Serialization with serde.

substrate/primitives/src/uint.rs

@@ -16,5 +16,98 @@
 
 //! An unsigned fixed-size integer.
 
+use std::fmt;
+use serde::{de, Serialize, Serializer, Deserialize, Deserializer};
+
+macro_rules! impl_serde {
+	($name: ident, $len: expr) => {
+		impl Serialize for $name {
+			fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
+				// TODO [ToDr] Use raw bytes if we switch to RLP / binencoding
+				// (serialize_bytes)
+				if self.is_zero() {
+					// TODO [ToDr] LowerHex of 0 is broken
+					serializer.serialize_str("0x0")
+				} else {
+					serializer.serialize_str(&format!("{:#x}", self))
+				}
+			}
+		}
+
+		impl<'de> Deserialize<'de> for $name {
+			fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
+				struct Visitor;
+				impl<'a> de::Visitor<'a> for Visitor {
+					type Value = $name;
+
+					fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+						write!(formatter, "a 0x-prefixed hex string")
+					}
+
+					fn visit_str<E: de::Error>(self, v: &str) -> Result<Self::Value, E> {
+						if v.len() < 2  || &v[0..2] != "0x" {
+							return Err(E::custom("prefix is missing"))
+						}
+
+						// 0x + len
+						if v.len() > 2 + $len * 16 {
+							return Err(E::invalid_length(v.len() - 2, &self));
+						}
+
+						let v = if v.len() % 2 == 0 { v[2..].to_owned() } else { format!("0{}", &v[2..]) };
+						let bytes = ::rustc_hex::FromHex::from_hex(v.as_str())
+							.map_err(|e| E::custom(&format!("invalid hex value: {:?}", e)))?;
+						Ok((&*bytes).into())
+					}
+
+					fn visit_string<E: de::Error>(self, v: String) -> Result<Self::Value, E> {
+						self.visit_str(&v)
+					}
+				}
+				// TODO [ToDr] Use raw bytes if we switch to RLP / binencoding
+				// (visit_bytes, visit_bytes_buf)
+				deserializer.deserialize_str(Visitor)
+			}
+		}
+	}
+}
+
 construct_uint!(U256, 4);
+impl_serde!(U256, 4);
 construct_uint!(U512, 8);
+impl_serde!(U512, 8);
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use polkadot_serializer as ser;
+
+	macro_rules! test {
+		($name: ident, $test_name: ident) => {
+			#[test]
+			fn $test_name() {
+				let tests = vec![
+					($name::from(0), "0x0"),
+					($name::from(1), "0x1"),
+					($name::from(2), "0x2"),
+					($name::from(10), "0xa"),
+					($name::from(15), "0xf"),
+					($name::from(15), "0xf"),
+					($name::from(16), "0x10"),
+					($name::from(1_000), "0x3e8"),
+					($name::from(100_000), "0x186a0"),
+					($name::from(u64::max_value()), "0xffffffffffffffff"),
+					($name::from(u64::max_value()) + 1.into(), "0x10000000000000000"),
+				];
+
+				for (number, expected) in tests {
+					assert_eq!(format!("{:?}", expected), ser::to_string_pretty(&number));
+					assert_eq!(number, ser::from_str(&format!("{:?}", expected)).unwrap());
+				}
+			}
+		}
+	}
+
+	test!(U256, test_u256);
+	test!(U512, test_u512);
+}