Added the ability to rename derived EnumDiscriminants.

Issue Peternator7#33

strum_macros/src/enum_discriminants.rs

@@ -1,15 +1,11 @@
 use proc_macro2::{Span, TokenStream};
 use syn;
 
-use helpers::{extract_meta, extract_meta_attrs};
+use helpers::{extract_meta, extract_meta_attrs, unique_meta_attr};
 
 pub fn enum_discriminants_inner(ast: &syn::DeriveInput) -> TokenStream {
     let name = &ast.ident;
     let vis = &ast.vis;
-    let enum_discriminants_name = syn::Ident::new(
-        &format!("{}Discriminants", name.to_string()),
-        Span::call_site(),
-    );
 
     let variants = match ast.data {
         syn::Data::Enum(ref v) => &v.variants,
@@ -22,6 +18,13 @@ pub fn enum_discriminants_inner(ast: &syn::DeriveInput) -> TokenStream {
         #[derive(Clone, Copy, Debug, PartialEq, Eq, #(#discriminant_derives),*)]
     };
 
+    let default_name = syn::Ident::new(
+        &format!("{}Discriminants", name.to_string()),
+        Span::call_site(),
+    );
+    let enum_discriminants_name =
+        unique_meta_attr(&type_meta, "strum_discriminants_name").unwrap_or(&default_name);
+
     let mut discriminants = Vec::new();
     for variant in variants {
         let ident = &variant.ident;

strum_macros/src/helpers.rs

@@ -31,6 +31,15 @@ pub fn extract_meta_attrs<'meta>(meta: &'meta [Meta], attr: &str) -> Vec<&'meta
         }).collect()
 }
 
+pub fn unique_meta_attr<'meta>(attrs: &'meta [Meta], attr: &str) -> Option<&'meta Ident> {
+    let mut curr = extract_meta_attrs(attrs, attr);
+    if curr.len() > 1 {
+        panic!("More than one `{}` attribute found on type", attr);
+    }
+
+    curr.pop()
+}
+
 pub fn extract_attrs(meta: &[Meta], attr: &str, prop: &str) -> Vec<String> {
     use syn::{Lit, MetaNameValue, NestedMeta};
     meta.iter()

strum_macros/src/lib.rs

@@ -117,7 +117,7 @@ pub fn enum_properties(input: proc_macro::TokenStream) -> proc_macro::TokenStrea
 
 #[proc_macro_derive(
     EnumDiscriminants,
-    attributes(strum, strum_discriminants_derive)
+    attributes(strum, strum_discriminants_derive, strum_discriminants_name)
 )]
 pub fn enum_discriminants(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let ast = syn::parse(input).unwrap();

strum_tests/tests/enum_discriminants.rs

@@ -84,3 +84,20 @@ enum WithDefault {
 fn with_default_test() {
     assert!(WithDefaultDiscriminants::A != WithDefaultDiscriminants::B);
 }
+
+#[allow(dead_code)]
+#[derive(Debug, Eq, PartialEq, EnumDiscriminants)]
+#[strum_discriminants_derive(EnumIter)]
+#[strum_discriminants_name(EnumBoo)]
+enum Renamed {
+    Variant0(bool),
+    Variant1(i32),
+}
+
+#[test]
+fn renamed_test() {
+    let discriminants = EnumBoo::iter().collect::<Vec<_>>();
+    let expected = vec![EnumBoo::Variant0, EnumBoo::Variant1];
+
+    assert_eq!(expected, discriminants);
+}