Impl push_into_stack for StdResult

src/multi.rs

@@ -23,6 +23,20 @@ impl<'lua, T: IntoLua<'lua>, E: IntoLua<'lua>> IntoLuaMulti<'lua> for StdResult<
         }
         Ok(result)
     }
+
+    #[inline]
+    unsafe fn push_into_stack_multi(self, lua: &'lua Lua) -> Result<c_int> {
+        match self {
+            Ok(v) => v.push_into_stack(lua).map(|_| 1),
+            Err(e) => {
+                let state = lua.state();
+                check_stack(state, 3)?;
+                ffi::lua_pushnil(state);
+                e.push_into_stack(lua)?;
+                Ok(2)
+            }
+        }
+    }
 }
 
 impl<'lua, E: IntoLua<'lua>> IntoLuaMulti<'lua> for StdResult<(), E> {
@@ -38,6 +52,20 @@ impl<'lua, E: IntoLua<'lua>> IntoLuaMulti<'lua> for StdResult<(), E> {
             }
         }
     }
+
+    #[inline]
+    unsafe fn push_into_stack_multi(self, lua: &'lua Lua) -> Result<c_int> {
+        match self {
+            Ok(_) => Ok(0),
+            Err(e) => {
+                let state = lua.state();
+                check_stack(state, 3)?;
+                ffi::lua_pushnil(state);
+                e.push_into_stack(lua)?;
+                Ok(2)
+            }
+        }
+    }
 }
 
 impl<'lua, T: IntoLua<'lua>> IntoLuaMulti<'lua> for T {

tests/multi.rs

@@ -0,0 +1,60 @@
+use mlua::{Error, ExternalError, IntoLuaMulti, Lua, Result, String, Value};
+
+#[test]
+fn test_result_conversions() -> Result<()> {
+    let lua = Lua::new();
+    let globals = lua.globals();
+
+    let ok = lua.create_function(|_, ()| Ok(Ok::<(), Error>(())))?;
+    let err = lua.create_function(|_, ()| Ok(Err::<(), _>("failure1".into_lua_err())))?;
+    let ok2 = lua.create_function(|_, ()| Ok(Ok::<_, Error>("!".to_owned())))?;
+    let err2 = lua.create_function(|_, ()| Ok(Err::<String, _>("failure2".into_lua_err())))?;
+
+    globals.set("ok", ok)?;
+    globals.set("ok2", ok2)?;
+    globals.set("err", err)?;
+    globals.set("err2", err2)?;
+
+    lua.load(
+        r#"
+        local r, e = ok()
+        assert(r == nil and e == nil)
+
+        local r, e = err()
+        assert(r == nil)
+        assert(tostring(e):find("failure1") ~= nil)
+
+        local r, e = ok2()
+        assert(r == "!")
+        assert(e == nil)
+
+        local r, e = err2()
+        assert(r == nil)
+        assert(tostring(e):find("failure2") ~= nil)
+    "#,
+    )
+    .exec()?;
+
+    // Try to convert Result into MultiValue
+    let ok1 = Ok::<(), Error>(());
+    let multi_ok1 = ok1.into_lua_multi(&lua)?;
+    assert_eq!(multi_ok1.len(), 0);
+    let err1 = Err::<(), _>("failure1");
+    let multi_err1 = err1.into_lua_multi(&lua)?;
+    assert_eq!(multi_err1.len(), 2);
+    assert_eq!(multi_err1[0], Value::Nil);
+    assert_eq!(multi_err1[1].as_str().unwrap(), "failure1");
+
+    let ok2 = Ok::<_, Error>("!");
+    let multi_ok2 = ok2.into_lua_multi(&lua)?;
+    assert_eq!(multi_ok2.len(), 1);
+    assert_eq!(multi_ok2[0].as_str().unwrap(), "!");
+    let err2 = Err::<String, _>("failure2".into_lua_err());
+    let multi_err2 = err2.into_lua_multi(&lua)?;
+    assert_eq!(multi_err2.len(), 2);
+    assert_eq!(multi_err2[0], Value::Nil);
+    assert!(matches!(multi_err2[1], Value::Error(_)));
+    assert_eq!(multi_err2[1].to_string()?, "failure2");
+
+    Ok(())
+}

tests/tests.rs

@@ -504,44 +504,6 @@ fn test_panic() -> Result<()> {
     Ok(())
 }
 
-#[test]
-fn test_result_conversions() -> Result<()> {
-    let lua = Lua::new();
-    let globals = lua.globals();
-
-    let ok = lua.create_function(|_, ()| Ok(Ok::<(), Error>(())))?;
-    let err = lua.create_function(|_, ()| Ok(Err::<(), _>("failure1".into_lua_err())))?;
-    let ok2 = lua.create_function(|_, ()| Ok(Ok::<_, Error>("!".to_owned())))?;
-    let err2 = lua.create_function(|_, ()| Ok(Err::<String, _>("failure2".into_lua_err())))?;
-
-    globals.set("ok", ok)?;
-    globals.set("ok2", ok2)?;
-    globals.set("err", err)?;
-    globals.set("err2", err2)?;
-
-    lua.load(
-        r#"
-        local r, e = ok()
-        assert(r == nil and e == nil)
-
-        local r, e = err()
-        assert(r == nil)
-        assert(tostring(e):find("failure1") ~= nil)
-
-        local r, e = ok2()
-        assert(r == "!")
-        assert(e == nil)
-
-        local r, e = err2()
-        assert(r == nil)
-        assert(tostring(e):find("failure2") ~= nil)
-    "#,
-    )
-    .exec()?;
-
-    Ok(())
-}
-
 #[test]
 fn test_num_conversion() -> Result<()> {
     let lua = Lua::new();