n-api: add napi_delete_element()

Refs: nodejs#13924 PR-URL: nodejs#13949 Reviewed-By: Jason Ginchereau <jasongin@microsoft.com>
gabrielschulhof · Apr 10, 2018 · ae0bdd5 · ae0bdd5
1 parent 922ea46
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diff --git a/doc/api/n-api.md b/doc/api/n-api.md
@@ -2400,6 +2400,27 @@ Returns `napi_ok` if the API succeeded.
 This API returns if the Object passed in has an element at the
 requested index.
 
+#### *napi_delete_element*
+<!-- YAML
+added: REPLACEME
+-->
+```C
+napi_status napi_delete_element(napi_env env,
+                                napi_value object,
+                                uint32_t index,
+                                bool* result);
+```
+
+- `[in] env`: The environment that the N-API call is invoked under.
+- `[in] object`: The object to query.
+- `[in] index`: The index of the property to delete.
+- `[out] result`: Whether the element deletion succeeded or not. `result` can
+optionally be ignored by passing `NULL`.
+
+Returns `napi_ok` if the API succeeded.
+
+This API attempts to delete the specified `index` from `object`.
+
 #### *napi_define_properties*
 <!-- YAML
 added: v8.0.0
@@ -3052,6 +3073,7 @@ support it:
 [`napi_define_class`]: #n_api_napi_define_class
 [`napi_delete_async_work`]: #n_api_napi_delete_async_work
 [`napi_define_class`]: #n_api_napi_define_class
+[`napi_delete_element`]: #n_api_napi_delete_element
 [`napi_delete_reference`]: #n_api_napi_delete_reference
 [`napi_escape_handle`]: #n_api_napi_escape_handle
 [`napi_get_array_length`]: #n_api_napi_get_array_length

diff --git a/src/node_api.cc b/src/node_api.cc
@@ -1142,6 +1142,26 @@ napi_status napi_get_element(napi_env env,
   return GET_RETURN_STATUS(env);
 }
 
+napi_status napi_delete_element(napi_env env,
+                                napi_value object,
+                                uint32_t index,
+                                bool* result) {
+  NAPI_PREAMBLE(env);
+
+  v8::Isolate* isolate = env->isolate;
+  v8::Local<v8::Context> context = isolate->GetCurrentContext();
+  v8::Local<v8::Object> obj;
+
+  CHECK_TO_OBJECT(env, context, obj, object);
+  v8::Maybe<bool> delete_maybe = obj->Delete(context, index);
+  CHECK_MAYBE_NOTHING(env, delete_maybe, napi_generic_failure);
+
+  if (result != NULL)
+    *result = delete_maybe.FromMaybe(false);
+
+  return GET_RETURN_STATUS(env);
+}
+
 napi_status napi_define_properties(napi_env env,
                                    napi_value object,
                                    size_t property_count,

diff --git a/src/node_api.h b/src/node_api.h
@@ -250,6 +250,10 @@ NAPI_EXTERN napi_status napi_get_element(napi_env env,
                                          napi_value object,
                                          uint32_t index,
                                          napi_value* result);
+NAPI_EXTERN napi_status napi_delete_element(napi_env env,
+                                            napi_value object,
+                                            uint32_t index,
+                                            bool* result);
 NAPI_EXTERN napi_status
 napi_define_properties(napi_env env,
                        napi_value object,

diff --git a/test/addons-napi/test_array/test.js b/test/addons-napi/test_array/test.js
@@ -47,3 +47,14 @@ assert(test_array.NewWithLength(0) instanceof Array);
 assert(test_array.NewWithLength(1) instanceof Array);
 // check max allowed length for an array 2^32 -1
 assert(test_array.NewWithLength(4294967295) instanceof Array);
+
+{
+  // Verify that array elements can be deleted.
+  const arr = ['a', 'b', 'c', 'd'];
+
+  assert.strictEqual(arr.length, 4);
+  assert.strictEqual(2 in arr, true);
+  assert.strictEqual(test_array.TestDeleteElement(arr, 2), true);
+  assert.strictEqual(arr.length, 4);
+  assert.strictEqual(2 in arr, false);
+}
diff --git a/test/addons-napi/test_array/test_array.c b/test/addons-napi/test_array/test_array.c
@@ -84,6 +84,41 @@ napi_value TestHasElement(napi_env env, napi_callback_info info) {
   return ret;
 }
 
+napi_value TestDeleteElement(napi_env env, napi_callback_info info) {
+  size_t argc = 2;
+  napi_value args[2];
+
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, args, NULL, NULL));
+  NAPI_ASSERT(env, argc == 2, "Wrong number of arguments");
+
+  napi_valuetype valuetype0;
+  NAPI_CALL(env, napi_typeof(env, args[0], &valuetype0));
+  NAPI_ASSERT(env, valuetype0 == napi_object,
+    "Wrong type of arguments. Expects an array as first argument.");
+
+  napi_valuetype valuetype1;
+  NAPI_CALL(env, napi_typeof(env, args[1], &valuetype1));
+  NAPI_ASSERT(env, valuetype1 == napi_number,
+    "Wrong type of arguments. Expects an integer as second argument.");
+
+  napi_value array = args[0];
+  int32_t index;
+  bool result;
+  napi_value ret;
+
+  NAPI_CALL(env, napi_get_value_int32(env, args[1], &index));
+  NAPI_CALL(env, napi_is_array(env, array, &result));
+
+  if (!result) {
+    return NULL;
+  }
+
+  NAPI_CALL(env, napi_delete_element(env, array, index, &result));
+  NAPI_CALL(env, napi_get_boolean(env, result, &ret));
+
+  return ret;
+}
+
 napi_value New(napi_env env, napi_callback_info info) {
   size_t argc = 1;
   napi_value args[1];
@@ -138,6 +173,7 @@ void Init(napi_env env, napi_value exports, napi_value module, void* priv) {
   napi_property_descriptor descriptors[] = {
     DECLARE_NAPI_PROPERTY("TestGetElement", TestGetElement),
     DECLARE_NAPI_PROPERTY("TestHasElement", TestHasElement),
+    DECLARE_NAPI_PROPERTY("TestDeleteElement", TestDeleteElement),
     DECLARE_NAPI_PROPERTY("New", New),
     DECLARE_NAPI_PROPERTY("NewWithLength", NewWithLength),
   };