Child Nodes have the same `Text`

[ash-aldujaili]

I tried running the tool on the module itself as follows.

Show-Ast .\ShowPSAst.psm1

I found the following children nodes with the same texts (why is that? I assume nodes would have distinct IDs), see below; two instances of TypeConstraintAst nodes of exactly the same offsets.

Debugging these two nodes, I found the following:

In a nutshell, one $child has
TypeNameOfValue System.Management.Automation.Language.AttributeBaseAst and the other has TypeNameOfValue : System.Management.Automation.Language.TypeConstraintAst, yet both map to the same text TypeConstraintAst [2918,2942).

Any thoughts on the above?

[lzybkr]

They are more than the same extent, they are the same reference, see Type property in ConvertExpressionAst and Attribute property in the base class AttributedExpressionAst.

Maybe it looks a little weird, but I don't see any real problems.

[ash-aldujaili]

Thanks for the prompt response.

I am using the tool to extract structural info from PS scripts from a graph-theoretic point of view. If they are the same reference, would it be safe to ignore the second node ( I am assuming that both point to the same object and its properties)?

In other words, An AST with two children of identical text (as provided in the tool) is---functionally---equivalent to another AST with one child of the same text?

[lzybkr]

Yes, I think it's safe to ignore a second immediate child with identical text.

[ash-aldujaili]

Noted, with thanks.
I wonder what the advantage of such a setting is for the parser!

[lzybkr]

There is a single field backing both properties, so it's simply a convenience api.

[lzybkr]

The derived property also adds a type cast which makes the convenience api even more useful when editing code - giving more appropriate completions.