source: branches/PushGP/HeuristicLab.PushGP/HeuristicLab.Problems.ProgramSynthesis/Push/Expressions/VectorIterateExpressions.cs @ 14834

using System.Collections.Generic;

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

  /// <summary>
  /// Iterates in reverse order (due to performance reasons) over the type vector using the code on the exec stack.If the vector isn't empty, expands to:
  /// ((first vector) (top-item :exec state) (rest vector) exec_do*vector_type (top-item :exec state) rest_of_program)
  /// </summary>
  /// <typeparam name="T"></typeparam>
  public abstract class VectorIterateExpression<T> : StatelessExpression {
    protected bool Eval(IInternalPushInterpreter interpter, IPushStack<List<T>> vectorStack, IPushStack<T> literalStack) {
      if (vectorStack.IsEmpty ||
          interpter.ExecStack.IsEmpty)
        return false;

      var vector = vectorStack.Top;

      if (vector.Count == 0) {
        interpter.ExecStack.Pop();
        vectorStack.Pop();
      } else if (vector.Count == 1) {
        literalStack.Push(vector[0]);
        vectorStack.Pop();
      } else {
        interpter.ExecStack.Push(this, interpter.ExecStack.Top);

        var last = vector.Count - 1;
        literalStack.Push(vector[last]);
        vector.RemoveAt(last);
      }

      return true;
    }
  }

  [PushExpression(StackTypes.IntegerVector, "INTEGER[].ITERATE", StackTypes.Integer | StackTypes.Exec)]
  public class IntegerVectorIterateExpression : VectorIterateExpression<long> {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      return Eval(interpreter, interpreter.IntegerVectorStack, interpreter.IntegerStack);
    }
  }

  [PushExpression(StackTypes.FloatVector, "FLOAT[].ITERATE", StackTypes.Float | StackTypes.Exec)]
  public class FloatVectorIterateExpression : VectorIterateExpression<double> {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      return Eval(interpreter, interpreter.FloatVectorStack, interpreter.FloatStack);
    }
  }

  [PushExpression(StackTypes.BooleanVector, "BOOLEAN[].ITERATE", StackTypes.Boolean | StackTypes.Exec)]
  public class BooleanVectorIterateExpression : VectorIterateExpression<bool> {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      return Eval(interpreter, interpreter.BooleanVectorStack, interpreter.BooleanStack);
    }
  }

  [PushExpression(StackTypes.StringVector, "STRING[].ITERATE", StackTypes.String | StackTypes.Exec)]
  public class StringVectorIterateExpression : VectorIterateExpression<string> {
    public override bool Eval(IInternalPushInterpreter interpreter) {
      return Eval(interpreter, interpreter.StringVectorStack, interpreter.StringStack);
    }
  }
}