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ladybird/Libraries/LibJS/SourceTextModule.cpp
Luke Wilde 6319dedbcd LibJS: Perform TLA async function construction in the module context 
Previously it was only pushing the module context for the call to
capture the module execution context. This is incorrect, as the capture
occurs upon function construction. This resulted in it capturing the
execution context that execute_module was called from, instead of the
newly created module_context.
f87041bf3a/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp (L92)

This can be demonstrated with the following setup:
index.html:
```html
<script>
    var foo = 1;
</script>
<script type="module">
    import {test} from "./scriptA.mjs";
</script>
```

scriptA.mjs:
```js
function foo() {
	return {a: "b"};
}
export let test = await foo();
```

Before this fix, this would throw:
```
[TypeError] 1 is not a function (evaluated from 'foo')
    at module code with top-level await
    at module code with top-level await
    at <unknown>
    at <unknown>
```

Fixes #2245.
2024-11-15 18:52:22 +01:00

791 lines
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/*
* Copyright (c) 2021-2023, Andreas Kling <andreas@ladybird.org>
* Copyright (c) 2022, David Tuin <davidot@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/QuickSort.h>
#include <LibJS/Bytecode/Interpreter.h>
#include <LibJS/Parser.h>
#include <LibJS/Runtime/AsyncFunctionDriverWrapper.h>
#include <LibJS/Runtime/ECMAScriptFunctionObject.h>
#include <LibJS/Runtime/GlobalEnvironment.h>
#include <LibJS/Runtime/ModuleEnvironment.h>
#include <LibJS/Runtime/PromiseCapability.h>
#include <LibJS/SourceTextModule.h>
namespace JS {
GC_DEFINE_ALLOCATOR(SourceTextModule);
// 16.2.2.2 Static Semantics: WithClauseToAttributes, https://tc39.es/proposal-import-attributes/#sec-with-clause-to-attributes
static Vector<ImportAttribute> with_clause_to_assertions(Vector<ImportAttribute> const& source_attributes)
{
// WithClause : AttributesKeyword { WithEntries , opt }
// 1. Let attributes be WithClauseToAttributes of WithEntries.
Vector<ImportAttribute> attributes;
// AssertEntries : AssertionKey : StringLiteral
// AssertEntries : AssertionKey : StringLiteral , WithEntries
for (auto const& attribute : source_attributes) {
// 1. Let key be the PropName of AttributeKey.
// 2. Let entry be the ImportAttribute Record { [[Key]]: key, [[Value]]: SV of StringLiteral }.
// 3. Return « entry ».
attributes.empend(attribute);
}
// 2. Sort attributes according to the lexicographic order of their [[Key]] fields, treating the value of each such field as a sequence of UTF-16 code unit values. NOTE: This sorting is observable only in that hosts are prohibited from distinguishing among attributes by the order they occur in.
// Note: The sorting is done in construction of the ModuleRequest object.
// 3. Return attributes.
return attributes;
}
// 16.2.1.3 Static Semantics: ModuleRequests, https://tc39.es/ecma262/#sec-static-semantics-modulerequests
static Vector<ModuleRequest> module_requests(Program& program)
{
// A List of all the ModuleSpecifier strings used by the module represented by this record to request the importation of a module.
// Note: The List is source text occurrence ordered!
struct RequestedModuleAndSourceIndex {
u32 source_offset { 0 };
ModuleRequest const* module_request { nullptr };
};
Vector<RequestedModuleAndSourceIndex> requested_modules_with_indices;
for (auto& import_statement : program.imports())
requested_modules_with_indices.empend(import_statement->start_offset(), &import_statement->module_request());
for (auto& export_statement : program.exports()) {
for (auto& export_entry : export_statement->entries()) {
if (!export_entry.is_module_request())
continue;
requested_modules_with_indices.empend(export_statement->start_offset(), &export_statement->module_request());
}
}
// Note: The List is source code occurrence ordered. https://tc39.es/proposal-import-attributes/#table-cyclic-module-fields
quick_sort(requested_modules_with_indices, [&](RequestedModuleAndSourceIndex const& lhs, RequestedModuleAndSourceIndex const& rhs) {
return lhs.source_offset < rhs.source_offset;
});
Vector<ModuleRequest> requested_modules_in_source_order;
requested_modules_in_source_order.ensure_capacity(requested_modules_with_indices.size());
for (auto& module : requested_modules_with_indices) {
// 16.2.1.3 Static Semantics: ModuleRequests, https://tc39.es/proposal-import-attributes/#sec-static-semantics-modulerequests
if (module.module_request->attributes.is_empty()) {
// ExportDeclaration : export ExportFromClause FromClause ;
// ImportDeclaration : import ImportClause FromClause ;
// 2. Let specifier be SV of FromClause.
// 3. Return a List whose sole element is the ModuleRequest Record { [[Specifer]]: specifier, [[Attributes]]: « » }.
requested_modules_in_source_order.empend(module.module_request->module_specifier);
} else {
// ExportDeclaration : export ExportFromClause FromClause WithClause ;
// ImportDeclaration : import ImportClause FromClause WithClause ;
// 1. Let specifier be the SV of FromClause.
// 2. Let attributes be WithClauseToAttributes of WithClause.
auto attributes = with_clause_to_assertions(module.module_request->attributes);
// NOTE: We have to modify the attributes in place because else it might keep unsupported ones.
const_cast<ModuleRequest*>(module.module_request)->attributes = move(attributes);
// 3. Return a List whose sole element is the ModuleRequest Record { [[Specifer]]: specifier, [[Attributes]]: attributes }.
requested_modules_in_source_order.empend(module.module_request->module_specifier, module.module_request->attributes);
}
}
return requested_modules_in_source_order;
}
SourceTextModule::SourceTextModule(Realm& realm, StringView filename, Script::HostDefined* host_defined, bool has_top_level_await, NonnullRefPtr<Program> body, Vector<ModuleRequest> requested_modules,
Vector<ImportEntry> import_entries, Vector<ExportEntry> local_export_entries,
Vector<ExportEntry> indirect_export_entries, Vector<ExportEntry> star_export_entries,
RefPtr<ExportStatement const> default_export)
: CyclicModule(realm, filename, has_top_level_await, move(requested_modules), host_defined)
, m_ecmascript_code(move(body))
, m_execution_context(ExecutionContext::create())
, m_import_entries(move(import_entries))
, m_local_export_entries(move(local_export_entries))
, m_indirect_export_entries(move(indirect_export_entries))
, m_star_export_entries(move(star_export_entries))
, m_default_export(move(default_export))
{
}
SourceTextModule::~SourceTextModule() = default;
void SourceTextModule::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_import_meta);
m_execution_context->visit_edges(visitor);
}
// 16.2.1.6.1 ParseModule ( sourceText, realm, hostDefined ), https://tc39.es/ecma262/#sec-parsemodule
Result<GC::Ref<SourceTextModule>, Vector<ParserError>> SourceTextModule::parse(StringView source_text, Realm& realm, StringView filename, Script::HostDefined* host_defined)
{
// 1. Let body be ParseText(sourceText, Module).
auto parser = Parser(Lexer(source_text, filename), Program::Type::Module);
auto body = parser.parse_program();
// 2. If body is a List of errors, return body.
if (parser.has_errors())
return parser.errors();
// 3. Let requestedModules be the ModuleRequests of body.
auto requested_modules = module_requests(*body);
// 4. Let importEntries be ImportEntries of body.
Vector<ImportEntry> import_entries;
for (auto const& import_statement : body->imports())
import_entries.extend(import_statement->entries());
// 5. Let importedBoundNames be ImportedLocalNames(importEntries).
// Note: Since we have to potentially extract the import entry we just use importEntries
// In the future it might be an optimization to have a set/map of string to speed up the search.
// 6. Let indirectExportEntries be a new empty List.
Vector<ExportEntry> indirect_export_entries;
// 7. Let localExportEntries be a new empty List.
Vector<ExportEntry> local_export_entries;
// 8. Let starExportEntries be a new empty List.
Vector<ExportEntry> star_export_entries;
// Note: Not in the spec but makes it easier to find the default.
RefPtr<ExportStatement const> default_export;
// 9. Let exportEntries be ExportEntries of body.
// 10. For each ExportEntry Record ee of exportEntries, do
for (auto const& export_statement : body->exports()) {
if (export_statement->is_default_export()) {
VERIFY(!default_export);
VERIFY(export_statement->entries().size() == 1);
VERIFY(export_statement->has_statement());
auto const& entry = export_statement->entries()[0];
VERIFY(entry.kind == ExportEntry::Kind::NamedExport);
VERIFY(!entry.is_module_request());
VERIFY(import_entries.find_if(
[&](ImportEntry const& import_entry) {
return import_entry.local_name == entry.local_or_import_name;
})
.is_end());
default_export = export_statement;
}
for (auto const& export_entry : export_statement->entries()) {
// Special case, export {} from "module" should add "module" to
// required_modules but not any import or export so skip here.
if (export_entry.kind == ExportEntry::Kind::EmptyNamedExport) {
VERIFY(export_statement->entries().size() == 1);
break;
}
// a. If ee.[[ModuleRequest]] is null, then
if (!export_entry.is_module_request()) {
auto in_imported_bound_names = import_entries.find_if(
[&](ImportEntry const& import_entry) {
return import_entry.local_name == export_entry.local_or_import_name;
});
// i. If ee.[[LocalName]] is not an element of importedBoundNames, then
if (in_imported_bound_names.is_end()) {
// 1. Append ee to localExportEntries.
local_export_entries.empend(export_entry);
}
// ii. Else,
else {
// 1. Let ie be the element of importEntries whose [[LocalName]] is the same as ee.[[LocalName]].
auto& import_entry = *in_imported_bound_names;
// 2. If ie.[[ImportName]] is namespace-object, then
if (import_entry.is_namespace()) {
// a. NOTE: This is a re-export of an imported module namespace object.
// b. Append ee to localExportEntries.
local_export_entries.empend(export_entry);
}
// 3. Else,
else {
// a. NOTE: This is a re-export of a single name.
// b. Append the ExportEntry Record { [[ModuleRequest]]: ie.[[ModuleRequest]], [[ImportName]]: ie.[[ImportName]], [[LocalName]]: null, [[ExportName]]: ee.[[ExportName]] } to indirectExportEntries.
indirect_export_entries.empend(ExportEntry::indirect_export_entry(import_entry.module_request(), export_entry.export_name, import_entry.import_name));
}
}
}
// b. Else if ee.[[ImportName]] is all-but-default, then
else if (export_entry.kind == ExportEntry::Kind::ModuleRequestAllButDefault) {
// i. Assert: ee.[[ExportName]] is null.
VERIFY(!export_entry.export_name.has_value());
// ii. Append ee to starExportEntries.
star_export_entries.empend(export_entry);
}
// c. Else,
else {
// i. Append ee to indirectExportEntries.
indirect_export_entries.empend(export_entry);
}
}
}
// 11. Let async be body Contains await.
bool async = body->has_top_level_await();
// 12. Return Source Text Module Record {
// [[Realm]]: realm, [[Environment]]: empty, [[Namespace]]: empty, [[CycleRoot]]: empty, [[HasTLA]]: async,
// [[AsyncEvaluation]]: false, [[TopLevelCapability]]: empty, [[AsyncParentModules]]: « »,
// [[PendingAsyncDependencies]]: empty, [[Status]]: unlinked, [[EvaluationError]]: empty,
// [[HostDefined]]: hostDefined, [[ECMAScriptCode]]: body, [[Context]]: empty, [[ImportMeta]]: empty,
// [[RequestedModules]]: requestedModules, [[ImportEntries]]: importEntries, [[LocalExportEntries]]: localExportEntries,
// [[IndirectExportEntries]]: indirectExportEntries, [[StarExportEntries]]: starExportEntries, [[DFSIndex]]: empty, [[DFSAncestorIndex]]: empty }.
return realm.heap().allocate<SourceTextModule>(
realm,
filename,
host_defined,
async,
move(body),
move(requested_modules),
move(import_entries),
move(local_export_entries),
move(indirect_export_entries),
move(star_export_entries),
move(default_export));
}
// 16.2.1.6.2 GetExportedNames ( [ exportStarSet ] ), https://tc39.es/ecma262/#sec-getexportednames
ThrowCompletionOr<Vector<DeprecatedFlyString>> SourceTextModule::get_exported_names(VM& vm, Vector<Module*> export_star_set)
{
dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] get_export_names of {}", filename());
// 1. Assert: module.[[Status]] is not new.
VERIFY(m_status != ModuleStatus::New);
// 2. If exportStarSet is not present, set exportStarSet to a new empty List.
// Note: This is done by default argument
// 3. If exportStarSet contains module, then
if (export_star_set.contains_slow(this)) {
// a. Assert: We've reached the starting point of an export * circularity.
// FIXME: How do we check that?
// b. Return a new empty List.
return Vector<DeprecatedFlyString> {};
}
// 4. Append module to exportStarSet.
export_star_set.append(this);
// 5. Let exportedNames be a new empty List.
Vector<DeprecatedFlyString> exported_names;
// 6. For each ExportEntry Record e of module.[[LocalExportEntries]], do
for (auto& entry : m_local_export_entries) {
// a. Assert: module provides the direct binding for this export.
// FIXME: How do we check that?
// b. Assert: e.[[ExportName]] is not null.
VERIFY(entry.export_name.has_value());
// c. Append e.[[ExportName]] to exportedNames.
exported_names.empend(entry.export_name.value());
}
// 7. For each ExportEntry Record e of module.[[IndirectExportEntries]], do
for (auto& entry : m_indirect_export_entries) {
// a. a. Assert: module imports a specific binding for this export.
// FIXME: How do we check that?
// b. Assert: e.[[ExportName]] is not null.
VERIFY(entry.export_name.has_value());
// c. Append e.[[ExportName]] to exportedNames.
exported_names.empend(entry.export_name.value());
}
// 8. For each ExportEntry Record e of module.[[StarExportEntries]], do
for (auto& entry : m_star_export_entries) {
// a. Assert: e.[[ModuleRequest]] is not null.
// b. Let requestedModule be GetImportedModule(module, e.[[ModuleRequest]]).
auto requested_module = get_imported_module(entry.module_request());
// c. Let starNames be ? requestedModule.GetExportedNames(exportStarSet).
auto star_names = TRY(requested_module->get_exported_names(vm, export_star_set));
// d. For each element n of starNames, do
for (auto& name : star_names) {
// i. If SameValue(n, "default") is false, then
if (name != "default"sv) {
// 1. If n is not an element of exportedNames, then
if (!exported_names.contains_slow(name)) {
// a. Append n to exportedNames.
exported_names.empend(name);
}
}
}
}
// 9. Return exportedNames.
return exported_names;
}
// 16.2.1.6.4 InitializeEnvironment ( ), https://tc39.es/ecma262/#sec-source-text-module-record-initialize-environment
ThrowCompletionOr<void> SourceTextModule::initialize_environment(VM& vm)
{
// 1. For each ExportEntry Record e of module.[[IndirectExportEntries]], do
for (auto& entry : m_indirect_export_entries) {
// a. Let resolution be ? module.ResolveExport(e.[[ExportName]]).
auto resolution = TRY(resolve_export(vm, entry.export_name.value()));
// b. If resolution is null or ambiguous, throw a SyntaxError exception.
if (!resolution.is_valid())
return vm.throw_completion<SyntaxError>(ErrorType::InvalidOrAmbiguousExportEntry, entry.export_name);
// c. Assert: resolution is a ResolvedBinding Record.
VERIFY(resolution.is_valid());
}
// 2. Assert: All named exports from module are resolvable.
// Note: We check all the indirect export entries above in step 1 and all
// the local named exports are resolvable by construction.
// 3. Let realm be module.[[Realm]].
// 4. Assert: realm is not undefined.
// Note: This must be true because we use a reference.
// 5. Let env be NewModuleEnvironment(realm.[[GlobalEnv]]).
auto environment = vm.heap().allocate<ModuleEnvironment>(&realm().global_environment());
// 6. Set module.[[Environment]] to env.
set_environment(environment);
// 7. For each ImportEntry Record in of module.[[ImportEntries]], do
for (auto& import_entry : m_import_entries) {
// a. Let importedModule be GetImportedModule(module, in.[[ModuleRequest]]).
auto imported_module = get_imported_module(import_entry.module_request());
// b. NOTE: The above call cannot fail because imported module requests are a subset of module.[[RequestedModules]], and these have been resolved earlier in this algorithm.
// c. If in.[[ImportName]] is namespace-object, then
if (import_entry.is_namespace()) {
// i. Let namespace be ? GetModuleNamespace(importedModule).
auto* namespace_ = TRY(imported_module->get_module_namespace(vm));
// ii. Perform ! env.CreateImmutableBinding(in.[[LocalName]], true).
MUST(environment->create_immutable_binding(vm, import_entry.local_name, true));
// iii. Perform ! env.InitializeBinding(in.[[LocalName]], namespace, normal).
MUST(environment->initialize_binding(vm, import_entry.local_name, namespace_, Environment::InitializeBindingHint::Normal));
}
// d. Else,
else {
// i. Let resolution be ? importedModule.ResolveExport(in.[[ImportName]]).
auto resolution = TRY(imported_module->resolve_export(vm, import_entry.import_name.value()));
// ii. If resolution is null or ambiguous, throw a SyntaxError exception.
if (!resolution.is_valid())
return vm.throw_completion<SyntaxError>(ErrorType::InvalidOrAmbiguousExportEntry, import_entry.import_name);
// iii. If resolution.[[BindingName]] is namespace, then
if (resolution.is_namespace()) {
// 1. Let namespace be ? GetModuleNamespace(resolution.[[Module]]).
auto* namespace_ = TRY(resolution.module->get_module_namespace(vm));
// 2. Perform ! env.CreateImmutableBinding(in.[[LocalName]], true).
MUST(environment->create_immutable_binding(vm, import_entry.local_name, true));
// 3. Perform ! env.InitializeBinding(in.[[LocalName]], namespace, normal).
MUST(environment->initialize_binding(vm, import_entry.local_name, namespace_, Environment::InitializeBindingHint::Normal));
}
// iv. Else,
else {
// 1. Perform env.CreateImportBinding(in.[[LocalName]], resolution.[[Module]], resolution.[[BindingName]]).
MUST(environment->create_import_binding(import_entry.local_name, resolution.module, resolution.export_name));
}
}
}
// 8. Let moduleContext be a new ECMAScript code execution context.
// Note: this has already been created during the construction of this object.
// 9. Set the Function of moduleContext to null.
// 10. Assert: module.[[Realm]] is not undefined.
// Note: This must be true because we use a reference.
// 11. Set the Realm of moduleContext to module.[[Realm]].
m_execution_context->realm = &realm();
// 12. Set the ScriptOrModule of moduleContext to module.
m_execution_context->script_or_module = GC::Ref<Module>(*this);
// 13. Set the VariableEnvironment of moduleContext to module.[[Environment]].
m_execution_context->variable_environment = environment;
// 14. Set the LexicalEnvironment of moduleContext to module.[[Environment]].
m_execution_context->lexical_environment = environment;
// 15. Set the PrivateEnvironment of moduleContext to null.
// 16. Set module.[[Context]] to moduleContext.
// Note: We're already working on that one.
// 17. Push moduleContext onto the execution context stack; moduleContext is now the running execution context.
TRY(vm.push_execution_context(*m_execution_context, {}));
// 18. Let code be module.[[ECMAScriptCode]].
// 19. Let varDeclarations be the VarScopedDeclarations of code.
// Note: We just loop through them in step 21.
// 20. Let declaredVarNames be a new empty List.
Vector<DeprecatedFlyString> declared_var_names;
// 21. For each element d of varDeclarations, do
// a. For each element dn of the BoundNames of d, do
// NOTE: Due to the use of MUST with `create_mutable_binding` and `initialize_binding` below,
// an exception should not result from `for_each_var_declared_identifier`.
MUST(m_ecmascript_code->for_each_var_declared_identifier([&](auto const& identifier) {
auto const& name = identifier.string();
// i. If dn is not an element of declaredVarNames, then
if (!declared_var_names.contains_slow(name)) {
// 1. Perform ! env.CreateMutableBinding(dn, false).
MUST(environment->create_mutable_binding(vm, name, false));
// 2. Perform ! env.InitializeBinding(dn, undefined, normal).
MUST(environment->initialize_binding(vm, name, js_undefined(), Environment::InitializeBindingHint::Normal));
// 3. Append dn to declaredVarNames.
declared_var_names.empend(name);
}
}));
// 22. Let lexDeclarations be the LexicallyScopedDeclarations of code.
// Note: We only loop through them in step 24.
// 23. Let privateEnv be null.
PrivateEnvironment* private_environment = nullptr;
// 24. For each element d of lexDeclarations, do
// NOTE: Due to the use of MUST in the callback, an exception should not result from `for_each_lexically_scoped_declaration`.
MUST(m_ecmascript_code->for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
// a. For each element dn of the BoundNames of d, do
// NOTE: Due to the use of MUST with `create_immutable_binding`, `create_mutable_binding` and `initialize_binding` below,
// an exception should not result from `for_each_bound_identifier`.
MUST(declaration.for_each_bound_identifier([&](auto const& identifier) {
auto const& name = identifier.string();
// i. If IsConstantDeclaration of d is true, then
if (declaration.is_constant_declaration()) {
// 1. Perform ! env.CreateImmutableBinding(dn, true).
MUST(environment->create_immutable_binding(vm, name, true));
}
// ii. Else,
else {
// 1. Perform ! env.CreateMutableBinding(dn, false).
MUST(environment->create_mutable_binding(vm, name, false));
}
// iii. If d is a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration, then
if (declaration.is_function_declaration()) {
VERIFY(is<FunctionDeclaration>(declaration));
auto const& function_declaration = static_cast<FunctionDeclaration const&>(declaration);
// 1. Let fo be InstantiateFunctionObject of d with arguments env and privateEnv.
// NOTE: Special case if the function is a default export of an anonymous function
// it has name "*default*" but internally should have name "default".
DeprecatedFlyString function_name = function_declaration.name();
if (function_name == ExportStatement::local_name_for_default)
function_name = "default"sv;
auto function = ECMAScriptFunctionObject::create(realm(), function_name, function_declaration.source_text(), function_declaration.body(), function_declaration.parameters(), function_declaration.function_length(), function_declaration.local_variables_names(), environment, private_environment, function_declaration.kind(), function_declaration.is_strict_mode(),
function_declaration.parsing_insights());
// 2. Perform ! env.InitializeBinding(dn, fo, normal).
MUST(environment->initialize_binding(vm, name, function, Environment::InitializeBindingHint::Normal));
}
}));
}));
// Note: The default export name is also part of the local lexical declarations but
// instead of making that a special case in the parser we just check it here.
// This is only needed for things which are not declarations.
// For more info check Parser::parse_export_statement.
// Furthermore, that declaration is not constant. so we take 24.a.ii
if (m_default_export) {
VERIFY(m_default_export->has_statement());
auto const& statement = m_default_export->statement();
if (!is<Declaration>(statement)) {
auto const& name = m_default_export->entries()[0].local_or_import_name;
dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] Adding default export to lexical declarations: local name: {}, Expression: {}", name, statement.class_name());
// 1. Perform ! env.CreateMutableBinding(dn, false).
MUST(environment->create_mutable_binding(vm, name.value(), false));
// Note: Since this is not a function declaration 24.a.iii never applies
}
}
// 25. Remove moduleContext from the execution context stack.
vm.pop_execution_context();
// 26. Return unused.
return {};
}
// 16.2.1.6.3 ResolveExport ( exportName [ , resolveSet ] ), https://tc39.es/ecma262/#sec-resolveexport
ThrowCompletionOr<ResolvedBinding> SourceTextModule::resolve_export(VM& vm, DeprecatedFlyString const& export_name, Vector<ResolvedBinding> resolve_set)
{
// 1. Assert: module.[[Status]] is not new.
VERIFY(m_status != ModuleStatus::New);
// 2. If resolveSet is not present, set resolveSet to a new empty List.
// Note: This is done by the default argument.
// 3. For each Record { [[Module]], [[ExportName]] } r of resolveSet, do
for (auto& [type, module, exported_name] : resolve_set) {
// a. If module and r.[[Module]] are the same Module Record and SameValue(exportName, r.[[ExportName]]) is true, then
if (module == this && exported_name == export_name) {
// i. Assert: This is a circular import request.
// ii. Return null.
return ResolvedBinding::null();
}
}
// 4. Append the Record { [[Module]]: module, [[ExportName]]: exportName } to resolveSet.
resolve_set.append({ ResolvedBinding::Type::BindingName, this, export_name });
// 5. For each ExportEntry Record e of module.[[LocalExportEntries]], do
for (auto& entry : m_local_export_entries) {
// a. If SameValue(exportName, e.[[ExportName]]) is true, then
if (export_name != entry.export_name)
continue;
// i. Assert: module provides the direct binding for this export.
// FIXME: What does this mean?
// ii. Return ResolvedBinding Record { [[Module]]: module, [[BindingName]]: e.[[LocalName]] }.
return ResolvedBinding {
ResolvedBinding::Type::BindingName,
this,
entry.local_or_import_name.value(),
};
}
// 5. For each ExportEntry Record e of module.[[IndirectExportEntries]], do
for (auto& entry : m_indirect_export_entries) {
// a. If SameValue(exportName, e.[[ExportName]]) is true, then
if (export_name != entry.export_name)
continue;
// i. Assert: e.[[ModuleRequest]] is not null.
// ii. Let importedModule be GetImportedModule(module, e.[[ModuleRequest]]).
auto imported_module = get_imported_module(entry.module_request());
// iii. If e.[[ImportName]] is all, then
if (entry.kind == ExportEntry::Kind::ModuleRequestAll) {
// 1. Assert: module does not provide the direct binding for this export.
// FIXME: What does this mean? / How do we check this
// 2. Return ResolvedBinding Record { [[Module]]: importedModule, [[BindingName]]: namespace }.
return ResolvedBinding {
ResolvedBinding::Type::Namespace,
imported_module.ptr(),
{}
};
}
// iv. Else,
else {
// 1. Assert: module imports a specific binding for this export.
// FIXME: What does this mean? / How do we check this
// 2. Return ? importedModule.ResolveExport(e.[[ImportName]], resolveSet).
return imported_module->resolve_export(vm, entry.local_or_import_name.value(), resolve_set);
}
}
// 7. If SameValue(exportName, "default") is true, then
if (export_name == "default"sv) {
// a. Assert: A default export was not explicitly defined by this module.
// FIXME: What does this mean? / How do we check this
// b. Return null.
return ResolvedBinding::null();
// c. NOTE: A default export cannot be provided by an export * from "mod" declaration.
}
// 8. Let starResolution be null.
ResolvedBinding star_resolution = ResolvedBinding::null();
// 9. For each ExportEntry Record e of module.[[StarExportEntries]], do
for (auto& entry : m_star_export_entries) {
// a. Assert: e.[[ModuleRequest]] is not null.
// b. Let importedModule be GetImportedModule(module, e.[[ModuleRequest]]).
auto imported_module = get_imported_module(entry.module_request());
// c. Let resolution be ? importedModule.ResolveExport(exportName, resolveSet).
auto resolution = TRY(imported_module->resolve_export(vm, export_name, resolve_set));
// d. If resolution is ambiguous, return ambiguous.
if (resolution.is_ambiguous())
return ResolvedBinding::ambiguous();
// e. If resolution is not null, then
if (resolution.type == ResolvedBinding::Null)
continue;
// i. Assert: resolution is a ResolvedBinding Record.
VERIFY(resolution.is_valid());
// ii. If starResolution is null, set starResolution to resolution.
if (star_resolution.type == ResolvedBinding::Null) {
star_resolution = resolution;
}
// iii. Else,
else {
// 1. Assert: There is more than one * import that includes the requested name.
// FIXME: Assert this
// 2. If resolution.[[Module]] and starResolution.[[Module]] are not the same Module Record, return ambiguous.
if (resolution.module != star_resolution.module)
return ResolvedBinding::ambiguous();
// 3. If resolution.[[BindingName]] is namespace and starResolution.[[BindingName]] is not namespace, or if resolution.[[BindingName]] is not namespace and starResolution.[[BindingName]] is namespace, return ambiguous.
if (resolution.is_namespace() != star_resolution.is_namespace())
return ResolvedBinding::ambiguous();
// 4. If resolution.[[BindingName]] is a String, starResolution.[[BindingName]] is a String, and SameValue(resolution.[[BindingName]], starResolution.[[BindingName]]) is false, return ambiguous.
if (!resolution.is_namespace() && resolution.export_name != star_resolution.export_name) {
// Note: Because we know from the previous if that either both are namespaces or both are string we can check just one
return ResolvedBinding::ambiguous();
}
}
}
// 10. Return starResolution.
return star_resolution;
}
// 16.2.1.6.5 ExecuteModule ( [ capability ] ), https://tc39.es/ecma262/#sec-source-text-module-record-execute-module
ThrowCompletionOr<void> SourceTextModule::execute_module(VM& vm, GC::Ptr<PromiseCapability> capability)
{
dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] SourceTextModule::execute_module({}, PromiseCapability @ {})", filename(), capability.ptr());
// 1. Let moduleContext be a new ECMAScript code execution context.
auto module_context = ExecutionContext::create();
// Note: This is not in the spec but we require it.
module_context->is_strict_mode = true;
// 2. Set the Function of moduleContext to null.
// 3. Set the Realm of moduleContext to module.[[Realm]].
module_context->realm = &realm();
// 4. Set the ScriptOrModule of moduleContext to module.
module_context->script_or_module = GC::Ref<Module>(*this);
// 5. Assert: module has been linked and declarations in its module environment have been instantiated.
VERIFY(m_status != ModuleStatus::New);
VERIFY(m_status != ModuleStatus::Unlinked);
VERIFY(m_status != ModuleStatus::Linking);
VERIFY(environment());
// 6. Set the VariableEnvironment of moduleContext to module.[[Environment]].
module_context->variable_environment = environment();
// 7. Set the LexicalEnvironment of moduleContext to module.[[Environment]].
module_context->lexical_environment = environment();
// 8. Suspend the currently running execution context.
// FIXME: We don't have suspend yet
// 9. If module.[[HasTLA]] is false, then
if (!m_has_top_level_await) {
// a. Assert: capability is not present.
VERIFY(capability == nullptr);
// b. Push moduleContext onto the execution context stack; moduleContext is now the running execution context.
TRY(vm.push_execution_context(*module_context, {}));
// c. Let result be the result of evaluating module.[[ECMAScriptCode]].
Completion result;
auto maybe_executable = Bytecode::compile(vm, m_ecmascript_code, FunctionKind::Normal, "ShadowRealmEval"sv);
if (maybe_executable.is_error())
result = maybe_executable.release_error();
else {
auto executable = maybe_executable.release_value();
auto result_and_return_register = vm.bytecode_interpreter().run_executable(*executable, {});
if (result_and_return_register.value.is_error()) {
result = result_and_return_register.value.release_error();
} else {
// Resulting value is in the accumulator.
result = result_and_return_register.return_register_value.value_or(js_undefined());
}
}
// d. Let env be moduleContext's LexicalEnvironment.
auto env = module_context->lexical_environment;
VERIFY(is<DeclarativeEnvironment>(*env));
// e. Set result to DisposeResources(env, result).
result = dispose_resources(vm, static_cast<DeclarativeEnvironment*>(env.ptr()), result);
// f. Suspend moduleContext and remove it from the execution context stack.
vm.pop_execution_context();
// g. Resume the context that is now on the top of the execution context stack as the running execution context.
// FIXME: We don't have resume yet.
// h. If result is an abrupt completion, then
if (result.is_error()) {
// i. Return ? result.
return result.release_error();
}
}
// 10. Else,
else {
// a. Assert: capability is a PromiseCapability Record.
VERIFY(capability != nullptr);
// b. Perform AsyncBlockStart(capability, module.[[ECMAScriptCode]], moduleContext).
// AD-HOC: We implement asynchronous execution via synthetic generator functions,
// so we fake "AsyncBlockStart" here by creating an async function to wrap
// the top-level module code.
// FIXME: Improve this situation, so we can match the spec better.
// AD-HOC: We push/pop the moduleContext around the function construction to ensure that the async execution context
// captures the module execution context.
vm.push_execution_context(*module_context);
FunctionParsingInsights parsing_insights;
parsing_insights.uses_this_from_environment = true;
parsing_insights.uses_this = true;
auto module_wrapper_function = ECMAScriptFunctionObject::create(
realm(), "module code with top-level await", StringView {}, this->m_ecmascript_code,
{}, 0, {}, environment(), nullptr, FunctionKind::Async, true, parsing_insights);
module_wrapper_function->set_is_module_wrapper(true);
vm.pop_execution_context();
auto result = call(vm, Value { module_wrapper_function }, js_undefined(), ReadonlySpan<Value> {});
// AD-HOC: This is basically analogous to what AsyncBlockStart would do.
if (result.is_throw_completion()) {
MUST(call(vm, *capability->reject(), js_undefined(), result.throw_completion().value().value()));
} else {
MUST(call(vm, *capability->resolve(), js_undefined(), result.value()));
}
}
// 11. Return unused.
return {};
}
}
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