N-API: Implement Promise for ChakraCore

Re nodejs/abi-stable-node#242

Author: Gabriel Schulhof

src/node_api.h

@@ -480,10 +480,18 @@ NAPI_EXTERN napi_status napi_queue_async_work(napi_env env,
 NAPI_EXTERN napi_status napi_cancel_async_work(napi_env env,
                                                napi_async_work work);
 
-
 // version management
 NAPI_EXTERN napi_status napi_get_version(napi_env env, uint32_t* result);
 
+// Methods to manage promises
+NAPI_EXTERN napi_status napi_create_promise(napi_env env,
+                                            napi_value* result,
+                                            napi_value* resolve_callback,
+                                            napi_value* reject_callback);
+NAPI_EXTERN napi_status napi_is_promise(napi_env env,
+                                        napi_value value,
+                                        bool* result);
+
 EXTERN_C_END
 
 #endif  // SRC_NODE_API_H_

src/node_api_jsrt.cc

@@ -2010,6 +2010,51 @@ napi_status napi_get_version(napi_env env, uint32_t* result) {
   return napi_ok;
 }
 
+NAPI_EXTERN napi_status napi_create_promise(napi_env env,
+                                            napi_value* result,
+                                            napi_value* resolve_callback,
+                                            napi_value* reject_callback) {
+  CHECK_ARG(env);
+  CHECK_ARG(result);
+  CHECK_ARG(resolve_callback);
+  CHECK_ARG(reject_callback);
+
+  JsValueRef promise, reject, resolve;
+
+  CHECK_JSRT(JsCreatePromise(&promise, &reject, &resolve));
+
+  (*result) = reinterpret_cast<napi_value>(promise);
+  (*resolve_callback) = reinterpret_cast<napi_value>(resolve);
+  (*reject_callback) = reinterpret_cast<napi_value>(reject);
+
+  return napi_ok;
+}
+
+NAPI_EXTERN napi_status napi_is_promise(napi_env env,
+                                        napi_value value,
+                                        bool* result) {
+  CHECK_ARG(env);
+  CHECK_ARG(value);
+  CHECK_ARG(result);
+
+  napi_status status;
+  napi_value js_promise_ctor, global;
+  bool is_instance;
+
+  status = napi_get_global(env, &global);
+  if (status != napi_ok) return status;
+
+  status = napi_get_named_property(env, global, "Promise", &js_promise_ctor);
+  if (status != napi_ok) return status;
+
+  status = napi_instanceof(env, value, js_promise_ctor, &is_instance);
+  if (status != napi_ok) return status;
+
+  (*result) = is_instance;
+
+  return napi_ok;
+}
+
 namespace uvimpl {
 
 napi_status ConvertUVErrorCode(int code) {

test/addons-napi/test_promise/binding.gyp

@@ -0,0 +1,8 @@
+{
+  "targets": [
+    {
+      "target_name": "test_promise",
+      "sources": [ "test_promise.c" ]
+    }
+  ]
+}

test/addons-napi/test_promise/test.js

@@ -0,0 +1,61 @@
+'use strict';
+
+const common = require('../../common');
+const test_promise = require(`./build/${common.buildType}/test_promise`);
+const assert = require('assert');
+
+var native_promise, conclude_value;
+
+// Create a native promise and resolve it.
+native_promise = test_promise.napi_create_promise();
+conclude_value = "Promise delivered";
+native_promise.promise
+  .then(
+    function( result ) {
+      assert.strictEqual( result, conclude_value, "Promise was resolved as expected" );
+    },
+    function( error ) {
+      assert.ok( false, "Promise was rejected when it should have been resolved: " +
+        error + ": " + JSON.stringify( error, null, 4 ) );
+    } );
+native_promise.resolve( conclude_value );
+
+// Make sure the native promise is recognized as a promise.
+assert.strictEqual( test_promise.napi_is_promise( native_promise.promise ), true,
+  "N-API correctly identifies a promise it created as a promise" );
+
+// Create a native promise and reject it.
+native_promise = test_promise.napi_create_promise();
+conclude_value = new Error( "I broke my promise" );
+native_promise.promise
+  .then(
+    function( result ) {
+      assert.ok( false, "Promise was resolved when it should have been rejected: " +
+        result + ": " + JSON.stringify( result, null, 4 ) );
+    },
+    function( error ) {
+      assert.strictEqual( error, conclude_value, "Promise was rejected as expected" );
+    } );
+
+// N-API correctly identifies a JS promise as a promise
+assert.strictEqual(
+  test_promise.napi_is_promise( Promise.reject( new Error( "No reason, just sayin'" ) ) ), true,
+  "N-API correctly identifies a JS promise as a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( 42 ), false,
+  "N-API correctly reports that a number is not a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( "Gumball" ), false,
+  "N-API correctly reports that a string is not a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( undefined ), false,
+  "N-API correctly reports that undefined is not a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( null ), false,
+  "N-API correctly reports that null is not a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( {} ), false,
+  "N-API correctly reports that an object is not a promise" );
+
+assert.strictEqual( test_promise.napi_is_promise( Symbol( "Espoo" ) ), false,
+  "N-API correctly reports that a symbol is not a promise" );

test/addons-napi/test_promise/test_promise.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <node_api.h>
+#include "../common.h"
+
+napi_value bind_napi_create_promise(napi_env env, napi_callback_info info) {
+  napi_value promise, resolve, reject, result;
+
+  NAPI_CALL(env, napi_create_promise(env, &promise, &resolve, &reject));
+  NAPI_CALL(env, napi_create_object(env, &result));
+
+  fprintf(stderr, "resolve: %p\n", resolve);
+
+  napi_valuetype value_type;
+  NAPI_CALL(env, napi_typeof(env, resolve, &value_type));
+  fprintf(stderr, "resolve: value_type: %d\n", value_type);
+
+  napi_property_descriptor properties[] = {
+    { "promise", NULL, NULL, NULL, NULL, promise, napi_default, NULL },
+    { "resolve", NULL, NULL, NULL, NULL, resolve, napi_default, NULL },
+    { "reject", NULL, NULL, NULL, NULL, reject, napi_default, NULL },
+  };
+
+  NAPI_CALL(env, napi_define_properties(env, result, 3, properties));
+
+  return result;
+}
+
+napi_value bind_napi_is_promise(napi_env env, napi_callback_info info) {
+  napi_value promise, result;
+  size_t argc = 1;
+  bool is_promise;
+
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, &promise, NULL, NULL));
+  NAPI_CALL(env, napi_is_promise(env, promise, &is_promise));
+  NAPI_CALL(env, napi_get_boolean(env, is_promise, &result));
+
+  return result;
+}
+
+void Init(napi_env env, napi_value exports, napi_value module, void* priv) {
+  napi_property_descriptor descriptors[] = {
+    DECLARE_NAPI_PROPERTY("napi_create_promise", bind_napi_create_promise),
+    DECLARE_NAPI_PROPERTY("napi_is_promise", bind_napi_is_promise)
+  };
+
+  NAPI_CALL_RETURN_VOID(env, napi_define_properties(
+    env, exports, sizeof(descriptors) / sizeof(*descriptors), descriptors));
+}
+
+NAPI_MODULE(addon, Init)