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| 1 | <?php |
| 2 | declare( strict_types = 1 ); |
| 3 | |
| 4 | namespace Wikimedia\Parsoid\Html2Wt; |
| 5 | |
| 6 | use Wikimedia\Assert\Assert; |
| 7 | use Wikimedia\Assert\UnreachableException; |
| 8 | use Wikimedia\Parsoid\Config\Env; |
| 9 | use Wikimedia\Parsoid\DOM\Comment; |
| 10 | use Wikimedia\Parsoid\DOM\DocumentFragment; |
| 11 | use Wikimedia\Parsoid\DOM\Element; |
| 12 | use Wikimedia\Parsoid\DOM\Node; |
| 13 | use Wikimedia\Parsoid\DOM\Text; |
| 14 | use Wikimedia\Parsoid\Ext\ParsoidExtensionAPI; |
| 15 | use Wikimedia\Parsoid\Utils\DiffDOMUtils; |
| 16 | use Wikimedia\Parsoid\Utils\DOMCompat; |
| 17 | use Wikimedia\Parsoid\Utils\DOMDataUtils; |
| 18 | use Wikimedia\Parsoid\Utils\DOMUtils; |
| 19 | use Wikimedia\Parsoid\Utils\PHPUtils; |
| 20 | use Wikimedia\Parsoid\Utils\WTUtils; |
| 21 | |
| 22 | /** |
| 23 | * A DOM diff helper class. |
| 24 | * |
| 25 | * Compares two DOMs and annotates a copy of the passed-in DOM with change |
| 26 | * information for the selective serializer. |
| 27 | */ |
| 28 | class DOMDiff { |
| 29 | |
| 30 | // These attributes are ignored for equality purposes if they are added to a node. |
| 31 | private const IGNORE_ATTRIBUTES = [ |
| 32 | // Note that we are explicitly not ignoring data-parsoid even though clients |
| 33 | // would never modify data-parsoid because SelectiveSerializer is wrapping text |
| 34 | // nodes in spans and speculatively computes DSR offsets for these span tags |
| 35 | // which are accurate for original DOM and may be inaccurate for the edited DOM. |
| 36 | // By diffing data-parsoid which diffs the DSR as well, we ensure we mark such |
| 37 | // nodes as modified and prevent use of those speculatively computed incorrect |
| 38 | // DSR values. |
| 39 | 'data-parsoid-diff', |
| 40 | 'about', |
| 41 | DOMDataUtils::DATA_OBJECT_ATTR_NAME, |
| 42 | ]; |
| 43 | |
| 44 | /** |
| 45 | * @var Env |
| 46 | */ |
| 47 | public $env; |
| 48 | |
| 49 | /** @var ParsoidExtensionAPI */ |
| 50 | public $extApi; |
| 51 | |
| 52 | /** |
| 53 | * @var array |
| 54 | */ |
| 55 | public $specializedAttribHandlers; |
| 56 | |
| 57 | public bool $skipEncapsulatedContent = true; |
| 58 | |
| 59 | private function nextAnalyzableSibling( Node $node ): ?Node { |
| 60 | if ( WTUtils::isEncapsulationWrapper( $node ) && $this->skipEncapsulatedContent ) { |
| 61 | return WTUtils::skipOverEncapsulatedContent( $node ); |
| 62 | } |
| 63 | return $node->nextSibling; |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * @param mixed ...$args |
| 68 | */ |
| 69 | private function debug( ...$args ): void { |
| 70 | $this->env->log( 'trace/domdiff', ...$args ); |
| 71 | } |
| 72 | |
| 73 | public function __construct( Env $env ) { |
| 74 | $this->env = $env; |
| 75 | $this->extApi = new ParsoidExtensionAPI( $env ); |
| 76 | $this->specializedAttribHandlers = [ |
| 77 | 'data-mw' => static function ( $nodeA, $dmwA, $nodeB, $dmwB ) { |
| 78 | return $dmwA == $dmwB; |
| 79 | }, |
| 80 | 'data-parsoid' => static function ( $nodeA, $dpA, $nodeB, $dpB ) { |
| 81 | return $dpA == $dpB; |
| 82 | }, |
| 83 | ]; |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Diff two HTML documents, and add / update data-parsoid-diff attributes with |
| 88 | * change information. |
| 89 | * |
| 90 | * @param Element $nodeA |
| 91 | * @param Element $nodeB |
| 92 | * @return array |
| 93 | */ |
| 94 | public function diff( Element $nodeA, Element $nodeB ): array { |
| 95 | Assert::invariant( |
| 96 | $nodeA->ownerDocument !== $nodeB->ownerDocument, |
| 97 | 'Expected to be diff\'ing different documents.' |
| 98 | ); |
| 99 | |
| 100 | $this->debug( static function () use( $nodeA, $nodeB ) { |
| 101 | return "ORIG:\n" . |
| 102 | DOMCompat::getOuterHTML( $nodeA ) . |
| 103 | "\nNEW :\n" . |
| 104 | DOMCompat::getOuterHTML( $nodeB ); |
| 105 | } ); |
| 106 | |
| 107 | // The root nodes are equal, call recursive differ |
| 108 | $foundChange = $this->doDOMDiff( $nodeA, $nodeB ); |
| 109 | return [ 'isEmpty' => !$foundChange ]; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Test if two DOM nodes are equal. |
| 114 | * |
| 115 | * @param Node $nodeA |
| 116 | * @param Node $nodeB |
| 117 | * @param bool $deep |
| 118 | * @return bool |
| 119 | */ |
| 120 | public function treeEquals( Node $nodeA, Node $nodeB, bool $deep ): bool { |
| 121 | if ( $nodeA->nodeType !== $nodeB->nodeType ) { |
| 122 | return false; |
| 123 | } elseif ( $nodeA instanceof Text ) { |
| 124 | // In the past we've had bugs where we let non-primitive strings |
| 125 | // leak into our DOM. Safety first: |
| 126 | Assert::invariant( $nodeA->nodeValue === (string)$nodeA->nodeValue, '' ); |
| 127 | Assert::invariant( $nodeB->nodeValue === (string)$nodeB->nodeValue, '' ); |
| 128 | // ok, now do the comparison. |
| 129 | return $nodeA->nodeValue === $nodeB->nodeValue; |
| 130 | } elseif ( $nodeA instanceof Comment ) { |
| 131 | return WTUtils::decodeComment( $nodeA->nodeValue ) === |
| 132 | WTUtils::decodeComment( $nodeB->nodeValue ); |
| 133 | } elseif ( $nodeA instanceof Element || $nodeA instanceof DocumentFragment ) { |
| 134 | if ( $nodeA instanceof DocumentFragment ) { |
| 135 | if ( !( $nodeB instanceof DocumentFragment ) ) { |
| 136 | return false; |
| 137 | } |
| 138 | } else { // $nodeA instanceof Element |
| 139 | // Compare node name and attribute length |
| 140 | if ( |
| 141 | !( $nodeB instanceof Element ) || |
| 142 | DOMCompat::nodeName( $nodeA ) !== DOMCompat::nodeName( $nodeB ) || |
| 143 | !DiffUtils::attribsEquals( |
| 144 | $nodeA, |
| 145 | $nodeB, |
| 146 | self::IGNORE_ATTRIBUTES, |
| 147 | $this->specializedAttribHandlers |
| 148 | ) |
| 149 | ) { |
| 150 | return false; |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | // Passed all tests, node itself is equal. |
| 155 | if ( $deep ) { |
| 156 | $childA = null; |
| 157 | $childB = null; |
| 158 | // Compare # of children, since that's fast. |
| 159 | // (Avoid de-optimizing DOM by using node#childNodes) |
| 160 | for ( $childA = $nodeA->firstChild, $childB = $nodeB->firstChild; |
| 161 | $childA && $childB; |
| 162 | $childA = $childA->nextSibling, $childB = $childB->nextSibling |
| 163 | ) { |
| 164 | /* don't look inside children yet, just look at # of children */ |
| 165 | } |
| 166 | |
| 167 | if ( $childA || $childB ) { |
| 168 | return false; /* nodes have different # of children */ |
| 169 | } |
| 170 | // Now actually compare the child subtrees |
| 171 | for ( $childA = $nodeA->firstChild, $childB = $nodeB->firstChild; |
| 172 | $childA && $childB; |
| 173 | $childA = $childA->nextSibling, $childB = $childB->nextSibling |
| 174 | ) { |
| 175 | if ( !$this->treeEquals( $childA, $childB, $deep ) ) { |
| 176 | return false; |
| 177 | } |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | // Did not find a diff yet, so the trees must be equal. |
| 182 | return true; |
| 183 | } |
| 184 | throw new UnreachableException( 'we shouldn\'t get here' ); |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Diff two DOM trees by comparing them node-by-node. |
| 189 | * |
| 190 | * TODO: Implement something more intelligent like |
| 191 | * http://gregory.cobena.free.fr/www/Publications/%5BICDE2002%5D%20XyDiff%20-%20published%20version.pdf, |
| 192 | * which uses hash signatures of subtrees to efficiently detect moves / |
| 193 | * wrapping. |
| 194 | * |
| 195 | * Adds / updates a data-parsoid-diff structure with change information. |
| 196 | * |
| 197 | * Returns true if subtree is changed, false otherwise. |
| 198 | * |
| 199 | * TODO: |
| 200 | * Assume typical CSS white-space, so ignore ws diffs in non-pre content. |
| 201 | * |
| 202 | * @param Node $baseParentNode |
| 203 | * @param Node $newParentNode |
| 204 | * @return bool |
| 205 | */ |
| 206 | public function doDOMDiff( Node $baseParentNode, Node $newParentNode ): bool { |
| 207 | // Perform a relaxed version of the recursive treeEquals algorithm that |
| 208 | // allows for some minor differences and tries to produce a sensible diff |
| 209 | // marking using heuristics like look-ahead on siblings. |
| 210 | $baseNode = $baseParentNode->firstChild; |
| 211 | $newNode = $newParentNode->firstChild; |
| 212 | $lookaheadNode = null; |
| 213 | $foundDiffOverall = false; |
| 214 | |
| 215 | while ( $baseNode && $newNode ) { |
| 216 | $dontAdvanceNewNode = false; |
| 217 | $this->debugOut( $baseNode, $newNode ); |
| 218 | // shallow check first |
| 219 | if ( !$this->treeEquals( $baseNode, $newNode, false ) ) { |
| 220 | $this->debug( '-- not equal --' ); |
| 221 | $savedNewNode = $newNode; |
| 222 | $foundDiff = false; |
| 223 | |
| 224 | // Some simplistic look-ahead, currently limited to a single level |
| 225 | // in the DOM. |
| 226 | |
| 227 | // look-ahead in *new* DOM to detect insertions |
| 228 | if ( DiffDOMUtils::isContentNode( $baseNode ) ) { |
| 229 | $this->debug( '--lookahead in new dom--' ); |
| 230 | $lookaheadNode = $newNode->nextSibling; |
| 231 | while ( $lookaheadNode ) { |
| 232 | $this->debugOut( $baseNode, $lookaheadNode, 'new' ); |
| 233 | if ( DiffDOMUtils::isContentNode( $lookaheadNode ) && |
| 234 | $this->treeEquals( $baseNode, $lookaheadNode, true ) |
| 235 | ) { |
| 236 | // mark skipped-over nodes as inserted |
| 237 | $markNode = $newNode; |
| 238 | while ( $markNode !== $lookaheadNode ) { |
| 239 | $this->debug( '--found diff: inserted--' ); |
| 240 | $this->markNode( $markNode, DiffMarkers::INSERTED ); |
| 241 | $markNode = $markNode->nextSibling; |
| 242 | } |
| 243 | $foundDiff = true; |
| 244 | $newNode = $lookaheadNode; |
| 245 | break; |
| 246 | } |
| 247 | $lookaheadNode = self::nextAnalyzableSibling( $lookaheadNode ); |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | // look-ahead in *base* DOM to detect deletions |
| 252 | if ( !$foundDiff && DiffDOMUtils::isContentNode( $newNode ) ) { |
| 253 | $isBlockNode = WTUtils::isBlockNodeWithVisibleWT( $baseNode ); |
| 254 | $this->debug( '--lookahead in old dom--' ); |
| 255 | $lookaheadNode = $baseNode->nextSibling; |
| 256 | while ( $lookaheadNode ) { |
| 257 | $this->debugOut( $lookaheadNode, $newNode, 'old' ); |
| 258 | if ( DiffDOMUtils::isContentNode( $lookaheadNode ) && |
| 259 | $this->treeEquals( $lookaheadNode, $newNode, true ) |
| 260 | ) { |
| 261 | $this->debug( '--found diff: deleted--' ); |
| 262 | // mark skipped-over nodes as deleted |
| 263 | $this->markNode( $newNode, DiffMarkers::DELETED, $isBlockNode ); |
| 264 | $baseNode = $lookaheadNode; |
| 265 | $foundDiff = true; |
| 266 | break; |
| 267 | } elseif ( !WTUtils::emitsSolTransparentSingleLineWT( $lookaheadNode ) ) { |
| 268 | // We only care about the deleted node prior to the one that |
| 269 | // gets a tree match (but, ignore nodes that show up in wikitext |
| 270 | // but don't affect sol-state or HTML rendering -- note that |
| 271 | // whitespace is being ignored, but that whitespace occurs |
| 272 | // between block nodes). |
| 273 | $isBlockNode = WTUtils::isBlockNodeWithVisibleWT( $lookaheadNode ); |
| 274 | } |
| 275 | $lookaheadNode = self::nextAnalyzableSibling( $lookaheadNode ); |
| 276 | } |
| 277 | } |
| 278 | |
| 279 | if ( !$foundDiff ) { |
| 280 | if ( !( $savedNewNode instanceof Element ) ) { |
| 281 | $this->debug( '--found diff: modified text/comment--' ); |
| 282 | $this->markNode( |
| 283 | $savedNewNode, DiffMarkers::DELETED, |
| 284 | WTUtils::isBlockNodeWithVisibleWT( $baseNode ) |
| 285 | ); |
| 286 | } elseif ( $baseNode instanceof Element && |
| 287 | DOMCompat::nodeName( $savedNewNode ) === DOMCompat::nodeName( $baseNode ) && |
| 288 | ( DOMDataUtils::getDataParsoid( $savedNewNode )->stx ?? null ) === |
| 289 | ( DOMDataUtils::getDataParsoid( $baseNode )->stx ?? null ) |
| 290 | ) { |
| 291 | // Identical wrapper-type, but modified. |
| 292 | // Mark modified-wrapper, and recurse. |
| 293 | $this->debug( '--found diff: modified-wrapper--' ); |
| 294 | $this->markNode( $savedNewNode, DiffMarkers::MODIFIED_WRAPPER ); |
| 295 | $this->subtreeDiffers( $baseNode, $savedNewNode ); |
| 296 | } else { |
| 297 | // We now want to compare current newNode with the next baseNode. |
| 298 | $dontAdvanceNewNode = true; |
| 299 | |
| 300 | // Since we are advancing in an old DOM without advancing |
| 301 | // in the new DOM, there were deletions. Add a deletion marker |
| 302 | // since this is important for accurate separator handling in selser. |
| 303 | $this->markNode( |
| 304 | $savedNewNode, DiffMarkers::DELETED, |
| 305 | WTUtils::isBlockNodeWithVisibleWT( $baseNode ) |
| 306 | ); |
| 307 | } |
| 308 | } |
| 309 | |
| 310 | // Record the fact that direct children changed in the parent node |
| 311 | $this->debug( '--found diff: children-changed--' ); |
| 312 | $this->markNode( $newParentNode, DiffMarkers::CHILDREN_CHANGED ); |
| 313 | |
| 314 | $foundDiffOverall = true; |
| 315 | } elseif ( $this->subtreeDiffers( $baseNode, $newNode ) ) { |
| 316 | $foundDiffOverall = true; |
| 317 | } |
| 318 | |
| 319 | // And move on to the next pair (skipping over template HTML) |
| 320 | if ( $baseNode && $newNode ) { |
| 321 | $baseNode = self::nextAnalyzableSibling( $baseNode ); |
| 322 | if ( !$dontAdvanceNewNode ) { |
| 323 | $newNode = self::nextAnalyzableSibling( $newNode ); |
| 324 | } |
| 325 | } |
| 326 | } |
| 327 | |
| 328 | // mark extra new nodes as inserted |
| 329 | while ( $newNode ) { |
| 330 | $this->debug( '--found trailing new node: inserted--' ); |
| 331 | $this->markNode( $newNode, DiffMarkers::INSERTED ); |
| 332 | $foundDiffOverall = true; |
| 333 | $newNode = self::nextAnalyzableSibling( $newNode ); |
| 334 | } |
| 335 | |
| 336 | // If there are extra base nodes, something was deleted. Mark the parent as |
| 337 | // having lost children for now. |
| 338 | if ( $baseNode ) { |
| 339 | $this->debug( '--found trailing base nodes: deleted--' ); |
| 340 | $this->markNode( $newParentNode, DiffMarkers::CHILDREN_CHANGED ); |
| 341 | // SSS FIXME: WTS checks for zero children in a few places |
| 342 | // That code would have to be upgraded if we emit mw:DiffMarker |
| 343 | // in this scenario. So, bailing out in this one case for now. |
| 344 | if ( $newParentNode->hasChildNodes() ) { |
| 345 | $meta = $newParentNode->ownerDocument->createElement( 'meta' ); |
| 346 | DOMUtils::addTypeOf( $meta, 'mw:DiffMarker/deleted' ); |
| 347 | if ( WTUtils::isBlockNodeWithVisibleWT( $baseNode ) ) { |
| 348 | $meta->setAttribute( 'data-is-block', 'true' ); |
| 349 | } |
| 350 | $newParentNode->appendChild( $meta ); |
| 351 | } |
| 352 | $foundDiffOverall = true; |
| 353 | } |
| 354 | |
| 355 | return $foundDiffOverall; |
| 356 | } |
| 357 | |
| 358 | /* *************************************************** |
| 359 | * Helpers |
| 360 | * ***************************************************/ |
| 361 | |
| 362 | /** |
| 363 | * @param Node $baseNode |
| 364 | * @param Node $newNode |
| 365 | * @return bool |
| 366 | */ |
| 367 | private function subtreeDiffers( Node $baseNode, Node $newNode ): bool { |
| 368 | $baseEncapsulated = WTUtils::isEncapsulationWrapper( $baseNode ); |
| 369 | $newEncapsulated = WTUtils::isEncapsulationWrapper( $newNode ); |
| 370 | |
| 371 | if ( !$baseEncapsulated && !$newEncapsulated ) { |
| 372 | $this->debug( '--shallow equal: recursing--' ); |
| 373 | // Recursively diff subtrees if not template-like content |
| 374 | $subtreeDiffers = $this->doDOMDiff( $baseNode, $newNode ); |
| 375 | } elseif ( $baseEncapsulated && $newEncapsulated ) { |
| 376 | '@phan-var Element $baseNode'; // @var Element $baseNode |
| 377 | '@phan-var Element $newNode'; // @var Element $newNode |
| 378 | |
| 379 | $ext = null; |
| 380 | |
| 381 | $baseExtTagName = WTUtils::getExtTagName( $baseNode ); |
| 382 | if ( $baseExtTagName ) { |
| 383 | $ext = $this->env->getSiteConfig()->getExtTagImpl( $baseExtTagName ); |
| 384 | } |
| 385 | |
| 386 | if ( $ext && ( $baseExtTagName === WTUtils::getExtTagName( $newNode ) ) ) { |
| 387 | $this->debug( '--diffing extension content--' ); |
| 388 | $subtreeDiffers = $ext->diffHandler( |
| 389 | $this->extApi, [ $this, 'doDOMDiff' ], $baseNode, $newNode |
| 390 | ); |
| 391 | } elseif ( $this->skipEncapsulatedContent ) { |
| 392 | // Otherwise, for encapsulated content, we don't know about the subtree. |
| 393 | $subtreeDiffers = false; |
| 394 | } else { |
| 395 | $this->debug( '--shallow equal (encapsulated): recursing--' ); |
| 396 | // Recursively diff subtrees if not template-like content |
| 397 | $subtreeDiffers = $this->doDOMDiff( $baseNode, $newNode ); |
| 398 | } |
| 399 | } else { |
| 400 | // FIXME: Maybe $editNode should be marked as inserted to avoid |
| 401 | // losing any edits, at the cost of more normalization. |
| 402 | // $state->inInsertedContent is only set when we're in inserted |
| 403 | // content, so not sure this is currently doing all that much. |
| 404 | $subtreeDiffers = true; |
| 405 | } |
| 406 | |
| 407 | if ( $subtreeDiffers ) { |
| 408 | $this->debug( '--found diff: subtree-changed--' ); |
| 409 | $this->markNode( $newNode, DiffMarkers::SUBTREE_CHANGED ); |
| 410 | } |
| 411 | return $subtreeDiffers; |
| 412 | } |
| 413 | |
| 414 | private function markNode( Node $node, string $mark, bool $blockNodeDeleted = false ): void { |
| 415 | $meta = DiffUtils::addDiffMark( $node, $this->env, $mark ); |
| 416 | |
| 417 | if ( $meta && $blockNodeDeleted ) { |
| 418 | $meta->setAttribute( 'data-is-block', 'true' ); |
| 419 | } |
| 420 | |
| 421 | if ( $mark === DiffMarkers::DELETED || $mark === DiffMarkers::INSERTED ) { |
| 422 | $this->markNode( $node->parentNode, DiffMarkers::CHILDREN_CHANGED ); |
| 423 | } |
| 424 | |
| 425 | // Clear out speculatively computed DSR values for data-mw-selser-wrapper nodes |
| 426 | // since they may be incorrect. This eliminates any inadvertent use of |
| 427 | // these incorrect values. |
| 428 | if ( $node instanceof Element && $node->hasAttribute( 'data-mw-selser-wrapper' ) ) { |
| 429 | DOMDataUtils::getDataParsoid( $node )->dsr = null; |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | private function debugOut( Node $nodeA, Node $nodeB, string $laPrefix = '' ): void { |
| 434 | $prefix = 'trace/domdiff'; |
| 435 | $this->env->log( $prefix, |
| 436 | static fn () => '--> A' . $laPrefix . ':' . |
| 437 | ( $nodeA instanceof Element |
| 438 | ? DOMCompat::getOuterHTML( $nodeA ) |
| 439 | : PHPUtils::jsonEncode( $nodeA->nodeValue ) ) |
| 440 | ); |
| 441 | $this->env->log( $prefix, |
| 442 | static fn () => '--> B' . $laPrefix . ':' . |
| 443 | ( $nodeB instanceof Element |
| 444 | ? DOMCompat::getOuterHTML( $nodeB ) |
| 445 | : PHPUtils::jsonEncode( $nodeB->nodeValue ) ) |
| 446 | ); |
| 447 | } |
| 448 | } |