/Microsoft.Scripting/Actions/DynamicSiteHelper.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;

using System.Diagnostics;

using System.Runtime.CompilerServices;

#if !CODEPLEX_40
using Microsoft.Runtime.CompilerServices;
#endif


using System.Threading;

using Microsoft.Scripting.Utils;

using System.Reflection.Emit;

using Microsoft.Scripting.Generation;

using System.Reflection;



namespace Microsoft.Scripting.Actions {

    // TODO: replace this class with calls to Expression.GetDelegateType

    public static class DynamicSiteHelpers {



        private delegate object CreateSite(CallSiteBinder binder);



        private const int MaximumArity = 17;



        private static Dictionary<ICollection<Type>, Type> _DelegateTypes;



        private const MethodAttributes CtorAttributes = MethodAttributes.RTSpecialName | MethodAttributes.HideBySig | MethodAttributes.Public;

        private const MethodImplAttributes ImplAttributes = MethodImplAttributes.Runtime | MethodImplAttributes.Managed;

        private const MethodAttributes InvokeAttributes = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.NewSlot | MethodAttributes.Virtual;



        private static readonly Type[] _DelegateCtorSignature = new Type[] { typeof(object), typeof(IntPtr) };





        // TODO: remove in favor of Expression.GetDelegateType

        internal static Type MakeCallSiteDelegate(params Type[] types) {

            Debug.Assert(types != null);

            return MakeDelegate(types.AddFirst(typeof(CallSite)));

        }



        private static Type MakeDelegate(Type[] types) {

            return GetStandardDelegateType(types) ?? MakeCustomDelegate(types);

        }



        public static Type GetStandardDelegateType(Type[] types) {

            ContractUtils.RequiresNotEmpty(types, "types");



            // Can only used predefined delegates if we have no byref types and

            // the arity is small enough to fit in Func<...> or Action<...>

            if (types.Length > MaximumArity || Any(types, t => t.IsByRef)) {

                return null;

            }



            Type result;

            if (types[types.Length - 1] == typeof(void)) {

                result = GetActionType(RemoveLast(types));

            } else {

                result = GetFuncType(types);

            }

            Debug.Assert(result != null);

            return result;

        }



        private static Type GetFuncType(Type[] types) {

            switch (types.Length) {

                #region Generated Delegate Microsoft Scripting Scripting Func Types



                // *** BEGIN GENERATED CODE ***

                // generated by function: gen_delegate_func from: generate_dynsites.py



                case 1: return typeof(Func<>).MakeGenericType(types);

                case 2: return typeof(Func<,>).MakeGenericType(types);

                case 3: return typeof(Func<,,>).MakeGenericType(types);

                case 4: return typeof(Func<,,,>).MakeGenericType(types);

                case 5: return typeof(Func<,,,,>).MakeGenericType(types);

                case 6: return typeof(Func<,,,,,>).MakeGenericType(types);

                case 7: return typeof(Func<,,,,,,>).MakeGenericType(types);

                case 8: return typeof(Func<,,,,,,,>).MakeGenericType(types);

                case 9: return typeof(Func<,,,,,,,,>).MakeGenericType(types);

                case 10: return typeof(Func<,,,,,,,,,>).MakeGenericType(types);

                case 11: return typeof(Func<,,,,,,,,,,>).MakeGenericType(types);

                case 12: return typeof(Func<,,,,,,,,,,,>).MakeGenericType(types);

                case 13: return typeof(Func<,,,,,,,,,,,,>).MakeGenericType(types);

                case 14: return typeof(Func<,,,,,,,,,,,,,>).MakeGenericType(types);

                case 15: return typeof(Func<,,,,,,,,,,,,,,>).MakeGenericType(types);

                case 16: return typeof(Func<,,,,,,,,,,,,,,,>).MakeGenericType(types);

                case 17: return typeof(Func<,,,,,,,,,,,,,,,,>).MakeGenericType(types);



                // *** END GENERATED CODE ***



                #endregion



                default: return null;

            }

        }



        private static Type GetActionType(Type[] types) {

            switch (types.Length) {

                case 0: return typeof(Action);



                #region Generated Delegate Microsoft Scripting Action Types



                // *** BEGIN GENERATED CODE ***

                // generated by function: gen_delegate_action from: generate_dynsites.py



                case 1: return typeof(Action<>).MakeGenericType(types);

                case 2: return typeof(Action<,>).MakeGenericType(types);

                case 3: return typeof(Action<,,>).MakeGenericType(types);

                case 4: return typeof(Action<,,,>).MakeGenericType(types);

                case 5: return typeof(Action<,,,,>).MakeGenericType(types);

                case 6: return typeof(Action<,,,,,>).MakeGenericType(types);

                case 7: return typeof(Action<,,,,,,>).MakeGenericType(types);

                case 8: return typeof(Action<,,,,,,,>).MakeGenericType(types);

                case 9: return typeof(Action<,,,,,,,,>).MakeGenericType(types);

                case 10: return typeof(Action<,,,,,,,,,>).MakeGenericType(types);

                case 11: return typeof(Action<,,,,,,,,,,>).MakeGenericType(types);

                case 12: return typeof(Action<,,,,,,,,,,,>).MakeGenericType(types);

                case 13: return typeof(Action<,,,,,,,,,,,,>).MakeGenericType(types);

                case 14: return typeof(Action<,,,,,,,,,,,,,>).MakeGenericType(types);

                case 15: return typeof(Action<,,,,,,,,,,,,,,>).MakeGenericType(types);

                case 16: return typeof(Action<,,,,,,,,,,,,,,,>).MakeGenericType(types);



                // *** END GENERATED CODE ***



                #endregion

                default: return null;

            }

        }



        private static T[] AddFirst<T>(this IList<T> list, T item) {

            T[] res = new T[list.Count + 1];

            res[0] = item;

            list.CopyTo(res, 1);

            return res;

        }



        private static bool Any<T>(this IEnumerable<T> source, Func<T, bool> predicate) {

            foreach (T element in source) {

                if (predicate(element)) {

                    return true;

                }

            }

            return false;

        }



        private static T[] RemoveLast<T>(this T[] array) {

            T[] result = new T[array.Length - 1];

            Array.Copy(array, 0, result, 0, result.Length);

            return result;

        }



        private static Type MakeCustomDelegate(Type[] types) {

            if (_DelegateTypes == null) {

                Interlocked.CompareExchange(

                    ref _DelegateTypes,

                    new Dictionary<ICollection<Type>, Type>(ListEqualityComparer<Type>.Instance),

                    null

                );

            }



            bool found;

            Type type;



            //

            // LOCK to retrieve the delegate type, if any

            //



            lock (_DelegateTypes) {

                found = _DelegateTypes.TryGetValue(types, out type);

            }



            if (!found && type != null) {

                return type;

            }



            //

            // Create new delegate type

            //



            type = MakeNewCustomDelegate(types);



            //

            // LOCK to insert new delegate into the cache. If we already have one (racing threads), use the one from the cache

            //



            lock (_DelegateTypes) {

                Type conflict;

                if (_DelegateTypes.TryGetValue(types, out conflict) && conflict != null) {

                    type = conflict;

                } else {

                    _DelegateTypes[types] = type;

                }

            }



            return type;

        }



        private static Type MakeNewCustomDelegate(Type[] types) {

            Type returnType = types[types.Length - 1];

            Type[] parameters = types.RemoveLast();



            TypeBuilder builder = Snippets.Shared.DefineDelegateType("Delegate" + types.Length);

            builder.DefineConstructor(CtorAttributes, CallingConventions.Standard, _DelegateCtorSignature).SetImplementationFlags(ImplAttributes);

            builder.DefineMethod("Invoke", InvokeAttributes, returnType, parameters).SetImplementationFlags(ImplAttributes);

            return builder.CreateType();

        }



        /// <summary>

        /// Returns true if the method should not be displayed in the stack frame.

        /// </summary>

        public static bool IsInvisibleDlrStackFrame(MethodBase mb) {

            //This method name is used for the dynamic method created for a delegate type signature.

            if (mb.Name == "_Scripting_") {

                return true;

            }



            //Filters out methods in Microsoft.Scripting namespaces.

            if (mb.DeclaringType != null && 

                mb.DeclaringType.Namespace != null &&

                mb.DeclaringType.Namespace.StartsWith("Microsoft.Scripting", StringComparison.Ordinal)) {

                return true;

            }



            //Filters out all the methods generated for DLR rules or used in DLR rules.

            return CallSiteHelpers.IsInternalFrame(mb);

        }

    }

}