/Microsoft.Scripting/Actions/Calls/ParamsDictArgBuilder.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;

#else

using System; using Microsoft;

#endif

using System.Collections.Generic;

#if CODEPLEX_40

using System.Dynamic;

using System.Linq.Expressions;

#else

using Microsoft.Scripting;

using Microsoft.Linq.Expressions;

#endif

using System.Reflection;

using Microsoft.Scripting.Runtime;

using AstUtils = Microsoft.Scripting.Ast.Utils;



namespace Microsoft.Scripting.Actions.Calls {

#if CODEPLEX_40

    using Ast = System.Linq.Expressions.Expression;

#else

    using Ast = Microsoft.Linq.Expressions.Expression;

#endif

    using Microsoft.Scripting.Utils;



    /// <summary>

    /// Builds the parameter for a params dictionary argument - this collects all the extra name/value

    /// pairs provided to the function into a SymbolDictionary which is passed to the function.

    /// </summary>

    internal sealed class ParamsDictArgBuilder : ArgBuilder {

        private readonly string[] _names;

        private readonly int[] _nameIndexes;

        private readonly int _argIndex;



        public ParamsDictArgBuilder(ParameterInfo info, int argIndex, string[] names, int[] nameIndexes) 

            : base(info) {

            Assert.NotNull(names, nameIndexes);



            _argIndex = argIndex;

            _names = names;

            _nameIndexes = nameIndexes;

        }



        public override int Priority {

            get { return 3; }

        }



        internal protected override Expression ToExpression(ParameterBinder parameterBinder, IList<Expression> parameters, bool[] hasBeenUsed) {

            Expression res = Ast.Call(

                typeof(BinderOps).GetMethod("MakeSymbolDictionary"),

                Ast.NewArrayInit(typeof(string), ConstantNames()),

                AstUtils.NewArrayHelper(typeof(object), GetParameters(parameters, hasBeenUsed))

            );



            return res;

        }



        public override Type Type {

            get {

                return typeof(IAttributesCollection);

            }

        }



        private List<Expression> GetParameters(IList<Expression> parameters, bool[] hasBeenUsed) {

            List<Expression> res = new List<Expression>(_nameIndexes.Length);

            for (int i = 0; i < _nameIndexes.Length; i++) {

                int parameterIndex = _nameIndexes[i] + _argIndex;

                if (!hasBeenUsed[parameterIndex]) {

                    res.Add(parameters[parameterIndex]);

                    hasBeenUsed[parameterIndex] = true;

                }

            }

            return res;

        }



        private int[] GetParameters(bool[] hasBeenUsed) {

            var res = new List<int>(_nameIndexes.Length);

            for (int i = 0; i < _nameIndexes.Length; i++) {

                int parameterIndex = _nameIndexes[i] + _argIndex;

                if (!hasBeenUsed[parameterIndex]) {

                    res.Add(parameterIndex);

                    hasBeenUsed[parameterIndex] = true;

                }

            }

            return res.ToArray();

        }



        private Expression[] ConstantNames() {

            Expression[] res = new Expression[_names.Length];

            for (int i = 0; i < _names.Length; i++) {

                res[i] = AstUtils.Constant(_names[i]);

            }

            return res;

        }



        internal override bool CanGenerateDelegate {

            get {

                return true;

            }

        }



        protected internal override Func<object[], object> ToDelegate(ParameterBinder parameterBinder, IList<DynamicMetaObject> knownTypes, bool[] hasBeenUsed) {

            string[] names = _names;

            int[] indexes = GetParameters(hasBeenUsed);



            return (args) => {

                object[] values = new object[indexes.Length];

                for (int i = 0; i < indexes.Length; i++) {

                    values[i] = args[indexes[i] + 1];

                }

                return BinderOps.MakeSymbolDictionary(names, values);

            };

        }

    }

}