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LibJS: Add spec comments to ScopeNode::block_declaration_instantiation

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Shannon Booth 2023-09-17 21:51:27 +12:00 • committed by Andreas Kling
parent 3aa49f268c
commit e67dd54878
1 changed files with 19 additions and 1 deletions
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20
Userland/Libraries/LibJS/AST.cpp
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@ -1619,13 +1619,20 @@ void ScopeNode::block_declaration_instantiation(VM& vm, Environment* environment
auto& realm = *vm.current_realm();
VERIFY(environment);
// 1. Let declarations be the LexicallyScopedDeclarations of code.
// 2. Let privateEnv be the running execution context's PrivateEnvironment.
auto private_environment = vm.running_execution_context().private_environment;
// Note: All the calls here are ! and thus we do not need to TRY this callback.
// We use MUST to ensure it does not throw and to avoid discarding the returned ThrowCompletionOr<void>.
// 3. For each element d of declarations, do
MUST(for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
auto is_constant_declaration = declaration.is_constant_declaration();
// NOTE: Due to the use of MUST with `create_immutable_binding` and `create_mutable_binding` below,
// an exception should not result from `for_each_bound_name`.
// a. For each element dn of the BoundNames of d, do
MUST(declaration.for_each_bound_identifier([&](auto const& identifier) {
if (identifier.is_local()) {
// NOTE: No need to create bindings for local variables as their values are not stored in an environment.
@ -1633,17 +1640,28 @@ void ScopeNode::block_declaration_instantiation(VM& vm, Environment* environment
}
auto const& name = identifier.string();
// i. If IsConstantDeclaration of d is true, then
if (is_constant_declaration) {
// 1. Perform ! env.CreateImmutableBinding(dn, true).
MUST(environment->create_immutable_binding(vm, name, true));
} else {
}
// ii. Else,
else {
// 1. Perform ! env.CreateMutableBinding(dn, false). NOTE: This step is replaced in section B.3.2.6.
if (!MUST(environment->has_binding(name)))
MUST(environment->create_mutable_binding(vm, name, false));
}
}));
// b. If d is either a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration, then
if (is<FunctionDeclaration>(declaration)) {
// i. Let fn be the sole element of the BoundNames of d.
auto& function_declaration = static_cast<FunctionDeclaration const&>(declaration);
// ii. Let fo be InstantiateFunctionObject of d with arguments env and privateEnv.
auto function = ECMAScriptFunctionObject::create(realm, function_declaration.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.might_need_arguments_object(), function_declaration.contains_direct_call_to_eval());
// iii. Perform ! env.InitializeBinding(fn, fo). NOTE: This step is replaced in section B.3.2.6.
if (function_declaration.name_identifier()->is_local()) {
vm.running_execution_context().local_variables[function_declaration.name_identifier()->local_variable_index()] = function;
} else {