private Expression ConversionFallback(ConvertBinder/*!*/ convertToAction) {
ConversionBinder cb = convertToAction as ConversionBinder;
if (cb != null) {
return GetConversionFailedReturnValue(cb, this);
}
return convertToAction.Defer(this).Expression;
}
private DynamicMetaObject/*!*/ MakeConvertRuleForCall(ConvertBinder/*!*/ convertToAction, DynamicMetaObject/*!*/ self, SymbolId symbolId, string returner) {
PythonType pt = ((IPythonObject)self.Value).PythonType;
PythonTypeSlot pts;
CodeContext context = BinderState.GetBinderState(convertToAction).Context;
if (pt.TryResolveSlot(context, symbolId, out pts) && !IsBuiltinConversion(context, pts, symbolId, pt)) {
ParameterExpression tmp = Ast.Variable(typeof(object), "func");
Expression callExpr = Ast.Call(
PythonOps.GetConversionHelper(returner, GetResultKind(convertToAction)),
Ast.Dynamic(
new PythonInvokeBinder(
BinderState.GetBinderState(convertToAction),
new CallSignature(0)
),
typeof(object),
BinderState.GetCodeContext(convertToAction),
tmp
)
);
if (typeof(Extensible<>).MakeGenericType(convertToAction.Type).IsAssignableFrom(self.GetLimitType())) {
// if we're doing a conversion to the underlying type and we're an
// Extensible<T> of that type:
// if an extensible type returns it's self in a conversion, then we need
// to actually return the underlying value. If an extensible just keeps
// returning more instances of it's self a stack overflow occurs - both
// behaviors match CPython.
callExpr = AstUtils.Convert(AddExtensibleSelfCheck(convertToAction, self, callExpr), typeof(object));
}
return new DynamicMetaObject(
Ast.Block(
new ParameterExpression[] { tmp },
Ast.Condition(
BindingHelpers.CheckTypeVersion(
self.Expression,
pt.Version
),
Ast.Condition(
MakeTryGetTypeMember(
BinderState.GetBinderState(convertToAction),
pts,
self.Expression,
tmp
),
callExpr,
AstUtils.Convert(
ConversionFallback(convertToAction),
typeof(object)
)
),
convertToAction.Defer(this).Expression
)
),
self.Restrict(self.GetRuntimeType()).Restrictions
);
}
return convertToAction.FallbackConvert(this);
}