115 lines
3.9 KiB
C#
115 lines
3.9 KiB
C#
/* ****************************************************************************
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*
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* Copyright (c) Microsoft Corporation.
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*
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* This source code is subject to terms and conditions of the Microsoft Public License. A
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* copy of the license can be found in the License.html file at the root of this distribution. If
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* you cannot locate the Microsoft Public License, please send an email to
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* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
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* by the terms of the Microsoft Public License.
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*
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* You must not remove this notice, or any other, from this software.
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*
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*
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* ***************************************************************************/
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using System; using Microsoft;
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#if !SILVERLIGHT // ComObject
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Globalization;
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#if CODEPLEX_40
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using System.Linq.Expressions;
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#else
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using Microsoft.Linq.Expressions;
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#endif
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using System.Reflection;
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using System.Reflection.Emit;
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using System.Runtime.InteropServices;
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#if CODEPLEX_40
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namespace System.Dynamic {
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#else
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namespace Microsoft.Scripting {
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#endif
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[StructLayout(LayoutKind.Sequential)]
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internal struct VariantArray1 {
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public Variant Element0;
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}
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[StructLayout(LayoutKind.Sequential)]
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internal struct VariantArray2 {
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public Variant Element0, Element1;
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}
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[StructLayout(LayoutKind.Sequential)]
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internal struct VariantArray4 {
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public Variant Element0, Element1, Element2, Element3;
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}
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[StructLayout(LayoutKind.Sequential)]
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internal struct VariantArray8 {
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public Variant Element0, Element1, Element2, Element3, Element4, Element5, Element6, Element7;
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}
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//
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// Helper for getting the right VariantArray struct for a given number of
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// arguments. Will generate a struct if needed.
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//
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// We use this because we don't have stackalloc or pinning in Expression
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// Trees, so we can't create an array of Variants directly.
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//
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internal static class VariantArray {
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// Don't need a dictionary for this, it will have very few elements
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// (guarenteed less than 28, in practice 0-2)
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private static readonly List<Type> _generatedTypes = new List<Type>(0);
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internal static MemberExpression GetStructField(ParameterExpression variantArray, int field) {
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return Expression.Field(variantArray, "Element" + field);
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}
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internal static Type GetStructType(int args) {
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Debug.Assert(args >= 0);
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if (args <= 1) return typeof(VariantArray1);
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if (args <= 2) return typeof(VariantArray2);
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if (args <= 4) return typeof(VariantArray4);
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if (args <= 8) return typeof(VariantArray8);
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int size = 1;
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while (args > size) {
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size *= 2;
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}
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lock (_generatedTypes) {
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// See if we can find an existing type
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foreach (Type t in _generatedTypes) {
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int arity = int.Parse(t.Name.Substring("VariantArray".Length), CultureInfo.InvariantCulture);
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if (size == arity) {
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return t;
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}
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}
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// Else generate a new type
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Type type = CreateCustomType(size).MakeGenericType(new Type[]{typeof(Variant)});
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_generatedTypes.Add(type);
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return type;
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}
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}
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private static Type CreateCustomType(int size) {
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var attrs = TypeAttributes.NotPublic | TypeAttributes.SequentialLayout;
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TypeBuilder type = UnsafeMethods.DynamicModule.DefineType("VariantArray" + size, attrs, typeof(ValueType));
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var T = type.DefineGenericParameters(new string[] { "T" })[0];
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for (int i = 0; i < size; i++) {
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type.DefineField("Element" + i, T, FieldAttributes.Public);
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}
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return type.CreateType();
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}
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}
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}
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#endif
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