v0.8.1

Closes #175

CHANGELOG.md

@@ -1,3 +1,9 @@
+## v0.8.1
+
+- Added `Lua::create_proxy` for accessing to UserData static fields and functions without instance
+- Added `Table::to_pointer()` and `String::to_pointer()` functions
+- Bugfixes and improvements (#176 #179)
+
 ## v0.8.0
 Changes since 0.7.4
 - Roblox Luau support

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mlua"
-version = "0.8.0" # remember to update html_root_url and mlua_derive
+version = "0.8.1" # remember to update html_root_url and mlua_derive
 authors = ["Aleksandr Orlenko <zxteam@pm.me>", "kyren <catherine@chucklefish.org>"]
 edition = "2021"
 repository = "https://github.com/khvzak/mlua"

src/chunk.rs

@@ -484,7 +484,7 @@ impl<'lua, 'a> Chunk<'lua, 'a> {
                     return ChunkMode::Binary;
                 }
                 #[cfg(feature = "luau")]
-                if *source.get(0).unwrap_or(&u8::MAX) < b'\n' {
+                if *source.first().unwrap_or(&u8::MAX) < b'\n' {
                     return ChunkMode::Binary;
                 }
                 ChunkMode::Text

src/lib.rs

@@ -72,7 +72,7 @@
 //! [`serde::Deserialize`]: https://docs.serde.rs/serde/de/trait.Deserialize.html
 
 // mlua types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/mlua/0.8.0")]
+#![doc(html_root_url = "https://docs.rs/mlua/0.8.1")]
 // Deny warnings inside doc tests / examples. When this isn't present, rustdoc doesn't show *any*
 // warnings at all.
 #![doc(test(attr(deny(warnings))))]

src/lua.rs

@@ -29,7 +29,7 @@ use crate::types::{
     Number, RegistryKey,
 };
 use crate::userdata::{AnyUserData, UserData, UserDataCell};
-use crate::userdata_impl::{StaticUserDataFields, StaticUserDataMethods};
+use crate::userdata_impl::{StaticUserDataFields, StaticUserDataMethods, UserDataProxy};
 use crate::util::{
     self, assert_stack, callback_error, check_stack, get_destructed_userdata_metatable,
     get_gc_metatable, get_gc_userdata, get_main_state, get_userdata, init_error_registry,
@@ -126,7 +126,7 @@ pub(crate) struct ExtraData {
     sandboxed: bool,
 }
 
-#[cfg_attr(any(feature = "lua51", feature = "luajit"), allow(dead_code))]
+#[derive(Default)]
 struct MemoryInfo {
     used_memory: isize,
     memory_limit: isize,
@@ -430,12 +430,16 @@ impl Lua {
             new_ptr
         }
 
-        let mem_info = Box::into_raw(Box::new(MemoryInfo {
-            used_memory: 0,
-            memory_limit: 0,
-        }));
+        // Skip Rust allocator for non-vendored LuaJIT (see https://github.com/khvzak/mlua/issues/176)
+        let use_rust_allocator = !(cfg!(feature = "luajit") && cfg!(not(feature = "vendored")));
 
-        let state = ffi::lua_newstate(allocator, mem_info as *mut c_void);
+        let (state, mem_info) = if use_rust_allocator {
+            let mem_info = Box::into_raw(Box::new(MemoryInfo::default()));
+            let state = ffi::lua_newstate(allocator, mem_info as *mut c_void);
+            (state, mem_info)
+        } else {
+            (ffi::luaL_newstate(), ptr::null_mut())
+        };
 
         ffi::luaL_requiref(state, cstr!("_G"), ffi::luaopen_base, 1);
         ffi::lua_pop(state, 1);
@@ -1717,6 +1721,9 @@ impl Lua {
     }
 
     /// Create a Lua userdata object from a custom userdata type.
+    ///
+    /// All userdata instances of type `T` shares the same metatable.
+    #[inline]
     pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData>
     where
         T: 'static + MaybeSend + UserData,
@@ -1729,6 +1736,7 @@ impl Lua {
     /// Requires `feature = "serialize"`
     #[cfg(feature = "serialize")]
     #[cfg_attr(docsrs, doc(cfg(feature = "serialize")))]
+    #[inline]
     pub fn create_ser_userdata<T>(&self, data: T) -> Result<AnyUserData>
     where
         T: 'static + MaybeSend + UserData + Serialize,
@@ -1736,6 +1744,46 @@ impl Lua {
         unsafe { self.make_userdata(UserDataCell::new_ser(data)) }
     }
 
+    /// Create a Lua userdata "proxy" object from a custom userdata type.
+    ///
+    /// Proxy object is an empty userdata object that has `T` metatable attached.
+    /// The main purpose of this object is to provide access to static fields and functions
+    /// without creating an instance of type `T`.
+    ///
+    /// You can get or set uservalues on this object but you cannot borrow any Rust type.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # use mlua::{Lua, Result, UserData, UserDataFields, UserDataMethods};
+    /// # fn main() -> Result<()> {
+    /// # let lua = Lua::new();
+    /// struct MyUserData(i32);
+    ///
+    /// impl UserData for MyUserData {
+    ///     fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+    ///         fields.add_field_method_get("val", |_, this| Ok(this.0));
+    ///     }
+    ///
+    ///     fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+    ///         methods.add_function("new", |_, value: i32| Ok(MyUserData(value)));
+    ///     }
+    /// }
+    ///
+    /// lua.globals().set("MyUserData", lua.create_proxy::<MyUserData>()?)?;
+    ///
+    /// lua.load("assert(MyUserData.new(321).val == 321)").exec()?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[inline]
+    pub fn create_proxy<T>(&self) -> Result<AnyUserData>
+    where
+        T: 'static + UserData,
+    {
+        unsafe { self.make_userdata(UserDataCell::new(UserDataProxy::<T>(PhantomData))) }
+    }
+
     /// Returns a handle to the global environment.
     pub fn globals(&self) -> Table {
         unsafe {
@@ -2866,7 +2914,7 @@ impl Lua {
         let _sg = StackGuard::new(state);
         assert_stack(state, 1);
         let extra = extra_data(state)?;
-        let inner = &*(*extra.get()).inner.as_ref().unwrap();
+        let inner = (*extra.get()).inner.as_ref().unwrap();
         Some(Lua(Arc::clone(inner)))
     }
 

src/luau.rs

@@ -85,10 +85,12 @@ fn lua_require(lua: &Lua, name: Option<std::string::String>) -> Result<Value> {
         search_path = "?.luau;?.lua".into();
     }
 
-    let mut source = None;
+    let (mut source, mut source_name) = (None, String::new());
     for path in search_path.split(';') {
-        if let Ok(buf) = std::fs::read(path.replacen('?', &name, 1)) {
+        let file_path = path.replacen('?', &name, 1);
+        if let Ok(buf) = std::fs::read(&file_path) {
             source = Some(buf);
+            source_name = file_path;
             break;
         }
     }
@@ -96,7 +98,7 @@ fn lua_require(lua: &Lua, name: Option<std::string::String>) -> Result<Value> {
 
     let value = lua
         .load(&source)
-        .set_name(&format!("={}", name))?
+        .set_name(&format!("={}", source_name))?
         .set_mode(ChunkMode::Text)
         .call::<_, Value>(())?;
 

src/scope.rs

@@ -597,6 +597,7 @@ impl<'lua, 'scope> Drop for Scope<'lua, 'scope> {
     }
 }
 
+#[allow(clippy::type_complexity)]
 enum NonStaticMethod<'lua, T> {
     Method(Box<dyn Fn(&'lua Lua, &T, MultiValue<'lua>) -> Result<MultiValue<'lua>>>),
     MethodMut(Box<dyn FnMut(&'lua Lua, &mut T, MultiValue<'lua>) -> Result<MultiValue<'lua>>>),

src/serde/de.rs

@@ -8,7 +8,6 @@ use rustc_hash::FxHashSet;
 use serde::de::{self, IntoDeserializer};
 
 use crate::error::{Error, Result};
-use crate::ffi;
 use crate::table::{Table, TablePairs, TableSequence};
 use crate::value::Value;
 
@@ -563,9 +562,7 @@ impl RecursionGuard {
     #[inline]
     fn new(table: &Table, visited: &Rc<RefCell<FxHashSet<*const c_void>>>) -> Self {
         let visited = Rc::clone(visited);
-        let lua = table.0.lua;
-        let ptr =
-            unsafe { lua.ref_thread_exec(|refthr| ffi::lua_topointer(refthr, table.0.index)) };
+        let ptr = table.to_pointer();
         visited.borrow_mut().insert(ptr);
         RecursionGuard { ptr, visited }
     }
@@ -585,9 +582,7 @@ fn check_value_if_skip(
 ) -> Result<bool> {
     match value {
         Value::Table(table) => {
-            let lua = table.0.lua;
-            let ptr =
-                unsafe { lua.ref_thread_exec(|refthr| ffi::lua_topointer(refthr, table.0.index)) };
+            let ptr = table.to_pointer();
             if visited.borrow().contains(&ptr) {
                 if options.deny_recursive_tables {
                     return Err(de::Error::custom("recursive table detected"));

src/string.rs

@@ -1,5 +1,6 @@
 use std::borrow::{Borrow, Cow};
 use std::hash::{Hash, Hasher};
+use std::os::raw::c_void;
 use std::string::String as StdString;
 use std::{slice, str};
 
@@ -112,6 +113,17 @@ impl<'lua> String<'lua> {
             slice::from_raw_parts(data as *const u8, size + 1)
         }
     }
+
+    /// Converts the string to a generic C pointer.
+    ///
+    /// There is no way to convert the pointer back to its original value.
+    ///
+    /// Typically this function is used only for hashing and debug information.
+    #[inline]
+    pub fn to_pointer(&self) -> *const c_void {
+        let lua = self.0.lua;
+        unsafe { lua.ref_thread_exec(|refthr| ffi::lua_topointer(refthr, self.0.index)) }
+    }
 }
 
 impl<'lua> AsRef<[u8]> for String<'lua> {

src/table.rs

@@ -1,10 +1,11 @@
 use std::marker::PhantomData;
+use std::os::raw::c_void;
 
 #[cfg(feature = "serialize")]
 use {
     rustc_hash::FxHashSet,
     serde::ser::{self, Serialize, SerializeMap, SerializeSeq, Serializer},
-    std::{cell::RefCell, os::raw::c_void, result::Result as StdResult},
+    std::{cell::RefCell, result::Result as StdResult},
 };
 
 use crate::error::{Error, Result};
@@ -382,6 +383,18 @@ impl<'lua> Table<'lua> {
         unsafe { lua.ref_thread_exec(|refthr| ffi::lua_getreadonly(refthr, self.0.index) != 0) }
     }
 
+    /// Converts the table to a generic C pointer.
+    ///
+    /// Different tables will give different pointers.
+    /// There is no way to convert the pointer back to its original value.
+    ///
+    /// Typically this function is used only for hashing and debug information.
+    #[inline]
+    pub fn to_pointer(&self) -> *const c_void {
+        let lua = self.0.lua;
+        unsafe { lua.ref_thread_exec(|refthr| ffi::lua_topointer(refthr, self.0.index)) }
+    }
+
     /// Consume this table and return an iterator over the pairs of the table.
     ///
     /// This works like the Lua `pairs` function, but does not invoke the `__pairs` metamethod.
@@ -699,8 +712,7 @@ impl<'lua> Serialize for Table<'lua> {
             static VISITED: RefCell<FxHashSet<*const c_void>> = RefCell::new(FxHashSet::default());
         }
 
-        let lua = self.0.lua;
-        let ptr = unsafe { lua.ref_thread_exec(|refthr| ffi::lua_topointer(refthr, self.0.index)) };
+        let ptr = self.to_pointer();
         let res = VISITED.with(|visited| {
             {
                 let mut visited = visited.borrow_mut();

src/userdata_impl.rs

@@ -622,3 +622,8 @@ lua_userdata_impl!(Arc<RwLock<T>>);
 lua_userdata_impl!(Arc<parking_lot::Mutex<T>>);
 #[cfg(feature = "parking_lot")]
 lua_userdata_impl!(Arc<parking_lot::RwLock<T>>);
+
+// A special proxy object for UserData
+pub(crate) struct UserDataProxy<T>(pub(crate) PhantomData<T>);
+
+lua_userdata_impl!(UserDataProxy<T>);

src/value.rs

@@ -1,4 +1,5 @@
 use std::iter::{self, FromIterator};
+use std::ops::Index;
 use std::os::raw::c_void;
 use std::{ptr, slice, str, vec};
 
@@ -103,13 +104,14 @@ impl<'lua> Value<'lua> {
     /// There is no way to convert the pointer back to its original value.
     ///
     /// Typically this function is used only for hashing and debug information.
+    #[inline]
     pub fn to_pointer(&self) -> *const c_void {
         unsafe {
             match self {
                 Value::LightUserData(ud) => ud.0,
-                Value::String(String(v))
-                | Value::Table(Table(v))
-                | Value::Function(Function(v))
+                Value::Table(t) => t.to_pointer(),
+                Value::String(s) => s.to_pointer(),
+                Value::Function(Function(v))
                 | Value::Thread(Thread(v))
                 | Value::UserData(AnyUserData(v)) => v
                     .lua
@@ -241,6 +243,15 @@ impl<'a, 'lua> IntoIterator for &'a MultiValue<'lua> {
     }
 }
 
+impl<'lua> Index<usize> for MultiValue<'lua> {
+    type Output = Value<'lua>;
+
+    #[inline]
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.0[self.0.len() - index - 1]
+    }
+}
+
 impl<'lua> MultiValue<'lua> {
     #[inline]
     pub fn from_vec(mut v: Vec<Value<'lua>>) -> MultiValue<'lua> {
@@ -261,13 +272,13 @@ impl<'lua> MultiValue<'lua> {
     }
 
     #[inline]
-    pub(crate) fn push_front(&mut self, value: Value<'lua>) {
-        self.0.push(value);
+    pub fn pop_front(&mut self) -> Option<Value<'lua>> {
+        self.0.pop()
     }
 
     #[inline]
-    pub(crate) fn pop_front(&mut self) -> Option<Value<'lua>> {
-        self.0.pop()
+    pub fn push_front(&mut self, value: Value<'lua>) {
+        self.0.push(value);
     }
 
     #[inline]

tests/luau.rs

@@ -15,8 +15,11 @@ fn test_require() -> Result<()> {
     fs::write(
         temp_dir.path().join("module.luau"),
         r#"
-        counter = counter or 0
-        return counter + 1
+        counter = (counter or 0) + 1
+        return {
+            counter = counter,
+            error = function() error("test") end,
+        }
     "#,
     )?;
 
@@ -24,9 +27,12 @@ fn test_require() -> Result<()> {
     lua.load(
         r#"
         local module = require("module")
-        assert(module == 1)
+        assert(module.counter == 1)
         module = require("module")
-        assert(module == 1)
+        assert(module.counter == 1)
+
+        local ok, err = pcall(module.error)
+        assert(not ok and string.find(err, "module.luau") ~= nil)
     "#,
     )
     .exec()

tests/userdata.rs

@@ -656,3 +656,44 @@ fn test_userdata_wrapped() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_userdata_proxy() -> Result<()> {
+    struct MyUserData(i64);
+
+    impl UserData for MyUserData {
+        fn add_fields<'lua, F: UserDataFields<'lua, Self>>(fields: &mut F) {
+            fields.add_field_function_get("static_field", |_, _| Ok(123));
+            fields.add_field_method_get("n", |_, this| Ok(this.0));
+        }
+
+        fn add_methods<'lua, M: UserDataMethods<'lua, Self>>(methods: &mut M) {
+            methods.add_function("new", |_, n| Ok(Self(n)));
+
+            methods.add_method("plus", |_, this, n: i64| Ok(this.0 + n));
+        }
+    }
+
+    let lua = Lua::new();
+    let globals = lua.globals();
+    globals.set("MyUserData", lua.create_proxy::<MyUserData>()?)?;
+
+    lua.load(
+        r#"
+        assert(MyUserData.static_field == 123)
+        local data = MyUserData.new(321)
+        assert(data.static_field == 123)
+        assert(data.n == 321)
+        assert(data:plus(1) == 322)
+
+        -- Error when accessing the proxy object fields and methods that require instance
+
+        local ok = pcall(function() return MyUserData.n end)
+        assert(not ok)
+
+        ok = pcall(function() return MyUserData:plus(1) end)
+        assert(not ok)
+    "#,
+    )
+    .exec()
+}