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/* ****************************************************************************
*
* 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.
*
*
* ***************************************************************************/
using System; using Microsoft;
#if !SILVERLIGHT
using System.Diagnostics;
#if CODEPLEX_40
using System.Dynamic;
using System.Dynamic.Utils;
using System.Linq.Expressions;
using System.Linq.Expressions.Compiler;
#else
using Microsoft.Scripting;
using Microsoft.Scripting.Utils;
using Microsoft.Linq.Expressions;
using Microsoft.Linq.Expressions.Compiler;
#endif
using System.Runtime.CompilerServices;
#if !CODEPLEX_40
using Microsoft.Runtime.CompilerServices;
#endif
using System.Runtime.InteropServices;
using System.Collections.Generic;
#if CODEPLEX_40
namespace System.Dynamic {
#else
namespace Microsoft.Scripting {
#endif
internal static class ComBinderHelpers {
internal static bool PreferPut(Type type, bool holdsNull) {
Debug.Assert(type != null);
if (type.IsValueType || type.IsArray) return true;
if (type == typeof(String) ||
type == typeof(DBNull) ||
holdsNull ||
type == typeof(System.Reflection.Missing) ||
type == typeof(CurrencyWrapper)) {
return true;
} else {
return false;
}
}
internal static bool IsByRef(DynamicMetaObject mo) {
ParameterExpression pe = mo.Expression as ParameterExpression;
return pe != null && pe.IsByRef;
}
internal static bool IsStrongBoxArg(DynamicMetaObject o) {
Type t = o.LimitType;
return t.IsGenericType && t.GetGenericTypeDefinition() == typeof(StrongBox<>);
}
// this helper prepares arguments for COM binding by transforming ByVal StongBox arguments
// into ByRef expressions that represent the argument's Value fields.
internal static bool[] ProcessArgumentsForCom(ref DynamicMetaObject[] args) {
Debug.Assert(args != null);
DynamicMetaObject[] newArgs = new DynamicMetaObject[args.Length];
bool[] isByRefArg = new bool[args.Length];
for (int i = 0; i < args.Length; i++) {
DynamicMetaObject curArgument = args[i];
// set new arg infos to their original values or set default ones
// we will do this fixup early so that we can assume we always have
// arginfos in COM binder.
if (IsByRef(curArgument)) {
newArgs[i] = curArgument;
isByRefArg[i] = true;
} else {
if (IsStrongBoxArg(curArgument)) {
var restrictions = curArgument.Restrictions.Merge(
GetTypeRestrictionForDynamicMetaObject(curArgument)
);
// we have restricted this argument to LimitType so we can convert and conversion will be trivial cast.
Expression boxedValueAccessor = Expression.Field(
Helpers.Convert(
curArgument.Expression,
curArgument.LimitType
),
curArgument.LimitType.GetField("Value")
);
IStrongBox value = curArgument.Value as IStrongBox;
object boxedValue = value != null ? value.Value : null;
newArgs[i] = new DynamicMetaObject(
boxedValueAccessor,
restrictions,
boxedValue
);
isByRefArg[i] = true;
} else {
newArgs[i] = curArgument;
isByRefArg[i] = false;
}
}
}
args = newArgs;
return isByRefArg;
}
internal static BindingRestrictions GetTypeRestrictionForDynamicMetaObject(DynamicMetaObject obj) {
if (obj.Value == null && obj.HasValue) {
//If the meta object holds a null value, create an instance restriction for checking null
return BindingRestrictions.GetInstanceRestriction(obj.Expression, null);
}
return BindingRestrictions.GetTypeRestriction(obj.Expression, obj.LimitType);
}
}
}
#endif
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