c/lua:extraspace

c/lua/_demo/extraspace/extraspace.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"unsafe"
+	_ "unsafe"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/lua"
+)
+
+func GetData(L *lua.State) c.Int {
+	extra := (*int)(L.Getextraspace())
+	L.Pushfstring(c.Str("Stored integer is: %d"), *extra)
+	return 1
+}
+
+func main() {
+	L := lua.Newstate__1()
+	defer L.Close()
+
+	L.Openlibs()
+
+	extra := (*int)(L.Getextraspace())
+	*extra = 42
+
+	difference := uintptr(unsafe.Pointer(L)) - uintptr(L.Getextraspace())
+	if difference == unsafe.Sizeof(uintptr(0)) {
+		c.Printf(c.Str("Extra space is pointer size\n"), unsafe.Sizeof(uintptr(0)))
+	}
+
+	L.Pushcfunction(GetData)
+	L.Setglobal(c.Str("GetData"))
+
+	if L.Dostring(c.Str("print(GetData())")) != lua.OK {
+		c.Printf(c.Str("Error: %s\n"), L.Tostring(-1))
+	}
+}
+
+/* Expected output:
+Extra space is pointer size
+Stored integer is: 42
+*/