Add AsStaticStr trait and let derive(AsRefStr) implement it

This will solve Peternator7#23.
lo48576 · May 23, 2018 · a1efb21 · a1efb21
1 parent 179e8ea
commit a1efb21
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Showing 3 changed files with 22 additions and 1 deletion.
diff --git a/strum/src/lib.rs b/strum/src/lib.rs
@@ -515,3 +515,9 @@ pub trait EnumProperty {
         Option::None
     }
 }
+
+
+// FIXME: documentation.
+pub trait AsStaticStr {
+    fn as_str(&self) -> &'static str;
+}
diff --git a/strum_macros/src/as_ref_str.rs b/strum_macros/src/as_ref_str.rs
@@ -48,12 +48,21 @@ pub fn as_ref_str_inner(ast: &syn::DeriveInput) -> quote::Tokens {
     }
 
     if arms.len() < variants.len() {
-        arms.push(quote!{ _ => panic!("AsRef<str>::as_ref() called on disabled variant.")})
+        arms.push(quote!{
+            _ => panic!("AsRef<str>::as_ref() or AsStaticStr::as_str() called on disabled variant.")
+        })
     }
 
+    let arms = &arms;
     quote!{
         impl #impl_generics ::std::convert::AsRef<str> for #name #ty_generics #where_clause {
             fn as_ref(&self) -> &str {
+                ::strum::AsStaticStr::as_str(self)
+            }
+        }
+
+        impl #impl_generics ::strum::AsStaticStr for #name #ty_generics #where_clause {
+            fn as_str(&self) -> &'static str {
                 match *self {
                     #(#arms),*
                 }

diff --git a/strum_tests/tests/as_ref_str.rs b/strum_tests/tests/as_ref_str.rs
@@ -4,6 +4,8 @@ extern crate strum_macros;
 
 use std::str::FromStr;
 
+use strum::AsStaticStr;
+
 #[derive(Debug,Eq,PartialEq,EnumString,AsRefStr)]
 enum Color {
     #[strum(to_string="RedRed")]
@@ -27,20 +29,24 @@ fn as_red_str() {
                (Color::Red).as_ref());
     assert_eq!(Color::Red,
                Color::from_str((Color::Red).as_ref()).unwrap());
+    let _: &'static str = Color::Red.as_str();
 }
 
 #[test]
 fn as_blue_str() {
     assert_eq!("blue",
                (Color::Blue { hue: 0 }).as_ref());
+    let _: &'static str = (Color::Blue { hue: 0 }).as_str();
 }
 
 #[test]
 fn as_yellow_str() {
     assert_eq!("yellow", (Color::Yellow).as_ref());
+    let _: &'static str = Color::Yellow.as_str();
 }
 
 #[test]
 fn as_green_str() {
     assert_eq!("Green", (Color::Green(String::default())).as_ref());
+    let _: &'static str = Color::Green(String::default()).as_str();
 }