/// <summary>
/// Cast a reference on the stack to the given reference type.
///
/// If the cast is not legal, a CastClassException will be thrown at runtime.
/// </summary>
public Emit <DelegateType> CastClass(Type referenceType)
{
if (referenceType == null)
{
throw new ArgumentNullException("referenceType");
}
if (referenceType.IsValueType)
{
throw new ArgumentException("Can only cast to ReferenceTypes, found " + referenceType);
}
var curIndex = IL.Index;
bool elided = false;
VerificationCallback before =
(stack, baseless) =>
{
// Can't reason about stack unless it's completely known
if (baseless || elided)
{
return;
}
var onStack = stack.First();
if (onStack.All(a => ExtensionMethods.IsAssignableFrom(referenceType, a)))
{
ElidableCasts.Add(curIndex);
elided = true;
}
};
var newType = TypeOnStack.Get(referenceType);
var transitions =
new[]
{
new StackTransition(new [] { typeof(object) }, new [] { referenceType }, before: before)
};
UpdateState(OpCodes.Castclass, referenceType, Wrap(transitions, "CastClass"));
return(this);
}
/// <summary>
/// Pops a value from the stack and casts to the given type if possible pushing the result, otherwise pushes a null.
///
/// This is analogous to C#'s `as` operator.
/// </summary>
public Emit <DelegateType> IsInstance(Type type)
{
if (type == null)
{
throw new ArgumentNullException("type");
}
var curIndex = IL.Index;
bool elided = false;
VerificationCallback before =
(stack, baseless) =>
{
// Can't reason about stack unless it's completely known
if (baseless || elided)
{
return;
}
var onStack = stack.First();
if (onStack.All(a => ExtensionMethods.IsAssignableFrom(type, a)))
{
ElidableCasts.Add(curIndex);
elided = true;
}
};
var transitions =
new[]
{
new StackTransition(new[] { typeof(WildcardType) }, new [] { type }, before)
};
UpdateState(OpCodes.Isinst, type, Wrap(transitions, "IsInstance"));
return(this);
}
