ActionCall.cs

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using Mercury.Exceptions;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Mercury.Interpreting
{
//=============================================================================
//  ActionCall
//=============================================================================

    public class ActionCall<T> : IFormalParameter, IEquatable<ActionCall<T>>
        where T : class
    {
        //--[  Private fields  ]-----------------------------------------------

        private int? memHash = null;

        //--[  Constructors  ]-------------------------------------------------

        public ActionCall(InterpreterAction<T> action, IEnumerable<IFormalParameter> formalparams)
        {
            if (action       == null) throw new ArgumentNullException("action");
            if (formalparams == null) throw new ArgumentNullException("formalparams");

            Action           = action;
            FormalParameters = formalparams.ToArray();
            Type             = ParameterType.ActionCall;

            if ((Action.Arity.Item2 < FormalParameters.Count) || (FormalParameters.Count < Action.Arity.Item1))
                throw new InvalidActionCallException(this.ToString(), "invalid number of formal parameters");
        }

        //--[  Properties  ]---------------------------------------------------

        public IReadOnlyList<IFormalParameter> FormalParameters { get; private set; }

        public InterpreterAction<T> Action { get; private set; }

        //--[  Overriden methods  ]--------------------------------------------

        #region [  Object            ]

        public override bool Equals(object obj)
        {
            ActionCall<T> other = obj as ActionCall<T>;
            return obj == null ? false : Equals(other);
        }

        public override int GetHashCode()
        {
            if (!memHash.HasValue)
            {
                memHash = 19 * Action.Name.GetHashCode();

                for (int ix = 0; ix < FormalParameters.Count; ++ix)
                    memHash = 17 * memHash + FormalParameters[ix].GetHashCode();
            }

            return memHash.Value;
        }

        public override string ToString()
        {
            StringBuilder sb = new StringBuilder("(").Append(Action.Name);

            if (FormalParameters.Count != 0)
            {
                sb.Append(' ').Append(FormalParameters[0]);

                for (int ix = 1; ix < FormalParameters.Count; ++ix)
                    sb.Append(' ').Append(FormalParameters[ix]);
            }

            return sb.Append(")").ToString();
        }

        #endregion

        //--[  Interface implementation  ]-------------------------------------

        #region [  IFormalParameter  ]

        public ParameterType Type { get; private set; }

        #endregion

        #region [  IEquatable        ]

        public bool Equals(ActionCall<T> other)
        {
            return (other                  != null)
                && (Action.Name            == other.Action.Name)
                && (FormalParameters.Count == other.FormalParameters.Count)
                && (FormalParameters.Zip(other.FormalParameters, (x, y) => x.Equals(y)).All(x => x));
        }

        #endregion

    }

}