use std::fmt;
use base64ct::Encoding;
use num_bigint::BigUint;
use serde::de;
use serde::{Deserializer, Serializer};
pub fn serialize<S>(value: &BigUint, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let bytes = value.to_bytes_be();
let base64 = crate::B64::encode_string(&bytes);
serializer.serialize_str(&base64)
}
pub fn deserialize<'de, D>(deserializer: D) -> Result<BigUint, D::Error>
where
D: Deserializer<'de>,
{
struct BigUintVisitor;
impl<'de> de::Visitor<'de> for BigUintVisitor {
type Value = BigUint;
fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("a Base64urlUInt string")
}
fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
where
E: de::Error,
{
let mut bytes = crate::B64::decode_vec(value).map_err(E::custom)?;
bytes.reverse();
Ok(BigUint::from_bytes_le(&bytes))
}
}
deserializer.deserialize_str(BigUintVisitor)
}
#[cfg(test)]
mod tests {
use num_bigint::BigUint;
use num_traits::cast::FromPrimitive;
use serde::{Deserialize, Serialize};
use serde_test::{assert_tokens, Token};
#[derive(Serialize, Deserialize, Eq, PartialEq, Debug)]
struct TestStruct {
#[serde(with = "super")]
bytes: BigUint,
}
#[test]
fn serialization_round_trip() {
let test_value = TestStruct {
bytes: BigUint::from_u64(12345).unwrap(),
};
assert_tokens(
&test_value,
&[
Token::Struct {
name: "TestStruct",
len: 1,
},
Token::Str("bytes"),
Token::Str("MDk"),
Token::StructEnd,
],
);
}
}