/Microsoft.Scripting/Actions/Argument.cs

/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Microsoft Public License. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the  Microsoft Public License, please send an email to 

 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Microsoft Public License.

 *

 * You must not remove this notice, or any other, from this software.

 *

 *

 * ***************************************************************************/



#if CODEPLEX_40

using System;

using System.Linq.Expressions;

#else

using System; using Microsoft;

using Microsoft.Linq.Expressions;

#endif

using Microsoft.Contracts;

using Microsoft.Scripting.Utils;

using AstUtils = Microsoft.Scripting.Ast.Utils;



namespace Microsoft.Scripting.Actions {

    /// <summary>

    /// TODO: Alternatively, it should be sufficient to remember indices for this, list, dict and block.

    /// </summary>

    public struct Argument : IEquatable<Argument> {

        private readonly ArgumentType _kind;

        private readonly string _name;



        public static readonly Argument Simple = new Argument(ArgumentType.Simple, null);



        public ArgumentType Kind { get { return _kind; } }

        public string Name { get { return _name; } }



        public Argument(string name) {

            _kind = ArgumentType.Named;

            _name = name;

        }



        public Argument(ArgumentType kind) {

            _kind = kind;

            _name = null;

        }



        public Argument(ArgumentType kind, string name) {

            ContractUtils.Requires((kind == ArgumentType.Named) ^ (name == null), "kind");

            _kind = kind;

            _name = name;

        }



        public override bool Equals(object obj) {

            return obj is Argument && Equals((Argument)obj);

        }



        [StateIndependent]

        public bool Equals(Argument other) {

            return _kind == other._kind && _name == other._name;

        }



        public static bool operator ==(Argument left, Argument right) {

            return left.Equals(right);

        }



        public static bool operator !=(Argument left, Argument right) {

            return !left.Equals(right);

        }



        public override int GetHashCode() {

            return (_name != null) ? _name.GetHashCode() ^ (int)_kind : (int)_kind;

        }



        public bool IsSimple {

            get {

                return Equals(Simple);

            }

        }



        public override string ToString() {

            return _name == null ? _kind.ToString() : _kind.ToString() + ":" + _name;

        }



        internal Expression CreateExpression() {

            return Expression.New(

                typeof(Argument).GetConstructor(new Type[] { typeof(ArgumentType), typeof(string) }),

                AstUtils.Constant(_kind),

                AstUtils.Constant(_name, typeof(string))

            );

        }

    }

}