public void Intercept(IInvocation invocation)
{
if (invocation.Method == GetGooseSourceMethod)
{
invocation.ReturnValue = _source;
return;
}
if (_source == null)
{
throw new NullReferenceException($"{nameof(invocation.Method)}: Object reference not set to an instance of an object.");
}
var sourceType = _source.GetType();
if (_blacklist.Contains(invocation.Method))
{
throw new GooseNotImplementedException(sourceType, invocation.Method);
}
if (_knownHandlers.ContainsKey(invocation.Method))
{
invocation.ReturnValue = _knownHandlers[invocation.Method](invocation.Arguments);
return;
}
var sourceCandidateMethods = sourceType
.GetMethods(BindingFlags.Public | BindingFlags.Instance)
.Where(m => m.Name.Equals(invocation.Method.Name));
var invocationParameters = invocation.Method.GetParameters();
var candidates = new List <MethodCompatibility>();
foreach (var sourceMethod in sourceCandidateMethods)
{
var sourceParameters = sourceMethod.GetParameters();
if (sourceParameters.Length != invocationParameters.Length)
{
continue;
}
var argumentCompatibilities = new TypeCompatibility[invocation.Arguments.Length];
var parameterCompatible = true;
for (var i = 0; i < sourceParameters.Length; i++)
{
argumentCompatibilities[i] = GetCompatibility(invocationParameters[i].ParameterType, sourceParameters[i].ParameterType);
if (argumentCompatibilities[i] == TypeCompatibility.Incompatible)
{
parameterCompatible = false;
break;
}
}
if (!parameterCompatible)
{
continue;
}
var returnTypeCompatibility = GetCompatibility(sourceMethod.ReturnType, invocation.Method.ReturnType);
if (returnTypeCompatibility == TypeCompatibility.Incompatible)
{
continue;
}
candidates.Add(new MethodCompatibility(sourceMethod, argumentCompatibilities, returnTypeCompatibility));
}
MethodCompatibility candidate = null;
if (candidates.Count > 1)
{
var highestScoredCandidates = candidates
.OrderByDescending(c => c.Score)
.TakeWhile((c, i) => i == 0 || candidates[i].Score == candidates[i - 1].Score)
.ToList();
if (highestScoredCandidates.Count == 1)
{
candidate = highestScoredCandidates.Single();
}
else
{
var orderByDeclaringTypes = highestScoredCandidates
.Select(c => new { Candidate = c, Inheritance = GetInheritanceString(c.Method.DeclaringType) })
.OrderByDescending(x => x.Inheritance)
.ToList();
if (orderByDeclaringTypes[0].Inheritance.Equals(orderByDeclaringTypes[1].Inheritance))
{
throw new GooseAmbiguousMatchException(orderByDeclaringTypes[0].Candidate.Method, orderByDeclaringTypes[1].Candidate.Method);
}
candidate = orderByDeclaringTypes[0].Candidate;
}
}
else if (candidates.Count == 1)
{
candidate = candidates.Single();
}
else if (candidates.Count == 0)
{
_blacklist.Add(invocation.Method);
throw new GooseNotImplementedException(sourceType, invocation.Method);
}
var handler = MakeHandler(invocation, candidate);
invocation.ReturnValue = handler(invocation.Arguments);
_knownHandlers.Add(invocation.Method, handler);
}
private Func <object[], object> MakeHandler(IInvocation invocation, MethodCompatibility candidate)
{
var parameter = Expression.Parameter(typeof(object[]));
var variables = new List <ParameterExpression>();
var beforeInvoke = new List <Expression>();
var invoke = new List <Expression>();
var afterInvoke = new List <Expression>();
var arguments = new List <Expression>();
var methodParameters = candidate.Method.GetParameters();
for (var i = 0; i < candidate.ArgumentCompatibilities.Length; i++)
{
var arrayIndex = Expression.ArrayIndex(parameter, Expression.Constant(i));
Expression argument = null;
if (candidate.ArgumentCompatibilities[i] == TypeCompatibility.Same)
{
argument = arrayIndex;
}
else if (candidate.ArgumentCompatibilities[i] == TypeCompatibility.FromGoose)
{
var asIGooseTarget = Expression.Convert(arrayIndex, typeof(IGooseTyped));
var getSource = Expression.Property(asIGooseTarget, nameof(IGooseTyped.Source));
argument = getSource;
}
else if (candidate.ArgumentCompatibilities[i] == TypeCompatibility.ToGoose)
{
var gooseType = Expression.Constant(methodParameters[i].ParameterType);
var callGooseExtension = Expression.Call(GooseExtensionMethod, arrayIndex, gooseType, Expression.Constant(_options.KnownTypes.ToArray()));
argument = callGooseExtension;
}
if (methodParameters[i].IsOut)
{
var local = Expression.Variable(methodParameters[i].ParameterType.GetElementType());
variables.Add(local);
var assignLocal = Expression.Assign(local, Expression.Convert(argument, methodParameters[i].ParameterType.GetElementType()));
beforeInvoke.Add(assignLocal);
var arrayAccess = Expression.ArrayAccess(parameter, Expression.Constant(i));
var assignBack = Expression.Assign(arrayAccess, Expression.Convert(local, typeof(object)));
afterInvoke.Add(assignBack);
arguments.Add(local);
}
else
{
arguments.Add(Expression.Convert(argument, methodParameters[i].ParameterType));
}
}
LabelTarget returnTarget = Expression.Label(typeof(object));
ParameterExpression returnVariable = Expression.Variable(typeof(object));
variables.Add(returnVariable);
LabelExpression returnLabel = Expression.Label(returnTarget, returnVariable);
afterInvoke.Add(Expression.Return(returnTarget, returnVariable));
afterInvoke.Add(returnLabel);
Expression invokeSource = Expression.Call(Expression.Constant(_source), candidate.Method, arguments);
if (candidate.ReturnCompatibility == TypeCompatibility.FromGoose)
{
var asIGooseTarget = Expression.Convert(invokeSource, typeof(IGooseTyped));
var getSource = Expression.Property(asIGooseTarget, nameof(IGooseTyped.Source));
invokeSource = getSource;
}
else if (candidate.ReturnCompatibility == TypeCompatibility.ToGoose)
{
var gooseType = Expression.Constant(invocation.Method.ReturnType);
invokeSource = Expression.Call(GooseExtensionMethod, invokeSource, gooseType, Expression.Constant(_options.KnownTypes.ToArray()));
}
invoke.Add(returnVariable);
if (candidate.Method.ReturnType == typeof(void))
{
invoke.Add(invokeSource);
invoke.Add(Expression.Assign(returnVariable, Expression.Constant(null)));
}
else
{
invoke.Add(Expression.Assign(returnVariable, Expression.Convert(invokeSource, typeof(object))));
}
Expression body = Expression.Block(variables, beforeInvoke.Concat(invoke).Concat(afterInvoke));
var exceptions = _options.KnownTypes
.Where(t => typeof(Exception).IsAssignableFrom(t.SourceType))
.ToList();
if (exceptions.Count > 0)
{
var catches = exceptions
.OrderByDescending(e => GetInheritanceString(e.SourceType))
.Select(e =>
{
var p = Expression.Parameter(e.SourceType);
var gooseType = Expression.Constant(e.TargetType);
var callGooseExtension = Expression.Call(GooseExtensionMethod, p, gooseType, Expression.Constant(_options.KnownTypes.ToArray()));
var ctor = typeof(WrappedException <>).MakeGenericType(e.TargetType).GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance).Single();
var throwWrap = Expression.Throw(Expression.New(ctor, Expression.Convert(callGooseExtension, e.TargetType)));
return(Expression.Catch(p, Expression.Block(throwWrap, Expression.Constant(null))));
});
body = Expression.TryCatch(body, catches.ToArray());
}
var lambda = Expression.Lambda <Func <object[], object> >(body, parameter);
return(lambda.Compile());
}