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//! Specialized serialization for flags types using `serde`.
use crate::{
parser::{self, ParseHex, WriteHex},
Flags,
};
use core::{fmt, str};
use serde::{
de::{Error, Visitor},
Deserialize, Deserializer, Serialize, Serializer,
};
/**
Serialize a set of flags as a human-readable string or their underlying bits.
Any unknown bits will be retained.
*/
pub fn serialize<B: Flags, S: Serializer>(flags: &B, serializer: S) -> Result<S::Ok, S::Error>
where
B::Bits: WriteHex + Serialize,
{
// Serialize human-readable flags as a string like `"A | B"`
if serializer.is_human_readable() {
serializer.collect_str(&parser::AsDisplay(flags))
}
// Serialize non-human-readable flags directly as the underlying bits
else {
flags.bits().serialize(serializer)
}
}
/**
Deserialize a set of flags from a human-readable string or their underlying bits.
Any unknown bits will be retained.
*/
pub fn deserialize<'de, B: Flags, D: Deserializer<'de>>(deserializer: D) -> Result<B, D::Error>
where
B::Bits: ParseHex + Deserialize<'de>,
{
if deserializer.is_human_readable() {
// Deserialize human-readable flags by parsing them from strings like `"A | B"`
struct FlagsVisitor<B>(core::marker::PhantomData<B>);
impl<'de, B: Flags> Visitor<'de> for FlagsVisitor<B>
where
B::Bits: ParseHex,
{
type Value = B;
fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("a string value of `|` separated flags")
}
fn visit_str<E: Error>(self, flags: &str) -> Result<Self::Value, E> {
parser::from_str(flags).map_err(|e| E::custom(e))
}
}
deserializer.deserialize_str(FlagsVisitor(Default::default()))
} else {
// Deserialize non-human-readable flags directly from the underlying bits
let bits = B::Bits::deserialize(deserializer)?;
Ok(B::from_bits_retain(bits))
}
}
#[cfg(test)]
mod tests {
use serde_test::{assert_tokens, Configure, Token::*};
bitflags! {
#[derive(serde_derive::Serialize, serde_derive::Deserialize, Debug, PartialEq, Eq)]
#[serde(transparent)]
struct SerdeFlags: u32 {
const A = 1;
const B = 2;
const C = 4;
const D = 8;
}
}
#[test]
fn test_serde_bitflags_default() {
assert_tokens(&SerdeFlags::empty().readable(), &[Str("")]);
assert_tokens(&SerdeFlags::empty().compact(), &[U32(0)]);
assert_tokens(&(SerdeFlags::A | SerdeFlags::B).readable(), &[Str("A | B")]);
assert_tokens(&(SerdeFlags::A | SerdeFlags::B).compact(), &[U32(1 | 2)]);
}
}