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LibJS: Update spec steps / links for the JSON modules proposal

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This proposal has reached stage 4 and been merged into the main ECMA-262
spec. See:

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Timothy Flynn 2025-04-28 16:22:48 -04:00 • committed by Tim Flynn
parent 3867a192a1
commit 2401764697
Notes: github-actions[bot] 2025-04-29 11:34:58 +00:00
5 changed files with 191 additions and 130 deletions
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212
Libraries/LibJS/SyntheticModule.cpp
View file

@ -7,6 +7,7 @@
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Completion.h>
#include <LibJS/Runtime/GlobalEnvironment.h>
#include <LibJS/Runtime/JSONObject.h>
#include <LibJS/Runtime/ModuleEnvironment.h>
#include <LibJS/Runtime/PromiseCapability.h>
#include <LibJS/Runtime/PromiseConstructor.h>
@ -17,23 +18,94 @@ namespace JS {
GC_DEFINE_ALLOCATOR(SyntheticModule);
// 1.2.1 CreateSyntheticModule ( exportNames, evaluationSteps, realm, hostDefined ), https://tc39.es/proposal-json-modules/#sec-createsyntheticmodule
SyntheticModule::SyntheticModule(Vector<FlyString> export_names, SyntheticModule::EvaluationFunction evaluation_steps, Realm& realm, StringView filename)
: Module(realm, filename)
SyntheticModule::SyntheticModule(Realm& realm, Vector<FlyString> export_names, SyntheticModule::EvaluationFunction evaluation_steps, ByteString filename)
: Module(realm, move(filename))
, m_export_names(move(export_names))
, m_evaluation_steps(move(evaluation_steps))
, m_evaluation_steps(evaluation_steps)
{
// 1. Return Synthetic Module Record { [[Realm]]: realm, [[Environment]]: undefined, [[Namespace]]: undefined, [[HostDefined]]: hostDefined, [[ExportNames]]: exportNames, [[EvaluationSteps]]: evaluationSteps }.
}
// 1.2.3.1 GetExportedNames( exportStarSet ), https://tc39.es/proposal-json-modules/#sec-smr-getexportednames
void SyntheticModule::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_evaluation_steps);
}
// 16.2.1.8.1 CreateDefaultExportSyntheticModule ( defaultExport ), https://tc39.es/ecma262/#sec-create-default-export-synthetic-module
GC::Ref<SyntheticModule> SyntheticModule::create_default_export_synthetic_module(Realm& realm, Value default_export, ByteString filename)
{
// 1. Let realm be the current Realm Record.
// 2. Let setDefaultExport be a new Abstract Closure with parameters (module) that captures defaultExport and
// performs the following steps when called:
auto set_default_export = GC::create_function(realm.heap(), [default_export](SyntheticModule& module) -> ThrowCompletionOr<void> {
// a. Perform SetSyntheticModuleExport(module, "default", defaultExport).
TRY(module.set_synthetic_module_export("default"_fly_string, default_export));
// b. Return NormalCompletion(UNUSED).
return {};
});
// 2. Return the Synthetic Module Record { [[Realm]]: realm, [[Environment]]: empty, [[Namespace]]: empty, [[HostDefined]]: undefined, [[ExportNames]]: « "default" », [[EvaluationSteps]]: setDefaultExport }.
return realm.heap().allocate<SyntheticModule>(realm, Vector<FlyString> { "default"_fly_string }, set_default_export, move(filename));
}
// 16.2.1.8.2 ParseJSONModule ( source ), https://tc39.es/ecma262/#sec-create-default-export-synthetic-module
ThrowCompletionOr<GC::Ref<Module>> parse_json_module(Realm& realm, StringView source_text, ByteString filename)
{
auto& vm = realm.vm();
// 1. Let json be ? ParseJSON(source).
auto json = TRY(JSONObject::parse_json(vm, source_text));
// 3. Return CreateDefaultExportSyntheticModule(json).
return SyntheticModule::create_default_export_synthetic_module(realm, json, move(filename));
}
// 16.2.1.8.3 SetSyntheticModuleExport ( module, exportName, exportValue ), https://tc39.es/ecma262/#sec-setsyntheticmoduleexport
ThrowCompletionOr<void> SyntheticModule::set_synthetic_module_export(FlyString const& export_name, Value export_value)
{
auto& vm = this->vm();
// 1. Assert: module.[[ExportNames]] contains exportName.
VERIFY(m_export_names.contains_slow(export_name));
// 2. Let envRec be module.[[Environment]].
auto environment_record = environment();
// 3. Assert: envRec is not EMPTY.
VERIFY(environment_record);
// 4. Perform envRec.SetMutableBinding(exportName, exportValue, true).
TRY(environment_record->set_mutable_binding(vm, export_name, export_value, true));
// 5. Return UNUSED.
return {};
}
// 16.2.1.8.4.1 LoadRequestedModules ( ), https://tc39.es/ecma262/#sec-smr-LoadRequestedModules
PromiseCapability& SyntheticModule::load_requested_modules(GC::Ptr<GraphLoadingState::HostDefined>)
{
auto& realm = this->realm();
auto& vm = realm.vm();
// 1. Return ! PromiseResolve(%Promise%, undefined).
auto promise_capability = MUST(new_promise_capability(vm, realm.intrinsics().promise_constructor()));
(void)MUST(call(vm, *promise_capability->resolve(), js_undefined(), js_undefined()));
// NOTE: We need to return a PromiseCapability, rather than a Promise, so we flatten PromiseResolve here.
// This is likely a spec bug, see https://matrixlogs.bakkot.com/WHATWG/2023-02-13#L1
return promise_capability;
}
// 16.2.1.8.4.2 GetExportedNames ( ), https://tc39.es/ecma262/#sec-smr-getexportednames
Vector<FlyString> SyntheticModule::get_exported_names(VM&, HashTable<Module const*>&)
{
// 1. Return module.[[ExportNames]].
return m_export_names;
}
// 1.2.3.2 ResolveExport( exportName, resolveSet ), https://tc39.es/proposal-json-modules/#sec-smr-resolveexport
// 16.2.1.8.4.3 ResolveExport ( exportName ), https://tc39.es/ecma262/#sec-smr-resolveexport
ResolvedBinding SyntheticModule::resolve_export(VM&, FlyString const& export_name, Vector<ResolvedBinding>)
{
// 1. If module.[[ExportNames]] does not contain exportName, return null.
@ -44,132 +116,78 @@ ResolvedBinding SyntheticModule::resolve_export(VM&, FlyString const& export_nam
return ResolvedBinding { ResolvedBinding::BindingName, this, export_name };
}
// 1.2.3.3 Link ( ), https://tc39.es/proposal-json-modules/#sec-smr-instantiate
// 16.2.1.8.4.4 Link ( ), https://tc39.es/ecma262/#sec-smr-Link
ThrowCompletionOr<void> SyntheticModule::link(VM& vm)
{
// Note: Has some changes from PR: https://github.com/tc39/proposal-json-modules/pull/13.
// Which includes renaming it from Instantiate ( ) to Link ( ).
// 1. Let realm be module.[[Realm]].
// 2. Assert: realm is not undefined.
// Note: This must be true because we use a reference.
auto& realm = this->realm();
// 3. Let env be NewModuleEnvironment(realm.[[GlobalEnv]]).
auto environment = vm.heap().allocate<ModuleEnvironment>(&realm().global_environment());
// 2. Let env be NewModuleEnvironment(realm.[[GlobalEnv]]).
auto environment = vm.heap().allocate<ModuleEnvironment>(&realm.global_environment());
// 4. Set module.[[Environment]] to env.
// 3. Set module.[[Environment]] to env.
set_environment(environment);
// 5. For each exportName in module.[[ExportNames]],
for (auto& export_name : m_export_names) {
// a. Perform ! envRec.CreateMutableBinding(exportName, false).
// 4. For each String exportName of module.[[ExportNames]], do
for (auto const& export_name : m_export_names) {
// a. Perform ! env.CreateMutableBinding(exportName, false).
MUST(environment->create_mutable_binding(vm, export_name, false));
// b. Perform ! envRec.InitializeBinding(exportName, undefined, normal).
// b. Perform ! env.InitializeBinding(exportName, undefined).
MUST(environment->initialize_binding(vm, export_name, js_undefined(), Environment::InitializeBindingHint::Normal));
}
// 6. Return unused.
// 5. Return NormalCompletion(unused).
return {};
}
// 1.2.3.4 Evaluate ( ), https://tc39.es/proposal-json-modules/#sec-smr-Evaluate
// 16.2.1.8.4.5 Evaluate ( ), https://tc39.es/ecma262/#sec-smr-Evaluate
ThrowCompletionOr<GC::Ref<Promise>> SyntheticModule::evaluate(VM& vm)
{
// Note: Has some changes from PR: https://github.com/tc39/proposal-json-modules/pull/13.
// 1. Suspend the currently running execution context.
// NOTE: Done by the push on step 8.
auto& realm = this->realm();
// 2. Let moduleContext be a new ECMAScript code execution context.
// 1. Let moduleContext be a new ECMAScript code execution context.
// 2. Set the Function of moduleContext to null.
ExecutionContext* module_context = nullptr;
ALLOCATE_EXECUTION_CONTEXT_ON_NATIVE_STACK(module_context, 0, 0);
// 3. Set the Function of moduleContext to null.
// Note: This is the default value.
// 3. Set the Realm of moduleContext to module.[[Realm]].
module_context->realm = &realm;
// 4. Set the Realm of moduleContext to module.[[Realm]].
module_context->realm = &realm();
// 5. Set the ScriptOrModule of moduleContext to module.
// 4. Set the ScriptOrModule of moduleContext to module.
module_context->script_or_module = GC::Ref<Module>(*this);
// 6. Set the VariableEnvironment of moduleContext to module.[[Environment]].
// 5. Set the VariableEnvironment of moduleContext to module.[[Environment]].
module_context->variable_environment = environment();
// 7. Set the LexicalEnvironment of moduleContext to module.[[Environment]].
// 6. Set the LexicalEnvironment of moduleContext to module.[[Environment]].
module_context->lexical_environment = environment();
// 8. Push moduleContext on to the execution context stack; moduleContext is now the running execution context.
// 7. Suspend the running execution context.
// 8. Push moduleContext onto the execution context stack; moduleContext is now the running execution context.
TRY(vm.push_execution_context(*module_context, {}));
// 9. Let result be the result of performing module.[[EvaluationSteps]](module).
auto result = m_evaluation_steps(*this);
// 9. Let steps be module.[[EvaluationSteps]].
// 10. Let result be Completion(steps(module)).
auto result = m_evaluation_steps->function()(*this);
// 10. Suspend moduleContext and remove it from the execution context stack.
// 11. Suspend moduleContext and remove it from the execution context stack.
// 12. Resume the context that is now on the top of the execution context stack as the running execution context.
vm.pop_execution_context();
// 11. Resume the context that is now on the top of the execution context stack as the running execution context.
// 13. Let pc be ! NewPromiseCapability(%Promise%).
auto promise_capability = MUST(new_promise_capability(vm, realm.intrinsics().promise_constructor()));
// 12. Return Completion(result).
// Note: Because we expect it to return a promise we convert this here.
auto promise = Promise::create(realm());
if (result.is_error()) {
promise->reject(result.throw_completion().value());
} else {
// Note: This value probably isn't visible to JS code? But undefined is fine anyway.
promise->fulfill(js_undefined());
}
// 14. IfAbruptRejectPromise(result, pc).
if (result.is_error())
MUST(call(vm, *promise_capability->reject(), JS::js_undefined(), result.release_error().value()));
return promise;
}
// 15. Perform ! Call(pc.[[Resolve]], undefined, « undefined »).
else
MUST(call(vm, *promise_capability->resolve(), js_undefined(), js_undefined()));
// 1.2.2 SetSyntheticModuleExport ( module, exportName, exportValue ), https://tc39.es/proposal-json-modules/#sec-setsyntheticmoduleexport
ThrowCompletionOr<void> SyntheticModule::set_synthetic_module_export(FlyString const& export_name, Value export_value)
{
auto& vm = this->realm().vm();
// Note: Has some changes from PR: https://github.com/tc39/proposal-json-modules/pull/13.
// 1. Return ? module.[[Environment]].SetMutableBinding(name, value, true).
return environment()->set_mutable_binding(vm, export_name, export_value, true);
}
// 1.3 CreateDefaultExportSyntheticModule ( defaultExport ), https://tc39.es/proposal-json-modules/#sec-create-default-export-synthetic-module
GC::Ref<SyntheticModule> SyntheticModule::create_default_export_synthetic_module(Value default_export, Realm& realm, StringView filename)
{
// Note: Has some changes from PR: https://github.com/tc39/proposal-json-modules/pull/13.
// 1. Let closure be the a Abstract Closure with parameters (module) that captures defaultExport and performs the following steps when called:
auto closure = [default_export = make_root(default_export)](SyntheticModule& module) -> ThrowCompletionOr<void> {
// a. Return ? module.SetSyntheticExport("default", defaultExport).
return module.set_synthetic_module_export("default"_fly_string, default_export.value());
};
// 2. Return CreateSyntheticModule("default", closure, realm)
return realm.heap().allocate<SyntheticModule>(Vector<FlyString> { "default"_fly_string }, move(closure), realm, filename);
}
// 1.4 ParseJSONModule ( source ), https://tc39.es/proposal-json-modules/#sec-parse-json-module
ThrowCompletionOr<GC::Ref<Module>> parse_json_module(StringView source_text, Realm& realm, StringView filename)
{
auto& vm = realm.vm();
// 1. Let jsonParse be realm's intrinsic object named "%JSON.parse%".
auto json_parse = realm.intrinsics().json_parse_function();
// 2. Let json be ? Call(jsonParse, undefined, « sourceText »).
auto json = TRY(call(vm, *json_parse, js_undefined(), PrimitiveString::create(realm.vm(), source_text)));
// 3. Return CreateDefaultExportSyntheticModule(json, realm, hostDefined).
return SyntheticModule::create_default_export_synthetic_module(json, realm, filename);
}
// 1.2.3.1 LoadRequestedModules ( ), https://tc39.es/proposal-json-modules/#sec-smr-LoadRequestedModules
PromiseCapability& SyntheticModule::load_requested_modules(GC::Ptr<GraphLoadingState::HostDefined>)
{
// 1. Return ! PromiseResolve(%Promise%, undefined).
auto& constructor = *vm().current_realm()->intrinsics().promise_constructor();
auto promise_capability = MUST(new_promise_capability(vm(), &constructor));
MUST(call(vm(), *promise_capability->resolve(), js_undefined(), js_undefined()));
return promise_capability;
// 16. Return pc.[[Promise]].
return static_cast<Promise&>(*promise_capability->promise());
}
}