macros: Add alias attribute to ruma_enum

crates/ruma-common/tests/serde/enum_derive.rs

@@ -12,6 +12,8 @@ enum MyEnum {
     #[ruma_enum(rename = "m.third")]
     Third,
     HelloWorld,
+    #[ruma_enum(rename = "io.ruma.unstable", alias = "m.stable", alias = "hs.notareal.unstable")]
+    Stable,
     _Custom(PrivOwnedStr),
 }
 
@@ -21,6 +23,7 @@ fn as_ref_str() {
     assert_eq!(MyEnum::Second.as_ref(), "second");
     assert_eq!(MyEnum::Third.as_ref(), "m.third");
     assert_eq!(MyEnum::HelloWorld.as_ref(), "hello_world");
+    assert_eq!(MyEnum::Stable.as_ref(), "io.ruma.unstable");
     assert_eq!(MyEnum::_Custom(PrivOwnedStr("HelloWorld".into())).as_ref(), "HelloWorld");
 }
 
@@ -30,6 +33,7 @@ fn display() {
     assert_eq!(MyEnum::Second.to_string(), "second");
     assert_eq!(MyEnum::Third.to_string(), "m.third");
     assert_eq!(MyEnum::HelloWorld.to_string(), "hello_world");
+    assert_eq!(MyEnum::Stable.to_string(), "io.ruma.unstable");
     assert_eq!(MyEnum::_Custom(PrivOwnedStr("HelloWorld".into())).to_string(), "HelloWorld");
 }
 
@@ -39,6 +43,9 @@ fn from_string() {
     assert_eq!(MyEnum::from("second"), MyEnum::Second);
     assert_eq!(MyEnum::from("m.third"), MyEnum::Third);
     assert_eq!(MyEnum::from("hello_world"), MyEnum::HelloWorld);
+    assert_eq!(MyEnum::from("io.ruma.unstable"), MyEnum::Stable);
+    assert_eq!(MyEnum::from("m.stable"), MyEnum::Stable);
+    assert_eq!(MyEnum::from("hs.notareal.unstable"), MyEnum::Stable);
     assert_eq!(MyEnum::from("HelloWorld"), MyEnum::_Custom(PrivOwnedStr("HelloWorld".into())));
 }
 
@@ -46,6 +53,7 @@ fn from_string() {
 fn serialize() {
     assert_eq!(to_json_value(MyEnum::First).unwrap(), json!("first"));
     assert_eq!(to_json_value(MyEnum::HelloWorld).unwrap(), json!("hello_world"));
+    assert_eq!(to_json_value(MyEnum::Stable).unwrap(), json!("io.ruma.unstable"));
     assert_eq!(
         to_json_value(MyEnum::_Custom(PrivOwnedStr("\\\n\\".into()))).unwrap(),
         json!("\\\n\\")
@@ -56,6 +64,9 @@ fn serialize() {
 fn deserialize() {
     assert_eq!(from_json_value::<MyEnum>(json!("first")).unwrap(), MyEnum::First);
     assert_eq!(from_json_value::<MyEnum>(json!("hello_world")).unwrap(), MyEnum::HelloWorld);
+    assert_eq!(from_json_value::<MyEnum>(json!("io.ruma.unstable")).unwrap(), MyEnum::Stable);
+    assert_eq!(from_json_value::<MyEnum>(json!("m.stable")).unwrap(), MyEnum::Stable);
+    assert_eq!(from_json_value::<MyEnum>(json!("hs.notareal.unstable")).unwrap(), MyEnum::Stable);
     assert_eq!(
         from_json_value::<MyEnum>(json!("\\\n\\")).unwrap(),
         MyEnum::_Custom(PrivOwnedStr("\\\n\\".into()))

crates/ruma-macros/src/serde/attr.rs

@@ -6,23 +6,36 @@ use syn::{
 use super::case::RenameRule;
 
 mod kw {
+    syn::custom_keyword!(alias);
     syn::custom_keyword!(rename);
     syn::custom_keyword!(rename_all);
 }
 
-pub struct RenameAttr(LitStr);
+#[derive(Default)]
-
+pub struct EnumAttrs {
-impl RenameAttr {
+    pub rename: Option<LitStr>,
-    pub fn into_inner(self) -> LitStr {
+    pub aliases: Vec<LitStr>,
-        self.0
-    }
 }
 
-impl Parse for RenameAttr {
+pub enum Attr {
+    Alias(LitStr),
+    Rename(LitStr),
+}
+
+impl Parse for Attr {
     fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        let _: kw::rename = input.parse()?;
+        let lookahead = input.lookahead1();
-        let _: Token![=] = input.parse()?;
+        if lookahead.peek(kw::alias) {
-        Ok(Self(input.parse()?))
+            let _: kw::alias = input.parse()?;
+            let _: Token![=] = input.parse()?;
+            Ok(Self::Alias(input.parse()?))
+        } else if lookahead.peek(kw::rename) {
+            let _: kw::rename = input.parse()?;
+            let _: Token![=] = input.parse()?;
+            Ok(Self::Rename(input.parse()?))
+        } else {
+            Err(lookahead.error())
+        }
     }
 }
 

crates/ruma-macros/src/serde/enum_as_ref_str.rs

@@ -2,7 +2,10 @@ use proc_macro2::TokenStream;
 use quote::{quote, ToTokens};
 use syn::{Fields, FieldsNamed, FieldsUnnamed, ItemEnum};
 
-use super::util::{get_rename, get_rename_rule};
+use super::{
+    attr::EnumAttrs,
+    util::{get_enum_attributes, get_rename_rule},
+};
 
 pub fn expand_enum_as_ref_str(input: &ItemEnum) -> syn::Result<TokenStream> {
     let enum_name = &input.ident;
@@ -12,7 +15,8 @@ pub fn expand_enum_as_ref_str(input: &ItemEnum) -> syn::Result<TokenStream> {
         .iter()
         .map(|v| {
             let variant_name = &v.ident;
-            let (field_capture, variant_str) = match (get_rename(v)?, &v.fields) {
+            let EnumAttrs { rename, .. } = get_enum_attributes(v)?;
+            let (field_capture, variant_str) = match (rename, &v.fields) {
                 (None, Fields::Unit) => (
                     None,
                     rename_rule.apply_to_variant(&variant_name.to_string()).into_token_stream(),

crates/ruma-macros/src/serde/enum_from_string.rs

@@ -2,7 +2,10 @@ use proc_macro2::{Span, TokenStream};
 use quote::{quote, ToTokens};
 use syn::{Fields, FieldsNamed, FieldsUnnamed, ItemEnum};
 
-use super::util::{get_rename, get_rename_rule};
+use super::{
+    attr::EnumAttrs,
+    util::{get_enum_attributes, get_rename_rule},
+};
 
 pub fn expand_enum_from_string(input: &ItemEnum) -> syn::Result<TokenStream> {
     let enum_name = &input.ident;
@@ -13,7 +16,8 @@ pub fn expand_enum_from_string(input: &ItemEnum) -> syn::Result<TokenStream> {
         .iter()
         .map(|v| {
             let variant_name = &v.ident;
-            let variant_str = match (get_rename(v)?, &v.fields) {
+            let EnumAttrs { rename, aliases } = get_enum_attributes(v)?;
+            let variant_str = match (rename, &v.fields) {
                 (None, Fields::Unit) => Some(
                     rename_rule.apply_to_variant(&variant_name.to_string()).into_token_stream(),
                 ),
@@ -56,7 +60,12 @@ pub fn expand_enum_from_string(input: &ItemEnum) -> syn::Result<TokenStream> {
                 }
             };
 
-            Ok(variant_str.map(|s| quote! { #s => #enum_name :: #variant_name }))
+            Ok(variant_str.map(|s| {
+                quote! {
+                    #( #aliases => #enum_name :: #variant_name, )*
+                    #s => #enum_name :: #variant_name
+                }
+            }))
         })
         .collect::<syn::Result<_>>()?;
 

crates/ruma-macros/src/serde/util.rs

@@ -1,8 +1,8 @@
 use proc_macro2::Span;
-use syn::{ItemEnum, LitStr, Variant};
+use syn::{punctuated::Punctuated, ItemEnum, Token, Variant};
 
 use super::{
-    attr::{RenameAllAttr, RenameAttr},
+    attr::{Attr, EnumAttrs, RenameAllAttr},
     case::RenameRule,
 };
 
@@ -24,16 +24,32 @@ pub fn get_rename_rule(input: &ItemEnum) -> syn::Result<RenameRule> {
     }
 }
 
-pub fn get_rename(input: &Variant) -> syn::Result<Option<LitStr>> {
+pub fn get_enum_attributes(input: &Variant) -> syn::Result<EnumAttrs> {
-    let renames: Vec<_> = input
+    let mut attributes = EnumAttrs::default();
-        .attrs
-        .iter()
-        .filter(|attr| attr.path.is_ident("ruma_enum"))
-        .map(|attr| attr.parse_args::<RenameAttr>().map(RenameAttr::into_inner))
-        .collect::<syn::Result<_>>()?;
 
-    match renames.len() {
+    for attr in &input.attrs {
-        0 | 1 => Ok(renames.into_iter().next()),
+        if !attr.path.is_ident("ruma_enum") {
-        _ => Err(syn::Error::new(Span::call_site(), "found multiple ruma_enum(rename) attributes")),
+            continue;
+        }
+
+        let enum_attrs = attr.parse_args_with(Punctuated::<_, Token![,]>::parse_terminated)?;
+        for enum_attr in enum_attrs {
+            match enum_attr {
+                Attr::Rename(s) => {
+                    if attributes.rename.is_some() {
+                        return Err(syn::Error::new(
+                            Span::call_site(),
+                            "found multiple ruma_enum(rename) attributes",
+                        ));
+                    }
+                    attributes.rename = Some(s);
+                }
+                Attr::Alias(s) => {
+                    attributes.aliases.push(s);
+                }
+            }
+        }
     }
+
+    Ok(attributes)
 }