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Need more examples with anonymous sequences #20
Description
Hi, I'm trying pest-ast for my project. So far, it's been super-helpful.
Now, I have a few cases for which I cannot find a type mapping. i have looked in issues, in the examples of pest-ast and the examples of derive.
A repetition of an anonymous sequence
comparison = { arith_expr ~ (comp_op ~ arith_expr)* }
In #8, I see an example:
struct assigns<'pest>(
#[pest_ast(outer)] Span<'pest>,
Vec<struct _1(assign<'pest>)>,
assign<'pest>,
);
But Vec<struct _1(assign<'pest>)> is not a valid Rust, there are no anonymous structs.
I can try to extract a named struct, but there is no grammar rule to put into pest_ast, and pest_ast is required:
#[derive(Debug, FromPest)]
// FIXME: This probably shouldn't work!
#[pest_ast(rule(Rule::comparison))]
pub struct ComparisonPart2 {
pub op: CompOr,
pub expr: ArithExpr
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::comparison))]
// comparison = { arith_expr ~ (comp_op ~ arith_expr)* }
pub struct Comparison {
pub expr: ArithExpr,
pub continuation: Vec<ComparisonPart2>,
// pub continuation: Vec<(CompOr, ArithExpr)>,
}
I'm not sure it will work (I haven't finished a mapping for my grammar yet).
A nested choice
arith_expr = { term ~ ((plus|minus) ~ term)* }
How do I map the (plus|minus) part? To an enum like this?
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::plus))]
pub struct Plus {
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::minus))]
pub struct Minus {
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::arith_expr))]
pub enum PlusMinus {
Plus{ plus: Plus },
Minus{ minus: Minus },
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::arith_expr))]
pub struct ArithExprPart2 {
pub op: PlusMinus,
pub term: Term,
}
#[derive(Debug, FromPest)]
#[pest_ast(rule(Rule::arith_expr))]
// arith_expr = { term ~ ((plus|minus) ~ term)* }
pub struct ArithExpr {
pub term: Term,
pub tail: Vec<ArithExprPart2>
}
It would be great to have a such example. It would be a bit less great to know it's impossible as of now.
Thank you!
Activity
[-]A repetition of an anonymous sequence?[/-][+]Need more examples with anonymous sequences[/+]