add StaticClosureSearcher

because evidently one does not merely accept `&'static str` OR `String`

src/searcher.rs

@@ -136,8 +136,8 @@ where
     }
 }
 
-/// Like `StaticSearcher`, but with closures as `modules` values, to facilitate setting
-/// up an `rlua::Context` with Rust code.
+/// Like `Searcher`, but with closures as `modules` values, to facilitate setting up an
+/// `rlua::Context` with Rust code.
 ///
 /// Enables exposing `UserData` types to an `rlua::Context`.
 pub struct ClosureSearcher {
@@ -200,6 +200,56 @@ impl UserData for ClosureSearcher {
     }
 }
 
+/// Like `ClosureSearcher`, but with `&'static str` keys in `modules`.
+pub struct StaticClosureSearcher {
+    modules: HashMap<
+        &'static str,
+        Box<
+            dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+                + Send,
+        >,
+    >,
+
+    globals: RegistryKey,
+}
+
+impl StaticClosureSearcher {
+    pub fn new(
+        modules: HashMap<
+            &'static str,
+            Box<
+                dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+                    + Send,
+            >,
+        >,
+        globals: RegistryKey,
+    ) -> Self {
+        Self { modules, globals }
+    }
+}
+
+impl UserData for StaticClosureSearcher {
+    fn add_methods<'lua, M>(methods: &mut M)
+    where
+        M: UserDataMethods<'lua, Self>,
+    {
+        methods.add_meta_method(
+            MetaMethod::Call,
+            |lua_ctx: Context<'lua>, this, name: String| {
+                let name = name.as_str();
+                match this.modules.get(name) {
+                    Some(ref closure) => Ok(Value::Function(closure(
+                        lua_ctx,
+                        lua_ctx.registry_value::<Table>(&this.globals)?,
+                        name,
+                    )?)),
+                    None => Ok(Value::Nil),
+                }
+            },
+        );
+    }
+}
+
 /// Extend `rlua::Context` to support `require`ing Lua modules by name.
 pub trait AddSearcher {
     /// Add a `HashMap` of Lua modules indexed by module name to Lua’s
@@ -227,8 +277,7 @@ pub trait AddSearcher {
     where
         P: 'static + AsRef<Path> + Send;
 
-    /// Like `add_static_searcher`, but with user-provided closure for `rlua::Context`
-    /// setup.
+    /// Like `add_searcher`, but with user-provided closure for `rlua::Context` setup.
     fn add_closure_searcher(
         &self,
         modules: HashMap<
@@ -239,6 +288,18 @@ pub trait AddSearcher {
             >,
         >,
     ) -> Result<()>;
+
+    /// Like `add_closure_searcher`, but with `&'static str` keys in `modules`.
+    fn add_static_closure_searcher(
+        &self,
+        modules: HashMap<
+            &'static str,
+            Box<
+                dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+                    + Send,
+            >,
+        >,
+    ) -> Result<()>;
 }
 
 impl<'a> AddSearcher for Context<'a> {
@@ -312,4 +373,23 @@ impl<'a> AddSearcher for Context<'a> {
             .set(searchers.len()? + 1, searcher)
             .map_err(|e| e.into())
     }
+
+    fn add_static_closure_searcher(
+        &self,
+        modules: HashMap<
+            &'static str,
+            Box<
+                dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+                    + Send,
+            >,
+        >,
+    ) -> Result<()> {
+        let globals = self.globals();
+        let searchers: Table = globals.get::<_, Table>("package")?.get("searchers")?;
+        let registry_key = self.create_registry_value(globals)?;
+        let searcher = StaticClosureSearcher::new(modules, registry_key);
+        searchers
+            .set(searchers.len()? + 1, searcher)
+            .map_err(|e| e.into())
+    }
 }

tests/tests.rs

@@ -212,6 +212,58 @@ fn add_closure_searcher_works() {
     assert_eq!(sound, "The ukulele goes twang");
 }
 
+#[test]
+fn add_static_closure_searcher_works() {
+    let lua = Lua::new();
+
+    let mut modules: HashMap<
+        &'static str,
+        Box<
+            dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>>
+                + Send,
+        >,
+    > = HashMap::new();
+
+    let instrument_loader: Box<
+        dyn for<'ctx> Fn(Context<'ctx>, Table<'ctx>, &str) -> rlua::Result<Function<'ctx>> + Send,
+    > = Box::new(|lua_ctx, env, name| {
+        let globals = lua_ctx.globals();
+        let new = lua_ctx.create_function(|_, (name, sound): (String, String)| {
+            Ok(Instrument::new(name, sound))
+        })?;
+        let tbl = lua_ctx.create_table()?;
+        tbl.set("new", new)?;
+        globals.set("instrument", tbl)?;
+        Ok(lua_ctx
+            .load("return instrument")
+            .set_name(name)?
+            .set_environment(env)?
+            .into_function()?)
+    });
+
+    modules.insert("instrument", instrument_loader);
+
+    let sound = lua
+        .context::<_, Result<String>>(|lua_ctx| {
+            lua_ctx.add_static_closure_searcher(modules)?;
+
+            // Ensure global variable `instrument` is unset.
+            let nil: String = lua_ctx.load("return type(instrument)").eval()?;
+            assert_eq!(nil, "nil");
+
+            Ok(lua_ctx
+                .load(
+                    r#"local instrument = require("instrument")
+                       local ukulele = instrument.new("ukulele", "twang")
+                       return ukulele:play()"#,
+                )
+                .eval()?)
+        })
+        .unwrap();
+
+    assert_eq!(sound, "The ukulele goes twang");
+}
+
 struct Instrument {
     name: String,
     sound: String,