werat wrote:
I went through the thread to understand the current consensus and I see various
nice ideas flying around. Let me try to summarize the requirements and the
current status quo.
* DIL should support synthetic children, whose names can be arbitrary in
general case, even `a+b*c`
* A common synthetic name is `[0]`, which is used for children of vectors/maps
and people want to write `print vec[0]`
* `frame variable` supports this by having special support for `[]`
"expressions"
* We want DIL to be easy & convenient to use in most (simple) cases, but also
to be able to support complicated cases and it doesn't have to be _super_
convenient for those
Possible behaviour for DIL:
* Make the definition of `identifier` in Lexer to roughly match C or similar
* Introduce escaping of identifiers, e.g. with backticks
* The expression ``foo->`a*b.c`+1`` is parsed as approx
`foo.GetChildWithName("a*b.c") + 1`
* Add special support for `[]` in the parser
* The expression ``foo.`[1]` `` is parsed as `foo.GetChildWithName("[1]")`
* The expression `foo[1]` tries the following:
* `foo.GetChildWithName("1")`
* `foo.GetChildWithName("[1]")`
* `foo.GetChildAtIndex(1)`
* The expression `foo["bar"]` tries:
* `foo.GetChildWithName("bar")`
* `foo.GetChildWithName("[bar]")`
* The expression `foo[<expr>]` -- `expr` is evaluated and treated as cases
above. If the result of `expr` is not a number or a string -- produce an error
For cases where the `GetChildWithName( "1" / "[1]" )` and `GetChildAtIndex(1)`
produce different valid results we could shows a warning/error to make it clear
to the user that there's some ambiguity. IMO this would be an improvement over
the current situation where `print` and `expr` simply produce different results.
This way all typical cases work as expected by users and more or less match the
current behaviour of frame variable. It's still possible to access synthetic
children with any names, but it requires knowledge about the escaping.
Does this sound like a reasonable approach?
https://github.com/llvm/llvm-project/pull/123521
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