From f2527c8c81385c105039420a967de9110c37edc3 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Sat, 21 Jan 2023 22:34:42 -0500
Subject: [PATCH] LibJS: Add a fallible variant of Array::create_from

---
 Userland/Libraries/LibJS/Runtime/Array.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Userland/Libraries/LibJS/Runtime/Array.h b/Userland/Libraries/LibJS/Runtime/Array.h
index 77224c4f1ba..601e90445ce 100644
--- a/Userland/Libraries/LibJS/Runtime/Array.h
+++ b/Userland/Libraries/LibJS/Runtime/Array.h
@@ -8,12 +8,14 @@
 #pragma once
 
 #include <AK/Assertions.h>
+#include <AK/Concepts.h>
 #include <AK/Function.h>
 #include <AK/Span.h>
 #include <AK/Vector.h>
 #include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Object.h>
+#include <LibJS/Runtime/VM.h>
 
 namespace JS {
 
@@ -23,6 +25,7 @@ class Array : public Object {
 public:
     static ThrowCompletionOr<NonnullGCPtr<Array>> create(Realm&, u64 length, Object* prototype = nullptr);
     static NonnullGCPtr<Array> create_from(Realm&, Vector<Value> const&);
+
     // Non-standard but equivalent to CreateArrayFromList.
     template<typename T>
     static NonnullGCPtr<Array> create_from(Realm& realm, Span<T const> elements, Function<Value(T const&)> map_fn)
@@ -35,6 +38,19 @@ public:
         return Array::create_from(realm, values);
     }
 
+    // Non-standard but equivalent to CreateArrayFromList.
+    template<typename T, FallibleFunction<T const&> Callback>
+    static ThrowCompletionOr<NonnullGCPtr<Array>> try_create_from(VM& vm, Realm& realm, Span<T const> elements, Callback map_fn)
+    {
+        auto values = MarkedVector<Value> { realm.heap() };
+        TRY_OR_THROW_OOM(vm, values.try_ensure_capacity(elements.size()));
+
+        for (auto const& element : elements)
+            TRY_OR_THROW_OOM(vm, values.try_append(TRY(map_fn(element))));
+
+        return Array::create_from(realm, values);
+    }
+
     virtual ~Array() override = default;
 
     virtual ThrowCompletionOr<Optional<PropertyDescriptor>> internal_get_own_property(PropertyKey const&) const override;