jomini::Value

[rlidwka]

It would be useful to have a structure that represents every possible value we can deserialize into. Example:

// here's deserializer into a generic Value
let value: HashMap<String, jomini::Value> = jomini::text::de::from_utf8_slice(r#"
    unquoted = 1234
    quoted = "567"
    operator > 0.5
    color = hsv { 0.3 0.4 0.5 }
    sequence = { 1 2 3 4 }
    map = { a = 1 b = 2 }
"#.as_bytes());

// and we can deserialize it into concrete type later
let unquoted = value.get("unquoted").unwrap();
assert_eq!(f32::deserialize(unquoted.clone()).unwrap(), 1234.0);

This is the similar idea to existing serde_value::Value, serde_json::Value, serde_yaml::Value and others.

• it should losslessly keep any value from jomini deserializer (i.e. I can deserialize tape into it)
• it should implement IntoDeserializer (i.e. I can deserialize it into any concrete value)
• it should be a static type (owned)
• it should implement Debug
• it should give user some API to inspect the value (e.g. is it a token or a sequence)

There's ValueKind in jomini right now, but it's a borrowed type, it doesn't implement Debug, and it's not public API.

There's also generic serde_value::Value, but it is not lossless (loses quotes, operators, headers, etc.). And the code above fails with it in multiple ways (e.g. loses hsv header, loses > operator, and unquoted number is transformed into string and can't be parsed within assert statement later).

Why? I want to solve #138 in more generic way (rather than adding yet another _internal_jomini_property hack) + make low level syntax more accessible in general. Plus some visual inspection of the file contents via Debug.

[nickbabcock]

Yeah an arbitrary lossless value would be nice. I can imagine it essentially being what ValueReader is today, except owned, which should check most everything off your list. I think it'd need to use a hack similar to _internal_jomini_property (or it can replace it) in order for the deserializer to properly handle it.