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parsingrust
MaiaVictor
MaiaVictor

Reputation: 53037

Is it possible to derive a parser for an arbitrary type that parses the corresponding Debug format?

In Haskell, it is possible, as a language feature, to derive a parser from a string to an arbitrary datatype: that's called the Read class. Is it possible to do so in Rust? That is, given an arbitrary enum such as:

#[derive(Debug)]
enum Foo {
    A { x: u32, s: String },
    B { v: Vec<u8> },
}

and, given that Rust includes the Debug trait as a language feature that serializes an arbitrary datatype, is it possible to also automatically generate its corresponding Parse trait?

In other words, is there a default Rust feature that allows me to derive a parse(&str) -> Foo function such that, for any string s either parse(&s) == None or format!("{:?}", parse(&s).unwrap()) == s?

Upvotes: 2

Views: 277

Answers (1)

Shepmaster
Shepmaster

Reputation: 431679

No, there is no such feature. Debug is intended for human/programmer consumption, not for machines.

There's no guarantee that the Debug output is even in a parseable format or that it contains the complete data of a type.

I recommend using Serde instead, paired with an existing defined serialization format of your choice.

If you wanted to, you could define your own derive attributes that implement Debug and FromStr by calling into Serde.

Upvotes: 5

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