protected override async Task <IBifoqlObject> DoApply(QueryContext context)
{
var lhs = await _leftHandSide.Apply(context);
// Propagate error
if (lhs is IBifoqlError)
{
return(lhs);
}
var leftHandSide = lhs as IBifoqlIndexInternal;
if (leftHandSide == null)
{
return(new AsyncError(this.Location, "Can't do index lookup on something that isn't an index"));
}
var args = await IndexArgumentList.Create(_arguments, context);
// Propagate error if there were any errors in evaluating the argument list.
if (args.ErrorResult != null)
{
return(args.ErrorResult);
}
var resultObj = await leftHandSide.Lookup(args);
return(resultObj.ToBifoqlObject());
}
private static async Task <object> ToSimpleObject(IBifoqlIndexInternal index)
{
// TODO - index lookup probably should return IBifoqlObject, not object.
var resultWithZeroArgs = await index.Lookup(IndexArgumentList.CreateEmpty());
if (resultWithZeroArgs is IBifoqlObject)
{
return(await((IBifoqlObject)resultWithZeroArgs).ToSimpleObject());
}
else
{
return(resultWithZeroArgs);
}
}
private static Func <Task <IBifoqlObject> > GetDefaultValueFromIndexFunc(object o)
{
if (o is IBifoqlObject)
{
return(GetDefaultValueFromIndexFunc((IBifoqlObject)o));
}
// For a key, we want to get the default value only if the thing before it is an index; it doesn't
// make sense to look up keys on an index after all.
if (o is IBifoqlIndex || o is IBifoqlIndexSync)
{
// First, is there a default value?
if (o is IDefaultValue)
{
var defaultValue = ((IDefaultValue)o).GetDefaultValue();
if (defaultValue != null)
{
return(async() => (await defaultValue).ToBifoqlObject());
}
}
else if (o is IDefaultValueSync)
{
var defaultValue = ((IDefaultValueSync)o).GetDefaultValue();
if (defaultValue != null)
{
return(() => Task.FromResult(defaultValue.ToBifoqlObject()));
}
}
else if (o is IBifoqlIndex)
{
return(async() => {
var value = await((IBifoqlIndex)o).Lookup(IndexArgumentList.CreateEmpty());
return value.ToBifoqlObject();
});
}
else if (o is IBifoqlIndexSync)
{
return(() => {
var value = ((IBifoqlIndexSync)o).Lookup(IndexArgumentList.CreateEmpty());
return Task.FromResult(value.ToBifoqlObject());
});
}
throw new Exception("UNEXPECTED");
}
return(null);
}
private static Func <Task <IBifoqlObject> > GetDefaultValueFromIndexFunc(IBifoqlObject o)
{
if (o is IBifoqlIndexInternal)
{
if (o is IBifoqlHasDefaultValue)
{
return(((IBifoqlHasDefaultValue)o).GetDefaultValue());
}
// Pass zero arguments to the index.
return(async() => {
var obj = await((IBifoqlIndexInternal)o).Lookup(IndexArgumentList.CreateEmpty());
return obj.ToBifoqlObject();
});
}
return(null);
}
public Task <object> Lookup(IndexArgumentList arguments)
{
return(_lookup(arguments));
}
public Task <object> InvokeIndex(IndexArgumentList filter)
{
return(Task.FromResult <object>(new AsyncError("This object has no indexes")));
}
