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LibJS: Implement LabelledStatement & LabelledEvaluation semantics
Instead of slapping 0..N labels on a statement like the current LabelableStatement does, we need the spec's LabelledStatement for a proper implementation of control flow using only completions - it always has one label and one labelled statement - what appears to be 'multiple labels' on the same statement is actually nested LabelledStatements. Note that this is unused yet and will fully replace LabelableStatement in the next commit.
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Linus Groh
parent
558fd5b166
commit
fc474966bc
2 changed files with 132 additions and 5 deletions
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@ -66,6 +66,11 @@ String ASTNode::class_name() const
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return demangle(typeid(*this).name()).substring(4);
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}
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static void print_indent(int indent)
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{
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out("{}", String::repeated(' ', indent * 2));
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}
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static void update_function_name(Value value, FlyString const& name)
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{
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if (!value.is_function())
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@ -104,6 +109,110 @@ Completion ScopeNode::evaluate_statements(Interpreter& interpreter, GlobalObject
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return completion;
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}
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// 14.13.4 Runtime Semantics: LabelledEvaluation, https://tc39.es/ecma262/#sec-runtime-semantics-labelledevaluation
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// BreakableStatement : IterationStatement
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static Completion labelled_evaluation(Interpreter& interpreter, GlobalObject& global_object, IterationStatement const& statement, Vector<FlyString> const& label_set)
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{
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// 1. Let stmtResult be LoopEvaluation of IterationStatement with argument labelSet.
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auto result = statement.loop_evaluation(interpreter, global_object, label_set);
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// 2. If stmtResult.[[Type]] is break, then
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if (result.type() == Completion::Type::Break) {
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// a. If stmtResult.[[Target]] is empty, then
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if (!result.target().has_value()) {
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// i. If stmtResult.[[Value]] is empty, set stmtResult to NormalCompletion(undefined).
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// ii. Else, set stmtResult to NormalCompletion(stmtResult.[[Value]]).
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result = normal_completion(result.value().value_or(js_undefined()));
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}
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}
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// 3. Return Completion(stmtResult).
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return result;
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}
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// 14.13.4 Runtime Semantics: LabelledEvaluation, https://tc39.es/ecma262/#sec-runtime-semantics-labelledevaluation
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// BreakableStatement : SwitchStatement
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static Completion labelled_evaluation(Interpreter& interpreter, GlobalObject& global_object, SwitchStatement const& statement, Vector<FlyString> const&)
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{
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// 1. Let stmtResult be the result of evaluating SwitchStatement.
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auto result = statement.execute_impl(interpreter, global_object);
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// 2. If stmtResult.[[Type]] is break, then
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if (result.type() == Completion::Type::Break) {
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// a. If stmtResult.[[Target]] is empty, then
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if (!result.target().has_value()) {
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// i. If stmtResult.[[Value]] is empty, set stmtResult to NormalCompletion(undefined).
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// ii. Else, set stmtResult to NormalCompletion(stmtResult.[[Value]]).
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result = normal_completion(result.value().value_or(js_undefined()));
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}
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}
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// 3. Return Completion(stmtResult).
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return result;
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}
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// 14.13.4 Runtime Semantics: LabelledEvaluation, https://tc39.es/ecma262/#sec-runtime-semantics-labelledevaluation
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// LabelledStatement : LabelIdentifier : LabelledItem
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static Completion labelled_evaluation(Interpreter& interpreter, GlobalObject& global_object, LabelledStatement const& statement, Vector<FlyString> const& label_set)
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{
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auto const& labelled_item = *statement.labelled_item();
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// 1. Let label be the StringValue of LabelIdentifier.
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auto const& label = statement.label();
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// 2. Let newLabelSet be the list-concatenation of labelSet and « label ».
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// Optimization: Avoid vector copy if possible.
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Optional<Vector<FlyString>> new_label_set;
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if (is<IterationStatement>(labelled_item) || is<SwitchStatement>(labelled_item) || is<LabelledStatement>(labelled_item)) {
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new_label_set = label_set;
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new_label_set->append(label);
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}
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// 3. Let stmtResult be LabelledEvaluation of LabelledItem with argument newLabelSet.
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Completion result;
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if (is<IterationStatement>(labelled_item))
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result = labelled_evaluation(interpreter, global_object, static_cast<IterationStatement const&>(labelled_item), *new_label_set);
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else if (is<SwitchStatement>(labelled_item))
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result = labelled_evaluation(interpreter, global_object, static_cast<SwitchStatement const&>(labelled_item), *new_label_set);
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else if (is<LabelledStatement>(labelled_item))
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result = labelled_evaluation(interpreter, global_object, static_cast<LabelledStatement const&>(labelled_item), *new_label_set);
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else
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result = labelled_item.execute(interpreter, global_object);
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// 4. If stmtResult.[[Type]] is break and SameValue(stmtResult.[[Target]], label) is true, then
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if (result.type() == Completion::Type::Break && result.target() == label) {
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// a. Set stmtResult to NormalCompletion(stmtResult.[[Value]]).
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result = normal_completion(result.value());
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}
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// 5. Return Completion(stmtResult).
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return result;
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}
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// 14.13.3 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-labelled-statements-runtime-semantics-evaluation
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Completion LabelledStatement::execute(Interpreter& interpreter, GlobalObject& global_object) const
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{
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InterpreterNodeScope node_scope { interpreter, *this };
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// 1. Let newLabelSet be a new empty List.
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// 2. Return LabelledEvaluation of this LabelledStatement with argument newLabelSet.
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return labelled_evaluation(interpreter, global_object, *this, {});
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}
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void LabelledStatement::dump(int indent) const
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{
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ASTNode::dump(indent);
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print_indent(indent + 1);
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outln("(Label)");
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print_indent(indent + 2);
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outln("\"{}\"", m_label);
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print_indent(indent + 1);
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outln("(Labelled item)");
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m_labelled_item->dump(indent + 2);
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}
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// 10.2.1.3 Runtime Semantics: EvaluateBody, https://tc39.es/ecma262/#sec-runtime-semantics-evaluatebody
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Completion FunctionBody::execute(Interpreter& interpreter, GlobalObject& global_object) const
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{
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@ -1764,11 +1873,6 @@ ThrowCompletionOr<Value> ClassDeclaration::binding_class_declaration_evaluation(
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return value;
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}
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static void print_indent(int indent)
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{
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out("{}", String::repeated(' ', indent * 2));
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}
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void ASTNode::dump(int indent) const
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{
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print_indent(indent);
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@ -86,6 +86,29 @@ public:
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}
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};
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// 14.13 Labelled Statements, https://tc39.es/ecma262/#sec-labelled-statements
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class LabelledStatement : public Statement {
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public:
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LabelledStatement(SourceRange source_range, FlyString label, NonnullRefPtr<Statement> labelled_item)
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: Statement(source_range)
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, m_label(move(label))
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, m_labelled_item(move(labelled_item))
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{
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}
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virtual Completion execute(Interpreter&, GlobalObject&) const override;
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virtual void dump(int indent) const override;
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FlyString const& label() const { return m_label; }
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FlyString& label() { return m_label; }
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NonnullRefPtr<Statement> const& labelled_item() const { return m_labelled_item; }
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NonnullRefPtr<Statement>& labelled_item() { return m_labelled_item; }
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private:
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FlyString m_label;
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NonnullRefPtr<Statement> m_labelled_item;
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};
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class LabelableStatement : public Statement {
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public:
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using Statement::Statement;
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