ladybird/Libraries/LibJS/Runtime/LexicalEnvironment.cpp
Andreas Kling 6861c619c6 LibJS: Move most of Interpreter into VM
This patch moves the exception state, call stack and scope stack from
Interpreter to VM. I'm doing this to help myself discover what the
split between Interpreter and VM should be, by shuffling things around
and seeing what falls where.

With these changes, we no longer have a persistent lexical environment
for the current global object on the Interpreter's call stack. Instead,
we push/pop that environment on Interpreter::run() enter/exit.
Since it should only be used to find the global "this", and not for
variable storage (that goes directly into the global object instead!),
I had to insert some short-circuiting when walking the environment
parent chain during variable lookup.

Note that this is a "stepping stone" commit, not a final design.
2020-09-27 20:26:58 +02:00

138 lines
4.6 KiB
C++

/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/Function.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/LexicalEnvironment.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
LexicalEnvironment::LexicalEnvironment()
{
}
LexicalEnvironment::LexicalEnvironment(EnvironmentRecordType environment_record_type)
: m_environment_record_type(environment_record_type)
{
}
LexicalEnvironment::LexicalEnvironment(HashMap<FlyString, Variable> variables, LexicalEnvironment* parent)
: m_parent(parent)
, m_variables(move(variables))
{
}
LexicalEnvironment::LexicalEnvironment(HashMap<FlyString, Variable> variables, LexicalEnvironment* parent, EnvironmentRecordType environment_record_type)
: m_parent(parent)
, m_variables(move(variables))
, m_environment_record_type(environment_record_type)
{
}
LexicalEnvironment::~LexicalEnvironment()
{
}
void LexicalEnvironment::visit_children(Visitor& visitor)
{
Cell::visit_children(visitor);
visitor.visit(m_parent);
visitor.visit(m_this_value);
visitor.visit(m_home_object);
visitor.visit(m_new_target);
visitor.visit(m_current_function);
for (auto& it : m_variables)
visitor.visit(it.value.value);
}
Optional<Variable> LexicalEnvironment::get(const FlyString& name) const
{
ASSERT(type() != EnvironmentRecordType::Global);
return m_variables.get(name);
}
void LexicalEnvironment::set(const FlyString& name, Variable variable)
{
if (type() == EnvironmentRecordType::Global)
interpreter().global_object().put(name, variable.value);
else
m_variables.set(name, variable);
}
bool LexicalEnvironment::has_super_binding() const
{
return m_environment_record_type == EnvironmentRecordType::Function && this_binding_status() != ThisBindingStatus::Lexical && m_home_object.is_object();
}
Value LexicalEnvironment::get_super_base()
{
ASSERT(has_super_binding());
if (m_home_object.is_object())
return m_home_object.as_object().prototype();
return {};
}
bool LexicalEnvironment::has_this_binding() const
{
// More like "is_capable_of_having_a_this_binding".
switch (m_environment_record_type) {
case EnvironmentRecordType::Declarative:
case EnvironmentRecordType::Object:
return false;
case EnvironmentRecordType::Function:
return this_binding_status() != ThisBindingStatus::Lexical;
case EnvironmentRecordType::Module:
case EnvironmentRecordType::Global:
return true;
}
ASSERT_NOT_REACHED();
}
Value LexicalEnvironment::get_this_binding() const
{
ASSERT(has_this_binding());
if (this_binding_status() == ThisBindingStatus::Uninitialized) {
interpreter().vm().throw_exception<ReferenceError>(interpreter().global_object(), ErrorType::ThisHasNotBeenInitialized);
return {};
}
return m_this_value;
}
void LexicalEnvironment::bind_this_value(Value this_value)
{
ASSERT(has_this_binding());
if (m_this_binding_status == ThisBindingStatus::Initialized) {
interpreter().vm().throw_exception<ReferenceError>(interpreter().global_object(), ErrorType::ThisIsAlreadyInitialized);
return;
}
m_this_value = this_value;
m_this_binding_status = ThisBindingStatus::Initialized;
}
}