gecko-dev/dom/xml/nsXMLPrettyPrinter.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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/. */

#include "nsXMLPrettyPrinter.h"
#include "nsContentUtils.h"
#include "nsICSSDeclaration.h"
#include "nsIObserver.h"
#include "nsSyncLoadService.h"
#include "nsPIDOMWindow.h"
#include "nsIServiceManager.h"
#include "nsNetUtil.h"
#include "mozilla/dom/Element.h"
#include "nsIScriptSecurityManager.h"
#include "mozilla/Preferences.h"
#include "nsIDocument.h"
#include "nsVariant.h"
#include "mozilla/dom/CustomEvent.h"
#include "mozilla/dom/DocumentFragment.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/dom/ToJSValue.h"
#include "mozilla/dom/txMozillaXSLTProcessor.h"

using namespace mozilla;
using namespace mozilla::dom;

NS_IMPL_ISUPPORTS(nsXMLPrettyPrinter,
                  nsIDocumentObserver,
                  nsIMutationObserver)

nsXMLPrettyPrinter::nsXMLPrettyPrinter() : mDocument(nullptr),
                                           mUnhookPending(false)
{
}

nsXMLPrettyPrinter::~nsXMLPrettyPrinter()
{
    NS_ASSERTION(!mDocument, "we shouldn't be referencing the document still");
}

nsresult
nsXMLPrettyPrinter::PrettyPrint(nsIDocument* aDocument,
                                bool* aDidPrettyPrint)
{
    *aDidPrettyPrint = false;

    // check the pref
    if (!Preferences::GetBool("layout.xml.prettyprint", true)) {
        return NS_OK;
    }

    // Ok, we should prettyprint. Let's do it!
    *aDidPrettyPrint = true;
    nsresult rv = NS_OK;

    // Load the XSLT
    nsCOMPtr<nsIURI> xslUri;
    rv = NS_NewURI(getter_AddRefs(xslUri),
                   NS_LITERAL_CSTRING("chrome://global/content/xml/XMLPrettyPrint.xsl"));
    NS_ENSURE_SUCCESS(rv, rv);

    nsCOMPtr<nsIDocument> xslDocument;
    rv = nsSyncLoadService::LoadDocument(xslUri, nsIContentPolicy::TYPE_XSLT,
                                         nsContentUtils::GetSystemPrincipal(),
                                         nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL,
                                         nullptr, true, mozilla::net::RP_Unset,
                                         getter_AddRefs(xslDocument));
    NS_ENSURE_SUCCESS(rv, rv);

    // Transform the document
    RefPtr<txMozillaXSLTProcessor> transformer = new txMozillaXSLTProcessor();
    ErrorResult err;
    transformer->ImportStylesheet(*xslDocument, err);
    if (NS_WARN_IF(err.Failed())) {
        return err.StealNSResult();
    }

    RefPtr<DocumentFragment> resultFragment =
        transformer->TransformToFragment(*aDocument, *aDocument, err);
    if (NS_WARN_IF(err.Failed())) {
        return err.StealNSResult();
    }

    // Find the root element
    RefPtr<Element> rootElement = aDocument->GetRootElement();
    NS_ENSURE_TRUE(rootElement, NS_ERROR_UNEXPECTED);

    // Attach a closed shadow root on it.
    RefPtr<ShadowRoot> shadowRoot =
        rootElement->AttachShadowWithoutNameChecks(ShadowRootMode::Closed);

    // Append the document fragment to the shadow dom.
    shadowRoot->AppendChild(*resultFragment, err);
    if (NS_WARN_IF(err.Failed())) {
        return err.StealNSResult();
    }

    // Observe the document so we know when to switch to "normal" view
    aDocument->AddObserver(this);
    mDocument = aDocument;

    NS_ADDREF_THIS();

    return NS_OK;
}

void
nsXMLPrettyPrinter::MaybeUnhook(nsIContent* aContent)
{
    // If aContent is null, the document-node was modified.
    // If it is not null but in the shadow tree or the <scrollbar> NACs,
    // the change was in the generated content, and it should be ignored.
    bool isGeneratedContent = !aContent ?
        false :
        aContent->GetBindingParent() || aContent->IsInShadowTree();

    if (!isGeneratedContent && !mUnhookPending) {
        // Can't blindly to mUnhookPending after AddScriptRunner,
        // since AddScriptRunner _could_ in theory run us
        // synchronously
        mUnhookPending = true;
        nsContentUtils::AddScriptRunner(NewRunnableMethod(
          "nsXMLPrettyPrinter::Unhook", this, &nsXMLPrettyPrinter::Unhook));
    }
}

void
nsXMLPrettyPrinter::Unhook()
{
    mDocument->RemoveObserver(this);
    nsCOMPtr<Element> element = mDocument->GetDocumentElement();

    if (element) {
        // Remove the shadow root
        element->UnattachShadow();
    }

    mDocument = nullptr;

    NS_RELEASE_THIS();
}

void
nsXMLPrettyPrinter::AttributeChanged(Element* aElement,
                                     int32_t aNameSpaceID,
                                     nsAtom* aAttribute,
                                     int32_t aModType,
                                     const nsAttrValue* aOldValue)
{
    MaybeUnhook(aElement);
}

void
nsXMLPrettyPrinter::ContentAppended(nsIContent* aFirstNewContent)
{
    MaybeUnhook(aFirstNewContent->GetParent());
}

void
nsXMLPrettyPrinter::ContentInserted(nsIContent* aChild)
{
    MaybeUnhook(aChild->GetParent());
}

void
nsXMLPrettyPrinter::ContentRemoved(nsIContent* aChild,
                                   nsIContent* aPreviousSibling)
{
    MaybeUnhook(aChild->GetParent());
}

void
nsXMLPrettyPrinter::NodeWillBeDestroyed(const nsINode* aNode)
{
    mDocument = nullptr;
    NS_RELEASE_THIS();
}


nsresult NS_NewXMLPrettyPrinter(nsXMLPrettyPrinter** aPrinter)
{
    *aPrinter = new nsXMLPrettyPrinter;
    NS_ADDREF(*aPrinter);
    return NS_OK;
}