From 5e3ece42ee1ac765433fdcc05b8eb47a548051f1 Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin.krahl@ireas.org>
Date: Tue, 7 Jan 2020 23:44:17 +0000
Subject: Add all_str function to enums generated by Enum! macro

To make it easier to list all possible values for a command-line option
mapped to an enum, we add the all_str function to the Enum! macro that
returns an array of the string representations of all variants.

We also use this new function to simplify the generation of the error
message in the FromStr implementation in Enum!.
---
 src/arg_util.rs | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/arg_util.rs b/src/arg_util.rs
index 2f04ccd..8cd8fe5 100644
--- a/src/arg_util.rs
+++ b/src/arg_util.rs
@@ -83,6 +83,15 @@ macro_rules! enum_int {
           )*
         ]
       }
+
+      #[allow(unused)]
+      pub fn all_str() -> [&'static str; count!($($var),*)] {
+        [
+          $(
+            $str,
+          )*
+        ]
+      }
     }
 
     impl ::std::convert::AsRef<str> for $name {
@@ -112,11 +121,7 @@ macro_rules! enum_int {
           _ => Err(
             format!(
               "expected one of {}",
-              $name::all_variants()
-                .iter()
-                .map(::std::convert::AsRef::as_ref)
-                .collect::<::std::vec::Vec<_>>()
-                .join(", "),
+              $name::all_str().join(", "),
              )
            )
         }
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