Support Luau buffer type and and library.

Buffer is an object that represents a fixed-size mutable block of memory and added to Luau 0.601.
See https://luau-lang.org/library#buffer-library for more details.

3 files changed, 57 insertions, 1 deletions

diff --git a/mlua-sys/src/luau/lauxlib.rs b/mlua-sys/src/luau/lauxlib.rs
index 4095155..73788af 100644
--- a/mlua-sys/src/luau/lauxlib.rs
+++ b/mlua-sys/src/luau/lauxlib.rs
@@ -52,6 +52,8 @@ extern "C-unwind" {
     pub fn luaL_newmetatable_(L: *mut lua_State, tname: *const c_char) -> c_int;
     pub fn luaL_checkudata(L: *mut lua_State, ud: c_int, tname: *const c_char) -> *mut c_void;
 
+    pub fn luaL_checkbuffer(L: *mut lua_State, narg: c_int, len: *mut usize) -> *mut c_void;
+
     pub fn luaL_where(L: *mut lua_State, lvl: c_int);
 
     #[link_name = "luaL_errorL"]
@@ -152,5 +154,48 @@ pub unsafe fn luaL_sandbox(L: *mut lua_State, enabled: c_int) {
 }
 
 //
-// TODO: Generic Buffer Manipulation
+// Generic Buffer Manipulation
 //
+
+/// Buffer size used for on-stack string operations. This limit depends on native stack size.
+pub const LUA_BUFFERSIZE: usize = 512;
+
+#[repr(C)]
+pub struct luaL_Strbuf {
+    p: *mut c_char,   // current position in buffer
+    end: *mut c_char, // end of the current buffer
+    L: *mut lua_State,
+    storage: *mut c_void, // TString
+    buffer: [c_char; LUA_BUFFERSIZE],
+}
+
+// For compatibility
+pub type luaL_Buffer = luaL_Strbuf;
+
+extern "C-unwind" {
+    pub fn luaL_buffinit(L: *mut lua_State, B: *mut luaL_Strbuf);
+    pub fn luaL_buffinitsize(L: *mut lua_State, B: *mut luaL_Strbuf, size: usize) -> *mut c_char;
+    pub fn luaL_prepbuffsize(B: *mut luaL_Strbuf, size: usize) -> *mut c_char;
+    pub fn luaL_addlstring(B: *mut luaL_Strbuf, s: *const c_char, l: usize);
+    pub fn luaL_addvalue(B: *mut luaL_Strbuf);
+    pub fn luaL_addvalueany(B: *mut luaL_Strbuf, idx: c_int);
+    pub fn luaL_pushresult(B: *mut luaL_Strbuf);
+    pub fn luaL_pushresultsize(B: *mut luaL_Strbuf, size: usize);
+}
+
+pub unsafe fn luaL_addchar(B: *mut luaL_Strbuf, c: c_char) {
+    if (*B).p >= (*B).end {
+        luaL_prepbuffsize(B, 1);
+    }
+    *(*B).p = c;
+    (*B).p = (*B).p.add(1);
+}
+
+pub unsafe fn luaL_addstring(B: *mut luaL_Strbuf, s: *const c_char) {
+    // Calculate length of s
+    let mut len = 0;
+    while *s.add(len) != 0 {
+        len += 1;
+    }
+    luaL_addlstring(B, s, len);
+}
diff --git a/mlua-sys/src/luau/lua.rs b/mlua-sys/src/luau/lua.rs
index 996f62e..2da5690 100644
--- a/mlua-sys/src/luau/lua.rs
+++ b/mlua-sys/src/luau/lua.rs
@@ -55,6 +55,7 @@ pub const LUA_TTABLE: c_int = 6;
 pub const LUA_TFUNCTION: c_int = 7;
 pub const LUA_TUSERDATA: c_int = 8;
 pub const LUA_TTHREAD: c_int = 9;
+pub const LUA_TBUFFER: c_int = 10;
 
 /// Guaranteed number of Lua stack slots available to a C function.
 pub const LUA_MINSTACK: c_int = 20;
@@ -147,6 +148,7 @@ extern "C-unwind" {
     pub fn lua_touserdatatagged(L: *mut lua_State, idx: c_int, tag: c_int) -> *mut c_void;
     pub fn lua_userdatatag(L: *mut lua_State, idx: c_int) -> c_int;
     pub fn lua_tothread(L: *mut lua_State, idx: c_int) -> *mut lua_State;
+    pub fn lua_tobuffer(L: *mut lua_State, idx: c_int, len: *mut usize) -> *mut c_void;
     pub fn lua_topointer(L: *mut lua_State, idx: c_int) -> *const c_void;
 
     //
@@ -181,6 +183,8 @@ extern "C-unwind" {
     pub fn lua_newuserdatatagged(L: *mut lua_State, sz: usize, tag: c_int) -> *mut c_void;
     pub fn lua_newuserdatadtor(L: *mut lua_State, sz: usize, dtor: lua_Udestructor) -> *mut c_void;
 
+    pub fn lua_newbuffer(L: *mut lua_State, sz: usize) -> *mut c_void;
+
     //
     // Get functions (Lua -> stack)
     //
@@ -373,6 +377,11 @@ pub unsafe fn lua_isthread(L: *mut lua_State, n: c_int) -> c_int {
 }
 
 #[inline(always)]
+pub unsafe fn lua_isbuffer(L: *mut lua_State, n: c_int) -> c_int {
+    (lua_type(L, n) == LUA_TBUFFER) as c_int
+}
+
+#[inline(always)]
 pub unsafe fn lua_isnone(L: *mut lua_State, n: c_int) -> c_int {
     (lua_type(L, n) == LUA_TNONE) as c_int
 }
diff --git a/mlua-sys/src/luau/lualib.rs b/mlua-sys/src/luau/lualib.rs
index 5593f8f..96864a0 100644
--- a/mlua-sys/src/luau/lualib.rs
+++ b/mlua-sys/src/luau/lualib.rs
@@ -9,6 +9,7 @@ pub const LUA_TABLIBNAME: &str = "table";
 pub const LUA_OSLIBNAME: &str = "os";
 pub const LUA_STRLIBNAME: &str = "string";
 pub const LUA_BITLIBNAME: &str = "bit32";
+pub const LUA_BUFFERLIBNAME: &str = "buffer";
 pub const LUA_UTF8LIBNAME: &str = "utf8";
 pub const LUA_MATHLIBNAME: &str = "math";
 pub const LUA_DBLIBNAME: &str = "debug";
@@ -20,6 +21,7 @@ extern "C-unwind" {
     pub fn luaopen_os(L: *mut lua_State) -> c_int;
     pub fn luaopen_string(L: *mut lua_State) -> c_int;
     pub fn luaopen_bit32(L: *mut lua_State) -> c_int;
+    pub fn luaopen_buffer(L: *mut lua_State) -> c_int;
     pub fn luaopen_utf8(L: *mut lua_State) -> c_int;
     pub fn luaopen_math(L: *mut lua_State) -> c_int;
     pub fn luaopen_debug(L: *mut lua_State) -> c_int;