LibJS: Convert IfAbruptRejectPromise AO to a GNU statement expression

GNU statement expressions fit the definition of IfAbruptRejectPromise
rather nicely, where we need to reject the failed promise (and return
the failed promise itself) on failure, and otherwise store a value on
success.

1 files changed, 24 insertions, 71 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/PromiseConstructor.cpp b/Userland/Libraries/LibJS/Runtime/PromiseConstructor.cpp
index 58374d8c4f..a0e3c5c0f9 100644
--- a/Userland/Libraries/LibJS/Runtime/PromiseConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/PromiseConstructor.cpp
@@ -35,33 +35,18 @@ static ThrowCompletionOr<Value> get_promise_resolve(GlobalObject& global_object,
 }
 
 // 27.2.1.1.1 IfAbruptRejectPromise ( value, capability ), https://tc39.es/ecma262/#sec-ifabruptrejectpromise
-template<typename ValueType>
-static Optional<Value> if_abrupt_reject_promise(GlobalObject& global_object, ValueType const& value_or_error, PromiseCapability capability)
-{
-    auto& vm = global_object.vm();
-
-    // FIXME: This is temporary multi-type support. When all callers to this method are transformed
-    //        to use ThrowCompletionOr, the 'else' clause (and template) can be dropped.
-    if constexpr (requires { value_or_error.is_throw_completion(); }) {
-        if (value_or_error.is_throw_completion()) {
-            vm.clear_exception();
-            vm.stop_unwind();
-
-            (void)vm.call(*capability.reject, js_undefined(), value_or_error.throw_completion().value());
-            return capability.promise;
-        }
-    } else {
-        if (auto* exception = vm.exception()) {
-            vm.clear_exception();
-            vm.stop_unwind();
-
-            (void)vm.call(*capability.reject, js_undefined(), exception->value());
-            return capability.promise;
-        }
-    }
-
-    return {};
-}
+#define TRY_OR_REJECT(vm, capability, expression)                                                         \
+    ({                                                                                                    \
+        auto _temporary_result = (expression);                                                            \
+        if (_temporary_result.is_error()) {                                                               \
+            vm.clear_exception();                                                                         \
+            vm.stop_unwind();                                                                             \
+                                                                                                          \
+            (void)vm.call(*capability.reject, js_undefined(), _temporary_result.release_error().value()); \
+            return capability.promise;                                                                    \
+        }                                                                                                 \
+        _temporary_result.release_value();                                                                \
+    })
 
 static bool iterator_record_is_complete(GlobalObject& global_object, Object& iterator_record)
 {
@@ -287,15 +272,8 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all)
     if (vm.exception())
         return {};
 
-    auto promise_resolve_or_error = get_promise_resolve(global_object, constructor);
-    if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto promise_resolve = promise_resolve_or_error.release_value();
-
-    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto* iterator_record = iterator_record_or_error.release_value();
+    auto promise_resolve = TRY_OR_REJECT(vm, promise_capability, get_promise_resolve(global_object, constructor));
+    auto* iterator_record = TRY_OR_REJECT(vm, promise_capability, get_iterator(global_object, vm.argument(0)));
 
     auto result = perform_promise_all(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (auto* exception = vm.exception()) {
@@ -307,8 +285,7 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all)
             result_error = iterator_close(*iterator_record, move(result_error));
         }
 
-        auto abrupt = if_abrupt_reject_promise(global_object, result_error, promise_capability);
-        return abrupt.value();
+        TRY_OR_REJECT(vm, promise_capability, result_error);
     }
 
     return result;
@@ -323,15 +300,8 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all_settled)
     if (vm.exception())
         return {};
 
-    auto promise_resolve_or_error = get_promise_resolve(global_object, constructor);
-    if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto promise_resolve = promise_resolve_or_error.release_value();
-
-    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto* iterator_record = iterator_record_or_error.release_value();
+    auto promise_resolve = TRY_OR_REJECT(vm, promise_capability, get_promise_resolve(global_object, constructor));
+    auto* iterator_record = TRY_OR_REJECT(vm, promise_capability, get_iterator(global_object, vm.argument(0)));
 
     auto result = perform_promise_all_settled(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (auto* exception = vm.exception()) {
@@ -343,8 +313,7 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::all_settled)
             result_error = iterator_close(*iterator_record, move(result_error));
         }
 
-        auto abrupt = if_abrupt_reject_promise(global_object, result_error, promise_capability);
-        return abrupt.value();
+        TRY_OR_REJECT(vm, promise_capability, result_error);
     }
 
     return result;
@@ -359,15 +328,8 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::any)
     if (vm.exception())
         return {};
 
-    auto promise_resolve_or_error = get_promise_resolve(global_object, constructor);
-    if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto promise_resolve = promise_resolve_or_error.release_value();
-
-    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto* iterator_record = iterator_record_or_error.release_value();
+    auto promise_resolve = TRY_OR_REJECT(vm, promise_capability, get_promise_resolve(global_object, constructor));
+    auto* iterator_record = TRY_OR_REJECT(vm, promise_capability, get_iterator(global_object, vm.argument(0)));
 
     auto result = perform_promise_any(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (auto* exception = vm.exception()) {
@@ -379,8 +341,7 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::any)
             result_error = iterator_close(*iterator_record, move(result_error));
         }
 
-        auto abrupt = if_abrupt_reject_promise(global_object, result_error, promise_capability);
-        return abrupt.value();
+        TRY_OR_REJECT(vm, promise_capability, result_error);
     }
 
     return result;
@@ -395,15 +356,8 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::race)
     if (vm.exception())
         return {};
 
-    auto promise_resolve_or_error = get_promise_resolve(global_object, constructor);
-    if (auto abrupt = if_abrupt_reject_promise(global_object, promise_resolve_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto promise_resolve = promise_resolve_or_error.release_value();
-
-    auto iterator_record_or_error = get_iterator(global_object, vm.argument(0));
-    if (auto abrupt = if_abrupt_reject_promise(global_object, iterator_record_or_error, promise_capability); abrupt.has_value())
-        return abrupt.value();
-    auto* iterator_record = iterator_record_or_error.release_value();
+    auto promise_resolve = TRY_OR_REJECT(vm, promise_capability, get_promise_resolve(global_object, constructor));
+    auto* iterator_record = TRY_OR_REJECT(vm, promise_capability, get_iterator(global_object, vm.argument(0)));
 
     auto result = perform_promise_race(global_object, *iterator_record, constructor, promise_capability, promise_resolve);
     if (auto* exception = vm.exception()) {
@@ -415,8 +369,7 @@ JS_DEFINE_OLD_NATIVE_FUNCTION(PromiseConstructor::race)
             result_error = iterator_close(*iterator_record, move(result_error)); // iterator_close() may invoke vm.call(), which VERIFYs no exception.
         }
 
-        auto abrupt = if_abrupt_reject_promise(global_object, result_error, promise_capability);
-        return abrupt.value();
+        TRY_OR_REJECT(vm, promise_capability, result_error);
     }
 
     return result;