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LibJS: Implement basic for..in and for..of loops

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Linus Groh 2020-04-21 19:21:26 +01:00 • committed by Andreas Kling
parent c378a1c730
commit 07af2e6b2c
8 changed files with 372 additions and 90 deletions
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144
Libraries/LibJS/AST.cpp
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@ -322,6 +322,128 @@ Value ForStatement::execute(Interpreter& interpreter) const
return last_value;
}
static FlyString variable_from_for_declaration(Interpreter& interpreter, NonnullRefPtr<ASTNode> node, RefPtr<BlockStatement> wrapper)
{
FlyString variable_name;
if (node->is_variable_declaration()) {
auto* variable_declaration = static_cast<const VariableDeclaration*>(node.ptr());
ASSERT(!variable_declaration->declarations().is_empty());
if (variable_declaration->declaration_kind() != DeclarationKind::Var) {
wrapper = create_ast_node<BlockStatement>();
interpreter.enter_scope(*wrapper, {}, ScopeType::Block);
}
variable_declaration->execute(interpreter);
variable_name = variable_declaration->declarations().first().id().string();
} else if (node->is_identifier()) {
variable_name = static_cast<const Identifier&>(*node).string();
} else {
ASSERT_NOT_REACHED();
}
return variable_name;
}
Value ForInStatement::execute(Interpreter& interpreter) const
{
if (!m_lhs->is_variable_declaration() && !m_lhs->is_identifier()) {
// FIXME: Implement "for (foo.bar in baz)", "for (foo[0] in bar)"
ASSERT_NOT_REACHED();
}
RefPtr<BlockStatement> wrapper;
auto variable_name = variable_from_for_declaration(interpreter, m_lhs, wrapper);
auto wrapper_cleanup = ScopeGuard([&] {
if (wrapper)
interpreter.exit_scope(*wrapper);
});
auto last_value = js_undefined();
auto rhs_result = m_rhs->execute(interpreter);
if (interpreter.exception())
return {};
auto* object = rhs_result.to_object(interpreter);
while (object) {
auto property_names = object->get_own_properties(*object, Object::GetOwnPropertyMode::Key, Attribute::Enumerable);
for (auto& property_name : static_cast<Array&>(property_names.as_object()).elements()) {
interpreter.set_variable(variable_name, property_name);
last_value = interpreter.run(*m_body);
if (interpreter.exception())
return {};
if (interpreter.should_unwind()) {
if (interpreter.should_unwind_until(ScopeType::Continuable)) {
interpreter.stop_unwind();
} else if (interpreter.should_unwind_until(ScopeType::Breakable)) {
interpreter.stop_unwind();
break;
} else {
return js_undefined();
}
}
}
object = object->prototype();
}
return last_value;
}
Value ForOfStatement::execute(Interpreter& interpreter) const
{
if (!m_lhs->is_variable_declaration() && !m_lhs->is_identifier()) {
// FIXME: Implement "for (foo.bar of baz)", "for (foo[0] of bar)"
ASSERT_NOT_REACHED();
}
RefPtr<BlockStatement> wrapper;
auto variable_name = variable_from_for_declaration(interpreter, m_lhs, wrapper);
auto wrapper_cleanup = ScopeGuard([&] {
if (wrapper)
interpreter.exit_scope(*wrapper);
});
auto last_value = js_undefined();
auto rhs_result = m_rhs->execute(interpreter);
if (interpreter.exception())
return {};
// FIXME: We need to properly implement the iterator protocol
auto is_iterable = rhs_result.is_array() || rhs_result.is_string() || (rhs_result.is_object() && rhs_result.as_object().is_string_object());
if (!is_iterable)
return interpreter.throw_exception<TypeError>("for..of right-hand side must be iterable");
size_t index = 0;
auto next = [&]() -> Optional<Value> {
if (rhs_result.is_array()) {
auto array_elements = static_cast<Array*>(&rhs_result.as_object())->elements();
if (index < array_elements.size())
return Value(array_elements.at(index));
} else if (rhs_result.is_string()) {
auto string = rhs_result.as_string().string();
if (index < string.length())
return js_string(interpreter, string.substring(index, 1));
} else if (rhs_result.is_object() && rhs_result.as_object().is_string_object()) {
auto string = static_cast<StringObject*>(&rhs_result.as_object())->primitive_string().string();
if (index < string.length())
return js_string(interpreter, string.substring(index, 1));
}
return {};
};
for (;;) {
auto next_item = next();
if (!next_item.has_value())
break;
interpreter.set_variable(variable_name, next_item.value());
last_value = interpreter.run(*m_body);
if (interpreter.exception())
return {};
if (interpreter.should_unwind()) {
if (interpreter.should_unwind_until(ScopeType::Continuable)) {
interpreter.stop_unwind();
} else if (interpreter.should_unwind_until(ScopeType::Breakable)) {
interpreter.stop_unwind();
break;
} else {
return js_undefined();
}
}
++index;
}
return last_value;
}
Value BinaryExpression::execute(Interpreter& interpreter) const
{
auto lhs_result = m_lhs->execute(interpreter);
@ -801,6 +923,28 @@ void ForStatement::dump(int indent) const
body().dump(indent + 1);
}
void ForInStatement::dump(int indent) const
{
ASTNode::dump(indent);
print_indent(indent);
printf("ForIn\n");
lhs().dump(indent + 1);
rhs().dump(indent + 1);
body().dump(indent + 1);
}
void ForOfStatement::dump(int indent) const
{
ASTNode::dump(indent);
print_indent(indent);
printf("ForOf\n");
lhs().dump(indent + 1);
rhs().dump(indent + 1);
body().dump(indent + 1);
}
Value Identifier::execute(Interpreter& interpreter) const
{
auto value = interpreter.get_variable(string());