WP_HTML_Tag_Processor::apply_attributes_updates( int $shift_this_point ): int

Source

private function apply_attributes_updates( int $shift_this_point ): int {
	if ( ! count( $this->lexical_updates ) ) {
		return 0;
	}

	$accumulated_shift_for_given_point = 0;

	/*
	 * Attribute updates can be enqueued in any order but updates
	 * to the document must occur in lexical order; that is, each
	 * replacement must be made before all others which follow it
	 * at later string indices in the input document.
	 *
	 * Sorting avoid making out-of-order replacements which
	 * can lead to mangled output, partially-duplicated
	 * attributes, and overwritten attributes.
	 */
	usort( $this->lexical_updates, array( self::class, 'sort_start_ascending' ) );

	$bytes_already_copied = 0;
	$output_buffer        = '';
	foreach ( $this->lexical_updates as $diff ) {
		$shift = strlen( $diff->text ) - $diff->length;

		// Adjust the cursor position by however much an update affects it.
		if ( $diff->start < $this->bytes_already_parsed ) {
			$this->bytes_already_parsed += $shift;
		}

		// Accumulate shift of the given pointer within this function call.
		if ( $diff->start < $shift_this_point ) {
			$accumulated_shift_for_given_point += $shift;
		}

		$output_buffer       .= substr( $this->html, $bytes_already_copied, $diff->start - $bytes_already_copied );
		$output_buffer       .= $diff->text;
		$bytes_already_copied = $diff->start + $diff->length;
	}

	$this->html = $output_buffer . substr( $this->html, $bytes_already_copied );

	/*
	 * Adjust bookmark locations to account for how the text
	 * replacements adjust offsets in the input document.
	 */
	foreach ( $this->bookmarks as $bookmark_name => $bookmark ) {
		$bookmark_end = $bookmark->start + $bookmark->length;

		/*
		 * Each lexical update which appears before the bookmark's endpoints
		 * might shift the offsets for those endpoints. Loop through each change
		 * and accumulate the total shift for each bookmark, then apply that
		 * shift after tallying the full delta.
		 */
		$head_delta = 0;
		$tail_delta = 0;

		foreach ( $this->lexical_updates as $diff ) {
			$diff_end = $diff->start + $diff->length;

			if ( $bookmark->start < $diff->start && $bookmark_end < $diff->start ) {
				break;
			}

			if ( $bookmark->start >= $diff->start && $bookmark_end < $diff_end ) {
				$this->release_bookmark( $bookmark_name );
				continue 2;
			}

			$delta = strlen( $diff->text ) - $diff->length;

			if ( $bookmark->start >= $diff->start ) {
				$head_delta += $delta;
			}

			if ( $bookmark_end >= $diff_end ) {
				$tail_delta += $delta;
			}
		}

		$bookmark->start  += $head_delta;
		$bookmark->length += $tail_delta - $head_delta;
	}

	$this->lexical_updates = array();

	return $accumulated_shift_for_given_point;
}

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