Add loadstring function to Luau

Closes #578

Author: khvzak

src/luau/mod.rs

@@ -1,9 +1,12 @@
 use std::ffi::CStr;
 use std::os::raw::c_int;
+use std::ptr;
 
+use crate::chunk::ChunkMode;
 use crate::error::Result;
 use crate::function::Function;
-use crate::state::Lua;
+use crate::state::{callback_error_ext, Lua};
+use crate::traits::{FromLuaMulti, IntoLua};
 
 pub use require::{NavigateError, Require};
 
@@ -22,6 +25,7 @@ impl Lua {
         let globals = self.globals();
 
         globals.raw_set("collectgarbage", self.create_c_function(lua_collectgarbage)?)?;
+        globals.raw_set("loadstring", self.create_c_function(lua_loadstring)?)?;
 
         // Set `_VERSION` global to include version number
         // The environment variable `LUAU_VERSION` set by the build script
@@ -74,4 +78,20 @@ unsafe extern "C-unwind" fn lua_collectgarbage(state: *mut ffi::lua_State) -> c_
     }
 }
 
+unsafe extern "C-unwind" fn lua_loadstring(state: *mut ffi::lua_State) -> c_int {
+    callback_error_ext(state, ptr::null_mut(), false, move |extra, nargs| {
+        let rawlua = (*extra).raw_lua();
+        let (chunk, chunk_name) =
+            <(String, Option<String>)>::from_stack_args(nargs, 1, Some("loadstring"), rawlua)?;
+        let chunk_name = chunk_name.as_deref().unwrap_or("=(loadstring)");
+        (rawlua.lua())
+            .load(chunk)
+            .set_name(chunk_name)
+            .set_mode(ChunkMode::Text)
+            .into_function()?
+            .push_into_stack(rawlua)?;
+        Ok(1)
+    })
+}
+
 mod require;

tests/luau.rs

@@ -7,7 +7,9 @@ use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::sync::atomic::{AtomicBool, AtomicPtr, AtomicU64, Ordering};
 use std::sync::Arc;
 
-use mlua::{Compiler, Error, Lua, LuaOptions, Result, StdLib, Table, ThreadStatus, Value, Vector, VmState};
+use mlua::{
+    Compiler, Error, Function, Lua, LuaOptions, Result, StdLib, Table, ThreadStatus, Value, Vector, VmState,
+};
 
 #[test]
 fn test_version() -> Result<()> {
@@ -415,5 +417,24 @@ fn test_thread_events() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_loadstring() -> Result<()> {
+    let lua = Lua::new();
+
+    let f = lua.load(r#"loadstring("return 123")"#).eval::<Function>()?;
+    assert_eq!(f.call::<i32>(())?, 123);
+
+    let err = lua
+        .load(r#"loadstring("retur 123", "chunk")"#)
+        .exec()
+        .err()
+        .unwrap();
+    assert!(err.to_string().contains(
+        r#"syntax error: [string "chunk"]:1: Incomplete statement: expected assignment or a function call"#
+    ));
+
+    Ok(())
+}
+
 #[path = "luau/require.rs"]
 mod require;