public static AsyncTransformExpression <TSource, TOuter> Then <TOuter>(AsyncTransformExpression <TSource, TResult> left, AsyncTransformExpression <TResult, TOuter> right)
{
Contract.NotNull(left, nameof(left));
Contract.NotNull(right, nameof(right));
if (left.IsIdentity())
{ // we can optimize the left expression away, since we know that TSource == TResult !
//note: fool the compiler into believing that TSource == TResult
return((AsyncTransformExpression <TSource, TOuter>)(object) right);
}
if (right.IsIdentity())
{ // we can optimize the right expression away, since we know that TResult == TOuter !
return((AsyncTransformExpression <TSource, TOuter>)(object) left);
}
if (left.m_transform != null)
{
var f = left.m_transform;
Contract.Assert(f != null);
if (right.m_transform != null)
{
var g = right.m_transform;
Contract.Assert(g != null);
return(new AsyncTransformExpression <TSource, TOuter>((x) => g(f(x))));
}
else
{
var g = right.m_asyncTransform;
Contract.Assert(g != null);
return(new AsyncTransformExpression <TSource, TOuter>((x, ct) => g(f(x), ct)));
}
}
else
{
var f = left.m_asyncTransform;
Contract.Assert(f != null);
if (right.m_asyncTransform != null)
{
var g = right.m_asyncTransform;
Contract.Assert(g != null);
return(new AsyncTransformExpression <TSource, TOuter>(async(x, ct) => await g(await f(x, ct).ConfigureAwait(false), ct).ConfigureAwait(false)));
}
else
{
var g = right.m_transform;
Contract.Assert(g != null);
return(new AsyncTransformExpression <TSource, TOuter>(async(x, ct) => g(await f(x, ct).ConfigureAwait(false))));
}
}
}
public AsyncTransformExpression <TSource, TOuter> Then <TOuter>(AsyncTransformExpression <TResult, TOuter> expr)
{
return(Then <TOuter>(this, expr));
}
