From 356bf24c5a046b4396303db4fdd513edb12599b5 Mon Sep 17 00:00:00 2001
From: OJ Kwon <kwon.ohjoong@gmail.com>
Date: Fri, 20 Jul 2018 14:54:03 -0700
Subject: [PATCH] feat(getfnptrhandler): wrapper to add, removefunction

---
 src/SassAsmModule.ts        |  2 ++
 src/interop/fnPtrHandler.ts | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 src/interop/fnPtrHandler.ts

diff --git a/src/SassAsmModule.ts b/src/SassAsmModule.ts
index dd3f73f..538c000 100644
--- a/src/SassAsmModule.ts
+++ b/src/SassAsmModule.ts
@@ -10,6 +10,8 @@ interface SassAsmModule extends Required<BaseAsmModule> {
   _libsass_version: () => number;
   _libsass_language_version: () => number;
   _sass2scss_version: () => number;
+  addFunction: (fn: Function) => number;
+  removeFunction: (fnPtr: number) => void;
 }
 
 export { SassAsmModule };
diff --git a/src/interop/fnPtrHandler.ts b/src/interop/fnPtrHandler.ts
new file mode 100644
index 0000000..7509c26
--- /dev/null
+++ b/src/interop/fnPtrHandler.ts
@@ -0,0 +1,26 @@
+import { SassAsmModule } from '../SassAsmModule';
+
+/**
+ * Returns handler object to wrap `addFunction` and `removeFunction`
+ */
+const getFnPtrHandler = ({ addFunction, removeFunction }: SassAsmModule) => {
+  let count = 0;
+
+  return {
+    add: (fn: Function) => {
+      if (count === 20) {
+        throw new Error('Maximum number of function pointer added');
+      }
+      count++;
+      return addFunction(fn);
+    },
+    remove: (fnPtr: number) => {
+      if (count > 0) {
+        count--;
+        removeFunction(fnPtr);
+      }
+    }
+  };
+};
+
+export { getFnPtrHandler };