rearrange builtins

builtins/ffi.go

@@ -0,0 +1,40 @@
+package builtins
+
+import "monkey/object"
+
+import (
+	"fmt"
+	"plugin"
+)
+
+// FFI ...
+func FFI(args ...object.Object) object.Object {
+	if len(args) != 2 {
+		return newError("wrong number of arguments. got=%d, want=2",
+			len(args))
+	}
+
+	arg, ok := args[0].(*object.String)
+	if !ok {
+		return newError("argument #1 to `ffi` expected to be `str` got=%T", args[0].Type())
+	}
+	name := arg.Value
+
+	arg, ok = args[1].(*object.String)
+	if !ok {
+		return newError("argument #2 to `ffi` expected to be `str` got=%T", args[0].Type())
+	}
+	symbol := arg.Value
+
+	p, err := plugin.Open(fmt.Sprintf("%s.so", name))
+	if err != nil {
+		return newError("error loading plugin: %s", err)
+	}
+
+	v, err := p.Lookup(symbol)
+	if err != nil {
+		return newError("error finding symbol: %s", err)
+	}
+
+	return &object.Builtin{Name: symbol, Fn: v.(func(...object.Object) object.Object)}
+}