RenderedRevision.php
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RenderedRevision.php
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	<?php
	/**
	* This file is part of MediaWiki.
	*
	* 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\Revision;

	use InvalidArgumentException;
	use LogicException;
	use MediaWiki\Content\Content;
	use MediaWiki\Content\Renderer\ContentRenderer;
	use MediaWiki\Page\PageReference;
	use MediaWiki\Parser\ParserOptions;
	use MediaWiki\Parser\ParserOutput;
	use MediaWiki\Parser\ParserOutputFlags;
	use MediaWiki\Permissions\Authority;
	use Psr\Log\LoggerInterface;
	use Psr\Log\NullLogger;
	use Wikimedia\Assert\Assert;

	/**
	* RenderedRevision represents the rendered representation of a revision. It acts as a lazy provider
	* of ParserOutput objects for the revision's individual slots, as well as a combined ParserOutput
	* of all slots.
	*
	* @since 1.32
	*/
	class RenderedRevision implements SlotRenderingProvider {

	/** @var RevisionRecord */
	private $revision;

	/**
	* @var ParserOptions
	*/
	private $options;

	/**
	* @var int Audience to check when accessing content.
	*/
	private $audience = RevisionRecord::FOR_PUBLIC;

	/**
	* @var Authority\|null The user to use for audience checks during content access.
	*/
	private $performer = null;

	/**
	* @var ParserOutput\|null The combined ParserOutput for the revision,
	* initialized lazily by getRevisionParserOutput().
	*/
	private $revisionOutput = null;

	/**
	* @var ParserOutput[] The ParserOutput for each slot,
	* initialized lazily by getSlotParserOutput().
	*/
	private $slotsOutput = [];

	/**
	* @var callable Callback for combining slot output into revision output.
	* Signature: function ( RenderedRevision $this, array $hints ): ParserOutput.
	*/
	private $combineOutput;

	/**
	* @var LoggerInterface For profiling ParserOutput re-use.
	*/
	private $saveParseLogger;

	/**
	* @var ContentRenderer Service to render content.
	*/
	private $contentRenderer;

	/**
	* @note Application logic should not instantiate RenderedRevision instances directly,
	* but should use a RevisionRenderer instead.
	*
	* @param RevisionRecord $revision The revision to render. The content for rendering will be
	* taken from this RevisionRecord. However, if the RevisionRecord is not complete
	* according isReadyForInsertion(), but a revision ID is known, the parser may load
	* the revision from the database if it needs revision meta data to handle magic
	* words like {{REVISIONUSER}}.
	* @param ParserOptions $options
	* @param ContentRenderer $contentRenderer
	* @param callable $combineOutput Callback for combining slot output into revision output.
	* Signature: function ( RenderedRevision $this, array $hints ): ParserOutput.
	* @param int $audience Use RevisionRecord::FOR_PUBLIC, FOR_THIS_USER, or RAW.
	* @param Authority\|null $performer Required if $audience is FOR_THIS_USER.
	*/
	public function __construct(
	RevisionRecord $revision,
	ParserOptions $options,
	ContentRenderer $contentRenderer,
	callable $combineOutput,
	$audience = RevisionRecord::FOR_PUBLIC,
	?Authority $performer = null
	) {
	$this->options = $options;

	$this->setRevisionInternal( $revision );

	$this->contentRenderer = $contentRenderer;
	$this->combineOutput = $combineOutput;
	$this->saveParseLogger = new NullLogger();

	if ( $audience === RevisionRecord::FOR_THIS_USER && !$performer ) {
	throw new InvalidArgumentException(
	'User must be specified when setting audience to FOR_THIS_USER'
	);
	}

	$this->audience = $audience;
	$this->performer = $performer;
	}

	/**
	* @param LoggerInterface $saveParseLogger
	*/
	public function setSaveParseLogger( LoggerInterface $saveParseLogger ) {
	$this->saveParseLogger = $saveParseLogger;
	}

	/**
	* @return bool Whether the revision's content has been hidden from unprivileged users.
	*/
	public function isContentDeleted() {
	return $this->revision->isDeleted( RevisionRecord::DELETED_TEXT );
	}

	/**
	* @return RevisionRecord
	*/
	public function getRevision() {
	return $this->revision;
	}

	/**
	* @return ParserOptions
	*/
	public function getOptions() {
	return $this->options;
	}

	/**
	* Sets a ParserOutput to be returned by getRevisionParserOutput().
	*
	* @note For internal use by RevisionRenderer only! This method may be modified
	* or removed without notice per the deprecation policy.
	*
	* @internal
	*
	* @param ParserOutput $output
	*/
	public function setRevisionParserOutput( ParserOutput $output ) {
	$this->revisionOutput = $output;

	// If there is only one slot, we assume that the combined output is identical
	// with the main slot's output. This is intended to prevent a redundant re-parse of
	// the content in case getSlotParserOutput( SlotRecord::MAIN ) is called, for instance
	// from ContentHandler::getSecondaryDataUpdates.
	if ( $this->revision->getSlotRoles() === [ SlotRecord::MAIN ] ) {
	$this->slotsOutput[ SlotRecord::MAIN ] = $output;
	}
	}

	/**
	* @param array $hints Hints given as an associative array. Known keys:
	* - 'generate-html' => bool: Whether the caller is interested in output HTML (as opposed
	* to just meta-data). Default is to generate HTML.
	* @phan-param array{generate-html?:bool} $hints
	*
	* @return ParserOutput
	*/
	public function getRevisionParserOutput( array $hints = [] ) {
	$withHtml = $hints['generate-html'] ?? true;

	if ( !$this->revisionOutput
	\|\| ( $withHtml && !$this->revisionOutput->hasText() )
	) {
	$output = call_user_func( $this->combineOutput, $this, $hints );

	Assert::postcondition(
	$output instanceof ParserOutput,
	'Callback did not return a ParserOutput object!'
	);

	$this->revisionOutput = $output;
	}

	return $this->revisionOutput;
	}

	/**
	* @param string $role
	* @param array $hints Hints given as an associative array. Known keys:
	* - 'generate-html' => bool: Whether the caller is interested in output HTML (as opposed
	* to just meta-data). Default is to generate HTML.
	* - 'previous-output' => ?ParserOutput: An optional "previously parsed"
	* version of this slot; used to allow Parsoid selective updates.
	* @phan-param array{generate-html?:bool,previous-output?:?ParserOutput} $hints
	*
	* @throws SuppressedDataException if the content is not accessible for the audience
	* specified in the constructor.
	* @throws BadRevisionException
	* @throws RevisionAccessException
	* @return ParserOutput
	*/
	public function getSlotParserOutput( $role, array $hints = [] ) {
	$withHtml = $hints['generate-html'] ?? true;

	if ( !isset( $this->slotsOutput[ $role ] )
	\|\| ( $withHtml && !$this->slotsOutput[ $role ]->hasText() )
	) {
	$content = $this->revision->getContentOrThrow( $role, $this->audience, $this->performer );

	// XXX: allow SlotRoleHandler to control the ParserOutput?
	$output = $this->getSlotParserOutputUncached( $content, $hints );

	if ( $withHtml && !$output->hasText() ) {
	throw new LogicException(
	'HTML generation was requested, but '
	. get_class( $content )
	. ' that passed to '
	. 'ContentRenderer::getParserOutput() returns a ParserOutput with no text set.'
	);
	}

	// Detach watcher, to ensure option use is not recorded in the wrong ParserOutput.
	$this->options->registerWatcher( null );

	$this->slotsOutput[ $role ] = $output;
	}

	return $this->slotsOutput[$role];
	}

	/**
	* @note This method exists to make duplicate parses easier to see during profiling
	* @param Content $content
	* @param array{generate-html?:bool,previous-output?:?ParserOutput} $hints
	* @return ParserOutput
	*/
	private function getSlotParserOutputUncached( Content $content, array $hints ): ParserOutput {
	return $this->contentRenderer->getParserOutput(
	$content,
	$this->revision->getPage(),
	$this->revision,
	$this->options,
	$hints
	);
	}

	/**
	* Updates the RevisionRecord after the revision has been saved. This can be used to discard
	* and cached ParserOutput so parser functions like {{REVISIONTIMESTAMP}} or {{REVISIONID}}
	* are re-evaluated.
	*
	* @note There should be no need to call this for null-edits.
	*
	* @param RevisionRecord $rev
	*/
	public function updateRevision( RevisionRecord $rev ) {
	if ( $rev->getId() === $this->revision->getId() ) {
	return;
	}

	if ( $this->revision->getId() ) {
	throw new LogicException( 'RenderedRevision already has a revision with ID '
	. $this->revision->getId() . ', can\'t update to revision with ID ' . $rev->getId() );
	}

	if ( !$this->revision->getSlots()->hasSameContent( $rev->getSlots() ) ) {
	throw new LogicException( 'Cannot update to a revision with different content!' );
	}

	$this->setRevisionInternal( $rev );

	$this->pruneRevisionSensitiveOutput(
	$this->revision->getPageId(),
	$this->revision->getId(),
	$this->revision->getTimestamp()
	);
	}

	/**
	* Prune any output that depends on the revision ID.
	*
	* @param int\|bool $actualPageId The actual page id, to check the used speculative page ID
	* against; false, to not purge on vary-page-id; true, to purge on vary-page-id
	* unconditionally.
	* @param int\|bool $actualRevId The actual rev id, to check the used speculative rev ID
	* against,; false, to not purge on vary-revision-id; true, to purge on
	* vary-revision-id unconditionally.
	* @param string\|bool $actualRevTimestamp The actual rev timestamp, to check against the
	* parser output revision timestamp; false, to not purge on vary-revision-timestamp;
	* true, to purge on vary-revision-timestamp unconditionally.
	*/
	private function pruneRevisionSensitiveOutput(
	$actualPageId,
	$actualRevId,
	$actualRevTimestamp
	) {
	if ( $this->revisionOutput ) {
	if ( $this->outputVariesOnRevisionMetaData(
	$this->revisionOutput,
	$actualPageId,
	$actualRevId,
	$actualRevTimestamp
	) ) {
	$this->revisionOutput = null;
	}
	} else {
	$this->saveParseLogger->debug( __METHOD__ . ": no prepared revision output" );
	}

	foreach ( $this->slotsOutput as $role => $output ) {
	if ( $this->outputVariesOnRevisionMetaData(
	$output,
	$actualPageId,
	$actualRevId,
	$actualRevTimestamp
	) ) {
	unset( $this->slotsOutput[$role] );
	}
	}
	}

	/**
	* @param RevisionRecord $revision
	*/
	private function setRevisionInternal( RevisionRecord $revision ) {
	$this->revision = $revision;

	// Force the parser to use $this->revision to resolve magic words like {{REVISIONUSER}}
	// if the revision is either known to be complete, or it doesn't have a revision ID set.
	// If it's incomplete and we have a revision ID, the parser can do better by loading
	// the revision from the database if needed to handle a magic word.
	//
	// The following considerations inform the logic described above:
	//
	// 1) If we have a saved revision already loaded, we want the parser to use it, instead of
	// loading it again.
	//
	// 2) If the revision is a fake that wraps some kind of synthetic content, such as an
	// error message from Article, it should be used directly and things like {{REVISIONUSER}}
	// should not expected to work, since there may not even be an actual revision to
	// refer to.
	//
	// 3) If the revision is a fake constructed around a page, a Content object, and
	// a revision ID, to provide backwards compatibility to code that has access to those
	// but not to a complete RevisionRecord for rendering, then we want the Parser to
	// load the actual revision from the database when it encounters a magic word like
	// {{REVISIONUSER}}, but we don't want to load that revision ahead of time just in case.
	//
	// 4) Previewing an edit to a template should use the submitted unsaved
	// MutableRevisionRecord for self-transclusions in the template's documentation (see T7278).
	// That revision would be complete except for the ID field.
	//
	// 5) Pre-save transform would provide a RevisionRecord that has all meta-data but is
	// incomplete due to not yet having content set. However, since it doesn't have a revision
	// ID either, the below code would still force it to be used, allowing
	// {{subst::REVISIONUSER}} to function as expected.

	if ( $this->revision->isReadyForInsertion() \|\| !$this->revision->getId() ) {
	$oldCallback = $this->options->getCurrentRevisionRecordCallback();
	$this->options->setCurrentRevisionRecordCallback(
	function ( PageReference $parserPage, $parser = null ) use ( $oldCallback ) {
	if ( $this->revision->getPage()->isSamePageAs( $parserPage ) ) {
	return $this->revision;
	} else {
	return call_user_func( $oldCallback, $parserPage, $parser );
	}
	}
	);
	}
	}

	/**
	* @param ParserOutput $parserOutput
	* @param int\|bool $actualPageId The actual page id, to check the used speculative page ID
	* against; false, to not purge on vary-page-id; true, to purge on vary-page-id
	* unconditionally.
	* @param int\|bool $actualRevId The actual rev id, to check the used speculative rev ID
	* against,; false, to not purge on vary-revision-id; true, to purge on
	* vary-revision-id unconditionally.
	* @param string\|bool $actualRevTimestamp The actual rev timestamp, to check against the
	* parser output revision timestamp; false, to not purge on vary-revision-timestamp;
	* true, to purge on vary-revision-timestamp unconditionally.
	* @return bool
	*/
	private function outputVariesOnRevisionMetaData(
	ParserOutput $parserOutput,
	$actualPageId,
	$actualRevId,
	$actualRevTimestamp
	) {
	$logger = $this->saveParseLogger;
	$varyMsg = __METHOD__ . ": cannot use prepared output for '{title}'";
	$context = [ 'title' => (string)$this->revision->getPage() ];

	if ( $parserOutput->getOutputFlag( ParserOutputFlags::VARY_REVISION ) ) {
	// If {{PAGEID}} resolved to 0, then that word need to resolve to the actual page ID
	$logger->info( "$varyMsg (vary-revision)", $context );
	return true;
	} elseif (
	$parserOutput->getOutputFlag( ParserOutputFlags::VARY_REVISION_ID )
	&& $actualRevId !== false
	&& ( $actualRevId === true \|\| $parserOutput->getSpeculativeRevIdUsed() !== $actualRevId )
	) {
	$logger->info( "$varyMsg (vary-revision-id and wrong ID)", $context );
	return true;
	} elseif (
	$parserOutput->getOutputFlag( ParserOutputFlags::VARY_REVISION_TIMESTAMP )
	&& $actualRevTimestamp !== false
	&& ( $actualRevTimestamp === true \|\|
	$parserOutput->getRevisionTimestampUsed() !== $actualRevTimestamp )
	) {
	$logger->info( "$varyMsg (vary-revision-timestamp and wrong timestamp)", $context );
	return true;
	} elseif (
	$parserOutput->getOutputFlag( ParserOutputFlags::VARY_PAGE_ID )
	&& $actualPageId !== false
	&& ( $actualPageId === true \|\| $parserOutput->getSpeculativePageIdUsed() !== $actualPageId )
	) {
	$logger->info( "$varyMsg (vary-page-id and wrong ID)", $context );
	return true;
	} elseif ( $parserOutput->getOutputFlag( ParserOutputFlags::VARY_REVISION_EXISTS ) ) {
	// If {{REVISIONID}} resolved to '', it now needs to resolve to '-'.
	// Note that edit stashing always uses '-', which can be used for both
	// edit filter checks and canonical parser cache.
	$logger->info( "$varyMsg (vary-revision-exists)", $context );
	return true;
	} elseif (
	$parserOutput->getOutputFlag( ParserOutputFlags::VARY_REVISION_SHA1 ) &&
	$parserOutput->getRevisionUsedSha1Base36() !== $this->revision->getSha1()
	) {
	// If a self-transclusion used the proposed page text, it must match the final
	// page content after PST transformations and automatically merged edit conflicts
	$logger->info( "$varyMsg (vary-revision-sha1 with wrong SHA-1)", $context );
	return true;
	}

	// NOTE: In the original fix for T135261, the output was discarded if ParserOutputFlags::VARY_USER was
	// set for a null-edit. The reason was that the original rendering in that case was
	// targeting the user making the null-edit, not the user who made the original edit,
	// causing {{REVISIONUSER}} to return the wrong name.
	// This case is now expected to be handled by the code in RevisionRenderer that
	// constructs the ParserOptions: For a null-edit, setCurrentRevisionRecordCallback is
	// called with the old, existing revision.
	$logger->debug( __METHOD__ . ": reusing prepared output for '{title}'", $context );
	return false;
	}
	}

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