text: /*
   * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #include <LibJS/Interpreter.h>
  #include <LibJS/Runtime/Completion.h>
  #include <LibJS/Runtime/FunctionEnvironment.h>
  #include <LibJS/Runtime/GlobalObject.h>
  
  namespace JS {
  
  FunctionEnvironment::FunctionEnvironment(Environment* parent_scope)
      : DeclarativeEnvironment(parent_scope)
  {
  }
  
  void FunctionEnvironment::visit_edges(Visitor& visitor)
  {
      Base::visit_edges(visitor);
      visitor.visit(m_this_value);
      visitor.visit(m_new_target);
      visitor.visit(m_function_object);
  }
  
  // 9.1.1.3.5 GetSuperBase ( ), https://tc39.es/ecma262/#sec-getsuperbase
  ThrowCompletionOr<Value> FunctionEnvironment::get_super_base() const
  {
      VERIFY(m_function_object);
  
      // 1. Let home be envRec.[[FunctionObject]].[[HomeObject]].
      auto home_object = m_function_object->home_object();
  
      // 2. If home has the value undefined, return undefined.
      if (!home_object)
          return js_undefined();
  
      // 3. Assert: Type(home) is Object.
  
      // 4. Return ? home.[[GetPrototypeOf]]().
      return TRY(home_object->internal_get_prototype_of());
  }
  
  // 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
  bool FunctionEnvironment::has_this_binding() const
  {
      if (this_binding_status() == ThisBindingStatus::Lexical)
          return false;
      return true;
  }
  
  // 9.1.1.3.3 HasSuperBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hassuperbinding
  bool FunctionEnvironment::has_super_binding() const
  {
      if (this_binding_status() == ThisBindingStatus::Lexical)
          return false;
      if (!function_object().home_object())
          return false;
      return true;
  }
  
  // 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
  ThrowCompletionOr<Value> FunctionEnvironment::get_this_binding(GlobalObject& global_object) const
  {
      // 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
      VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
  
      // 2. If envRec.[[ThisBindingStatus]] is uninitialized, throw a ReferenceError exception.
      if (m_this_binding_status == ThisBindingStatus::Uninitialized)
          return vm().throw_completion<ReferenceError>(global_object, ErrorType::ThisHasNotBeenInitialized);
  
      // 3. Return envRec.[[ThisValue]].
      return m_this_value;
  }
  
  // 9.1.1.3.1 BindThisValue ( V ), https://tc39.es/ecma262/#sec-bindthisvalue
  ThrowCompletionOr<Value> FunctionEnvironment::bind_this_value(GlobalObject& global_object, Value this_value)
  {
      VERIFY(!this_value.is_empty());
  
      // 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
      VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
  
      // 2. If envRec.[[ThisBindingStatus]] is initialized, throw a ReferenceError exception.
      if (m_this_binding_status == ThisBindingStatus::Initialized)
          return vm().throw_completion<ReferenceError>(global_object, ErrorType::ThisIsAlreadyInitialized);
  
      // 3. Set envRec.[[ThisValue]] to V.
      m_this_value = this_value;
  
      // 4. Set envRec.[[ThisBindingStatus]] to initialized.
      m_this_binding_status = ThisBindingStatus::Initialized;
  
      // 5. Return V.
      return this_value;
  }
  
  }
  