internal Type Build(Type parent, Type target, IIntrospect introspector)
{
Assertion.IsNotNull("parent", parent);
Assertion.IsNotNull("target", target);
var ident = Ident.Create(parent, target);
Type type;
if (Built.TryGetValue(ident, out type))
{
return(type);
}
lock (Built)
{
if (Built.TryGetValue(ident, out type))
{
return(type);
}
return(Built[ident] = Build(ident, introspector));
}
}
Type Build(Ident ident, IIntrospect introspector)
{
var parent = ident.Item1;
var target = ident.Item2;
Assertion.IsNotNull("introspector", introspector);
Assertion.IsAccessible("parent", parent);
Assertion.IsAccessible("target", target);
Assertion.IsClass("parent", parent);
Assertion.ExtendsSkeleton("parent", parent);
Assertion.IsNotSealed("parent", parent);
Assertion.IsInterface("target", target);
var methods = Methods(target).Where(ReflectionExtensions.IsMethod);
var maps = parent.GetInterfaces()
.Select(parent.GetInterfaceMap)
.SelectMany(ZipMap)
.ToDictionary(x => x.Item1, x => x.Item2);
var name = parent.Derived(target);
var typB = ModB.DefineType(name: name,
attr: TypeAttributes.Class,
parent: parent,
interfaces: new [] { target });
foreach (var method in methods)
{
MethodInfo over;
if (maps.TryGetValue(method, out over) && !over.IsAbstract)
{
continue;
}
Assertion.IsAsync(method);
var call = introspector.Call(parent, method);
Assertion.HasValidDescription(method, call);
call.Headers = call.Headers ?? new Headers();
call.Body = call.Body ?? new Body();
call.Static = call.Static ?? new Static();
var args = method.GetParameters();
var metB = typB.DefineMethod(name: method.DeclaringType.Name + "." + method.Name,
attributes: method.Attributes & ~MethodAttributes.Abstract,
callingConvention: method.CallingConvention,
returnType: method.ReturnType,
parameterTypes: args.Select(x => x.ParameterType).ToArray());
var ilG = metB.GetILGenerator();
typB.DefineMethodOverride(metB, method);
if (null != over)
{
typB.DefineMethodOverride(metB, over);
}
// Separate parameters
var bodyP = call.Body.Keys.ToArray();
var headP = call.Headers.Keys.ToArray();
var restP = args.Except(bodyP.Union(headP)).ToArray();
var caTok = args.FirstOrDefault(x => typeof(CancellationToken?).IsAssignableFrom(x.ParameterType));
// Decide immediately if we can tail call from SendAsync
var thrmT = typeof(Task <HttpResponseMessage>);
var tail = thrmT == method.ReturnType;
var ctHM = typeof(HttpMethod).GetConstructor(new [] { typeof(string) });
ilG.Emit(OpCodes.Ldarg_0);
if (!tail)
{
ilG.Emit(OpCodes.Dup);
}
ilG.Emit(OpCodes.Ldstr, call.Verb.Method);
ilG.Emit(OpCodes.Newobj, ctHM);
ilG.EmitString(call.Template);
var dict = typeof(Params);
var ctor = dict.GetConstructor(EmpT);
var madd = dict.GetProperty("Item").SetMethod;
// Construct parameters dictionary
ilG.Emit(OpCodes.Newobj, ctor);
foreach (var arg in restP)
{
ilG.Emit(OpCodes.Dup);
ilG.Emit(OpCodes.Ldstr, arg.Name);
ilG.Emit(OpCodes.Ldarg, arg.Position + 1);
if (arg.ParameterType.IsValueType)
{
ilG.Emit(OpCodes.Box, arg.ParameterType);
}
ilG.Emit(OpCodes.Call, madd);
}
// Construct headers dictionary
ilG.Emit(OpCodes.Newobj, ctor);
// Pack static headers, but ignore the ones we would replace
foreach (var head in call.Static)
{
ilG.Emit(OpCodes.Dup);
ilG.Emit(OpCodes.Ldstr, head.Key);
ilG.Emit(OpCodes.Ldc_I4, head.Value.Length);
ilG.Emit(OpCodes.Newarr, typeof(string));
for (int i = 0, end = head.Value.Length; i < end; ++i)
{
ilG.Emit(OpCodes.Dup);
ilG.Emit(OpCodes.Ldc_I4, i);
ilG.Emit(OpCodes.Ldstr, head.Value[i]);
ilG.Emit(OpCodes.Stelem, typeof(string));
}
ilG.Emit(OpCodes.Call, madd);
}
// Pack parameter headers
foreach (var head in headP)
{
ilG.Emit(OpCodes.Dup);
ilG.Emit(OpCodes.Ldstr, call.Headers[head]);
ilG.Emit(OpCodes.Ldarg, head.Position + 1);
if (head.ParameterType.IsValueType)
{
ilG.Emit(OpCodes.Box, head.ParameterType);
}
ilG.Emit(OpCodes.Call, madd);
}
var delM = GetMethod(parent, "SendAsync", null, SendAsyncParams());
// Build content
if (0 == bodyP.Length)
{
ilG.Emit(OpCodes.Ldnull);
}
else
{
var imp = Imp;
var ctb = typeof(SkeletonClient).GetMethod("ContentBuilder", BindingFlags.NonPublic | BindingFlags.Instance);
ilG.Emit(OpCodes.Ldarg_0);
ilG.Emit(OpCodes.Callvirt, ctb);
imp.Process(ilG, call);
}
// Load cancellation token
if (caTok != null)
{
ilG.Emit(OpCodes.Ldarg, caTok.Position + 1);
ilG.EmitNullConversion(caTok.ParameterType);
}
else
{
LocalBuilder caTokF = ilG.DeclareLocal(typeof(CancellationToken?));
ilG.Emit(OpCodes.Ldloca, caTokF);
ilG.Emit(OpCodes.Initobj, typeof(CancellationToken?));
ilG.Emit(OpCodes.Ldloc, caTokF);
}
// Call SendAsync
if (tail)
{
ilG.Emit(OpCodes.Tailcall);
}
ilG.EmitCall(delM);
// Convert return type if necessary
if (!tail)
{
var conM = method.ReturnType.IsGenericType
? GetMethod(parent, "Return", method.ReturnType.GetGenericArguments(), new [] { thrmT })
: GetMethod(parent, "Return", null, new [] { thrmT });
ilG.Emit(OpCodes.Tailcall);
ilG.EmitCall(conM);
}
ilG.Emit(OpCodes.Ret);
}
// Generate constructors
foreach (var ctor in parent.GetConstructors(BindingFlags.Public | BindingFlags.Instance))
{
var ctorP = ctor.GetParameters();
var ctorB = typB.DefineConstructor(MethodAttributes.Public,
CallingConventions.Standard | CallingConventions.HasThis,
ctorP.Select(x => x.ParameterType).ToArray());
var ilG = ctorB.GetILGenerator();
ilG.Emit(OpCodes.Ldarg_0);
foreach (var param in ctorP)
{
var p = ctorB.DefineParameter(param.Position + 1, param.Attributes, param.Name);
ilG.Emit(OpCodes.Ldarg, p.Position);
}
ilG.Emit(OpCodes.Call, ctor);
ilG.Emit(OpCodes.Ret);
}
return(typB.CreateType());
}