/* ****************************************************************************
*
* 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 !CLR2
using System.Linq.Expressions;
#else
using Microsoft.Scripting.Ast;
#endif
using System;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.CompilerServices;
using Microsoft.Scripting.Utils;
using AstUtilsMicrosoft.Scripting.Ast.Utils;
using RuntimeHelpersMicrosoft.Scripting.Runtime.ScriptingRuntimeHelpers;
namespace Microsoft.Scripting.Actions.Calls{
/// <summary>
/// An argument that the user wants to explicitly pass by-reference (with copy-in copy-out semantics).
/// The user passes a StrongBox[T] object whose value will get updated when the call returns.
/// </summary>
internal sealed class ReferenceArgBuilder : SimpleArgBuilder {
private readonly Type _elementType;
private ParameterExpression _tmp;
public ReferenceArgBuilder(ParameterInfo info, Type elementType, Type strongBox, int index)
: base(info, strongBox, index, false, false) {
_elementType = elementType;
}
protected override SimpleArgBuilder Copy(int newIndex) {
return new ReferenceArgBuilder(ParameterInfo, _elementType, Type, newIndex);
}
public override ArgBuilder Clone(ParameterInfo newType) {
Type elementType = newType.ParameterType.GetElementType();
return new ReferenceArgBuilder(newType, elementType, typeof(StrongBox<>).MakeGenericType(elementType), Index);
}
public override int Priority {
get { return 5; }
}
internal protected override Expression ToExpression(OverloadResolver resolver, RestrictedArguments args, bool[] hasBeenUsed) {
if (_tmp == null) {
_tmp = resolver.GetTemporary(_elementType, "outParam");
}
Debug.Assert(!hasBeenUsed[Index]);
hasBeenUsed[Index] = true;
Expression arg = args.GetObject(Index).Expression;
return Expression.Condition(
Expression.TypeIs(arg, Type),
Expression.Assign(
_tmp,
Expression.Field(
AstUtils.Convert(arg, Type),
Type.GetField("Value")
)
),
Expression.Throw(
Expression.Call(
new Func<Type, object, Exception>(RuntimeHelpers.MakeIncorrectBoxTypeError).Method,
AstUtils.Constant(_elementType),
AstUtils.Convert(arg, typeof(object))
),
_elementType
)
);
}
protected internal override Func<object[], object> ToDelegate(OverloadResolver resolver, RestrictedArguments args, bool[] hasBeenUsed) {
return null;
}
internal override Expression UpdateFromReturn(OverloadResolver resolver, RestrictedArguments args) {
return Expression.Assign(
Expression.Field(
Expression.Convert(args.GetObject(Index).Expression, Type),
Type.GetField("Value")
),
_tmp
);
}
internal override Expression ByRefArgument {
get { return _tmp; }
}
}
}
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