ax_types 0.1.0

Core types for use by and with the ax family
Documentation 
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use crate::types::ArcVal;
use cbor_data::{
    codec::{ReadCbor, WriteCbor},
    Cbor,
};
use serde::{de::Error, Deserialize, Deserializer, Serialize, Serializer};
use std::sync::Arc;

/// A ref-counted slice of memory holding a compact binary representation of an event payload
///
/// see [`Event::extract`](struct.Event.html#method.extract) for supported ways of using the
/// data
#[derive(Debug, Clone, PartialEq, Eq, Ord, PartialOrd)]
pub struct Opaque(ArcVal<[u8]>);

impl Opaque {
    pub fn new(bytes: Arc<[u8]>) -> Self {
        Opaque(bytes.into())
    }

    pub fn from_bytes(bytes: &[u8]) -> Self {
        Opaque(ArcVal::clone_from_unsized(bytes))
    }

    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }

    pub fn len(&self) -> usize {
        self.0.len()
    }

    /// Rough estimate of the in memory size of an opaque value
    pub fn rough_size(&self) -> usize {
        self.len() + 16
    }
}

impl AsRef<[u8]> for Opaque {
    fn as_ref(&self) -> &[u8] {
        self.0.as_ref()
    }
}

impl Serialize for Opaque {
    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
        let mut deserializer = serde_cbor::Deserializer::from_slice(&self.0);
        serde_transcode::transcode(&mut deserializer, serializer)
    }
}

impl<'de> Deserialize<'de> for Opaque {
    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
        let res = Vec::new();
        let mut serializer = serde_cbor::Serializer::new(res);
        serde_transcode::transcode(deserializer, &mut serializer).map_err(D::Error::custom)?;
        let res = serializer.into_inner();
        Ok(Opaque(ArcVal::from_boxed(res.into())))
    }
}

impl WriteCbor for Opaque {
    fn write_cbor<W: cbor_data::Writer>(&self, w: W) -> W::Output {
        w.write_trusting(self.0.as_ref())
    }
}

impl ReadCbor for Opaque {
    fn fmt(f: &mut impl std::fmt::Write) -> std::fmt::Result {
        write!(f, "Opaque")
    }

    fn read_cbor_impl(cbor: &Cbor) -> cbor_data::codec::Result<Self>
    where
        Self: Sized,
    {
        Ok(Self::from_bytes(cbor.as_slice()))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::event::from_cbor_me;
    use libipld::{
        cbor::DagCborCodec,
        codec::Codec,
        prelude::{Decode, Encode},
        raw_value::RawValue,
    };
    use serde_json::json;

    impl Encode<DagCborCodec> for Opaque {
        fn encode<W: std::io::Write>(&self, _c: DagCborCodec, w: &mut W) -> anyhow::Result<()> {
            // we know that an opaque contains cbor, so we just write it
            Ok(w.write_all(self.as_ref())?)
        }
    }

    impl Decode<DagCborCodec> for Opaque {
        fn decode<R: std::io::Read + std::io::Seek>(c: DagCborCodec, r: &mut R) -> anyhow::Result<Self> {
            let tmp = RawValue::<DagCborCodec>::decode(c, r)?;
            Ok(Self(ArcVal::from_boxed(tmp.into())))
        }
    }

    #[test]
    fn opaque_dag_cbor_roundtrip() -> anyhow::Result<()> {
        let text = "";
        // using JSON value allows CBOR to use known-length array encoding
        let o1: Opaque = serde_json::from_value(json!([text]))?;
        let tmp = DagCborCodec.encode(&o1)?;
        let expected = from_cbor_me(
            r#"
81     # array(1)
   60  # text(0)
       # ""
"#,
        )?;
        assert_eq!(tmp, expected);
        let o2: Opaque = DagCborCodec.decode(&tmp)?;
        assert_eq!(o1, o2);
        Ok(())
    }

    #[test]
    fn u128_is_f64() {
        // this test is to ensure that serde_json does not convert long integers to u128, which CBOR does not support
        let text = format!("{}", u128::max_value());
        let value: serde_json::Value = serde_json::from_str(&text).unwrap();
        assert!(value.is_f64());
    }

    #[test]
    fn i128_is_f64() {
        // this test is to ensure that serde_json does not convert long signed integers to u128, which CBOR does not support
        let text = format!("{}", i128::min_value());
        let value: serde_json::Value = serde_json::from_str(&text).unwrap();
        assert!(value.is_f64());
    }
}