source: addons/HeuristicLab.PushGP/HeuristicLab.Problems.ProgramSynthesis/Push/Attributes/PushExpressionAttriubte.cs @ 17104

using System;

namespace HeuristicLab.Problems.ProgramSynthesis.Push.Attributes {
  using HeuristicLab.Problems.ProgramSynthesis.Push.Stack;

  [AttributeUsage(AttributeTargets.Class)]
  public class PushExpressionAttribute : Attribute {
    public readonly StackTypes StackType;
    public readonly StackTypes AdditionalStackDependencies;
    public readonly string Name;
    public readonly string Description;
    public readonly int? InExpressionNr;

    /// <summary>
    /// Determines if this expression manipulates the exec stack.
    /// </summary>
    public readonly bool ManipulatesExec;

    /// <summary>
    /// Determines the amount of items fetched form the EXEC stack required for this expression. Used for mapping individuals.
    /// </summary>
    public readonly uint RequiredBlockCount;

    /// <summary>
    /// Determines if the expression is visible to the user for configuration purposes.
    /// </summary>
    public readonly bool IsHidden;

    public PushExpressionAttribute(
      StackTypes stackType,
      string name,
      string description,
      StackTypes additionalStackDependencies = default(StackTypes),
      uint requiredBlockCount = 0,
      bool isHidden = false,
      int inExpressionNr = -1) {

      StackType = stackType;
      AdditionalStackDependencies = additionalStackDependencies;
      Name = name;
      Description = description;
      RequiredBlockCount = requiredBlockCount;
      IsHidden = isHidden;
      InExpressionNr = inExpressionNr > 0 ? inExpressionNr : default(int?);
      ManipulatesExec = stackType == StackTypes.Exec || AdditionalStackDependencies.HasFlag(StackTypes.Exec);
    }

    public bool IsInExpression { get { return this.InExpressionNr.HasValue; } }
  }
}