implemented flattern for stack:tree and support for {Fn::GetAtt:[resource,attribute]}

[dng-dev]

Hey @fbrnc i added the flattern of the tree and also the possibility for inline {Fn::GetAtt:[resource,attribute]} which is an feature request by you #31

[fbrnc]

You're awesome! Thanks for picking this up and implementing this so quickly. I'll test the tree later today, but here's already one thing I noticed about the Fn:GetAtt feature:

The regex you're using does not allow adding whitespace everywhere. E.g. EIP="{Fn::GetAtt:[NatIp,AllocationId] }" (notice the extra space before the last }) would not be a match.

While of course it's easy to fix that I'd like to suggest a simpler snytax that also matches the scheme of other inline functions and value lookups:

{Attribute:<resource>:<attribure>}
(your example then would be {Attribute:NatIp:AllocationId}

What do you think?

[dng-dev]

Hey @fbrnc i will fix the regex you are right. I don't think its an good idea to introduce a new syntax for the Fn::GetAtt part. I think it can produce more confusion. But the final decision is up to you.

[dng-dev]

Hey @fbrnc i updated the regex in the simulator. When you have time play around. If you don't see problems, i will update the regexp.

https://regex101.com/r/vN8qT9/2

[dng-dev]

Hey @fbrnc i updated the regexp