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57 lines
2.2 KiB
Markdown
57 lines
2.2 KiB
Markdown
# serde_v8
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Author: Aaron O'Mullan <aaron.omullan@gmail.com>
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Serde support for encoding/decoding (rusty_)v8 values.
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Broadly `serde_v8` aims to provide an expressive but ~maximally efficient
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encoding layer to biject rust & v8/js values. It's a core component of deno's
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op-layer and is used to encode/decode all non-buffer values.
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**Original issue:**
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[denoland/deno#9540](https://github.com/denoland/deno/issues/9540)
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## Quickstart
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`serde_v8` fits naturally into the serde ecosystem, so if you've already used
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`serde` or `serde_json`, `serde_v8`'s API should be very familiar.
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`serde_v8` exposes two key-functions:
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- `to_v8`: maps `rust->v8`, similar to `serde_json::to_string`, ...
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- `from_v8`: maps `v8->rust`, similar to `serde_json::from_str`, ...
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## Best practices
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Whilst `serde_v8` is compatible with `serde_json::Value` it's important to keep
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in mind that `serde_json::Value` is essentially a loosely-typed value (think
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nested HashMaps), so when writing ops we recommend directly using rust
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structs/tuples or primitives, since mapping to `serde_json::Value` will add
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extra overhead and result in slower ops.
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I also recommend avoiding unecessary "wrappers", if your op takes a single-keyed
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struct, consider unwrapping that as a plain value unless you plan to add fields
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in the near-future.
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Instead of returning "nothing" via `Ok(json!({}))`, change your return type to
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rust's unit type `()` and returning `Ok(())`, `serde_v8` will efficiently encode
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that as a JS `null`.
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## Advanced features
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If you need to mix rust & v8 values in structs/tuples, you can use the special
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`serde_v8::Value` type, which will passthrough the original v8 value untouched
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when encoding/decoding.
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## TODO
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- [ ] Experiment with KeyCache to optimize struct keys
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- [ ] Experiment with external v8 strings
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- [ ] Explore using
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[json-stringifier.cc](https://chromium.googlesource.com/v8/v8/+/refs/heads/master/src/json/json-stringifier.cc)'s
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fast-paths for arrays
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- [ ] Improve tests to test parity with `serde_json` (should be mostly
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interchangeable)
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- [ ] Consider a `Payload` type that's deserializable by itself (holds scope &
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value)
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- [ ] Ensure we return errors instead of panicking on `.unwrap()`s
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