UXP/dom/script/ModuleScript.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * A class that handles loading and evaluation of <script> elements.
 */

#include "ScriptLoader.h"
#include "ModuleScript.h"
#include "mozilla/HoldDropJSObjects.h"

#include "jsfriendapi.h"

namespace mozilla {
namespace dom {

//////////////////////////////////////////////////////////////
// LoadedScript
//////////////////////////////////////////////////////////////

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(LoadedScript)
NS_INTERFACE_MAP_END

NS_IMPL_CYCLE_COLLECTION_CLASS(LoadedScript)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(LoadedScript)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mFetchOptions)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mBaseURL)
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(LoadedScript)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFetchOptions)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(LoadedScript)
NS_IMPL_CYCLE_COLLECTION_TRACE_END

NS_IMPL_CYCLE_COLLECTING_ADDREF(LoadedScript)
NS_IMPL_CYCLE_COLLECTING_RELEASE(LoadedScript)

LoadedScript::LoadedScript(ScriptKind aKind,
                           ScriptFetchOptions* aFetchOptions, nsIURI* aBaseURL)
    : mKind(aKind),
      mFetchOptions(aFetchOptions),
      mBaseURL(aBaseURL) 
{
  MOZ_ASSERT(mFetchOptions);
  MOZ_ASSERT(mBaseURL);
}

LoadedScript::~LoadedScript() { DropJSObjects(this); }

void LoadedScript::AssociateWithScript(JSScript* aScript) {
  // Set a JSScript's private value to point to this object and
  // increment our reference count. This is decremented by
  // HostFinalizeTopLevelScript() below when the JSScript dies.

  MOZ_ASSERT(JS::GetScriptPrivate(aScript).isUndefined());
  JS::SetScriptPrivate(aScript, JS::PrivateValue(this));
  AddRef();
}

void HostFinalizeTopLevelScript(JSFreeOp* aFop, const JS::Value& aPrivate) {
  // Decrement the reference count of a LoadedScript object that is
  // pointed to by a dying JSScript. The reference count was
  // originally incremented by AssociateWithScript() above.

  auto script = static_cast<LoadedScript*>(aPrivate.toPrivate());

#ifdef DEBUG
  if (script->IsModuleScript()) {
    JSObject* module = script->AsModuleScript()->mModuleRecord.unbarrieredGet();
    MOZ_ASSERT_IF(module, JS::GetModulePrivate(module) == aPrivate);
  }
#endif

  script->Release();
}

//////////////////////////////////////////////////////////////
// ClassicScript
//////////////////////////////////////////////////////////////

ClassicScript::ClassicScript(ScriptFetchOptions* aFetchOptions,
                             nsIURI* aBaseURL)
    : LoadedScript(ScriptKind::Classic, aFetchOptions, aBaseURL) {}

//////////////////////////////////////////////////////////////
// ModuleScript
//////////////////////////////////////////////////////////////

NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ModuleScript)
NS_INTERFACE_MAP_END_INHERITING(LoadedScript)

NS_IMPL_CYCLE_COLLECTION_CLASS(ModuleScript)

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(ModuleScript, LoadedScript)
  tmp->UnlinkModuleRecord();
  tmp->mParseError.setUndefined();
  tmp->mErrorToRethrow.setUndefined();
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ModuleScript, LoadedScript)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(ModuleScript, LoadedScript)
  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mModuleRecord)
  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mParseError)
  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mErrorToRethrow)
NS_IMPL_CYCLE_COLLECTION_TRACE_END

NS_IMPL_ADDREF_INHERITED(ModuleScript, LoadedScript)
NS_IMPL_RELEASE_INHERITED(ModuleScript, LoadedScript)

ModuleScript::ModuleScript(ScriptFetchOptions* aFetchOptions, nsIURI* aBaseURL)
    : LoadedScript(ScriptKind::Module, aFetchOptions, aBaseURL) {
  MOZ_ASSERT(!ModuleRecord());
  MOZ_ASSERT(!HasParseError());
  MOZ_ASSERT(!HasErrorToRethrow());
}

void
ModuleScript::UnlinkModuleRecord()
{
  // Remove the module record's pointer to this object if present and
  // decrement our reference count. The reference is added by
  // SetModuleRecord() below.
  if (mModuleRecord) {
    MOZ_ASSERT(JS::GetModulePrivate(mModuleRecord).toPrivate() ==
               this);
    JS::SetModulePrivate(mModuleRecord, JS::UndefinedValue());
    mModuleRecord = nullptr;
    Release();
  }
}

ModuleScript::~ModuleScript()
{
  // The object may be destroyed without being unlinked first.
  UnlinkModuleRecord();
}

void
ModuleScript::SetModuleRecord(JS::Handle<JSObject*> aModuleRecord)
{
  MOZ_ASSERT(!mModuleRecord);
  MOZ_ASSERT_IF(IsModuleScript(), !AsModuleScript()->HasParseError());
  MOZ_ASSERT_IF(IsModuleScript(), !AsModuleScript()->HasErrorToRethrow());

  mModuleRecord = aModuleRecord;

  // Make module's host defined field point to this object and
  // increment our reference count. This is decremented by
  // UnlinkModuleRecord() above.
  MOZ_ASSERT(JS::GetModulePrivate(mModuleRecord).isUndefined());
  JS::SetModulePrivate(mModuleRecord, JS::PrivateValue(this));
  HoldJSObjects(this);
  AddRef();
}

void
ModuleScript::SetParseError(const JS::Value& aError)
{
  MOZ_ASSERT(!aError.isUndefined());
  MOZ_ASSERT(!HasParseError());
  MOZ_ASSERT(!HasErrorToRethrow());

  UnlinkModuleRecord();
  mParseError = aError;
  HoldJSObjects(this);
}

void
ModuleScript::SetErrorToRethrow(const JS::Value& aError)
{
  MOZ_ASSERT(!aError.isUndefined());

  // This is only called after SetModuleRecord() or SetParseError() so we don't
  // need to call HoldJSObjects() here.
  MOZ_ASSERT(ModuleRecord() || HasParseError());

  mErrorToRethrow = aError;
}

} // dom namespace
} // mozilla namespace