//! Hex encoding with `serde`. #[cfg_attr( all(feature = "alloc", feature = "serde"), doc = r##" # Example ``` use serde::{Serialize, Deserialize}; #[derive(Serialize, Deserialize)] struct Foo { #[serde(with = "hex")] bar: Vec, } ``` "## )] use serde::de::{Error, Visitor}; use serde::Deserializer; #[cfg(feature = "alloc")] use serde::Serializer; #[cfg(feature = "alloc")] use alloc::string::String; use core::fmt; use core::marker::PhantomData; use crate::FromHex; #[cfg(feature = "alloc")] use crate::ToHex; /// Serializes `data` as hex string using uppercase characters. /// /// Apart from the characters' casing, this works exactly like `serialize()`. #[cfg(feature = "alloc")] pub fn serialize_upper(data: T, serializer: S) -> Result where S: Serializer, T: ToHex, { let s = data.encode_hex_upper::(); serializer.serialize_str(&s) } /// Serializes `data` as hex string using lowercase characters. /// /// Lowercase characters are used (e.g. `f9b4ca`). The resulting string's length /// is always even, each byte in data is always encoded using two hex digits. /// Thus, the resulting string contains exactly twice as many bytes as the input /// data. #[cfg(feature = "alloc")] pub fn serialize(data: T, serializer: S) -> Result where S: Serializer, T: ToHex, { let s = data.encode_hex::(); serializer.serialize_str(&s) } /// Deserializes a hex string into raw bytes. /// /// Both, upper and lower case characters are valid in the input string and can /// even be mixed (e.g. `f9b4ca`, `F9B4CA` and `f9B4Ca` are all valid strings). pub fn deserialize<'de, D, T>(deserializer: D) -> Result where D: Deserializer<'de>, T: FromHex, ::Error: fmt::Display, { struct HexStrVisitor(PhantomData); impl<'de, T> Visitor<'de> for HexStrVisitor where T: FromHex, ::Error: fmt::Display, { type Value = T; fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "a hex encoded string") } fn visit_str(self, data: &str) -> Result where E: Error, { FromHex::from_hex(data).map_err(Error::custom) } fn visit_borrowed_str(self, data: &'de str) -> Result where E: Error, { FromHex::from_hex(data).map_err(Error::custom) } } deserializer.deserialize_str(HexStrVisitor(PhantomData)) }