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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/StringBuilder.h>
#include <LibJS/AST.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/LexicalEnvironment.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/Reference.h>
#include <LibJS/Runtime/ScriptFunction.h>
#include <LibJS/Runtime/Shape.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
NonnullOwnPtr<Interpreter> Interpreter::create_with_existing_global_object(GlobalObject& global_object)
{
DeferGC defer_gc(global_object.heap());
auto interpreter = adopt_own(*new Interpreter(global_object.vm()));
interpreter->m_global_object = make_handle(static_cast<Object*>(&global_object));
return interpreter;
}
Interpreter::Interpreter(VM& vm)
: m_vm(vm)
{
}
Interpreter::~Interpreter()
{
}
void Interpreter::run(GlobalObject& global_object, const Program& program)
{
auto& vm = this->vm();
VERIFY(!vm.exception());
VM::InterpreterExecutionScope scope(*this);
vm.set_last_value(Badge<Interpreter> {}, {});
CallFrame global_call_frame;
global_call_frame.current_node = &program;
global_call_frame.this_value = &global_object;
static FlyString global_execution_context_name = "(global execution context)";
global_call_frame.function_name = global_execution_context_name;
global_call_frame.scope = &global_object;
VERIFY(!vm.exception());
global_call_frame.is_strict_mode = program.is_strict_mode();
vm.push_call_frame(global_call_frame, global_object);
VERIFY(!vm.exception());
auto value = program.execute(*this, global_object);
vm.set_last_value(Badge<Interpreter> {}, value.value_or(js_undefined()));
vm.pop_call_frame();
// At this point we may have already run any queued promise jobs via on_call_stack_emptied,
// in which case this is a no-op.
vm.run_queued_promise_jobs();
}
GlobalObject& Interpreter::global_object()
{
return static_cast<GlobalObject&>(*m_global_object.cell());
}
const GlobalObject& Interpreter::global_object() const
{
return static_cast<const GlobalObject&>(*m_global_object.cell());
}
void Interpreter::enter_scope(const ScopeNode& scope_node, ScopeType scope_type, GlobalObject& global_object)
{
ScopeGuard guard([&] {
for (auto& declaration : scope_node.functions()) {
auto* function = ScriptFunction::create(global_object, declaration.name(), declaration.body(), declaration.parameters(), declaration.function_length(), current_scope(), declaration.is_generator(), declaration.is_strict_mode());
vm().set_variable(declaration.name(), function, global_object);
}
});
if (scope_type == ScopeType::Function) {
push_scope({ scope_type, scope_node, false });
for (auto& declaration : scope_node.functions())
current_scope()->put_to_scope(declaration.name(), { js_undefined(), DeclarationKind::Var });
return;
}
HashMap<FlyString, Variable> scope_variables_with_declaration_kind;
scope_variables_with_declaration_kind.ensure_capacity(16);
bool is_program_node = is<Program>(scope_node);
for (auto& declaration : scope_node.variables()) {
for (auto& declarator : declaration.declarations()) {
if (is_program_node && declaration.declaration_kind() == DeclarationKind::Var) {
declarator.target().visit(
[&](const NonnullRefPtr<Identifier>& id) {
global_object.put(id->string(), js_undefined());
},
[&](const NonnullRefPtr<BindingPattern>& binding) {
binding->for_each_assigned_name([&](const auto& name) {
global_object.put(name, js_undefined());
});
});
if (exception())
return;
} else {
declarator.target().visit(
[&](const NonnullRefPtr<Identifier>& id) {
scope_variables_with_declaration_kind.set(id->string(), { js_undefined(), declaration.declaration_kind() });
},
[&](const NonnullRefPtr<BindingPattern>& binding) {
binding->for_each_assigned_name([&](const auto& name) {
scope_variables_with_declaration_kind.set(name, { js_undefined(), declaration.declaration_kind() });
});
});
}
}
}
bool pushed_lexical_environment = false;
if (!scope_variables_with_declaration_kind.is_empty()) {
auto* block_lexical_environment = heap().allocate<LexicalEnvironment>(global_object, move(scope_variables_with_declaration_kind), current_scope());
vm().call_frame().scope = block_lexical_environment;
pushed_lexical_environment = true;
}
push_scope({ scope_type, scope_node, pushed_lexical_environment });
}
void Interpreter::exit_scope(const ScopeNode& scope_node)
{
while (!m_scope_stack.is_empty()) {
auto popped_scope = m_scope_stack.take_last();
if (popped_scope.pushed_environment)
vm().call_frame().scope = vm().call_frame().scope->parent();
if (popped_scope.scope_node.ptr() == &scope_node)
break;
}
// If we unwind all the way, just reset m_unwind_until so that future "return" doesn't break.
if (m_scope_stack.is_empty())
vm().stop_unwind();
}
void Interpreter::push_scope(ScopeFrame frame)
{
m_scope_stack.append(move(frame));
}
Value Interpreter::execute_statement(GlobalObject& global_object, const Statement& statement, ScopeType scope_type)
{
if (!is<ScopeNode>(statement))
return statement.execute(*this, global_object);
auto& block = static_cast<const ScopeNode&>(statement);
enter_scope(block, scope_type, global_object);
Value last_value;
for (auto& node : block.children()) {
auto value = node.execute(*this, global_object);
if (!value.is_empty())
last_value = value;
if (vm().should_unwind()) {
if (!block.label().is_null() && vm().should_unwind_until(ScopeType::Breakable, block.label()))
vm().stop_unwind();
break;
}
}
if (scope_type == ScopeType::Function) {
bool did_return = vm().unwind_until() == ScopeType::Function;
if (!did_return)
last_value = js_undefined();
}
if (vm().unwind_until() == scope_type)
vm().stop_unwind();
exit_scope(block);
return last_value;
}
LexicalEnvironment* Interpreter::current_environment()
{
VERIFY(is<LexicalEnvironment>(vm().call_frame().scope));
return static_cast<LexicalEnvironment*>(vm().call_frame().scope);
}
}
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