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ladybird/Libraries/LibJS/SourceTextModule.cpp

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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 {
JS_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<NonnullGCPtr<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_without_realm<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_without_realm<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 = NonnullGCPtr<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, GCPtr<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 = NonnullGCPtr<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.
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);
// AD-HOC: We push/pop the moduleContext around the call to ensure that the async execution context
// captures the module execution context.
vm.push_execution_context(*module_context);
auto result = call(vm, Value { module_wrapper_function }, js_undefined(), ReadonlySpan<Value> {});
vm.pop_execution_context();
// 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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