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macro_rules! id { ($newtype_name:ident, $prefix:expr) => { #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)] pub struct $newtype_name(String); impl $newtype_name { #[inline] pub fn prefix() -> &'static str { $prefix } } impl ::std::fmt::Display for $newtype_name { fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result { self.0.fmt(f) } } impl ::std::str::FromStr for $newtype_name { type Err = ParseIdError; fn from_str(s: &str) -> Result<Self, Self::Err> { if !s.starts_with($prefix) { Err(ParseIdError { typename: stringify!($newtype_name), expected: stringify!(id to start with $prefix), }) } else { Ok($newtype_name(s.to_owned())) } } } impl ::serde::Serialize for $newtype_name { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: ::serde::ser::Serializer { self.to_string().serialize(serializer) } } impl<'de> ::serde::Deserialize<'de> for $newtype_name { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: ::serde::de::Deserializer<'de> { let s: String = ::serde::Deserialize::deserialize(deserializer)?; s.parse::<Self>().map_err(|e| ::serde::de::Error::custom(e)) } } }; ($enum_name:ident { $( $variant_name:ident($($variant_type:tt)*) ),* $(,)* }) => { #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)] pub enum $enum_name {$( $variant_name($($variant_type)*), )*} impl ::std::fmt::Display for $enum_name { fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result { match *self {$( $enum_name::$variant_name(ref id) => id.fmt(f), )*} } } impl ::std::str::FromStr for $enum_name { type Err = ParseIdError; fn from_str(s: &str) -> Result<Self, Self::Err> { let prefix = s.find('_') .map(|i| &s[0..i+1]) .ok_or_else(|| ParseIdError { typename: stringify!($enum_name), expected: "id to start with a prefix (as in 'prefix_')" })?; match prefix { $(_ if prefix == $($variant_type)*::prefix() => { Ok($enum_name::$variant_name(s.parse()?)) })* _ => { Err(ParseIdError { typename: stringify!($enum_name), expected: "unknown id prefix", }) } } } } impl ::serde::Serialize for $enum_name { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: ::serde::ser::Serializer { self.to_string().serialize(serializer) } } impl<'de> ::serde::Deserialize<'de> for $enum_name { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: ::serde::de::Deserializer<'de> { let s: String = ::serde::Deserialize::deserialize(deserializer)?; s.parse::<Self>().map_err(|e| ::serde::de::Error::custom(e)) } } $( impl From<$($variant_type)*> for $enum_name { fn from(id: $($variant_type)*) -> Self { $enum_name::$variant_name(id) } } )* }; } #[derive(Clone, Debug)] pub struct ParseIdError { typename: &'static str, expected: &'static str } impl ::std::fmt::Display for ParseIdError { fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result { write!(f, "invalid `{}`, expected {}", self.typename, self.expected) } } impl ::std::error::Error for ParseIdError { fn description(&self) -> &str { "error parsing an id" } } id!(BankAccountId, "ba_"); id!(CardId, "card_"); id!(SourceId, "src_"); id!(TokenId, "tok_"); id!(PaymentSourceId { BankAcccount(BankAccountId), Card(CardId), Source(SourceId), });