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//! jsonrpc version field
use serde::{Serialize, Serializer, Deserialize, Deserializer};
use serde::de::{self, Visitor};

use std::fmt;

/// Protocol Version
#[derive(Debug, PartialEq, Clone, Copy, Hash, Eq)]
pub enum Version {
	/// JSONRPC 2.0
	V2
}

impl Serialize for Version {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
	where S: Serializer {
		match self {
			&Version::V2 => serializer.serialize_str("2.0")
		}
	}
}

impl<'a> Deserialize<'a> for Version {
	fn deserialize<D>(deserializer: D) -> Result<Version, D::Error>
	where D: Deserializer<'a> {
		deserializer.deserialize_identifier(VersionVisitor)
	}
}

struct VersionVisitor;

impl<'a> Visitor<'a> for VersionVisitor {
	type Value = Version;

	fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
		formatter.write_str("a string")
	}

	fn visit_str<E>(self, value: &str) -> Result<Self::Value, E> where E: de::Error {
		match value {
			"2.0" => Ok(Version::V2),
			_ => Err(de::Error::custom("invalid version"))
		}
	}
}