wikimedia/mediawiki-core

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includes/parser/ParserOutput.php

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<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

namespace MediaWiki\Parser;

use CacheTime;
use InvalidArgumentException;
use LogicException;
use MediaWiki\Edit\ParsoidRenderID;
use MediaWiki\Json\JsonUnserializable;
use MediaWiki\Json\JsonUnserializableTrait;
use MediaWiki\Json\JsonUnserializer;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Output\OutputPage;
use MediaWiki\Parser\Parsoid\PageBundleParserOutputConverter;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleValue;
use ParserOptions;
use UnexpectedValueException;
use Wikimedia\Bcp47Code\Bcp47Code;
use Wikimedia\Bcp47Code\Bcp47CodeValue;
use Wikimedia\Parsoid\Core\ContentMetadataCollector;
use Wikimedia\Parsoid\Core\ContentMetadataCollectorCompat;
use Wikimedia\Parsoid\Core\LinkTarget as ParsoidLinkTarget;
use Wikimedia\Parsoid\Core\TOCData;
use Wikimedia\Reflection\GhostFieldAccessTrait;

/**
 * ParserOutput is a rendering of a Content object or a message.
 * Content objects and messages often contain wikitext, but not always.
 *
 * `ParserOutput` object combine the HTML rendering of Content objects
 * or messages, available via `::getRawText()`, with various bits of
 * metadata generated during rendering, which may include categories,
 * links, page properties, and extension data, among others.
 *
 * `ParserOutput` objects corresponding to the content of page revisions
 * are created by the `ParserOutputAccess` service, which
 * automatically caches them via `ParserCache` where appropriate and
 * produces new output via `ContentHandler` as needed.
 *
 * In addition, wikitext from system messages as well as odd bits of
 * wikitext rendered to create special pages and other UX elements are
 * rendered to `ParserOutput` objects.  In these cases the metadata
 * from the `ParserOutput` is generally discarded and the
 * `ParserOutput` is not cached.  These bits of wikitext are generally
 * rendered with `ParserOptions::setInterfaceMessage(true)` when
 * content is intended to be in the user interface language, but
 * sometimes rendered to the content language and displayed in the
 * content area instead.
 *
 * A `ParserOutput` object corresponding to a given revision may be a
 * combination of the renderings of multiple "slots":
 * the Multi-Content Revisions (MCR) work allows articles to be
 * composed from multiple `Content` objects.  Each `Content` renders
 * to a `ParserOutput`, and those `ParserOutput`s are merged by
 * `RevisionRenderer::combineSlotOutput()` to create the final article
 * output.
 *
 * Similarly, `OutputPage` maintains metadata overlapping
 * with the metadata kept by `ParserOutput` (T301020) and may merge
 * several `ParserOutput`s using `OutputPage::addParserOutput()` to
 * create the final output page.  Parsoid parses certain transclusions
 * in independent top-level contexts using
 * `Parser::parseExtensionTagAsTopLevelDoc()` and these also result in
 * `ParserOutput`s which are merged via
 * `ParserOutput::collectMetadata()`.
 *
 * Future plans for incremental parsing and asynchronous rendering may
 * result in several of these component `ParserOutput` objects being
 * cached independently and then recombined asynchronously, so
 * operations on `ParserOutput` objects should be compatible with that
 * model (T300979).
 *
 * @ingroup Parser
 */
class ParserOutput extends CacheTime implements ContentMetadataCollector {
    use GhostFieldAccessTrait;
    use JsonUnserializableTrait;
    // This is used to break cyclic dependencies and allow a measure
    // of compatibility when new methods are added to ContentMetadataCollector
    // by Parsoid.
    use ContentMetadataCollectorCompat;

    /**
     * Feature flags to indicate to extensions that MediaWiki core supports and
     * uses getText() stateless transforms.
     *
     * @since 1.31
     */
    public const SUPPORTS_STATELESS_TRANSFORMS = 1;

    /**
     * @since 1.31
     */
    public const SUPPORTS_UNWRAP_TRANSFORM = 1;

    /**
     * @internal
     * @since 1.38
     */
    public const MW_MERGE_STRATEGY_KEY = '_mw-strategy';

    /**
     * Merge strategy to use for ParserOutput accumulators: "union"
     * means that values are strings, stored as a set, and exposed as
     * a PHP associative array mapping from values to `true`.
     *
     * This constant should be treated as @internal until we expose
     * alternative merge strategies for external use.
     * @internal
     * @since 1.38
     */
    public const MW_MERGE_STRATEGY_UNION = 'union';

    /**
     * @var string|null The output text
     */
    private $mRawText = null;

    /**
     * @var string[] List of the full text of language links, in the order they appear.
     */
    private $mLanguageLinks;

    /**
     * @var array<string,string> Map of category names to sort keys
     */
    private $mCategories;

    /**
     * @var array<string,string> Page status indicators, usually displayed in top-right corner.
     */
    private $mIndicators = [];

    /**
     * @var string Title text of the chosen language variant, as HTML.
     */
    private $mTitleText;

    /**
     * @var array<int,array<string,int>> 2-D map of NS/DBK to ID for the links in the document.
     *  ID=zero for broken.
     */
    private $mLinks = [];

    /**
     * @var array<string,int> Keys are DBKs for the links to special pages in the document.
     * @since 1.35
     */
    private $mLinksSpecial = [];

    /**
     * @var array<int,array<string,int>> 2-D map of NS/DBK to ID for the template references.
     *  ID=zero for broken.
     */
    private $mTemplates = [];

    /**
     * @var array<int,array<string,int>> 2-D map of NS/DBK to rev ID for the template references.
     *  ID=zero for broken.
     */
    private $mTemplateIds = [];

    /**
     * @var array<string,int> DB keys of the images used, in the array key only
     */
    private $mImages = [];

    /**
     * @var array<string,array<string,string>> DB keys of the images used mapped to sha1 and MW timestamp.
     */
    private $mFileSearchOptions = [];

    /**
     * @var array<string,int> External link URLs, in the key only.
     */
    private $mExternalLinks = [];

    /**
     * @var array<string,array<string,int>> 2-D map of prefix/DBK (in keys only)
     *  for the inline interwiki links in the document.
     */
    private $mInterwikiLinks = [];

    /**
     * @var bool Show a new section link?
     */
    private $mNewSection = false;

    /**
     * @var bool Hide the new section link?
     */
    private $mHideNewSection = false;

    /**
     * @var bool No gallery on category page? (__NOGALLERY__).
     */
    private $mNoGallery = false;

    /**
     * @var string[] Items to put in the <head> section
     */
    private $mHeadItems = [];

    /**
     * @var array<string,true> Modules to be loaded by ResourceLoader
     */
    private $mModuleSet = [];

    /**
     * @var array<string,true> Modules of which only the CSS will be loaded by ResourceLoader.
     */
    private $mModuleStyleSet = [];

    /**
     * @var array JavaScript config variable for mw.config combined with this page.
     */
    private $mJsConfigVars = [];

    /**
     * @var array<string,int> Warning text to be returned to the user.
     *  Wikitext formatted, in the key only.
     */
    private $mWarnings = [];

    /**
     * @var array<string,array> *Unformatted* warning messages and
     * arguments to be returned to the user.  This is for internal use
     * when merging ParserOutputs and are not serialized/deserialized.
     */
    private $mWarningMsgs = [];

    /**
     * @var ?TOCData Table of contents data, or null if it hasn't been set.
     */
    private $mTOCData;

    /**
     * @var array Name/value pairs to be cached in the DB.
     */
    private $mProperties = [];

    /**
     * @var ?string Timestamp of the revision.
     */
    private $mTimestamp;

    /**
     * @var bool Whether OOUI should be enabled.
     */
    private $mEnableOOUI = false;

    /**
     * @var bool Whether the index policy has been set to 'index'.
     */
    private $mIndexSet = false;

    /**
     * @var bool Whether the index policy has been set to 'noindex'.
     */
    private $mNoIndexSet = false;

    /**
     * @var array extra data used by extensions.
     */
    private $mExtensionData = [];

    /**
     * @var array Parser limit report data.
     */
    private $mLimitReportData = [];

    /** @var array Parser limit report data for JSON */
    private $mLimitReportJSData = [];

    /** @var string Debug message added by ParserCache */
    private $mCacheMessage = '';

    /**
     * @var array Timestamps for getTimeSinceStart().
     */
    private $mParseStartTime = [];

    /**
     * @var array Durations for getTimeProfile().
     */
    private $mTimeProfile = [];

    /**
     * @var bool Whether to emit X-Frame-Options: DENY.
     */
    private $mPreventClickjacking = false;

    /**
     * @var string[] Extra script-src for CSP
     */
    private $mExtraScriptSrcs = [];

    /**
     * @var string[] Extra default-src for CSP [Everything but script and style]
     */
    private $mExtraDefaultSrcs = [];

    /**
     * @var string[] Extra style-src for CSP
     */
    private $mExtraStyleSrcs = [];

    /**
     * @var array<string,true> Generic flags.
     */
    private $mFlags = [];

    /** @var string[] */
    private const SPECULATIVE_FIELDS = [
        'speculativePageIdUsed',
        'mSpeculativeRevId',
        'revisionTimestampUsed',
    ];

    /** @var int|null Assumed rev ID for {{REVISIONID}} if no revision is set */
    private $mSpeculativeRevId;
    /** @var int|null Assumed page ID for {{PAGEID}} if no revision is set */
    private $speculativePageIdUsed;
    /** @var string|null Assumed rev timestamp for {{REVISIONTIMESTAMP}} if no revision is set */
    private $revisionTimestampUsed;

    /** @var string|null SHA-1 base 36 hash of any self-transclusion */
    private $revisionUsedSha1Base36;

    /** string CSS classes to use for the wrapping div, stored in the array keys.
     * If no class is given, no wrapper is added.
     */
    private $mWrapperDivClasses = [];

    /** @var int Upper bound of expiry based on parse duration */
    private $mMaxAdaptiveExpiry = INF;

    // finalizeAdaptiveCacheExpiry() uses TTL = MAX( m * PARSE_TIME + b, MIN_AR_TTL)
    // Current values imply that m=3933.333333 and b=-333.333333
    // See https://www.nngroup.com/articles/website-response-times/
    private const PARSE_FAST_SEC = 0.100; // perceived "fast" page parse
    private const PARSE_SLOW_SEC = 1.0; // perceived "slow" page parse
    private const FAST_AR_TTL = 60; // adaptive TTL for "fast" pages
    private const SLOW_AR_TTL = 3600; // adaptive TTL for "slow" pages
    private const MIN_AR_TTL = 15; // min adaptive TTL (for pool counter, and edit stashing)

    /**
     * @param string|null $text HTML. Use null to indicate that this ParserOutput contains only
     *        meta-data, and the HTML output is undetermined, as opposed to empty. Passing null
     *        here causes hasText() to return false. In 1.39 the default value changed from ''
     *        to null.
     * @param array $languageLinks
     * @param array $categoryLinks
     * @param bool $unused
     * @param string $titletext
     */
    public function __construct( $text = null, $languageLinks = [], $categoryLinks = [],
        $unused = false, $titletext = ''
    ) {
        $this->mRawText = $text;
        $this->mLanguageLinks = $languageLinks;
        $this->mCategories = $categoryLinks;
        $this->mTitleText = $titletext;
    }

    /**
     * Returns true if text was passed to the constructor, or set using setText(). Returns false
     * if null was passed to the $text parameter of the constructor to indicate that this
     * ParserOutput only contains meta-data, and the HTML output is undetermined.
     *
     * @since 1.32
     *
     * @return bool Whether this ParserOutput contains rendered text. If this returns false, the
     *         ParserOutput contains meta-data only.
     */
    public function hasText(): bool {
        return ( $this->mRawText !== null );
    }

    /**
     * Get the cacheable text with <mw:editsection> markers still in it. The
     * return value is suitable for writing back via setText() but is not valid
     * for display to the user.
     *
     * @return string
     * @since 1.27
     */
    public function getRawText() {
        if ( $this->mRawText === null ) {
            throw new LogicException( 'This ParserOutput contains no text!' );
        }

        return $this->mRawText;
    }

    /**
     * Get the output HTML
     *
     * T293512: in the future, ParserOutput::getText() will be deprecated in favor of invoking the
     * ParserOutputTransform pipeline directly on a ParserOutput.
     * @param array $options (since 1.31) Transformations to apply to the HTML
     *  - allowTOC: (bool) Show the TOC, assuming there were enough headings
     *     to generate one and `__NOTOC__` wasn't used. Default is true,
     *     but might be statefully overridden.
     *  - injectTOC: (bool) Replace the TOC_PLACEHOLDER with TOC contents;
     *     otherwise the marker will be left in the article (and the skin
     *     will be responsible for replacing or removing it).  Default is
     *     true.
     *  - enableSectionEditLinks: (bool) Include section edit links, assuming
     *     section edit link tokens are present in the HTML. Default is true,
     *     but might be statefully overridden.
     *  - userLang: (Language) Language object used for localizing UX messages,
     *    for example the heading of the table of contents. If omitted, will
     *    use the language of the main request context.
     *  - skin: (Skin) Skin object used for transforming section edit links.
     *  - unwrap: (bool) Return text without a wrapper div. Default is false,
     *    meaning a wrapper div will be added if getWrapperDivClass() returns
     *    a non-empty string.
     *  - wrapperDivClass: (string) Wrap the output in a div and apply the given
     *    CSS class to that div. This overrides the output of getWrapperDivClass().
     *    Setting this to an empty string has the same effect as 'unwrap' => true.
     *  - deduplicateStyles: (bool) When true, which is the default, `<style>`
     *    tags with the `data-mw-deduplicate` attribute set are deduplicated by
     *    value of the attribute: all but the first will be replaced by `<link
     *    rel="mw-deduplicated-inline-style" href="mw-data:..."/>` tags, where
     *    the scheme-specific-part of the href is the (percent-encoded) value
     *    of the `data-mw-deduplicate` attribute.
     *  - absoluteURLs: (bool) use absolute URLs in all links. Default: false
     *  - includeDebugInfo: (bool) render PP limit report in HTML. Default: false
     * @return string HTML
     * @return-taint escaped
     * @deprecated since 1.42, this method has side-effects on the ParserOutput
     *  (see T353257) and so should be avoided in favor of directly invoking
     *  the default output pipeline on a ParserOutput.
     */
    public function getText( $options = [] ) {
        $pipeline = MediaWikiServices::getInstance()->getDefaultOutputPipeline();
        $oldText = $this->mRawText; // T353257
        $options += [
            'suppressClone' => true, // T353257
            'allowTOC' => true,
            'injectTOC' => true,
            'enableSectionEditLinks' => !$this->getOutputFlag( ParserOutputFlags::NO_SECTION_EDIT_LINKS ),
            'userLang' => null,
            'skin' => null,
            'unwrap' => false,
            'wrapperDivClass' => $this->getWrapperDivClass(),
            'deduplicateStyles' => true,
            'absoluteURLs' => false,
            'includeDebugInfo' => false,
            'isParsoidContent' => PageBundleParserOutputConverter::hasPageBundle( $this ),
        ];
        $po = $pipeline->run( $this, null, $options );
        $newText = $po->getContentHolderText();
        // T353257: for back-compat only mutations to metadata performed by
        // the pipeline should be preserved; mutations to $mText should be
        // discarded.
        $this->setRawText( $oldText );
        return $newText;
    }

    /**
     * Adds a comment notice about cache state to the text of the page
     * @param string $msg
     * @internal used by ParserCache
     */
    public function addCacheMessage( string $msg ): void {
        $this->mCacheMessage .= $msg;
    }

    /**
     * Add a CSS class to use for the wrapping div. If no class is given, no wrapper is added.
     *
     * @param string $class
     */
    public function addWrapperDivClass( $class ): void {
        $this->mWrapperDivClasses[$class] = true;
    }

    /**
     * Clears the CSS class to use for the wrapping div, effectively disabling the wrapper div
     * until addWrapperDivClass() is called.
     */
    public function clearWrapperDivClass(): void {
        $this->mWrapperDivClasses = [];
    }

    /**
     * Returns the class (or classes) to be used with the wrapper div for this output.
     * If there is no wrapper class given, no wrapper div should be added.
     * The wrapper div is added automatically by getText().
     *
     * @return string
     */
    public function getWrapperDivClass(): string {
        return implode( ' ', array_keys( $this->mWrapperDivClasses ) );
    }

    /**
     * @param int $id
     * @since 1.28
     */
    public function setSpeculativeRevIdUsed( $id ): void {
        $this->mSpeculativeRevId = $id;
    }

    /**
     * @return int|null
     * @since 1.28
     */
    public function getSpeculativeRevIdUsed(): ?int {
        return $this->mSpeculativeRevId;
    }

    /**
     * @param int $id
     * @since 1.34
     */
    public function setSpeculativePageIdUsed( $id ): void {
        $this->speculativePageIdUsed = $id;
    }

    /**
     * @return int|null
     * @since 1.34
     */
    public function getSpeculativePageIdUsed() {
        return $this->speculativePageIdUsed;
    }

    /**
     * @param string $timestamp TS_MW timestamp
     * @since 1.34
     */
    public function setRevisionTimestampUsed( $timestamp ): void {
        $this->revisionTimestampUsed = $timestamp;
    }

    /**
     * @return string|null TS_MW timestamp or null if not used
     * @since 1.34
     */
    public function getRevisionTimestampUsed() {
        return $this->revisionTimestampUsed;
    }

    /**
     * @param string $hash Lowercase SHA-1 base 36 hash
     * @since 1.34
     */
    public function setRevisionUsedSha1Base36( $hash ): void {
        if ( $hash === null ) {
            return; // e.g. RevisionRecord::getSha1() returned null
        }

        if (
            $this->revisionUsedSha1Base36 !== null &&
            $this->revisionUsedSha1Base36 !== $hash
        ) {
            $this->revisionUsedSha1Base36 = ''; // mismatched
        } else {
            $this->revisionUsedSha1Base36 = $hash;
        }
    }

    /**
     * @return string|null Lowercase SHA-1 base 36 hash, null if unused, or "" on inconsistency
     * @since 1.34
     */
    public function getRevisionUsedSha1Base36() {
        return $this->revisionUsedSha1Base36;
    }

    public function &getLanguageLinks() {
        return $this->mLanguageLinks;
    }

    public function getInterwikiLinks() {
        return $this->mInterwikiLinks;
    }

    /**
     * Return the names of the categories on this page.
     * Unlike ::getCategories(), sort keys are *not* included in the
     * return value.
     * @return array<string> The names of the categories
     * @since 1.38
     */
    public function getCategoryNames(): array {
        # Note that numeric category names get converted to 'int' when
        # stored as array keys; stringify the keys to ensure they
        # return to original string form so as not to confuse callers.
        return array_map( 'strval', array_keys( $this->mCategories ) );
    }

    /**
     * Return category names and sort keys as a map.
     *
     * BEWARE that numeric category names get converted to 'int' when stored
     * as array keys.  Because of this, use of this method is not recommended
     * in new code; using ::getCategoryNames() and ::getCategorySortKey() will
     * be less error-prone.
     *
     * @return array<string|int,string>
     * @internal
     */
    public function getCategoryMap(): array {
        return $this->mCategories;
    }

    /**
     * Return the sort key for a given category name, or `null` if the
     * category is not present in this ParserOutput.  Returns the
     * empty string if the category is to use the default sort key.
     *
     * @note The effective sort key in the database may vary from what
     * is returned here; see note in ParserOutput::addCategory().
     *
     * @param string $name The category name
     * @return ?string The sort key for the category, or `null` if the
     *  category is not present in this ParserOutput
     * @since 1.40
     */
    public function getCategorySortKey( string $name ): ?string {
        // This API avoids exposing the fact that numeric string category
        // names are going to be converted to 'int' when used as array
        // keys for the `mCategories` field.
        return $this->mCategories[$name] ?? null;
    }

    /**
     * @return string[]
     * @since 1.25
     */
    public function getIndicators(): array {
        return $this->mIndicators;
    }

    public function getTitleText() {
        return $this->mTitleText;
    }

    /**
     * @return ?TOCData the table of contents data, or null if it hasn't been
     * set.
     */
    public function getTOCData(): ?TOCData {
        return $this->mTOCData;
    }

    /**
     * @internal
     * @return string
     */
    public function getCacheMessage(): string {
        return $this->mCacheMessage;
    }

    /**
     * @internal
     * @return array
     */
    public function getSections(): array {
        if ( $this->mTOCData !== null ) {
            return $this->mTOCData->toLegacy();
        }
        // For compatibility
        return [];
    }

    public function &getLinks() {
        return $this->mLinks;
    }

    /**
     * @return array Keys are DBKs for the links to special pages in the document
     * @since 1.35
     */
    public function &getLinksSpecial() {
        return $this->mLinksSpecial;
    }

    public function &getTemplates() {
        return $this->mTemplates;
    }

    public function &getTemplateIds() {
        return $this->mTemplateIds;
    }

    public function &getImages() {
        return $this->mImages;
    }

    public function &getFileSearchOptions() {
        return $this->mFileSearchOptions;
    }

    public function &getExternalLinks() {
        return $this->mExternalLinks;
    }

    public function setNoGallery( $value ): void {
        $this->mNoGallery = (bool)$value;
    }

    public function getNoGallery() {
        return $this->mNoGallery;
    }

    public function getHeadItems() {
        return $this->mHeadItems;
    }

    public function getModules() {
        return array_keys( $this->mModuleSet );
    }

    public function getModuleStyles() {
        return array_keys( $this->mModuleStyleSet );
    }

    /**
     * @param bool $showStrategyKeys Defaults to false; if set to true will
     *  expose the internal `MW_MERGE_STRATEGY_KEY` in the result.  This
     *  should only be used internally to allow safe merge of config vars.
     * @return array
     * @since 1.23
     */
    public function getJsConfigVars( bool $showStrategyKeys = false ) {
        $result = $this->mJsConfigVars;
        // Don't expose the internal strategy key
        foreach ( $result as &$value ) {
            if ( is_array( $value ) && !$showStrategyKeys ) {
                unset( $value[self::MW_MERGE_STRATEGY_KEY] );
            }
        }
        return $result;
    }

    public function getWarnings(): array {
        return array_keys( $this->mWarnings );
    }

    public function getIndexPolicy(): string {
        // 'noindex' wins if both are set. (T16899)
        if ( $this->mNoIndexSet ) {
            return 'noindex';
        } elseif ( $this->mIndexSet ) {
            return 'index';
        }
        return '';
    }

    /**
     * @return string|null TS_MW timestamp of the revision content
     */
    public function getRevisionTimestamp(): ?string {
        return $this->mTimestamp;
    }

    /**
     * @return string|null TS_MW timestamp of the revision content
     * @deprecated since 1.42; use ::getRevisionTimestamp() instead
     */
    public function getTimestamp() {
        return $this->getRevisionTimestamp();
    }

    public function getLimitReportData() {
        return $this->mLimitReportData;
    }

    public function getLimitReportJSData() {
        return $this->mLimitReportJSData;
    }

    public function getEnableOOUI() {
        return $this->mEnableOOUI;
    }

    /**
     * Get extra Content-Security-Policy 'default-src' directives
     * @since 1.35
     * @return string[]
     */
    public function getExtraCSPDefaultSrcs() {
        return $this->mExtraDefaultSrcs;
    }

    /**
     * Get extra Content-Security-Policy 'script-src' directives
     * @since 1.35
     * @return string[]
     */
    public function getExtraCSPScriptSrcs() {
        return $this->mExtraScriptSrcs;
    }

    /**
     * Get extra Content-Security-Policy 'style-src' directives
     * @since 1.35
     * @return string[]
     */
    public function getExtraCSPStyleSrcs() {
        return $this->mExtraStyleSrcs;
    }

    /**
     * Set the raw text of the ParserOutput.
     *
     * If you did not generate html, pass null to mark it as such.
     *
     * @since 1.42
     * @param string|null $text HTML content of ParserOutput or null if not generated
     * @param-taint $text exec_html
     */
    public function setRawText( ?string $text ): void {
        $this->mRawText = $text;
    }

    /**
     * Set the raw text of the ParserOutput.
     *
     * If you did not generate html, pass null to mark it as such.
     *
     * @since 1.39 You can now pass null to this function
     * @param string|null $text HTML content of ParserOutput or null if not generated
     * @param-taint $text exec_html
     * @return string|null Previous value of ParserOutput's raw text
     * @deprecated since 1.42; use ::setRawText() which matches the getter ::getRawText()
     */
    public function setText( $text ) {
        return wfSetVar( $this->mRawText, $text, true );
    }

    /**
     * @deprecated since 1.42, use ::addLanguageLink() instead.
     */
    public function setLanguageLinks( $ll ) {
        return wfSetVar( $this->mLanguageLinks, $ll );
    }

    public function setTitleText( $t ) {
        return wfSetVar( $this->mTitleText, $t );
    }

    /**
     * @param TOCData $tocData Table of contents data for the page
     */
    public function setTOCData( TOCData $tocData ): void {
        $this->mTOCData = $tocData;
    }

    /**
     * @param array $sectionArray
     * @return array Previous value of ::getSections()
     */
    public function setSections( array $sectionArray ) {
        $oldValue = $this->getSections();
        $this->setTOCData( TOCData::fromLegacy( $sectionArray ) );
        return $oldValue;
    }

    public function setIndexPolicy( $policy ): string {
        $old = $this->getIndexPolicy();
        if ( $policy === 'noindex' ) {
            $this->mNoIndexSet = true;
        } elseif ( $policy === 'index' ) {
            $this->mIndexSet = true;
        }
        return $old;
    }

    /**
     * @param ?string $timestamp TS_MW timestamp of the revision content
     */
    public function setRevisionTimestamp( ?string $timestamp ): void {
        $this->mTimestamp = $timestamp;
    }

    /**
     * @param ?string $timestamp TS_MW timestamp of the revision content
     *
     * @return ?string The previous value of the timestamp
     * @deprecated since 1.42; use ::setRevisionTimestamp() instead
     */
    public function setTimestamp( $timestamp ) {
        return wfSetVar( $this->mTimestamp, $timestamp );
    }

    /**
     * Add a category.
     *
     * Although ParserOutput::getCategorySortKey() will return exactly
     * the sort key you specify here, before storing in the database
     * all sort keys will be language converted, HTML entities will be
     * decoded, newlines stripped, and then they will be truncated to
     * 255 bytes. Thus the "effective" sort key in the DB may be different
     * from what is passed to `$sort` here and returned by
     * ::getCategorySortKey().
     *
     * @param string|ParsoidLinkTarget $c The category name
     * @param string $sort The sort key; an empty string indicates
     *  that the default sort key for the page should be used.
     */
    public function addCategory( $c, $sort = '' ): void {
        if ( $c instanceof ParsoidLinkTarget ) {
            $c = $c->getDBkey();
        }
        $this->mCategories[$c] = $sort;
    }

    /**
     * Overwrite the category map.
     * @param array<string,string> $c Map of category names to sort keys
     * @since 1.38
     */
    public function setCategories( array $c ): void {
        $this->mCategories = $c;
    }

    /**
     * @param string $id
     * @param string $content
     * @param-taint $content exec_html
     * @since 1.25
     */
    public function setIndicator( $id, $content ): void {
        $this->mIndicators[$id] = $content;
    }

    /**
     * Enables OOUI, if true, in any OutputPage instance this ParserOutput
     * object is added to.
     *
     * @since 1.26
     * @param bool $enable If OOUI should be enabled or not
     */
    public function setEnableOOUI( bool $enable = false ): void {
        $this->mEnableOOUI = $enable;
    }

    /**
     * Add a language link.
     * @param ParsoidLinkTarget|string $t
     */
    public function addLanguageLink( $t ): void {
        if ( $t instanceof ParsoidLinkTarget ) {
            // language links are unusual in using 'text' rather than 'db key'
            // T296019: This should be made more efficient so we don't need
            // a full title lookup.
            $t = Title::newfromLinkTarget( $t )->getFullText();
        }
        $this->mLanguageLinks[] = $t;
    }

    /**
     * Add a warning to the output for this page.
     * @param string $msg The localization message key for the warning
     * @param mixed|JsonUnserializable ...$args Optional arguments for the
     *   message. These arguments must be serializable/unserializable with
     *   JsonCodec; see the @note on ParserOutput::setExtensionData()
     * @since 1.38
     */
    public function addWarningMsg( string $msg, ...$args ): void {
        // preserve original arguments in $mWarningMsgs to allow merge
        // @todo: these aren't serialized/unserialized yet -- before we
        // turn on serialization of $this->mWarningMsgs we need to ensure
        // callers aren't passing nonserializable arguments: T343048.
        $jsonCodec = MediaWikiServices::getInstance()->getJsonCodec();
        $path = $jsonCodec->detectNonSerializableData( $args, true );
        if ( $path !== null ) {
            wfDeprecatedMsg(
                "ParserOutput::addWarningMsg() called with nonserializable arguments: $path",
                '1.41'
            );
        }
        $this->mWarningMsgs[$msg] = $args;
        $s = wfMessage( $msg, ...$args )
            // some callers set the title here?
            ->inContentLanguage() // because this ends up in cache
            ->text();
        $this->mWarnings[$s] = 1;
    }

    public function setNewSection( $value ): void {
        $this->mNewSection = (bool)$value;
    }

    /**
     * @param bool $value Hide the new section link?
     */
    public function setHideNewSection( bool $value ): void {
        $this->mHideNewSection = $value;
    }

    public function getHideNewSection(): bool {
        return (bool)$this->mHideNewSection;
    }

    public function getNewSection(): bool {
        return (bool)$this->mNewSection;
    }

    /**
     * Checks, if a url is pointing to the own server
     *
     * @param string $internal The server to check against
     * @param string $url The url to check
     * @return bool
     * @internal
     */
    public static function isLinkInternal( $internal, $url ): bool {
        return (bool)preg_match( '/^' .
            # If server is proto relative, check also for http/https links
            ( substr( $internal, 0, 2 ) === '//' ? '(?:https?:)?' : '' ) .
            preg_quote( $internal, '/' ) .
            # check for query/path/anchor or end of link in each case
            '(?:[\?\/\#]|$)/i',
            $url
        );
    }

    public function addExternalLink( $url ): void {
        # We don't register links pointing to our own server, unless... :-)
        $config = MediaWikiServices::getInstance()->getMainConfig();
        $server = $config->get( MainConfigNames::Server );
        $registerInternalExternals = $config->get( MainConfigNames::RegisterInternalExternals );
        # Replace unnecessary URL escape codes with the referenced character
        # This prevents spammers from hiding links from the filters
        $url = Parser::normalizeLinkUrl( $url );

        $registerExternalLink = true;
        if ( !$registerInternalExternals ) {
            $registerExternalLink = !self::isLinkInternal( $server, $url );
        }
        if ( $registerExternalLink ) {
            $this->mExternalLinks[$url] = 1;
        }
    }

    /**
     * Record a local or interwiki inline link for saving in future link tables.
     *
     * @param ParsoidLinkTarget $link (used to require Title until 1.38)
     * @param int|null $id Optional known page_id so we can skip the lookup
     */
    public function addLink( ParsoidLinkTarget $link, $id = null ): void {
        if ( $link->isExternal() ) {
            // Don't record interwikis in pagelinks
            $this->addInterwikiLink( $link );
            return;
        }
        $ns = $link->getNamespace();
        $dbk = $link->getDBkey();
        if ( $ns === NS_MEDIA ) {
            // Normalize this pseudo-alias if it makes it down here...
            $ns = NS_FILE;
        } elseif ( $ns === NS_SPECIAL ) {
            // We don't want to record Special: links in the database, so put them in a separate place.
            // It might actually be wise to, but we'd need to do some normalization.
            $this->mLinksSpecial[$dbk] = 1;
            return;
        } elseif ( $dbk === '' ) {
            // Don't record self links -  [[#Foo]]
            return;
        }
        if ( $id === null ) {
            // T357048: This actually kills performance; we should batch these.
            $page = MediaWikiServices::getInstance()->getPageStore()->getPageForLink( $link );
            $id = $page->getId();
        }
        $this->mLinks[$ns][$dbk] = $id;
    }

    /**
     * Register a file dependency for this output
     * @param string|ParsoidLinkTarget $name Title dbKey
     * @param string|false|null $timestamp MW timestamp of file creation (or false if non-existing)
     * @param string|false|null $sha1 Base 36 SHA-1 of file (or false if non-existing)
     */
    public function addImage( $name, $timestamp = null, $sha1 = null ): void {
        if ( $name instanceof ParsoidLinkTarget ) {
            $name = $name->getDBkey();
        }
        $this->mImages[$name] = 1;
        if ( $timestamp !== null && $sha1 !== null ) {
            $this->mFileSearchOptions[$name] = [ 'time' => $timestamp, 'sha1' => $sha1 ];
        }
    }

    /**
     * Register a template dependency for this output
     *
     * @param ParsoidLinkTarget $link (used to require Title until 1.38)
     * @param int $page_id
     * @param int $rev_id
     */
    public function addTemplate( $link, $page_id, $rev_id ): void {
        if ( $link->isExternal() ) {
            // Will throw an InvalidArgumentException in a future release.
            wfDeprecated( __METHOD__ . " with interwiki link", '1.42' );
            return;
        }
        $ns = $link->getNamespace();
        $dbk = $link->getDBkey();
        // T357048: Parsoid doesn't have page_id
        $this->mTemplates[$ns][$dbk] = $page_id;
        $this->mTemplateIds[$ns][$dbk] = $rev_id; // For versioning
    }

    /**
     * @param ParsoidLinkTarget $link must be an interwiki link
     *       (used to require Title until 1.38).
     */
    public function addInterwikiLink( $link ): void {
        if ( !$link->isExternal() ) {
            throw new InvalidArgumentException( 'Non-interwiki link passed, internal parser error.' );
        }
        $prefix = $link->getInterwiki();
        $this->mInterwikiLinks[$prefix][$link->getDBkey()] = 1;
    }

    /**
     * Add some text to the "<head>".
     * If $tag is set, the section with that tag will only be included once
     * in a given page.
     * @param string $section
     * @param string|false $tag
     */
    public function addHeadItem( $section, $tag = false ): void {
        if ( $tag !== false ) {
            $this->mHeadItems[$tag] = $section;
        } else {
            $this->mHeadItems[] = $section;
        }
    }

    /**
     * @see OutputPage::addModules
     * @param string[] $modules
     */
    public function addModules( array $modules ): void {
        $modules = array_fill_keys( $modules, true );
        $this->mModuleSet = array_merge( $this->mModuleSet, $modules );
    }

    /**
     * @see OutputPage::addModuleStyles
     * @param string[] $modules
     */
    public function addModuleStyles( array $modules ): void {
        $modules = array_fill_keys( $modules, true );
        $this->mModuleStyleSet = array_merge( $this->mModuleStyleSet, $modules );
    }

    /**
     * Add one or more variables to be set in mw.config in JavaScript.
     *
     * @param string|array $keys Key or array of key/value pairs.
     * @param mixed|null $value [optional] Value of the configuration variable.
     * @since 1.23
     * @deprecated since 1.38, use ::setJsConfigVar() or ::appendJsConfigVar()
     *  which ensures compatibility with asynchronous parsing.
     */
    public function addJsConfigVars( $keys, $value = null ): void {
        if ( is_array( $keys ) ) {
            foreach ( $keys as $key => $value ) {
                $this->mJsConfigVars[$key] = $value;
            }
            return;
        }

        $this->mJsConfigVars[$keys] = $value;
    }

    /**
     * Add a variable to be set in mw.config in JavaScript.
     *
     * In order to ensure the result is independent of the parse order, the values
     * set here must be unique -- that is, you can pass the same $key
     * multiple times but ONLY if the $value is identical each time.
     * If you want to collect multiple pieces of data under a single key,
     * use ::appendJsConfigVar().
     *
     * @param string $key Key to use under mw.config
     * @param mixed|null $value Value of the configuration variable.
     * @since 1.38
     */
    public function setJsConfigVar( string $key, $value ): void {
        if (
            array_key_exists( $key, $this->mJsConfigVars ) &&
            $this->mJsConfigVars[$key] !== $value
        ) {
            // Ensure that a key is mapped to only a single value in order
            // to prevent the resulting array from varying if content
            // is parsed in a different order.
            throw new InvalidArgumentException( "Multiple conflicting values given for $key" );
        }
        $this->mJsConfigVars[$key] = $value;
    }

    /**
     * Append a value to a variable to be set in mw.config in JavaScript.
     *
     * In order to ensure the result is independent of the parse order,
     * the value of this key will be an associative array, mapping all of
     * the values set under that key to true.  (The array is implicitly
     * ordered in PHP, but you should treat it as unordered.)
     * If you want a non-array type for the key, and can ensure that only
     * a single value will be set, you should use ::setJsConfigVar() instead.
     *
     * @param string $key Key to use under mw.config
     * @param string $value Value to append to the configuration variable.
     * @param string $strategy Merge strategy:
     *  only MW_MERGE_STRATEGY_UNION is currently supported and external callers
     *  should treat this parameter as @internal at this time and omit it.
     * @since 1.38
     */
    public function appendJsConfigVar(
        string $key,
        string $value,
        string $strategy = self::MW_MERGE_STRATEGY_UNION
    ): void {
        if ( $strategy !== self::MW_MERGE_STRATEGY_UNION ) {
            throw new InvalidArgumentException( "Unknown merge strategy $strategy." );
        }
        if ( !array_key_exists( $key, $this->mJsConfigVars ) ) {
            $this->mJsConfigVars[$key] = [
                // Indicate how these values are to be merged.
                self::MW_MERGE_STRATEGY_KEY => $strategy,
            ];
        } elseif ( !is_array( $this->mJsConfigVars[$key] ) ) {
            throw new InvalidArgumentException( "Mixing set and append for $key" );
        } elseif ( ( $this->mJsConfigVars[$key][self::MW_MERGE_STRATEGY_KEY] ?? null ) !== $strategy ) {
            throw new InvalidArgumentException( "Conflicting merge strategies for $key" );
        }
        $this->mJsConfigVars[$key][$value] = true;
    }

    /**
     * Accommodate very basic transcluding of a temporary OutputPage object into parser output.
     *
     * This is a fragile method that cannot be relied upon in any meaningful way.
     * It exists solely to support the wikitext feature of transcluding a SpecialPage, and
     * only has to work for that use case to ensure relevant styles are loaded, and that
     * essential config vars needed between SpecialPage and a JS feature are added.
     *
     * This relies on there being no overlap between modules or config vars added by
     * the SpecialPage and those added by parser extensions. If there is overlap,
     * then arise and break one or both sides. This is expected and unsupported.
     *
     * @internal For use by Parser for basic special page transclusion
     * @param OutputPage $out
     */
    public function addOutputPageMetadata( OutputPage $out ): void {
        // This should eventually use the same merge mechanism used
        // internally to merge ParserOutputs together.

        // Take the strictest click-jacking policy. This is to ensure any one-click features
        // such as patrol or rollback on the transcluded special page will result in the wiki page
        // disallowing embedding in cross-origin iframes. Articles are generally allowed to be
        // embedded. Pages that transclude special pages are expected to be user pages or
        // other non-content pages that content re-users won't discover or care about.
        $this->mPreventClickjacking = $this->mPreventClickjacking || $out->getPreventClickjacking();

        $this->addModuleStyles( $out->getModuleStyles() );

        // TODO: Figure out if style modules suffice, or whether the below is needed as well.
        // Are there special pages that permit transcluding/including and also have JS modules
        // that should be activate on the host page?
        $this->addModules( $out->getModules() );
        $this->mJsConfigVars = self::mergeMapStrategy(
            $this->mJsConfigVars, $out->getJsConfigVars()
        );
        $this->mHeadItems = array_merge( $this->mHeadItems, $out->getHeadItemsArray() );
    }

    /**
     * Override the title to be used for display
     *
     * @note this is assumed to have been validated
     * (check equal normalisation, etc.)
     *
     * @note this is expected to be safe HTML,
     * ready to be served to the client.
     *
     * @param string $text Desired title text
     */
    public function setDisplayTitle( $text ): void {
        $this->setTitleText( $text );
        $this->setPageProperty( 'displaytitle', $text );
    }

    /**
     * Get the title to be used for display.
     *
     * As per the contract of setDisplayTitle(), this is safe HTML,
     * ready to be served to the client.
     *
     * @return string|false HTML
     */
    public function getDisplayTitle() {
        $t = $this->getTitleText();
        if ( $t === '' ) {
            return false;
        }
        return $t;
    }

    /**
     * Get the primary language code of the output.
     *
     * This returns the primary language of the output, including
     * any LanguageConverter variant applied.
     *
     * NOTE: This may differ from the wiki's default content language
     * ($wgLanguageCode, MediaWikiServices::getContentLanguage), because
     * each page may have its own "page language" set (PageStoreRecord,
     * Title::getDbPageLanguageCode, ContentHandler::getPageLanguage).
     *
     * NOTE: This may differ from the "page language" when parsing
     * user interface messages, in which case this reflects the user
     * language (including any variant preference).
     *
     * NOTE: This may differ from the Parser's "target language" that was
     * set while the Parser was parsing the page, because the final output
     * is converted to the current user's preferred LanguageConverter variant
     * (assuming this is a variant of the target language).
     * See Parser::getTargetLanguageConverter()->getPreferredVariant(); use
     * LanguageFactory::getParentLanguage() on the language code to obtain
     * the base language code. LanguageConverter::getPreferredVariant()
     * depends on the global RequestContext for the URL and the User
     * language preference.
     *
     * Finally, note that a single ParserOutput object may contain
     * HTML content in multiple different languages and directions
     * (T114640). Authors of wikitext and of parser extensions are
     * expected to mark such subtrees with a `lang` attribute (set to
     * a BCP-47 value, see Language::toBcp47Code()) and a corresponding
     * `dir` attribute (see Language::getDir()). This method returns
     * the language code for wrapper of the HTML content.
     *
     * @see Parser::internalParseHalfParsed
     * @since 1.40
     * @return ?Bcp47Code The primary language for this output,
     *   or `null` if a language was not set.
     */
    public function getLanguage(): ?Bcp47Code {
        // This information is temporarily stored in extension data (T303329)
        $code = $this->getExtensionData( 'core:target-lang-variant' );
        // This is null if the ParserOutput was cached by MW 1.40 or earlier,
        // or not constructed by Parser/ParserCache.
        return $code === null ? null : new Bcp47CodeValue( $code );
    }

    /**
     * Set the primary language of the output.
     *
     * See the discussion and caveats in ::getLanguage().
     *
     * @param Bcp47Code $lang The primary language for this output, including
     *   any variant specification.
     * @since 1.40
     */
    public function setLanguage( Bcp47Code $lang ): void {
        $this->setExtensionData( 'core:target-lang-variant', $lang->toBcp47Code() );
    }

    /**
     * Return an HTML prefix to be applied on redirect pages, or null
     * if this is not a redirect.
     * @return ?string HTML to prepend to redirect pages, or null
     * @internal
     */
    public function getRedirectHeader(): ?string {
        return $this->getExtensionData( 'core:redirect-header' );
    }

    /**
     * Set an HTML prefix to be applied on redirect pages.
     * @param string $html HTML to prepend to redirect pages
     */
    public function setRedirectHeader( string $html ): void {
        $this->setExtensionData( 'core:redirect-header', $html );
    }

    /**
     * Store a unique rendering id for this ParserOutput.  This is used
     * whenever a client needs to record a dependency on a specific parse.
     * It is typically set only when a parser output is cached.
     *
     * @param string $renderId a UUID identifying a specific parse
     * @internal
     */
    public function setRenderId( string $renderId ): void {
        $this->setExtensionData( 'core:render-id', $renderId );
    }

    /**
     * Return the unique rendering id for this ParserOutput. This is used
     * whenever a client needs to record a dependency on a specific parse.
     *
     * @return string|null
     * @internal
     */
    public function getRenderId(): ?string {
        // Backward-compatibility with old cache contents
        // Can be removed after parser cache contents have expired
        $old = $this->getExtensionData( 'parsoid-render-id' );
        if ( $old !== null ) {
            return ParsoidRenderId::newFromKey( $old )->getUniqueID();
        }
        return $this->getExtensionData( 'core:render-id' );
    }

    /**
     * @return string[] List of flags signifying special cases
     * @internal
     */
    public function getAllFlags(): array {
        return array_keys( $this->mFlags );
    }

    /**
     * Set a page property to be stored in the page_props database table.
     *
     * page_props is a key-value store indexed by the page ID. This allows
     * the parser to set a property on a page which can then be quickly
     * retrieved given the page ID or via a DB join when given the page
     * title.
     *
     * Since 1.23, page_props are also indexed by numeric value, to allow
     * for efficient "top k" queries of pages wrt a given property.
     * This only works if the value is passed as a int, float, or
     * bool. Since 1.42 you should use ::setNumericPageProperty()
     * if you want your page property value to be indexed, which will ensure
     * that the value is of the proper type.
     *
     * setPageProperty() is thus used to propagate properties from the parsed
     * page to request contexts other than a page view of the currently parsed
     * article.
     *
     * Some applications examples:
     *
     *   * To implement hidden categories, hiding pages from category listings
     *     by storing a page property.
     *
     *   * Overriding the displayed article title (ParserOutput::setDisplayTitle()).
     *
     *   * To implement image tagging, for example displaying an icon on an
     *     image thumbnail to indicate that it is listed for deletion on
     *     Wikimedia Commons.
     *     This is not actually implemented, yet but would be pretty cool.
     *
     * @note Use of non-scalar values (anything other than
     *  `string|int|float|bool`) has been deprecated in 1.42.
     *  Although any JSON-serializable value can be stored/fetched in
     *  ParserOutput, when the values are stored to the database
     *  (in `deferred/LinksUpdate/PagePropsTable.php`) they will be
     *  converted: booleans will be converted to '0' and '1', null
     *  will become '', and everything else will be cast to string
     *  (not JSON-serialized).  Page properties obtained from the
     *  PageProps service will thus always be strings.
     *
     * @note The sort key stored in the database *will be NULL* unless
     *  the value passed here is an `int|float|bool`.  If you *do not*
     *  want your property *value* indexed and sorted (for example, the
     *  value is a title string which can be numeric but only
     *  incidentally, like when it gets retrieved from an array key)
     *  be sure to cast to string or use
     *  `::setUnsortedPageProperty()`.  If you *do* want your property
     *  *value* indexed and sorted, you should use
     *  `::setNumericPageProperty()` instead as this will ensure the
     *  value type is correct. Note that either way it is possible to
     *  efficiently look up all the pages with a certain property; we
     *  are only talking about sorting the *values* assigned to the
     *  property, for example for a "top N values of the property"
     *  query.
     *
     * @note Note that `::getPageProperty()`/`::setPageProperty()` do
     *  not do any conversions themselves; you should therefore be
     *  careful to distinguish values returned from the PageProp
     *  service (always strings) from values retrieved from a
     *  ParserOutput.
     *
     * @note Do not use setPageProperty() to set a property which is only used
     * in a context where the ParserOutput object itself is already available,
     * for example a normal page view. There is no need to save such a property
     * in the database since the text is already parsed; use
     * ::setExtensionData() instead.
     *
     * @par Example:
     * @code
     *    $parser->getOutput()->setExtensionData( 'my_ext_foo', '...' );
     * @endcode
     *
     * And then later, in OutputPageParserOutput or similar:
     *
     * @par Example:
     * @code
     *    $output->getExtensionData( 'my_ext_foo' );
     * @endcode
     *
     * @note The use of `null` as a value is deprecated since 1.42; use
     * the empty string instead if you need a placeholder value, or
     * ::unsetPageProperty() if you mean to remove a page property.
     *
     * @note The use of non-string values is deprecated since 1.42; if you
     * need an page property value with a sort index
     * use ::setNumericPageProperty().
     *
     * @param string $name
     * @param ?scalar $value
     * @since 1.38
     */
    public function setPageProperty( string $name, $value ): void {
        if ( !is_scalar( $value ) ) {
            wfDeprecated( __METHOD__ . " with non-scalar value for $name" );
        }
        $this->mProperties[$name] = $value;
    }

    /**
     * Set a numeric page property whose *value* is intended to be sorted
     * and indexed.  The sort key used for the property will be the value,
     * coerced to a number.
     *
     * See `::setPageProperty()` for details.
     *
     * In the future, we may allow the value to be specified independent
     * of sort key (T357783).
     *
     * @param string $propName The name of the page property
     * @param int|float|string $numericValue the numeric value
     * @since 1.42
     */
    public function setNumericPageProperty( string $propName, $numericValue ): void {
        if ( !is_numeric( $numericValue ) ) {
            throw new \TypeError( __METHOD__ . " with non-numeric value" );
        }
        // Coerce numeric sort key to a number.
        $this->mProperties[$propName] = 0 + $numericValue;
    }

    /**
     * Set a page property whose *value* is not intended to be sorted and
     * indexed.
     *
     * See `::setPageProperty()` for details.  It is recommended to
     * use the empty string if you need a placeholder value (ie, if
     * it is the *presence* of the property which is important, not
     * the *value* the property is set to).
     *
     * It is still possible to efficiently look up all the pages with
     * a certain property (the "presence" of it *is* indexed; see
     * Special:PagesWithProp, list=pageswithprop).
     *
     * @param string $propName The name of the page property
     * @param string $value Optional value; defaults to the empty string.
     * @since 1.42
     */
    public function setUnsortedPageProperty( string $propName, string $value = '' ): void {
        $this->mProperties[$propName] = $value;
    }

    /**
     * Look up a page property.
     * @param string $name The page property name to look up.
     * @return ?scalar The value previously set using
     * ::setPageProperty(), ::setUnsortedPageProperty(), or
     * ::setNumericPageProperty().
     * Returns null if no value was set for the given property name.
     *
     * @note You would need to use ::getPageProperties() to test for an
     *  explicitly-set null value; but see the note in ::setPageProperty()
     *  deprecating the use of null values.
     * @since 1.38
     */
    public function getPageProperty( string $name ) {
        return $this->mProperties[$name] ?? null;
    }

    /**
     * Remove a page property.
     * @param string $name The page property name.
     * @since 1.38
     */
    public function unsetPageProperty( string $name ): void {
        unset( $this->mProperties[$name] );
    }

    /**
     * Return all the page properties set on this ParserOutput.
     * @return array<string,?scalar>
     * @since 1.38
     */
    public function getPageProperties(): array {
        if ( !isset( $this->mProperties ) ) {
            $this->mProperties = [];
        }
        return $this->mProperties;
    }

    /**
     * Provides a uniform interface to various boolean flags stored
     * in the ParserOutput.  Flags internal to MediaWiki core should
     * have names which are constants in ParserOutputFlags.  Extensions
     * should use ::setExtensionData() rather than creating new flags
     * with ::setOutputFlag() in order to prevent namespace conflicts.
     *
     * Flags are always combined with OR.  That is, the flag is set in
     * the resulting ParserOutput if the flag is set in *any* of the
     * fragments composing the ParserOutput.
     *
     * @note The combination policy means that a ParserOutput may end
     * up with both INDEX_POLICY and NO_INDEX_POLICY set.  It is
     * expected that NO_INDEX_POLICY "wins" in that case. (T16899)
     * (This resolution is implemented in ::getIndexPolicy().)
     *
     * @param string $name A flag name
     * @param bool $val
     * @since 1.38
     */
    public function setOutputFlag( string $name, bool $val = true ): void {
        switch ( $name ) {
            case ParserOutputFlags::NO_GALLERY:
                $this->setNoGallery( $val );
                break;

            case ParserOutputFlags::ENABLE_OOUI:
                $this->setEnableOOUI( $val );
                break;

            case ParserOutputFlags::NO_INDEX_POLICY:
                $this->mNoIndexSet = $val;
                break;

            case ParserOutputFlags::INDEX_POLICY:
                $this->mIndexSet = $val;
                break;

            case ParserOutputFlags::NEW_SECTION:
                $this->setNewSection( $val );
                break;

            case ParserOutputFlags::HIDE_NEW_SECTION:
                $this->setHideNewSection( $val );
                break;

            case ParserOutputFlags::PREVENT_CLICKJACKING:
                $this->setPreventClickjacking( $val );
                break;

            default:
                if ( $val ) {
                    $this->mFlags[$name] = true;
                } else {
                    unset( $this->mFlags[$name] );
                }
                break;
        }
    }

    /**
     * Provides a uniform interface to various boolean flags stored
     * in the ParserOutput.  Flags internal to MediaWiki core should
     * have names which are constants in ParserOutputFlags.  Extensions
     * should only use ::getOutputFlag() to query flags defined in
     * ParserOutputFlags in core; they should use ::getExtensionData()
     * to define their own flags.
     *
     * @param string $name A flag name
     * @return bool The flag value
     * @since 1.38
     */
    public function getOutputFlag( string $name ): bool {
        switch ( $name ) {
            case ParserOutputFlags::NO_GALLERY:
                return $this->getNoGallery();

            case ParserOutputFlags::ENABLE_OOUI:
                return $this->getEnableOOUI();

            case ParserOutputFlags::INDEX_POLICY:
                return $this->mIndexSet;

            case ParserOutputFlags::NO_INDEX_POLICY:
                return $this->mNoIndexSet;

            case ParserOutputFlags::NEW_SECTION:
                return $this->getNewSection();

            case ParserOutputFlags::HIDE_NEW_SECTION:
                return $this->getHideNewSection();

            case ParserOutputFlags::PREVENT_CLICKJACKING:
                return $this->getPreventClickjacking();

            default:
                return isset( $this->mFlags[$name] );

        }
    }

    /**
     * Provides a uniform interface to various string sets stored
     * in the ParserOutput.  String sets internal to MediaWiki core should
     * have names which are constants in ParserOutputStringSets.  Extensions
     * should use ::appendExtensionData() rather than creating new string sets
     * with ::appendOutputStrings() in order to prevent namespace conflicts.
     *
     * @param string $name A string set name
     * @param string[] $value
     * @since 1.41
     */
    public function appendOutputStrings( string $name, array $value ): void {
        switch ( $name ) {
            case ParserOutputStringSets::MODULE:
                $this->addModules( $value );
                break;
            case ParserOutputStringSets::MODULE_STYLE:
                $this->addModuleStyles( $value );
                break;
            case ParserOutputStringSets::EXTRA_CSP_DEFAULT_SRC:
                foreach ( $value as $v ) {
                    $this->addExtraCSPDefaultSrc( $v );
                }
                break;
            case ParserOutputStringSets::EXTRA_CSP_SCRIPT_SRC:
                foreach ( $value as $v ) {
                    $this->addExtraCSPScriptSrc( $v );
                }
                break;
            case ParserOutputStringSets::EXTRA_CSP_STYLE_SRC:
                foreach ( $value as $v ) {
                    $this->addExtraCSPStyleSrc( $v );
                }
                break;
            default:
                throw new UnexpectedValueException( "Unknown output string set name $name" );
        }
    }

    /**
     * Provides a uniform interface to various boolean string sets stored
     * in the ParserOutput.  String sets internal to MediaWiki core should
     * have names which are constants in ParserOutputStringSets.  Extensions
     * should only use ::getOutputStrings() to query string sets defined in
     * ParserOutputStringSets in core; they should use ::appendExtensionData()
     * to define their own string sets.
     *
     * @param string $name A string set name
     * @return string[] The string set value
     * @since 1.41
     */
    public function getOutputStrings( string $name ): array {
        switch ( $name ) {
            case ParserOutputStringSets::MODULE:
                return $this->getModules();
            case ParserOutputStringSets::MODULE_STYLE:
                return $this->getModuleStyles();
            case ParserOutputStringSets::EXTRA_CSP_DEFAULT_SRC:
                return $this->getExtraCSPDefaultSrcs();
            case ParserOutputStringSets::EXTRA_CSP_SCRIPT_SRC:
                return $this->getExtraCSPScriptSrcs();
            case ParserOutputStringSets::EXTRA_CSP_STYLE_SRC:
                return $this->getExtraCSPStyleSrcs();
            default:
                throw new UnexpectedValueException( "Unknown output string set name $name" );
        }
    }

    /**
     * Attaches arbitrary data to this ParserObject. This can be used to store some information in
     * the ParserOutput object for later use during page output. The data will be cached along with
     * the ParserOutput object, but unlike data set using setPageProperty(), it is not recorded in the
     * database.
     *
     * This method is provided to overcome the unsafe practice of attaching extra information to a
     * ParserObject by directly assigning member variables.
     *
     * To use setExtensionData() to pass extension information from a hook inside the parser to a
     * hook in the page output, use this in the parser hook:
     *
     * @par Example:
     * @code
     *    $parser->getOutput()->setExtensionData( 'my_ext_foo', '...' );
     * @endcode
     *
     * And then later, in OutputPageParserOutput or similar:
     *
     * @par Example:
     * @code
     *    $output->getExtensionData( 'my_ext_foo' );
     * @endcode
     *
     * In MediaWiki 1.20 and older, you have to use a custom member variable
     * within the ParserOutput object:
     *
     * @par Example:
     * @code
     *    $parser->getOutput()->my_ext_foo = '...';
     * @endcode
     *
     * @note Only scalar values, e.g. numbers, strings, arrays or MediaWiki\Json\JsonUnserializable
     * instances are supported as a value. Attempt to set other class instance as extension data
     * will break ParserCache for the page.
     *
     * @note Since MW 1.38 the practice of setting conflicting values for
     * the same key has been deprecated.  As with ::setJsConfigVar(), if
     * you set the same key multiple times on a ParserOutput, it is expected
     * that the value will be identical each time.  If you want to collect
     * multiple pieces of data under a single key, use ::appendExtensionData().
     *
     * @param string $key The key for accessing the data. Extensions should take care to avoid
     *   conflicts in naming keys. It is suggested to use the extension's name as a prefix.
     *
     * @param mixed|JsonUnserializable $value The value to set.
     *   Setting a value to null is equivalent to removing the value.
     * @since 1.21
     */
    public function setExtensionData( $key, $value ): void {
        if (
            array_key_exists( $key, $this->mExtensionData ) &&
            $this->mExtensionData[$key] !== $value
        ) {
            // This behavior was deprecated in 1.38.  We will eventually
            // emit a warning here, then throw an exception.
        }
        if ( $value === null ) {
            unset( $this->mExtensionData[$key] );
        } else {
            $this->mExtensionData[$key] = $value;
        }
    }

    /**
     * Appends arbitrary data to this ParserObject. This can be used
     * to store some information in the ParserOutput object for later
     * use during page output. The data will be cached along with the
     * ParserOutput object, but unlike data set using
     * setPageProperty(), it is not recorded in the database.
     *
     * See ::setExtensionData() for more details on rationale and use.
     *
     * In order to provide for out-of-order/asynchronous/incremental
     * parsing, this method appends values to a set.  See
     * ::setExtensionData() for the flag-like version of this method.
     *
     * @note Only values which can be array keys are currently supported
     * as values.
     *
     * @param string $key The key for accessing the data. Extensions should take care to avoid
     *   conflicts in naming keys. It is suggested to use the extension's name as a prefix.
     *
     * @param int|string $value The value to append to the list.
     * @param string $strategy Merge strategy:
     *  only MW_MERGE_STRATEGY_UNION is currently supported and external callers
     *  should treat this parameter as @internal at this time and omit it.
     * @since 1.38
     */
    public function appendExtensionData(
        string $key,
        $value,
        string $strategy = self::MW_MERGE_STRATEGY_UNION
    ): void {
        if ( $strategy !== self::MW_MERGE_STRATEGY_UNION ) {
            throw new InvalidArgumentException( "Unknown merge strategy $strategy." );
        }
        if ( !array_key_exists( $key, $this->mExtensionData ) ) {
            $this->mExtensionData[$key] = [
                // Indicate how these values are to be merged.
                self::MW_MERGE_STRATEGY_KEY => $strategy,
            ];
        } elseif ( !is_array( $this->mExtensionData[$key] ) ) {
            throw new InvalidArgumentException( "Mixing set and append for $key" );
        } elseif ( ( $this->mExtensionData[$key][self::MW_MERGE_STRATEGY_KEY] ?? null ) !== $strategy ) {
            throw new InvalidArgumentException( "Conflicting merge strategies for $key" );
        }
        $this->mExtensionData[$key][$value] = true;
    }

    /**
     * Gets extensions data previously attached to this ParserOutput using setExtensionData().
     * Typically, such data would be set while parsing the page, e.g. by a parser function.
     *
     * @since 1.21
     *
     * @param string $key The key to look up.
     *
     * @return mixed|null The value previously set for the given key using setExtensionData()
     *         or null if no value was set for this key.
     */
    public function getExtensionData( $key ) {
        $value = $this->mExtensionData[$key] ?? null;
        if ( is_array( $value ) ) {
            // Don't expose our internal merge strategy key.
            unset( $value[self::MW_MERGE_STRATEGY_KEY] );
        }
        return $value;
    }

    private static function getTimes( $clock = null ): array {
        $ret = [];
        if ( !$clock || $clock === 'wall' ) {
            $ret['wall'] = microtime( true );
        }
        if ( !$clock || $clock === 'cpu' ) {
            $ru = getrusage( 0 /* RUSAGE_SELF */ );
            $ret['cpu'] = $ru['ru_utime.tv_sec'] + $ru['ru_utime.tv_usec'] / 1e6;
            $ret['cpu'] += $ru['ru_stime.tv_sec'] + $ru['ru_stime.tv_usec'] / 1e6;
        }
        return $ret;
    }

    /**
     * Resets the parse start timestamps for future calls to getTimeSinceStart()
     * and recordTimeProfile().
     *
     * @since 1.22
     */
    public function resetParseStartTime(): void {
        $this->mParseStartTime = self::getTimes();
        $this->mTimeProfile = [];
    }

    /**
     * Record the time since resetParseStartTime() was last called.
     * The recorded time can be accessed using getTimeProfile().
     *
     * After resetParseStartTime() was called, the first call to recordTimeProfile()
     * will record the time profile. Subsequent calls to recordTimeProfile() will have
     * no effect until resetParseStartTime() is called again.
     *
     * @since 1.42
     */
    public function recordTimeProfile() {
        if ( !$this->mParseStartTime ) {
            // If resetParseStartTime was never called, there is nothing to record
            return;
        }

        if ( $this->mTimeProfile !== [] ) {
            // Don't override the times recorded by the previous call to recordTimeProfile().
            return;
        }

        $now = self::getTimes();
        $this->mTimeProfile = [
            'wall' => $now['wall'] - $this->mParseStartTime['wall'],
            'cpu' => $now['cpu'] - $this->mParseStartTime['cpu'],
        ];
    }

    /**
     * Returns the time that elapsed between the most recent call to resetParseStartTime()
     * and the first call to recordTimeProfile() after that.
     *
     * Clocks available are:
     *  - wall: Wall clock time
     *  - cpu: CPU time (requires getrusage)
     *
     * If recordTimeProfile() has noit been called since the most recent call to
     * resetParseStartTime(), or if resetParseStartTime() was never called, then
     * this method will return null.
     *
     * @param string $clock
     *
     * @since 1.42
     * @return float|null
     */
    public function getTimeProfile( string $clock ) {
        return $this->mTimeProfile[ $clock ] ?? null;
    }

    /**
     * Returns the time since resetParseStartTime() was last called
     *
     * Clocks available are:
     *  - wall: Wall clock time
     *  - cpu: CPU time (requires getrusage)
     *
     * @since 1.22
     * @deprecated since 1.42, use getTimeProfile() instead.
     * @param string $clock
     * @return float|null
     */
    public function getTimeSinceStart( $clock ) {
        wfDeprecated( __METHOD__, '1.42' );

        if ( !isset( $this->mParseStartTime[$clock] ) ) {
            return null;
        }

        $end = self::getTimes( $clock );
        return $end[$clock] - $this->mParseStartTime[$clock];
    }

    /**
     * Sets parser limit report data for a key
     *
     * The key is used as the prefix for various messages used for formatting:
     *  - $key: The label for the field in the limit report
     *  - $key-value-text: Message used to format the value in the "NewPP limit
     *      report" HTML comment. If missing, uses $key-format.
     *  - $key-value-html: Message used to format the value in the preview
     *      limit report table. If missing, uses $key-format.
     *  - $key-value: Message used to format the value. If missing, uses "$1".
     *
     * Note that all values are interpreted as wikitext, and so should be
     * encoded with htmlspecialchars() as necessary, but should avoid complex
     * HTML for display in the "NewPP limit report" comment.
     *
     * @since 1.22
     * @param string $key Message key
     * @param mixed $value Appropriate for Message::params()
     */
    public function setLimitReportData( $key, $value ): void {
        $this->mLimitReportData[$key] = $value;

        if ( is_array( $value ) ) {
            if ( array_keys( $value ) === [ 0, 1 ]
                && is_numeric( $value[0] )
                && is_numeric( $value[1] )
            ) {
                $data = [ 'value' => $value[0], 'limit' => $value[1] ];
            } else {
                $data = $value;
            }
        } else {
            $data = $value;
        }

        if ( strpos( $key, '-' ) ) {
            [ $ns, $name ] = explode( '-', $key, 2 );
            $this->mLimitReportJSData[$ns][$name] = $data;
        } else {
            $this->mLimitReportJSData[$key] = $data;
        }
    }

    /**
     * Check whether the cache TTL was lowered from the site default.
     *
     * When content is determined by more than hard state (e.g. page edits),
     * such as template/file transclusions based on the current timestamp or
     * extension tags that generate lists based on queries, this return true.
     *
     * This method mainly exists to facilitate the logic in
     * WikiPage::triggerOpportunisticLinksUpdate. As such, beware that reducing the TTL for
     * reasons that do not relate to "dynamic content", may have the side-effect of incurring
     * more RefreshLinksJob executions.
     *
     * @internal For use by Parser and WikiPage
     * @since 1.37
     * @return bool
     */
    public function hasReducedExpiry(): bool {
        $parserCacheExpireTime = MediaWikiServices::getInstance()->getMainConfig()->get(
            MainConfigNames::ParserCacheExpireTime );

        return $this->getCacheExpiry() < $parserCacheExpireTime;
    }

    /**
     * Set the prevent-clickjacking flag.  If set this will cause an
     * `X-Frame-Options` header appropriate for edit pages to be sent.
     * The header value is controlled by `$wgEditPageFrameOptions`.
     *
     * This is the default for special pages.  If you display a CSRF-protected
     * form on an ordinary view page, then you need to call this function
     * with `$flag = true`.
     *
     * @param bool $flag New flag value
     * @since 1.38
     */
    public function setPreventClickjacking( bool $flag ) {
        $this->mPreventClickjacking = $flag;
    }

    /**
     * Get the prevent-clickjacking flag.
     *
     * @return bool Flag value
     * @since 1.38
     * @see ::setPreventClickjacking
     */
    public function getPreventClickjacking(): bool {
        return $this->mPreventClickjacking;
    }

    /**
     * Lower the runtime adaptive TTL to at most this value
     *
     * @param int $ttl
     * @since 1.28
     */
    public function updateRuntimeAdaptiveExpiry( $ttl ): void {
        $this->mMaxAdaptiveExpiry = min( $ttl, $this->mMaxAdaptiveExpiry );
        $this->updateCacheExpiry( $ttl );
    }

    /**
     * Add an extra value to Content-Security-Policy default-src directive
     *
     * Call this if you are including a resource (e.g. image) from a third party domain.
     * This is used for all source types except style and script.
     *
     * @since 1.35
     * @param string $src CSP source e.g. example.com
     */
    public function addExtraCSPDefaultSrc( $src ): void {
        $this->mExtraDefaultSrcs[] = $src;
    }

    /**
     * Add an extra value to Content-Security-Policy style-src directive
     *
     * @since 1.35
     * @param string $src CSP source e.g. example.com
     */
    public function addExtraCSPStyleSrc( $src ): void {
        $this->mExtraStyleSrcs[] = $src;
    }

    /**
     * Add an extra value to Content-Security-Policy script-src directive
     *
     * Call this if you are loading third-party Javascript
     *
     * @since 1.35
     * @param string $src CSP source e.g. example.com
     */
    public function addExtraCSPScriptSrc( $src ): void {
        $this->mExtraScriptSrcs[] = $src;
    }

    /**
     * Call this when parsing is done to lower the TTL based on low parse times
     *
     * @since 1.28
     */
    public function finalizeAdaptiveCacheExpiry(): void {
        if ( is_infinite( $this->mMaxAdaptiveExpiry ) ) {
            return; // not set
        }

        $runtime = $this->getTimeProfile( 'wall' );
        if ( is_float( $runtime ) ) {
            $slope = ( self::SLOW_AR_TTL - self::FAST_AR_TTL )
                / ( self::PARSE_SLOW_SEC - self::PARSE_FAST_SEC );
            // SLOW_AR_TTL = PARSE_SLOW_SEC * $slope + $point
            $point = self::SLOW_AR_TTL - self::PARSE_SLOW_SEC * $slope;

            $adaptiveTTL = min(
                max( $slope * $runtime + $point, self::MIN_AR_TTL ),
                $this->mMaxAdaptiveExpiry
            );
            $this->updateCacheExpiry( $adaptiveTTL );
        }
    }

    /**
     * Transfer parser options which affect post-processing from ParserOptions
     * to this ParserOutput.
     * @param ParserOptions $parserOptions
     */
    public function setFromParserOptions( ParserOptions $parserOptions ) {
        // Copied from Parser.php::parse and should probably be abstracted
        // into the parent base class (probably as part of T236809)
        // Wrap non-interface parser output in a <div> so it can be targeted
        // with CSS (T37247)
        $class = $parserOptions->getWrapOutputClass();
        if ( $class !== false && !$parserOptions->getInterfaceMessage() ) {
            $this->addWrapperDivClass( $class );
        }

        // Record whether we should suppress section edit links
        if ( $parserOptions->getSuppressSectionEditLinks() ) {
            $this->setOutputFlag( ParserOutputFlags::NO_SECTION_EDIT_LINKS );
        }

        // Record whether we should wrap sections for collapsing them
        if ( $parserOptions->getCollapsibleSections() ) {
            $this->setOutputFlag( ParserOutputFlags::COLLAPSIBLE_SECTIONS );
        }

        // Record whether this is a preview parse in the output (T341010)
        if ( $parserOptions->getIsPreview() ) {
            $this->setOutputFlag( ParserOutputFlags::IS_PREVIEW, true );
            // Ensure that previews aren't cacheable, just to be safe.
            $this->updateCacheExpiry( 0 );
        }
    }

    public function __sleep() {
        return array_filter( array_keys( get_object_vars( $this ) ),
            static function ( $field ) {
                if ( $field === 'mParseStartTime' || $field === 'mWarningMsgs' ) {
                    return false;
                }
                // Unserializing unknown private fields in HHVM causes
                // member variables with nulls in their names (T229366)
                return strpos( $field, "\0" ) === false;
            }
        );
    }

    /**
     * Merges internal metadata such as flags, accessed options, and profiling info
     * from $source into this ParserOutput. This should be used whenever the state of $source
     * has any impact on the state of this ParserOutput.
     *
     * @param ParserOutput $source
     */
    public function mergeInternalMetaDataFrom( ParserOutput $source ): void {
        $this->mWarnings = self::mergeMap( $this->mWarnings, $source->mWarnings ); // don't use getter
        $this->mTimestamp = $this->useMaxValue( $this->mTimestamp, $source->getRevisionTimestamp() );
        if ( $source->hasCacheTime() ) {
            $sourceCacheTime = $source->getCacheTime();
            if (
                !$this->hasCacheTime() ||
                // "undocumented use of -1 to mean not cacheable"
                // deprecated, but still supported by ::setCacheTime()
                strval( $sourceCacheTime ) === '-1' ||
                (
                    strval( $this->getCacheTime() ) !== '-1' &&
                    // use newer of the two times
                    $this->getCacheTime() < $sourceCacheTime
                )
            ) {
                $this->setCacheTime( $sourceCacheTime );
            }
        }
        if ( $source->getRenderId() !== null ) {
            // Final render ID should be a function of all component POs
            $rid = ( $this->getRenderId() ?? '' ) . $source->getRenderId();
            $this->setRenderId( $rid );
        }
        if ( $source->getCacheRevisionId() !== null ) {
            $sourceCacheRevisionId = $source->getCacheRevisionId();
            $thisCacheRevisionId = $this->getCacheRevisionId();
            if ( $thisCacheRevisionId === null ) {
                $this->setCacheRevisionId( $sourceCacheRevisionId );
            } elseif ( $sourceCacheRevisionId !== $thisCacheRevisionId ) {
                // May throw an exception here in the future
                wfDeprecated(
                    __METHOD__ . ": conflicting revision IDs " .
                    "$thisCacheRevisionId and $sourceCacheRevisionId"
                );
            }
        }

        foreach ( self::SPECULATIVE_FIELDS as $field ) {
            if ( $this->$field && $source->$field && $this->$field !== $source->$field ) {
                wfLogWarning( __METHOD__ . ": inconsistent '$field' properties!" );
            }
            $this->$field = $this->useMaxValue( $this->$field, $source->$field );
        }

        $this->mParseStartTime = $this->useEachMinValue(
            $this->mParseStartTime,
            $source->mParseStartTime
        );

        $this->mTimeProfile = $this->useEachTotalValue(
            $this->mTimeProfile,
            $source->mTimeProfile
        );

        $this->mFlags = self::mergeMap( $this->mFlags, $source->mFlags );
        $this->mParseUsedOptions = self::mergeMap( $this->mParseUsedOptions, $source->mParseUsedOptions );

        // TODO: maintain per-slot limit reports!
        if ( !$this->mLimitReportData ) {
            $this->mLimitReportData = $source->mLimitReportData;
        }
        if ( !$this->mLimitReportJSData ) {
            $this->mLimitReportJSData = $source->mLimitReportJSData;
        }
    }

    /**
     * Merges HTML metadata such as head items, JS config vars, and HTTP cache control info
     * from $source into this ParserOutput. This should be used whenever the HTML in $source
     * has been somehow merged into the HTML of this ParserOutput.
     *
     * @param ParserOutput $source
     */
    public function mergeHtmlMetaDataFrom( ParserOutput $source ): void {
        // HTML and HTTP
        $this->mHeadItems = self::mergeMixedList( $this->mHeadItems, $source->getHeadItems() );
        $this->addModules( $source->getModules() );
        $this->addModuleStyles( $source->getModuleStyles() );
        $this->mJsConfigVars = self::mergeMapStrategy( $this->mJsConfigVars, $source->mJsConfigVars );
        $this->mMaxAdaptiveExpiry = min( $this->mMaxAdaptiveExpiry, $source->mMaxAdaptiveExpiry );
        $this->mExtraStyleSrcs = self::mergeList(
            $this->mExtraStyleSrcs,
            $source->getExtraCSPStyleSrcs()
        );
        $this->mExtraScriptSrcs = self::mergeList(
            $this->mExtraScriptSrcs,
            $source->getExtraCSPScriptSrcs()
        );
        $this->mExtraDefaultSrcs = self::mergeList(
            $this->mExtraDefaultSrcs,
            $source->getExtraCSPDefaultSrcs()
        );

        // "noindex" always wins!
        $this->mIndexSet = $this->mIndexSet || $source->mIndexSet;
        $this->mNoIndexSet = $this->mNoIndexSet || $source->mNoIndexSet;

        // Skin control
        $this->mNewSection = $this->mNewSection || $source->getNewSection();
        $this->mHideNewSection = $this->mHideNewSection || $source->getHideNewSection();
        $this->mNoGallery = $this->mNoGallery || $source->getNoGallery();
        $this->mEnableOOUI = $this->mEnableOOUI || $source->getEnableOOUI();
        $this->mPreventClickjacking = $this->mPreventClickjacking || $source->getPreventClickjacking();

        $tocData = $this->getTOCData();
        $sourceTocData = $source->getTOCData();
        if ( $tocData !== null ) {
            if ( $sourceTocData !== null ) {
                // T327429: Section merging is broken, since it doesn't respect
                // global numbering, but there are tests which expect section
                // metadata to be concatenated.
                // There should eventually be a deprecation warning here.
                foreach ( $sourceTocData->getSections() as $s ) {
                    $tocData->addSection( $s );
                }
            }
        } elseif ( $sourceTocData !== null ) {
            $this->setTOCData( $sourceTocData );
        }

        // XXX: we don't want to concatenate title text, so first write wins.
        // We should use the first *modified* title text, but we don't have the original to check.
        if ( $this->mTitleText === null || $this->mTitleText === '' ) {
            $this->mTitleText = $source->mTitleText;
        }

        // class names are stored in array keys
        $this->mWrapperDivClasses = self::mergeMap(
            $this->mWrapperDivClasses,
            $source->mWrapperDivClasses
        );

        // NOTE: last write wins, same as within one ParserOutput
        $this->mIndicators = self::mergeMap( $this->mIndicators, $source->getIndicators() );

        // NOTE: include extension data in "tracking meta data" as well as "html meta data"!
        // TODO: add a $mergeStrategy parameter to setExtensionData to allow different
        // kinds of extension data to be merged in different ways.
        $this->mExtensionData = self::mergeMapStrategy(
            $this->mExtensionData,
            $source->mExtensionData
        );
    }

    /**
     * Merges dependency tracking metadata such as backlinks, images used, and extension data
     * from $source into this ParserOutput. This allows dependency tracking to be done for the
     * combined output of multiple content slots.
     *
     * @param ParserOutput $source
     */
    public function mergeTrackingMetaDataFrom( ParserOutput $source ): void {
        $this->mLanguageLinks = self::mergeList( $this->mLanguageLinks, $source->getLanguageLinks() );
        $this->mCategories = self::mergeMap( $this->mCategories, $source->getCategoryMap() );
        $this->mLinks = self::merge2D( $this->mLinks, $source->getLinks() );
        $this->mTemplates = self::merge2D( $this->mTemplates, $source->getTemplates() );
        $this->mTemplateIds = self::merge2D( $this->mTemplateIds, $source->getTemplateIds() );
        $this->mImages = self::mergeMap( $this->mImages, $source->getImages() );
        $this->mFileSearchOptions = self::mergeMap(
            $this->mFileSearchOptions,
            $source->getFileSearchOptions()
        );
        $this->mExternalLinks = self::mergeMap( $this->mExternalLinks, $source->getExternalLinks() );
        $this->mInterwikiLinks = self::merge2D(
            $this->mInterwikiLinks,
            $source->getInterwikiLinks()
        );

        // TODO: add a $mergeStrategy parameter to setPageProperty to allow different
        // kinds of properties to be merged in different ways.
        // (Model this after ::appendJsConfigVar(); use ::mergeMapStrategy here)
        $this->mProperties = self::mergeMap( $this->mProperties, $source->getPageProperties() );

        // NOTE: include extension data in "tracking meta data" as well as "html meta data"!
        $this->mExtensionData = self::mergeMapStrategy(
            $this->mExtensionData,
            $source->mExtensionData
        );
    }

    /**
     * Adds the metadata collected in this ParserOutput to the supplied
     * ContentMetadataCollector.  This is similar to ::mergeHtmlMetaDataFrom()
     * but in the opposite direction, since ParserOutput is read/write while
     * ContentMetadataCollector is write-only.
     *
     * @param ContentMetadataCollector $metadata
     * @since 1.38
     */
    public function collectMetadata( ContentMetadataCollector $metadata ): void {
        // Uniform handling of all boolean flags: they are OR'ed together.
        $flags = array_keys(
            $this->mFlags + array_flip( ParserOutputFlags::cases() )
        );
        foreach ( $flags as $name ) {
            if ( $this->getOutputFlag( $name ) ) {
                $metadata->setOutputFlag( $name );
            }
        }

        // Uniform handling of string sets: they are unioned.
        // (This includes modules, style modes, and CSP src.)
        foreach ( ParserOutputStringSets::cases() as $name ) {
            $metadata->appendOutputStrings(
                $name, $this->getOutputStrings( $name )
            );
        }

        foreach ( $this->mCategories as $cat => $key ) {
            // Numeric category strings are going to come out of the
            // `mCategories` array as ints; cast back to string.
            // Also convert back to a LinkTarget!
            $lt = TitleValue::tryNew( NS_CATEGORY, (string)$cat );
            $metadata->addCategory( $lt, $key );
        }

        foreach ( $this->mJsConfigVars as $key => $value ) {
            if ( is_array( $value ) && isset( $value[self::MW_MERGE_STRATEGY_KEY] ) ) {
                $strategy = $value[self::MW_MERGE_STRATEGY_KEY];
                foreach ( $value as $item => $ignore ) {
                    if ( $item !== self::MW_MERGE_STRATEGY_KEY ) {
                        $metadata->appendJsConfigVar( $key, $item, $strategy );
                    }
                }
            } elseif ( $metadata instanceof ParserOutput &&
                array_key_exists( $key, $metadata->mJsConfigVars )
            ) {
                // This behavior is deprecated, will likely result in
                // incorrect output, and we'll eventually emit a
                // warning here---but at the moment this is usually
                // caused by limitations in Parsoid and/or use of
                // the ParserAfterParse hook: T303015#7770480
                $metadata->mJsConfigVars[$key] = $value;
            } else {
                $metadata->setJsConfigVar( $key, $value );
            }
        }
        foreach ( $this->mExtensionData as $key => $value ) {
            if ( is_array( $value ) && isset( $value[self::MW_MERGE_STRATEGY_KEY] ) ) {
                $strategy = $value[self::MW_MERGE_STRATEGY_KEY];
                foreach ( $value as $item => $ignore ) {
                    if ( $item !== self::MW_MERGE_STRATEGY_KEY ) {
                        $metadata->appendExtensionData( $key, $item, $strategy );
                    }
                }
            } elseif ( $metadata instanceof ParserOutput &&
                array_key_exists( $key, $metadata->mExtensionData )
            ) {
                // This behavior is deprecated, will likely result in
                // incorrect output, and we'll eventually emit a
                // warning here---but at the moment this is usually
                // caused by limitations in Parsoid and/or use of
                // the ParserAfterParse hook: T303015#7770480
                $metadata->mExtensionData[$key] = $value;
            } else {
                $metadata->setExtensionData( $key, $value );
            }
        }
        foreach ( $this->mExternalLinks as $url => $ignore ) {
            $metadata->addExternalLink( $url );
        }
        foreach ( $this->mProperties as $prop => $value ) {
            $metadata->setPageProperty( $prop, $value );
        }
        foreach ( $this->mWarningMsgs as $msg => $args ) {
            $metadata->addWarningMsg( $msg, ...$args );
        }
        foreach ( $this->mLimitReportData as $key => $value ) {
            $metadata->setLimitReportData( $key, $value );
        }

        // ParserOutput-only fields; maintained "behind the curtain"
        // since Parsoid doesn't have to know about them.
        //
        // In production use, the $metadata supplied to this method
        // will almost always be an instance of ParserOutput, passed to
        // Parsoid by core when parsing begins and returned to core by
        // Parsoid as a ContentMetadataCollector (Parsoid's name for
        // ParserOutput) when DataAccess::parseWikitext() is called.
        //
        // We may use still Parsoid's StubMetadataCollector for testing or
        // when running Parsoid in standalone mode, so forcing a downcast
        // here would lose some flexibility.

        if ( $metadata instanceof ParserOutput ) {
            foreach ( $this->getUsedOptions() as $opt ) {
                $metadata->recordOption( $opt );
            }
            if ( $this->mCacheExpiry !== null ) {
                $metadata->updateCacheExpiry( $this->mCacheExpiry );
            }
            if ( $this->mCacheTime !== '' ) {
                $metadata->setCacheTime( $this->mCacheTime );
            }
            if ( $this->mCacheRevisionId !== null ) {
                $metadata->setCacheRevisionId( $this->mCacheRevisionId );
            }
            // T293514: We should use the first *modified* title text, but
            // we don't have the original to check.
            $otherTitle = $metadata->getTitleText();
            if ( $otherTitle === null || $otherTitle === '' ) {
                $metadata->setTitleText( $this->getTitleText() );
            }
        }
    }

    private static function mergeMixedList( array $a, array $b ): array {
        return array_unique( array_merge( $a, $b ), SORT_REGULAR );
    }

    private static function mergeList( array $a, array $b ): array {
        return array_values( array_unique( array_merge( $a, $b ), SORT_REGULAR ) );
    }

    private static function mergeMap( array $a, array $b ): array {
        return array_replace( $a, $b );
    }

    private static function mergeMapStrategy( array $a, array $b ): array {
        foreach ( $b as $key => $bValue ) {
            if ( !array_key_exists( $key, $a ) ) {
                $a[$key] = $bValue;
            } elseif (
                is_array( $a[$key] ) &&
                isset( $a[$key][self::MW_MERGE_STRATEGY_KEY] ) &&
                isset( $bValue[self::MW_MERGE_STRATEGY_KEY] )
            ) {
                $strategy = $bValue[self::MW_MERGE_STRATEGY_KEY];
                if ( $strategy !== $a[$key][self::MW_MERGE_STRATEGY_KEY] ) {
                    throw new InvalidArgumentException( "Conflicting merge strategy for $key" );
                }
                if ( $strategy === self::MW_MERGE_STRATEGY_UNION ) {
                    // Note the array_merge is *not* safe to use here, because
                    // the $bValue is expected to be a map from items to `true`.
                    // If the item is a numeric string like '1' then array_merge
                    // will convert it to an integer and renumber the array!
                    $a[$key] = array_replace( $a[$key], $bValue );
                } else {
                    throw new InvalidArgumentException( "Unknown merge strategy $strategy" );
                }
            } else {
                $valuesSame = ( $a[$key] === $bValue );
                if ( ( !$valuesSame ) &&
                    is_object( $a[$key] ) &&
                    is_object( $bValue )
                ) {
                    $jsonCodec = MediaWikiServices::getInstance()->getJsonCodec();
                    $valuesSame = ( $jsonCodec->serialize( $a[$key] ) === $jsonCodec->serialize( $bValue ) );
                }
                if ( !$valuesSame ) {
                    // Silently replace for now; in the future will first emit
                    // a deprecation warning, and then (later) throw.
                    $a[$key] = $bValue;
                }
            }
        }
        return $a;
    }

    private static function merge2D( array $a, array $b ): array {
        $values = [];
        $keys = array_merge( array_keys( $a ), array_keys( $b ) );

        foreach ( $keys as $k ) {
            if ( empty( $a[$k] ) ) {
                $values[$k] = $b[$k];
            } elseif ( empty( $b[$k] ) ) {
                $values[$k] = $a[$k];
            } elseif ( is_array( $a[$k] ) && is_array( $b[$k] ) ) {
                $values[$k] = array_replace( $a[$k], $b[$k] );
            } else {
                $values[$k] = $b[$k];
            }
        }

        return $values;
    }

    private static function useEachMinValue( array $a, array $b ): array {
        $values = [];
        $keys = array_merge( array_keys( $a ), array_keys( $b ) );

        foreach ( $keys as $k ) {
            $values[$k] = min( $a[$k] ?? INF, $b[$k] ?? INF );
        }

        return $values;
    }

    private static function useEachTotalValue( array $a, array $b ): array {
        $values = [];
        $keys = array_merge( array_keys( $a ), array_keys( $b ) );

        foreach ( $keys as $k ) {
            $values[$k] = ( $a[$k] ?? 0 ) + ( $b[$k] ?? 0 );
        }

        return $values;
    }

    private static function useMaxValue( $a, $b ) {
        if ( $a === null ) {
            return $b;
        }

        if ( $b === null ) {
            return $a;
        }

        return max( $a, $b );
    }

    /**
     * Returns a JSON serializable structure representing this ParserOutput instance.
     * @see newFromJson()
     *
     * @return array
     */
    protected function toJsonArray(): array {
        // WARNING: When changing how this class is serialized, follow the instructions
        // at <https://www.mediawiki.org/wiki/Manual:Parser_cache/Serialization_compatibility>!

        $data = [
            'Text' => $this->mRawText,
            'LanguageLinks' => $this->mLanguageLinks,
            'Categories' => $this->mCategories,
            'Indicators' => $this->mIndicators,
            'TitleText' => $this->mTitleText,
            'Links' => $this->mLinks,
            'LinksSpecial' => $this->mLinksSpecial,
            'Templates' => $this->mTemplates,
            'TemplateIds' => $this->mTemplateIds,
            'Images' => $this->mImages,
            'FileSearchOptions' => $this->mFileSearchOptions,
            'ExternalLinks' => $this->mExternalLinks,
            'InterwikiLinks' => $this->mInterwikiLinks,
            'NewSection' => $this->mNewSection,
            'HideNewSection' => $this->mHideNewSection,
            'NoGallery' => $this->mNoGallery,
            'HeadItems' => $this->mHeadItems,
            'Modules' => array_keys( $this->mModuleSet ),
            'ModuleStyles' => array_keys( $this->mModuleStyleSet ),
            'JsConfigVars' => $this->mJsConfigVars,
            'Warnings' => $this->mWarnings,
            'Sections' => $this->getSections(),
            'Properties' => self::detectAndEncodeBinary( $this->mProperties ),
            'Timestamp' => $this->mTimestamp,
            'EnableOOUI' => $this->mEnableOOUI,
            'IndexPolicy' => $this->getIndexPolicy(),
            // may contain arbitrary structures!
            'ExtensionData' => $this->mExtensionData,
            'LimitReportData' => $this->mLimitReportData,
            'LimitReportJSData' => $this->mLimitReportJSData,
            'CacheMessage' => $this->mCacheMessage,
            'TimeProfile' => $this->mTimeProfile,
            'ParseStartTime' => $this->mParseStartTime, // useless
            'PreventClickjacking' => $this->mPreventClickjacking,
            'ExtraScriptSrcs' => $this->mExtraScriptSrcs,
            'ExtraDefaultSrcs' => $this->mExtraDefaultSrcs,
            'ExtraStyleSrcs' => $this->mExtraStyleSrcs,
            'Flags' => $this->mFlags + (
                // backward-compatibility: distinguish "no sections" from
                // "sections not set" (Will be unnecessary after T327439.)
                $this->mTOCData === null ? [] : [ 'mw:toc-set' => true ]
            ),
            'SpeculativeRevId' => $this->mSpeculativeRevId,
            'SpeculativePageIdUsed' => $this->speculativePageIdUsed,
            'RevisionTimestampUsed' => $this->revisionTimestampUsed,
            'RevisionUsedSha1Base36' => $this->revisionUsedSha1Base36,
            'WrapperDivClasses' => $this->mWrapperDivClasses,
        ];

        // Fill in missing fields from parents. Array addition does not override existing fields.
        $data += parent::toJsonArray();

        // TODO: make more fields optional!

        if ( $this->mMaxAdaptiveExpiry !== INF ) {
            // NOTE: JSON can't encode infinity!
            $data['MaxAdaptiveExpiry'] = $this->mMaxAdaptiveExpiry;
        }

        if ( $this->mTOCData ) {
            // Temporarily add information from TOCData extension data
            // T327439: We should eventually make the entire mTOCData
            // serializable
            $toc = $this->mTOCData->jsonSerialize();
            if ( isset( $toc['extensionData'] ) ) {
                $data['TOCExtensionData'] = $toc['extensionData'];
            }
        }

        return $data;
    }

    public static function newFromJsonArray( JsonUnserializer $unserializer, array $json ): ParserOutput {
        $parserOutput = new ParserOutput();
        $parserOutput->initFromJson( $unserializer, $json );
        return $parserOutput;
    }

    /**
     * Initialize member fields from an array returned by jsonSerialize().
     * @param JsonUnserializer $unserializer
     * @param array $jsonData
     */
    protected function initFromJson( JsonUnserializer $unserializer, array $jsonData ): void {
        parent::initFromJson( $unserializer, $jsonData );

        // WARNING: When changing how this class is serialized, follow the instructions
        // at <https://www.mediawiki.org/wiki/Manual:Parser_cache/Serialization_compatibility>!

        $this->mRawText = $jsonData['Text'];
        $this->mLanguageLinks = $jsonData['LanguageLinks'];
        $this->mCategories = $jsonData['Categories'];
        $this->mIndicators = $jsonData['Indicators'];
        $this->mTitleText = $jsonData['TitleText'];
        $this->mLinks = $jsonData['Links'];
        $this->mLinksSpecial = $jsonData['LinksSpecial'];
        $this->mTemplates = $jsonData['Templates'];
        $this->mTemplateIds = $jsonData['TemplateIds'];
        $this->mImages = $jsonData['Images'];
        $this->mFileSearchOptions = $jsonData['FileSearchOptions'];
        $this->mExternalLinks = $jsonData['ExternalLinks'];
        $this->mInterwikiLinks = $jsonData['InterwikiLinks'];
        $this->mNewSection = $jsonData['NewSection'];
        $this->mHideNewSection = $jsonData['HideNewSection'];
        $this->mNoGallery = $jsonData['NoGallery'];
        $this->mHeadItems = $jsonData['HeadItems'];
        $this->mModuleSet = array_fill_keys( $jsonData['Modules'], true );
        $this->mModuleStyleSet = array_fill_keys( $jsonData['ModuleStyles'], true );
        $this->mJsConfigVars = $jsonData['JsConfigVars'];
        $this->mWarnings = $jsonData['Warnings'];
        $this->mFlags = $jsonData['Flags'];
        if (
            $jsonData['Sections'] !== [] ||
            // backward-compatibility: distinguish "no sections" from
            // "sections not set" (Will be unnecessary after T327439.)
            $this->getOutputFlag( 'mw:toc-set' )
        ) {
            $this->setSections( $jsonData['Sections'] );
            unset( $this->mFlags['mw:toc-set'] );
            if ( isset( $jsonData['TOCExtensionData'] ) ) {
                $tocData = $this->getTOCData(); // created by setSections() above
                foreach ( $jsonData['TOCExtensionData'] as $key => $value ) {
                    $tocData->setExtensionData( $key, $value );
                }
            }
        }
        $this->mProperties = self::detectAndDecodeBinary( $jsonData['Properties'] );
        $this->mTimestamp = $jsonData['Timestamp'];
        $this->mEnableOOUI = $jsonData['EnableOOUI'];
        $this->setIndexPolicy( $jsonData['IndexPolicy'] );
        $this->mExtensionData = $jsonData['ExtensionData'] ?? [];
        $this->mLimitReportData = $jsonData['LimitReportData'];
        $this->mLimitReportJSData = $jsonData['LimitReportJSData'];
        $this->mCacheMessage = $jsonData['CacheMessage'] ?? '';
        $this->mParseStartTime = $jsonData['ParseStartTime']; // useless!
        $this->mTimeProfile = $jsonData['TimeProfile'] ?? [];
        $this->mPreventClickjacking = $jsonData['PreventClickjacking'];
        $this->mExtraScriptSrcs = $jsonData['ExtraScriptSrcs'];
        $this->mExtraDefaultSrcs = $jsonData['ExtraDefaultSrcs'];
        $this->mExtraStyleSrcs = $jsonData['ExtraStyleSrcs'];
        $this->mSpeculativeRevId = $jsonData['SpeculativeRevId'];
        $this->speculativePageIdUsed = $jsonData['SpeculativePageIdUsed'];
        $this->revisionTimestampUsed = $jsonData['RevisionTimestampUsed'];
        $this->revisionUsedSha1Base36 = $jsonData['RevisionUsedSha1Base36'];
        $this->mWrapperDivClasses = $jsonData['WrapperDivClasses'];
        $this->mMaxAdaptiveExpiry = $jsonData['MaxAdaptiveExpiry'] ?? INF;
    }

    /**
     * Finds any non-utf8 strings in the given array and replaces them with
     * an associative array that wraps a base64 encoded version of the data.
     * Inverse of detectAndDecodeBinary().
     *
     * @param array $properties
     *
     * @return array
     */
    private static function detectAndEncodeBinary( array $properties ) {
        foreach ( $properties as $key => $value ) {
            if ( is_string( $value ) ) {
                if ( !mb_detect_encoding( $value, 'UTF-8', true ) ) {
                    $properties[$key] = [
                        // T313818: This key name conflicts with JsonCodec
                        '_type_' => 'string',
                        '_encoding_' => 'base64',
                        '_data_' => base64_encode( $value ),
                    ];
                }
            }
        }

        return $properties;
    }

    /**
     * Finds any associative arrays that represent encoded binary strings, and
     * replaces them with the decoded binary data.
     *
     * @param array $properties
     *
     * @return array
     */
    private static function detectAndDecodeBinary( array $properties ) {
        foreach ( $properties as $key => $value ) {
            if ( is_array( $value ) && isset( $value['_encoding_'] ) ) {
                if ( $value['_encoding_'] === 'base64' ) {
                    $properties[$key] = base64_decode( $value['_data_'] );
                }
            }
        }

        return $properties;
    }

    public function __wakeup() {
        $oldAliases = [
            // This was the pre-namespace name of the class, which is still
            // used in pre-1.42 serialized objects.
            'ParserOutput',
        ];
        // Backwards compatibility, pre 1.36
        $priorAccessedOptions = $this->getGhostFieldValue( 'mAccessedOptions', ...$oldAliases );
        if ( $priorAccessedOptions ) {
            $this->mParseUsedOptions = $priorAccessedOptions;
        }
        // Backwards compatibility, pre 1.39
        $priorIndexPolicy = $this->getGhostFieldValue( 'mIndexPolicy', ...$oldAliases );
        if ( $priorIndexPolicy ) {
            $this->setIndexPolicy( $priorIndexPolicy );
        }
        // Backwards compatibility, pre 1.40
        $mSections = $this->getGhostFieldValue( 'mSections', ...$oldAliases );
        if ( $mSections !== null && $mSections !== [] ) {
            $this->setSections( $mSections );
        }
        // Backwards compatibility, pre 1.42
        $mModules = $this->getGhostFieldValue( 'mModules', ...$oldAliases );
        if ( $mModules !== null && $mModules !== [] ) {
            $this->addModules( $mModules );
        }
        // Backwards compatibility, pre 1.42
        $mModuleStyles = $this->getGhostFieldValue( 'mModuleStyles', ...$oldAliases );
        if ( $mModuleStyles !== null && $mModuleStyles !== [] ) {
            $this->addModuleStyles( $mModuleStyles );
        }
        // Backwards compatibility, pre 1.42
        $mText = $this->getGhostFieldValue( 'mText', ...$oldAliases );
        if ( $mText !== null ) {
            $this->setRawText( $mText );
        }
        // Backward compatibility with private fields, pre 1.42
        $oldPrivateFields = [
            'mRawText',
            'mLanguageLinks',
            'mCategories',
            'mIndicators',
            'mTitleText',
            'mLinks',
            'mLinksSpecial',
            'mTemplates',
            'mTemplateIds',
            'mImages',
            'mFileSearchOptions',
            'mExternalLinks',
            'mInterwikiLinks',
            'mNewSection',
            'mHideNewSection',
            'mNoGallery',
            'mHeadItems',
            'mModuleSet',
            'mModuleStyleSet',
            'mJsConfigVars',
            'mWarnings',
            'mWarningMsgs',
            'mTOCData',
            'mProperties',
            'mTimestamp',
            'mEnableOOUI',
            'mIndexSet',
            'mNoIndexSet',
            'mExtensionData',
            'mLimitReportData',
            'mLimitReportJSData',
            'mCacheMessage',
            'mParseStartTime',
            'mTimeProfile',
            'mPreventClickjacking',
            'mExtraScriptSrcs',
            'mExtraDefaultSrcs',
            'mExtraStyleSrcs',
            'mFlags',
            'mSpeculativeRevId',
            'speculativePageIdUsed',
            'revisionTimestampUsed',
            'revisionUsedSha1Base36',
            'mWrapperDivClasses',
            'mMaxAdaptiveExpiry',
        ];
        foreach ( $oldPrivateFields as $f ) {
            $this->restoreAliasedGhostField( $f, ...$oldAliases );
        }
    }

    public function __clone() {
        // It seems that very little of this object needs to be explicitly deep-cloned
        // while keeping copies reasonably separated.
        // Most of the non-scalar properties of this object are either
        // - (potentially multi-nested) arrays of scalars (which get deep-cloned), or
        // - arrays that may contain arbitrary elements (which don't necessarily get
        //   deep-cloned), but for which no particular care elsewhere is given to
        //   copying their references around (e.g. mJsConfigVars).
        // Hence, we are not going out of our way to ensure that the references to innermost
        // objects that may appear in a ParserOutput are unique. If that becomes the
        // expectation at any point, this method will require updating as well.
        // The exception is TOCData (which is an object), which we clone explicitly.
        if ( $this->mTOCData ) {
            $this->mTOCData = clone $this->mTOCData;
        }
    }

    /**
     * Returns the content holder text of the ParserOutput.
     * This will eventually be replaced by something like getContentHolder()->getText() when we have a
     * ContentHolder/HtmlHolder class.
     * @internal
     * @unstable
     * @return string
     */
    public function getContentHolderText(): string {
        return $this->getRawText();
    }

    /**
     * Sets the content holder text of the ParserOutput.
     * This will eventually be replaced by something like getContentHolder()->setText() when we have a
     * ContentHolder/HtmlHolder class.
     * @internal
     * @unstable
     */
    public function setContentHolderText( string $s ): void {
        $this->setRawText( $s );
    }

    public function __get( $name ) {
        if ( property_exists( get_called_class(), $name ) ) {
            // Direct access to a public property, deprecated.
            wfDeprecatedMsg( "ParserOutput::{$name} public read access deprecated", '1.38' );
            return $this->$name;
        } elseif ( property_exists( $this, $name ) ) {
            // Dynamic property access, deprecated.
            wfDeprecatedMsg( "ParserOutput::{$name} dynamic property read access deprecated", '1.38' );
            return $this->$name;
        } else {
            trigger_error( "Inaccessible property via __get(): $name" );
            return null;
        }
    }

    public function __set( $name, $value ) {
        if ( property_exists( get_called_class(), $name ) ) {
            // Direct access to a public property, deprecated.
            wfDeprecatedMsg( "ParserOutput::$name public write access deprecated", '1.38' );
            $this->$name = $value;
        } else {
            // Dynamic property access, deprecated.
            wfDeprecatedMsg( "ParserOutput::$name dynamic property write access deprecated", '1.38' );
            $this->$name = $value;
        }
    }
}

/** @deprecated class alias since 1.41 */
class_alias( ParserOutput::class, 'ParserOutput' );