source: branches/PushGP/HeuristicLab.Algorithms.PushGP/HeuristicLab.Algorithms.PushGP/Expressions/BooleanExpressions.cs @ 14398

using HeuristicLab.Algorithms.PushGP.Interpreter;

namespace HeuristicLab.Algorithms.PushGP.Expressions
{
    /// <summary>
    /// Pushes the logical AND of the top two BOOLEANs.
    /// </summary>
    public class BooleanAndExpression : PushResultExpression<bool>
    {
        protected override string InitStringRepresentation()
        {
            return "BOOLEAN.AND";
        }

        public override void Eval(IInterpreter interpreter)
        {
            Eval(interpreter.BooleanStack, 2, values => values[0] && values[1]);
        }
    }

    /// <summary>
    /// Pushes the logical OR of the top two BOOLEANs.
    /// </summary>
    public class BooleanOrExpression : PushResultExpression<bool>
    {
        protected override string InitStringRepresentation()
        {
            return "BOOLEAN.OR";
        }

        public override void Eval(IInterpreter interpreter)
        {
            Eval(interpreter.BooleanStack, 2, values => values[0] || values[1]);
        }
    }

    /// <summary>
    /// Pushes the logical NOT of the top BOOLEAN.
    /// </summary>
    public class BooleanNotExpression : PushResultExpression<bool>
    {
        protected override string InitStringRepresentation() { return "BOOLEAN.NOT"; }

        public override void Eval(IInterpreter interpreter)
        {
            Eval(interpreter.BooleanStack, 1, values => !values[0]);
        }
    }

    /// <summary>
    /// Pushes FALSE if the top FLOAT is 0.0, or TRUE otherwise.
    /// </summary>
    public class BooleanFromFloatExpression : StatelessExpression
    {
        protected override string InitStringRepresentation() { return "BOOLEAN.FROMFLOAT"; }

        public override void Eval(IInterpreter interpreter)
        {
            if (interpreter.FloatStack.Count == 0)
                return;

            var value = interpreter.FloatStack.Pop() != 0.0;

            interpreter.BooleanStack.Push(value);
        }
    }

    /// <summary>
    /// Pushes FALSE if the top INTEGER is 0, or TRUE otherwise.
    /// </summary>
    public class BooleanFromIntegerExpression : StatelessExpression
    {
        protected override string InitStringRepresentation() { return "BOOLEAN.FROMINTEGER"; }

        public override void Eval(IInterpreter interpreter)
        {
            if (interpreter.IntegerStack.Count == 0)
                return;

            var value = interpreter.IntegerStack.Pop() != 0;

            interpreter.BooleanStack.Push(value);
        }
    }
}