fix the candid encoding example

examples/candid_encoding/src/index.did

@@ -1,4 +1,4 @@
 service: () -> {
-    candidEncode: (text) -> (vec nat8) query;
     candidDecode: (vec nat8) -> (text) query;
+    candidEncode: (text) -> (vec nat8) query;
 }

src/compiler/rust/canister/src/ic/candid_decode.rs

@@ -1,21 +1,19 @@
 use std::convert::TryInto;
 
-use quickjs_wasm_rs::{to_qjs_value, CallbackArg, JSContextRef, JSValue, JSValueRef};
+use wasmedge_quickjs::{Context, JsArrayBuffer, JsFn, JsString, JsValue};
 
-pub fn native_function<'a>(
-    context: &'a JSContextRef,
-    _this: &CallbackArg,
-    _args: &[CallbackArg],
-) -> Result<JSValueRef<'a>, anyhow::Error> {
-    let candid_encoded: Vec<u8> = _args
-        .get(0)
-        .expect("candidDecode must have at least one argument")
-        .to_js_value()?
-        .try_into()?;
+pub struct NativeFunction;
+impl JsFn for NativeFunction {
+    fn call(context: &mut Context, this_val: JsValue, argv: &[JsValue]) -> JsValue {
+        let candid_encoded = if let JsValue::ArrayBuffer(js_array_buffer) = argv.get(0).unwrap() {
+            js_array_buffer.to_vec()
+        } else {
+            panic!("conversion from JsValue to JsArrayBuffer failed")
+        };
 
-    let candid_args: candid::IDLArgs = candid::IDLArgs::from_bytes(&candid_encoded)?;
-    let candid_string = candid_args.to_string();
+        let candid_args: candid::IDLArgs = candid::IDLArgs::from_bytes(&candid_encoded).unwrap();
+        let candid_string = candid_args.to_string();
 
-    let candid_string_js_value: JSValue = candid_string.into();
-    to_qjs_value(&context, &candid_string_js_value)
+        context.new_string(&candid_string).into()
+    }
 }

src/compiler/rust/canister/src/ic/candid_encode.rs

@@ -1,21 +1,19 @@
 use std::convert::TryInto;
 
-use quickjs_wasm_rs::{to_qjs_value, CallbackArg, JSContextRef, JSValue, JSValueRef};
+use wasmedge_quickjs::{Context, JsArrayBuffer, JsFn, JsValue};
 
-pub fn native_function<'a>(
-    context: &'a JSContextRef,
-    _this: &CallbackArg,
-    _args: &[CallbackArg],
-) -> Result<JSValueRef<'a>, anyhow::Error> {
-    let candid_string: String = _args
-        .get(0)
-        .expect("candidEncode must have at least one argument")
-        .to_js_value()?
-        .try_into()?;
+pub struct NativeFunction;
+impl JsFn for NativeFunction {
+    fn call(context: &mut Context, this_val: JsValue, argv: &[JsValue]) -> JsValue {
+        let candid_string = if let JsValue::String(js_string) = argv.get(0).unwrap() {
+            js_string.to_string()
+        } else {
+            panic!("conversion from JsValue to JsString failed")
+        };
 
-    let candid_args: candid::IDLArgs = candid_string.parse()?;
-    let candid_encoded: Vec<u8> = candid_args.to_bytes()?;
+        let candid_args: candid::IDLArgs = candid_string.parse().unwrap();
+        let candid_encoded = candid_args.to_bytes().unwrap();
 
-    let candid_encoded_js_value: JSValue = candid_encoded.into();
-    to_qjs_value(&context, &candid_encoded_js_value)
+        context.new_array_buffer(&candid_encoded).into()
+    }
 }

src/compiler/rust/canister/src/ic/mod.rs

@@ -4,8 +4,8 @@
 // mod call_raw;
 // mod call_raw128;
 // mod caller;
-// mod candid_decode;
-// mod candid_encode;
+mod candid_decode;
+mod candid_encode;
 // mod canister_balance;
 // mod canister_balance128;
 // mod canister_version;
@@ -97,20 +97,21 @@ pub fn register(context: &mut wasmedge_quickjs::Context) {
     //     context.wrap_callback2(caller::native_function).unwrap(),
     // )
     // .unwrap();
-    // ic.set_property(
-    //     "candidDecode",
-    //     context
-    //         .wrap_callback2(candid_decode::native_function)
-    //         .unwrap(),
-    // )
-    // .unwrap();
-    // ic.set_property(
-    //     "candidEncode",
-    //     context
-    //         .wrap_callback2(candid_encode::native_function)
-    //         .unwrap(),
-    // )
-    // .unwrap();
+
+    ic.set(
+        "candidDecode",
+        context
+            .new_function::<candid_decode::NativeFunction>("")
+            .into(),
+    );
+
+    ic.set(
+        "candidEncode",
+        context
+            .new_function::<candid_encode::NativeFunction>("")
+            .into(),
+    );
+
     // ic.set_property(
     //     "canisterBalance",
     //     context