deser-transcode

Converts values from one data format to another with deser: every deserializer can be transcoded into every serializer, without types in between and without code that is specific to the formats.

let mut de = deser_json::Deserializer::from_str(r#"{"name": "deser", "tags": ["a", "b"]}"#);
let mut ser = deser_yaml::Serializer::new();
deser_transcode::transcode(&mut de, &mut ser).unwrap();
assert_eq!(ser.finish(), "name: deser\ntags:\n  - a\n  - b\n");

The values are passed on as the deserializer emitted them and each serializer does with them what it does with any value: values whose type YAML infers from their text are written as that type, keys that are not strings are written the way the target writes such keys, TOML skips map entries that are null and so on. One value is buffered at a time, strings that the deserializer borrows from the input are not copied, and the lengths of maps and sequences are known before they are written, so CBOR and MessagePack write them upfront even when the input is JSON.

Streams of values (JSON Lines, YAML documents) are transcoded value by value with a Transcoder, which reuses its buffer. Layers (such as limits for untrusted input) can be added to both sides with transcode_with.