Faster lua_rotate for Lua < 5.3

3 files changed, 21 insertions, 0 deletions

diff --git a/src/ffi/lua51/compat.rs b/src/ffi/lua51/compat.rs
index 892c507..9cd46fb 100644
--- a/src/ffi/lua51/compat.rs
+++ b/src/ffi/lua51/compat.rs
@@ -155,6 +155,13 @@ pub unsafe fn lua_absindex(L: *mut lua_State, mut idx: c_int) -> c_int {
 
 pub unsafe fn lua_rotate(L: *mut lua_State, mut idx: c_int, mut n: c_int) {
     idx = lua_absindex(L, idx);
+    if n > 0 {
+        // Faster version
+        for _ in 0..n {
+            lua_insert(L, idx);
+        }
+        return;
+    }
     let n_elems = lua_gettop(L) - idx + 1;
     if n < 0 {
         n += n_elems;
diff --git a/src/ffi/lua52/compat.rs b/src/ffi/lua52/compat.rs
index 7ff962d..b834ab1 100644
--- a/src/ffi/lua52/compat.rs
+++ b/src/ffi/lua52/compat.rs
@@ -27,6 +27,13 @@ unsafe fn compat53_reverse(L: *mut lua_State, mut a: c_int, mut b: c_int) {
 
 pub unsafe fn lua_rotate(L: *mut lua_State, mut idx: c_int, mut n: c_int) {
     idx = lua_absindex(L, idx);
+    if n > 0 {
+        // Faster version
+        for _ in 0..n {
+            lua_insert(L, idx);
+        }
+        return;
+    }
     let n_elems = lua_gettop(L) - idx + 1;
     if n < 0 {
         n += n_elems;
diff --git a/src/ffi/luau/compat.rs b/src/ffi/luau/compat.rs
index f92e858..eae4612 100644
--- a/src/ffi/luau/compat.rs
+++ b/src/ffi/luau/compat.rs
@@ -90,6 +90,13 @@ unsafe fn compat53_pushfuncname(L: *mut lua_State, level: c_int, ar: *mut lua_De
 
 pub unsafe fn lua_rotate(L: *mut lua_State, mut idx: c_int, mut n: c_int) {
     idx = lua_absindex(L, idx);
+    if n > 0 {
+        // Faster version
+        for _ in 0..n {
+            lua_insert(L, idx);
+        }
+        return;
+    }
     let n_elems = lua_gettop(L) - idx + 1;
     if n < 0 {
         n += n_elems;