add encoder for &str

rustler/src/types/string.rs

@@ -19,6 +19,12 @@ impl<'a> Decoder<'a> for &'a str {
 
 use std::io::Write;
 
+impl<'a> Encoder for &'a str {
+    fn encode<'b>(&self, env: Env<'b>) -> Term<'b> {
+        (*self).encode(env)
+    }
+}
+
 impl Encoder for str {
     fn encode<'b>(&self, env: Env<'b>) -> Term<'b> {
         let str_len = self.len();

rustler_tests/lib/rustler_test.ex

@@ -37,6 +37,7 @@ defmodule RustlerTest do
   def unowned_to_owned(_), do: err()
   def realloc_shrink(), do: err()
   def realloc_grow(), do: err()
+  def encode_string(), do: err()
 
   def atom_to_string(_), do: err()
   def atom_equals_ok(_), do: err()

rustler_tests/src/lib.rs

@@ -55,6 +55,7 @@ rustler_export_nifs!(
         ("unowned_to_owned", 1, test_binary::unowned_to_owned),
         ("realloc_shrink", 0, test_binary::realloc_shrink),
         ("realloc_grow", 0, test_binary::realloc_grow),
+        ("encode_string", 0, test_binary::encode_string),
 
         ("threaded_fac", 1, test_thread::threaded_fac),
         ("threaded_sleep", 1, test_thread::threaded_sleep),

rustler_tests/src/test_binary.rs

@@ -48,6 +48,10 @@ pub fn realloc_grow<'a>(env: Env<'a>, _args: &[Term<'a>]) -> NifResult<Term<'a>>
     Ok(binary.release(env).encode(env))
 }
 
+pub fn encode_string<'a>(env: Env<'a>, _args: &[Term<'a>]) -> NifResult<Term<'a>> {
+    Ok(("first".to_string(), "second").encode(env))
+}
+
 // OwnedBinary::new
 // OwnedBinary::from_unowned
 // OwnedBinary::realloc

rustler_tests/test/binary_test.exs

@@ -31,4 +31,8 @@ defmodule RustlerTest.BinaryTest do
     assert RustlerTest.realloc_grow() == <<1, 2, 3, 4, 5>>
   end
 
+  test "encode string" do
+    assert RustlerTest.encode_string() == {"first", "second"}
+  end
+
 end