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LibJS: Add basic support for module code with top-level await

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For now, we handle this by creating a synthetic async function to wrap
the top-level module code. This allows us to piggyback on the async
function driver wrapper mechanism.
This commit is contained in:
Andreas Kling 2023-12-06 11:35:40 +01:00
parent 26c21fba8e
commit a2c3db8367
4 changed files with 35 additions and 3 deletions
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26
Userland/Libraries/LibJS/SourceTextModule.cpp
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@ -9,9 +9,11 @@
#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 {
@ -748,7 +750,29 @@ ThrowCompletionOr<void> SourceTextModule::execute_module(VM& vm, GCPtr<PromiseCa
VERIFY(capability != nullptr);
// b. Perform AsyncBlockStart(capability, module.[[ECMAScriptCode]], moduleContext).
async_block_start<NonnullRefPtr<Statement const>>(vm, m_ecmascript_code, *capability, *module_context);
// 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.
auto module_wrapper_function = ECMAScriptFunctionObject::create(
realm(), "module code with top-level await", StringView {}, this->m_ecmascript_code,
{}, 0, {}, environment(), nullptr, FunctionKind::Async, true, false, false);
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.