LibJS: Rewrite String.raw() closer to the specification

This includes not throwing a custom exception and using the
length_of_array_like abstract operation where required.

3 files changed, 29 insertions, 20 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
index 93434515ba..fd8477593e 100644
--- a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
+++ b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
@@ -150,7 +150,6 @@
     M(SpeciesConstructorDidNotCreate, "Species constructor did not create {}")                                                          \
     M(SpeciesConstructorReturned, "Species constructor returned {}")                                                                    \
     M(StringMatchAllNonGlobalRegExp, "RegExp argument is non-global")                                                                   \
-    M(StringRawCannotConvert, "Cannot convert property 'raw' to object from {}")                                                        \
     M(StringRepeatCountMustBe, "repeat count must be a {} number")                                                                      \
     M(ThisHasNotBeenInitialized, "|this| has not been initialized")                                                                     \
     M(ThisIsAlreadyInitialized, "|this| is already initialized")                                                                        \
diff --git a/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp b/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
index 7762f8c69e..c89bdd22af 100644
--- a/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
@@ -6,6 +6,7 @@
 
 #include <AK/StringBuilder.h>
 #include <AK/Utf32View.h>
+#include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Array.h>
 #include <LibJS/Runtime/Error.h>
 #include <LibJS/Runtime/GlobalObject.h>
@@ -68,41 +69,50 @@ Value StringConstructor::construct(FunctionObject&)
 // 22.1.2.4 String.raw ( template, ...substitutions ), https://tc39.es/ecma262/#sec-string.raw
 JS_DEFINE_NATIVE_FUNCTION(StringConstructor::raw)
 {
-    auto* template_object = vm.argument(0).to_object(global_object);
+    auto* cooked = vm.argument(0).to_object(global_object);
     if (vm.exception())
         return {};
 
-    auto raw = template_object->get(vm.names.raw);
+    auto raw_value = cooked->get(vm.names.raw).value_or(js_undefined());
     if (vm.exception())
         return {};
-    if (raw.is_empty() || raw.is_nullish()) {
-        vm.throw_exception<TypeError>(global_object, ErrorType::StringRawCannotConvert, raw.is_null() ? "null" : "undefined");
+
+    auto* raw = raw_value.to_object(global_object);
+    if (vm.exception())
         return {};
-    }
-    // FIXME: This should use length_of_array_like() and work with any object
-    if (!raw.is_object() || !raw.as_object().is_array())
+
+    auto literal_segments = length_of_array_like(global_object, *raw);
+    if (vm.exception())
+        return {};
+
+    if (literal_segments == 0)
         return js_string(vm, "");
 
-    auto* array = static_cast<Array*>(raw.to_object(global_object));
-    auto& raw_array_elements = array->indexed_properties();
-    StringBuilder builder;
+    const auto number_of_substituions = vm.argument_count() - 1;
 
-    for (size_t i = 0; i < raw_array_elements.array_like_size(); ++i) {
-        auto result = raw_array_elements.get(array, i);
+    StringBuilder builder;
+    for (size_t i = 0; i < literal_segments; ++i) {
+        auto next_key = String::number(i);
+        auto next_segment_value = raw->get(next_key).value_or(js_undefined());
         if (vm.exception())
             return {};
-        if (!result.has_value())
-            continue;
-        builder.append(result.value().value.to_string(global_object));
+        auto next_segment = next_segment_value.to_string(global_object);
         if (vm.exception())
             return {};
-        if (i + 1 < vm.argument_count() && i < raw_array_elements.array_like_size() - 1) {
-            builder.append(vm.argument(i + 1).to_string(global_object));
+
+        builder.append(next_segment);
+
+        if (i + 1 == literal_segments)
+            break;
+
+        if (i < number_of_substituions) {
+            auto next = vm.argument(i + 1);
+            auto next_sub = next.to_string(global_object);
             if (vm.exception())
                 return {};
+            builder.append(next_sub);
         }
     }
-
     return js_string(vm, builder.build());
 }
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/String/String.raw.js b/Userland/Libraries/LibJS/Tests/builtins/String/String.raw.js
index a866276034..27414d57ce 100644
--- a/Userland/Libraries/LibJS/Tests/builtins/String/String.raw.js
+++ b/Userland/Libraries/LibJS/Tests/builtins/String/String.raw.js
@@ -27,5 +27,5 @@ test("basic functionality", () => {
 test("passing object with no 'raw' property", () => {
     expect(() => {
         String.raw({});
-    }).toThrowWithMessage(TypeError, "Cannot convert property 'raw' to object from undefined");
+    }).toThrowWithMessage(TypeError, "ToObject on null or undefined");
 });