ProgramSynthesis.Base.Erc {
  using HeuristicLab.Common;
  using HeuristicLab.Core;
  using HeuristicLab.Data;
  using HeuristicLab.Parameters;
  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

  [StorableClass]
  public abstract class ConstantsWeightedErc<T, TArray> : WeightedErcItem<T>
    where T : struct
    where TArray : ValueTypeArray<T>, new() {

    private const string ConstantsParameterName = "Constants";

    protected ConstantsWeightedErc(TArray array) : this(true, array) { }
    protected ConstantsWeightedErc(bool isEnabled, TArray array, double weight = 1d) : base(isEnabled, weight) {
      Parameters.Add(new FixedValueParameter<TArray>(ConstantsParameterName, array));
      array.ToStringChanged += (sender, args) => UpdateName();
      UpdateName();
    }

    private void UpdateName() {
      Name = Constants.ToString();
    }

    [StorableConstructor]
    protected ConstantsWeightedErc(bool deserializing) : base(deserializing) { }

    protected ConstantsWeightedErc(ConstantsWeightedErc<T, TArray> origin, Cloner cloner) : base(origin, cloner) { }

    public IValueParameter<TArray> ConstantsParameter
    {
      get { return (IValueParameter<TArray>)Parameters[ConstantsParameterName]; }
    }

    public TArray Constants
    {
      get { return ConstantsParameter.Value; }
    }

    public override T GetErcValue(IRandom random) {
      if (Constants.Length == 0) return default(T);

      var x = random.Next(Constants.Length);
      return Constants[x];
    }
  }
}