// example based on the MSDN Explicit Interface Implementation Sample (explicit.cs)
public static void GenExplicit2(AssemblyGen ag)
{
var st = ag.StaticFactory;
var exp = ag.ExpressionFactory;
ITypeMapper m = ag.TypeMapper;
// Declare the English units interface:
TypeGen IEnglishDimensions = ag.Interface("IEnglishDimensions");
{
IEnglishDimensions.Method(typeof(float), "Length");
IEnglishDimensions.Method(typeof(float), "Width");
}
// Declare the metric units interface:
TypeGen IMetricDimensions = ag.Interface("IMetricDimensions");
{
IMetricDimensions.Method(typeof(float), "Length");
IMetricDimensions.Method(typeof(float), "Width");
}
// Declare the "Box" class that implements the two interfaces:
// IEnglishDimensions and IMetricDimensions:
TypeGen Box = ag.Class("Box", typeof(object), IEnglishDimensions, IMetricDimensions);
{
FieldGen lengthInches = Box.Field(typeof(float), "lengthInches");
FieldGen widthInches = Box.Field(typeof(float), "widthInches");
CodeGen g = Box.Public.Constructor()
.Parameter(typeof(float), "length")
.Parameter(typeof(float), "width")
;
{
g.Assign(lengthInches, g.Arg("length"));
g.Assign(widthInches, g.Arg("width"));
}
// Explicitly implement the members of IEnglishDimensions:
g = Box.MethodImplementation(IEnglishDimensions, typeof(float), "Length");
{
g.Return(lengthInches);
}
g = Box.MethodImplementation(IEnglishDimensions, typeof(float), "Width");
{
g.Return(widthInches);
}
// Explicitly implement the members of IMetricDimensions:
g = Box.MethodImplementation(IMetricDimensions, typeof(float), "Length");
{
g.Return(lengthInches * 2.54f);
}
g = Box.MethodImplementation(IMetricDimensions, typeof(float), "Width");
{
g.Return(widthInches * 2.54f);
}
g = Box.Public.Static.Method(typeof(void), "Main");
{
// Declare a class instance "myBox":
var myBox = g.Local(exp.New(Box, 30.0f, 20.0f));
// Declare an instance of the English units interface:
var eDimensions = g.Local(myBox.Cast(IEnglishDimensions));
// Declare an instance of the metric units interface:
var mDimensions = g.Local(myBox.Cast(IMetricDimensions));
// Print dimensions in English units:
g.WriteLine("Length(in): {0}", eDimensions.Invoke("Length"));
g.WriteLine("Width (in): {0}", eDimensions.Invoke("Width"));
// Print dimensions in metric units:
g.WriteLine("Length(cm): {0}", mDimensions.Invoke("Length"));
g.WriteLine("Width (cm): {0}", mDimensions.Invoke("Width"));
}
}
}
/// <summary>
/// Create a wrapper class for a generic interface with more general type parameters than the wrapped interface.
/// Downcasts to the correct more specific type are generated where necessary.
/// This of course breaks type safety, and only calls to the class with the correct orginal types will work.
/// Incorrect calls will throw <see cref = "InvalidCastException" />.
/// </summary>
/// <remarks>
/// This is useful during reflection, when you don't want to know about specific types, but you can guarantee
/// that a certain call will always be done with objects of the correct type.
/// TODO: This non-generic method is only needed since RunSharp can't call generic methods, needed to generate wrappers recursively.
/// TODO: Possibly Castle DynamicProxy could replace this if it allows creating 'non-matching' proxies and thus support the downcasting.
/// </remarks>
/// <param name = "typeToCreate">The less-specific generic type of the wrapper which will be generated.</param>
/// <param name = "o">The object to wrap, which should implement the desired interface, with arbitrary type parameters.</param>
/// <returns>An instance of the specified type which wraps the given object.</returns>
public static object CreateGenericInterfaceWrapper(Type typeToCreate, object o)
{
Contract.Requires(o.GetType().IsOfGenericType(typeToCreate.GetGenericTypeDefinition()));
Contract.Requires(typeToCreate.IsInterface);
Type typeToCreateGeneric = typeToCreate.GetGenericTypeDefinition();
Type innerType = o.GetType();
Type innerMatchingType = innerType.GetMatchingGenericType(typeToCreateGeneric);
// Implement passed type and redirect all public calls to inner instance.
var assembly = new AssemblyGen("Whathecode.System.RunSharp");
TypeGen type = assembly.Public.Class("Wrapped" + typeToCreate.Name, typeof(object), typeToCreate);
{
const string inner = "inner";
FieldGen innerInstance = type.Private.Field(innerType, "_innerInstance");
FieldGen returnCached = type.Private.Field(typeof(Dictionary <int, object>), "_returnCached");
FieldGen returnWrappers = type.Private.Field(typeof(Dictionary <int, object>), "_returnWrappers");
// Create constructor which takes the wrapped instance as an argument.
ConstructorGen constructor = type.Public.Constructor();
{
constructor.Parameter(innerType, inner);
CodeGen code = constructor.GetCode();
{
code.Assign(innerInstance, code.Arg(inner));
code.Assign(returnCached, Exp.New(typeof(Dictionary <int, object>)));
code.Assign(returnWrappers, Exp.New(typeof(Dictionary <int, object>)));
}
}
// Create methods.
int methodCount = 0;
MethodInfo[] innerMethods = innerMatchingType.GetFlattenedInterfaceMethods(ReflectionHelper.FlattenedInstanceMembers).ToArray();
MethodInfo[] toCreateMethods = typeToCreate.GetFlattenedInterfaceMethods(ReflectionHelper.FlattenedInstanceMembers).ToArray();
MethodInfo[] genericMethods = typeToCreateGeneric.GetFlattenedInterfaceMethods(ReflectionHelper.FlattenedInstanceMembers).ToArray();
foreach (var method in innerMethods
.Zip(toCreateMethods, genericMethods,
(matching, toCreate, generic) => new
{
Id = methodCount++,
Matching = matching,
ToCreate = toCreate,
Generic = generic
})
.Where(z => z.Matching.IsPublic || z.Matching.IsFamily))
{
// TODO: Not quite certain why override is required for extended interfaces (DeclaringType != typeTocreate),
// but this seems to work.
MethodInfo toCreate = method.ToCreate;
MethodGen methodGen = toCreate.DeclaringType == typeToCreate
? type.MethodImplementation(typeToCreate, toCreate.ReturnType, toCreate.Name)
: type.Public.Override.Method(toCreate.ReturnType, toCreate.Name);
{
ParameterInfo[] toCreateParameters = toCreate.GetParameters();
var parameters = toCreateParameters
.Select(p =>
{
var info = methodGen.BeginParameter(p.ParameterType, p.Name);
info.End();
return(info);
}).ToArray();
CodeGen code = methodGen.GetCode();
{
// Cast arguments to the type of the inner instance.
Operand[] args = parameters.Select(p => code.Arg(p.Name)).ToArray();
Operand[] castArgs = { };
if (args.Length > 0)
{
Type[] parameterTypes = method.Matching.GetParameters().Select(p => p.ParameterType).ToArray();
// TODO: When searching for generic methods, GetMethod returns null. http://stackoverflow.com/questions/4035719/getmethod-for-generic-method
// Even when the correct method is found through custom filtering, RunSharp does not seem to be able to create generic methods yet.
MethodInfo methodToCall
= innerType.GetMethod(toCreate.Name, ReflectionHelper.FlattenedInstanceMembers, parameterTypes);
castArgs = methodToCall.GetParameters()
.Select((p, index) => args[index].Cast(typeof(object)).Cast(p.ParameterType)).ToArray();
}
// Call inner instance and return value when needed.
if (toCreate.ReturnType != typeof(void))
{
Operand result = innerInstance.Invoke(toCreate.Name, castArgs);
// Wrappers will recursively need to be created for generic return types.
Type genericReturnType = method.Generic.ReturnType;
if (genericReturnType.IsGenericType && genericReturnType.ContainsGenericParameters && genericReturnType.IsInterface)
{
// Check whether a new result is returned.
Operand innerCached = code.Local(typeof(object));
code.If(returnCached.Invoke("TryGetValue", method.Id, innerCached.Ref()));
{
code.If((innerCached == result).LogicalNot());
{
code.Invoke(returnWrappers, "Remove", method.Id);
code.Invoke(returnCached, "Remove", method.Id);
code.Invoke(returnCached, "Add", method.Id, result);
}
code.End();
}
code.Else();
{
code.Invoke(returnCached, "Add", method.Id, result);
}
code.End();
// Check whether a wrapper needs to be generated.
Operand wrappedCached = code.Local(typeof(object));
code.If(returnWrappers.Invoke("TryGetValue", method.Id, wrappedCached.Ref()).LogicalNot());
{
Operand proxied = Static.Invoke(typeof(Proxy), "CreateGenericInterfaceWrapper", toCreate.ReturnType, result);
code.Assign(wrappedCached, proxied);
code.Invoke(returnWrappers, "Add", method.Id, wrappedCached);
}
code.End();
code.Return(wrappedCached.Cast(toCreate.ReturnType));
}
else
{
// A simple cast will work.
// TODO: Throw proper exception when this is known to fail. E.g. generic type which is not an interface?
code.Return(result.Cast(toCreate.ReturnType));
}
}
else
{
code.Invoke(innerInstance, toCreate.Name, castArgs);
}
}
}
}
}
Type wrapperType = type.GetCompletedType(true);
return(Activator.CreateInstance(wrapperType, new[] { o }));
}