--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/html-api/class-wp-html-doctype-info.php Fri Sep 05 18:52:52 2025 +0200
@@ -0,0 +1,616 @@
+<?php
+/**
+ * HTML API: WP_HTML_Doctype_Info class
+ *
+ * @package WordPress
+ * @subpackage HTML-API
+ * @since 6.7.0
+ */
+
+/**
+ * Core class used by the HTML API to represent a DOCTYPE declaration.
+ *
+ * This class parses DOCTYPE tokens for the full parser in the HTML Processor.
+ * Most code interacting with HTML won't need to parse DOCTYPE declarations;
+ * the HTML Processor is one exception. Consult the HTML Processor for proper
+ * parsing of an HTML document.
+ *
+ * A DOCTYPE declaration may indicate its document compatibility mode, which impacts
+ * the structure of the following HTML as well as the behavior of CSS class selectors.
+ * There are three possible modes:
+ *
+ * - "no-quirks" and "limited-quirks" modes (also called "standards mode").
+ * - "quirks" mode.
+ *
+ * These modes mostly determine whether CSS class name selectors match values in the
+ * HTML `class` attribute in an ASCII-case-insensitive way (quirks mode), or whether
+ * they match only when byte-for-byte identical (no-quirks mode).
+ *
+ * All HTML documents should start with the standard HTML5 DOCTYPE: `<!DOCTYPE html>`.
+ *
+ * > DOCTYPEs are required for legacy reasons. When omitted, browsers tend to use a different
+ * > rendering mode that is incompatible with some specifications. Including the DOCTYPE in a
+ * > document ensures that the browser makes a best-effort attempt at following the
+ * > relevant specifications.
+ *
+ * @see https://html.spec.whatwg.org/#the-doctype
+ *
+ * DOCTYPE declarations comprise four properties: a name, public identifier, system identifier,
+ * and an indication of which document compatability mode they would imply if an HTML parser
+ * hadn't already determined it from other information.
+ *
+ * @see https://html.spec.whatwg.org/#the-initial-insertion-mode
+ *
+ * Historically, the DOCTYPE declaration was used in SGML documents to instruct a parser how
+ * to interpret the various tags and entities within a document. Its role in HTML diverged
+ * from how it was used in SGML and no meaning should be back-read into HTML based on how it
+ * is used in SGML, XML, or XHTML documents.
+ *
+ * @see https://www.iso.org/standard/16387.html
+ *
+ * @since 6.7.0
+ *
+ * @see WP_HTML_Processor
+ */
+class WP_HTML_Doctype_Info {
+ /**
+ * Name of the DOCTYPE: should be "html" for HTML documents.
+ *
+ * This value should be considered "read only" and not modified.
+ *
+ * Historically the DOCTYPE name indicates name of the document's root element.
+ *
+ * <!DOCTYPE html>
+ * ╰──┴── name is "html".
+ *
+ * @see https://html.spec.whatwg.org/#tokenization
+ *
+ * @since 6.7.0
+ *
+ * @var string|null
+ */
+ public $name = null;
+
+ /**
+ * Public identifier of the DOCTYPE.
+ *
+ * This value should be considered "read only" and not modified.
+ *
+ * The public identifier is optional and should not appear in HTML documents.
+ * A `null` value indicates that no public identifier was present in the DOCTYPE.
+ *
+ * Historically the presence of the public identifier indicated that a document
+ * was meant to be shared between computer systems and the value indicated to a
+ * knowledgeable parser how to find the relevant document type definition (DTD).
+ *
+ * <!DOCTYPE html PUBLIC "public id goes here in quotes">
+ * │ │ ╰─── public identifier ─────╯
+ * ╰──┴── name is "html".
+ *
+ * @see https://html.spec.whatwg.org/#tokenization
+ *
+ * @since 6.7.0
+ *
+ * @var string|null
+ */
+ public $public_identifier = null;
+
+ /**
+ * System identifier of the DOCTYPE.
+ *
+ * This value should be considered "read only" and not modified.
+ *
+ * The system identifier is optional and should not appear in HTML documents.
+ * A `null` value indicates that no system identifier was present in the DOCTYPE.
+ *
+ * Historically the system identifier specified where a relevant document type
+ * declaration for the given document is stored and may be retrieved.
+ *
+ * <!DOCTYPE html SYSTEM "system id goes here in quotes">
+ * │ │ ╰──── system identifier ────╯
+ * ╰──┴── name is "html".
+ *
+ * If a public identifier were provided it would indicate to a knowledgeable
+ * parser how to interpret the system identifier.
+ *
+ * <!DOCTYPE html PUBLIC "public id goes here in quotes" "system id goes here in quotes">
+ * │ │ ╰─── public identifier ─────╯ ╰──── system identifier ────╯
+ * ╰──┴── name is "html".
+ *
+ * @see https://html.spec.whatwg.org/#tokenization
+ *
+ * @since 6.7.0
+ *
+ * @var string|null
+ */
+ public $system_identifier = null;
+
+ /**
+ * Which document compatability mode this DOCTYPE declaration indicates.
+ *
+ * This value should be considered "read only" and not modified.
+ *
+ * When an HTML parser has not already set the document compatability mode,
+ * (e.g. "quirks" or "no-quirks" mode), it will infer if from the properties
+ * of the appropriate DOCTYPE declaration, if one exists. The DOCTYPE can
+ * indicate one of three possible document compatability modes:
+ *
+ * - "no-quirks" and "limited-quirks" modes (also called "standards" mode).
+ * - "quirks" mode (also called `CSS1Compat` mode).
+ *
+ * An appropriate DOCTYPE is one encountered in the "initial" insertion mode,
+ * before the HTML element has been opened and before finding any other
+ * DOCTYPE declaration tokens.
+ *
+ * @see https://html.spec.whatwg.org/#the-initial-insertion-mode
+ *
+ * @since 6.7.0
+ *
+ * @var string One of "no-quirks", "limited-quirks", or "quirks".
+ */
+ public $indicated_compatability_mode;
+
+ /**
+ * Constructor.
+ *
+ * This class should not be instantiated directly.
+ * Use the static {@see self::from_doctype_token} method instead.
+ *
+ * The arguments to this constructor correspond to the "DOCTYPE token"
+ * as defined in the HTML specification.
+ *
+ * > DOCTYPE tokens have a name, a public identifier, a system identifier,
+ * > and a force-quirks flag. When a DOCTYPE token is created, its name, public identifier,
+ * > and system identifier must be marked as missing (which is a distinct state from the
+ * > empty string), and the force-quirks flag must be set to off (its other state is on).
+ *
+ * @see https://html.spec.whatwg.org/multipage/parsing.html#tokenization
+ *
+ * @since 6.7.0
+ *
+ * @param string|null $name Name of the DOCTYPE.
+ * @param string|null $public_identifier Public identifier of the DOCTYPE.
+ * @param string|null $system_identifier System identifier of the DOCTYPE.
+ * @param bool $force_quirks_flag Whether the force-quirks flag is set for the token.
+ */
+ private function __construct(
+ ?string $name,
+ ?string $public_identifier,
+ ?string $system_identifier,
+ bool $force_quirks_flag
+ ) {
+ $this->name = $name;
+ $this->public_identifier = $public_identifier;
+ $this->system_identifier = $system_identifier;
+
+ /*
+ * > If the DOCTYPE token matches one of the conditions in the following list,
+ * > then set the Document to quirks mode:
+ */
+
+ /*
+ * > The force-quirks flag is set to on.
+ */
+ if ( $force_quirks_flag ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * Normative documents will contain the literal `<!DOCTYPE html>` with no
+ * public or system identifiers; short-circuit to avoid extra parsing.
+ */
+ if ( 'html' === $name && null === $public_identifier && null === $system_identifier ) {
+ $this->indicated_compatability_mode = 'no-quirks';
+ return;
+ }
+
+ /*
+ * > The name is not "html".
+ *
+ * The tokenizer must report the name in lower case even if provided in
+ * the document in upper case; thus no conversion is required here.
+ */
+ if ( 'html' !== $name ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * Set up some variables to handle the rest of the conditions.
+ *
+ * > set...the public identifier...to...the empty string if the public identifier was missing.
+ * > set...the system identifier...to...the empty string if the system identifier was missing.
+ * >
+ * > The system identifier and public identifier strings must be compared...
+ * > in an ASCII case-insensitive manner.
+ * >
+ * > A system identifier whose value is the empty string is not considered missing
+ * > for the purposes of the conditions above.
+ */
+ $system_identifier_is_missing = null === $system_identifier;
+ $public_identifier = null === $public_identifier ? '' : strtolower( $public_identifier );
+ $system_identifier = null === $system_identifier ? '' : strtolower( $system_identifier );
+
+ /*
+ * > The public identifier is set to…
+ */
+ if (
+ '-//w3o//dtd w3 html strict 3.0//en//' === $public_identifier ||
+ '-/w3c/dtd html 4.0 transitional/en' === $public_identifier ||
+ 'html' === $public_identifier
+ ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * > The system identifier is set to…
+ */
+ if ( 'http://www.ibm.com/data/dtd/v11/ibmxhtml1-transitional.dtd' === $system_identifier ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * All of the following conditions depend on matching the public identifier.
+ * If the public identifier is empty, none of the following conditions will match.
+ */
+ if ( '' === $public_identifier ) {
+ $this->indicated_compatability_mode = 'no-quirks';
+ return;
+ }
+
+ /*
+ * > The public identifier starts with…
+ *
+ * @todo Optimize this matching. It shouldn't be a large overall performance issue,
+ * however, as only a single DOCTYPE declaration token should ever be parsed,
+ * and normative documents will have exited before reaching this condition.
+ */
+ if (
+ str_starts_with( $public_identifier, '+//silmaril//dtd html pro v0r11 19970101//' ) ||
+ str_starts_with( $public_identifier, '-//as//dtd html 3.0 aswedit + extensions//' ) ||
+ str_starts_with( $public_identifier, '-//advasoft ltd//dtd html 3.0 aswedit + extensions//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0 level 1//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0 level 2//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0 strict level 1//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0 strict level 2//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0 strict//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.0//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 2.1e//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 3.0//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 3.2 final//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 3.2//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html 3//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html level 0//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html level 1//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html level 2//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html level 3//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html strict level 0//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html strict level 1//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html strict level 2//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html strict level 3//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html strict//' ) ||
+ str_starts_with( $public_identifier, '-//ietf//dtd html//' ) ||
+ str_starts_with( $public_identifier, '-//metrius//dtd metrius presentational//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 2.0 html strict//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 2.0 html//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 2.0 tables//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 3.0 html strict//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 3.0 html//' ) ||
+ str_starts_with( $public_identifier, '-//microsoft//dtd internet explorer 3.0 tables//' ) ||
+ str_starts_with( $public_identifier, '-//netscape comm. corp.//dtd html//' ) ||
+ str_starts_with( $public_identifier, '-//netscape comm. corp.//dtd strict html//' ) ||
+ str_starts_with( $public_identifier, "-//o'reilly and associates//dtd html 2.0//" ) ||
+ str_starts_with( $public_identifier, "-//o'reilly and associates//dtd html extended 1.0//" ) ||
+ str_starts_with( $public_identifier, "-//o'reilly and associates//dtd html extended relaxed 1.0//" ) ||
+ str_starts_with( $public_identifier, '-//sq//dtd html 2.0 hotmetal + extensions//' ) ||
+ str_starts_with( $public_identifier, '-//softquad software//dtd hotmetal pro 6.0::19990601::extensions to html 4.0//' ) ||
+ str_starts_with( $public_identifier, '-//softquad//dtd hotmetal pro 4.0::19971010::extensions to html 4.0//' ) ||
+ str_starts_with( $public_identifier, '-//spyglass//dtd html 2.0 extended//' ) ||
+ str_starts_with( $public_identifier, '-//sun microsystems corp.//dtd hotjava html//' ) ||
+ str_starts_with( $public_identifier, '-//sun microsystems corp.//dtd hotjava strict html//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 3 1995-03-24//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 3.2 draft//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 3.2 final//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 3.2//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 3.2s draft//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.0 frameset//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.0 transitional//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html experimental 19960712//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html experimental 970421//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd w3 html//' ) ||
+ str_starts_with( $public_identifier, '-//w3o//dtd w3 html 3.0//' ) ||
+ str_starts_with( $public_identifier, '-//webtechs//dtd mozilla html 2.0//' ) ||
+ str_starts_with( $public_identifier, '-//webtechs//dtd mozilla html//' )
+ ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * > The system identifier is missing and the public identifier starts with…
+ */
+ if (
+ $system_identifier_is_missing && (
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.01 frameset//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.01 transitional//' )
+ )
+ ) {
+ $this->indicated_compatability_mode = 'quirks';
+ return;
+ }
+
+ /*
+ * > Otherwise, if the DOCTYPE token matches one of the conditions in
+ * > the following list, then set the Document to limited-quirks mode.
+ */
+
+ /*
+ * > The public identifier starts with…
+ */
+ if (
+ str_starts_with( $public_identifier, '-//w3c//dtd xhtml 1.0 frameset//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd xhtml 1.0 transitional//' )
+ ) {
+ $this->indicated_compatability_mode = 'limited-quirks';
+ return;
+ }
+
+ /*
+ * > The system identifier is not missing and the public identifier starts with…
+ */
+ if (
+ ! $system_identifier_is_missing && (
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.01 frameset//' ) ||
+ str_starts_with( $public_identifier, '-//w3c//dtd html 4.01 transitional//' )
+ )
+ ) {
+ $this->indicated_compatability_mode = 'limited-quirks';
+ return;
+ }
+
+ $this->indicated_compatability_mode = 'no-quirks';
+ }
+
+ /**
+ * Creates a WP_HTML_Doctype_Info instance by parsing a raw DOCTYPE declaration token.
+ *
+ * Use this method to parse a DOCTYPE declaration token and get access to its properties
+ * via the returned WP_HTML_Doctype_Info class instance. The provided input must parse
+ * properly as a DOCTYPE declaration, though it must not represent a valid DOCTYPE.
+ *
+ * Example:
+ *
+ * // Normative HTML DOCTYPE declaration.
+ * $doctype = WP_HTML_Doctype_Info::from_doctype_token( '<!DOCTYPE html>' );
+ * 'no-quirks' === $doctype->indicated_compatability_mode;
+ *
+ * // A nonsensical DOCTYPE is still valid, and will indicate "quirks" mode.
+ * $doctype = WP_HTML_Doctype_Info::from_doctype_token( '<!doctypeJSON SILLY "nonsense\'>' );
+ * 'quirks' === $doctype->indicated_compatability_mode;
+ *
+ * // Textual quirks present in raw HTML are handled appropriately.
+ * $doctype = WP_HTML_Doctype_Info::from_doctype_token( "<!DOCTYPE\nhtml\n>" );
+ * 'no-quirks' === $doctype->indicated_compatability_mode;
+ *
+ * // Anything other than a proper DOCTYPE declaration token fails to parse.
+ * null === WP_HTML_Doctype_Info::from_doctype_token( ' <!DOCTYPE>' );
+ * null === WP_HTML_Doctype_Info::from_doctype_token( '<!DOCTYPE ><p>' );
+ * null === WP_HTML_Doctype_Info::from_doctype_token( '<!TYPEDOC>' );
+ * null === WP_HTML_Doctype_Info::from_doctype_token( 'html' );
+ * null === WP_HTML_Doctype_Info::from_doctype_token( '<?xml version="1.0" encoding="UTF-8" ?>' );
+ *
+ * @since 6.7.0
+ *
+ * @param string $doctype_html The complete raw DOCTYPE HTML string, e.g. `<!DOCTYPE html>`.
+ *
+ * @return WP_HTML_Doctype_Info|null A WP_HTML_Doctype_Info instance will be returned if the
+ * provided DOCTYPE HTML is a valid DOCTYPE. Otherwise, null.
+ */
+ public static function from_doctype_token( string $doctype_html ): ?self {
+ $doctype_name = null;
+ $doctype_public_id = null;
+ $doctype_system_id = null;
+
+ $end = strlen( $doctype_html ) - 1;
+
+ /*
+ * This parser combines the rules for parsing DOCTYPE tokens found in the HTML
+ * specification for the DOCTYPE related tokenizer states.
+ *
+ * @see https://html.spec.whatwg.org/#doctype-state
+ */
+
+ /*
+ * - Valid DOCTYPE HTML token must be at least `<!DOCTYPE>` assuming a complete token not
+ * ending in end-of-file.
+ * - It must start with an ASCII case-insensitive match for `<!DOCTYPE`.
+ * - The only occurrence of `>` must be the final byte in the HTML string.
+ */
+ if (
+ $end < 9 ||
+ 0 !== substr_compare( $doctype_html, '<!DOCTYPE', 0, 9, true )
+ ) {
+ return null;
+ }
+
+ $at = 9;
+ // Is there one and only one `>`?
+ if ( '>' !== $doctype_html[ $end ] || ( strcspn( $doctype_html, '>', $at ) + $at ) < $end ) {
+ return null;
+ }
+
+ /*
+ * Perform newline normalization and ensure the $end value is correct after normalization.
+ *
+ * @see https://html.spec.whatwg.org/#preprocessing-the-input-stream
+ * @see https://infra.spec.whatwg.org/#normalize-newlines
+ */
+ $doctype_html = str_replace( "\r\n", "\n", $doctype_html );
+ $doctype_html = str_replace( "\r", "\n", $doctype_html );
+ $end = strlen( $doctype_html ) - 1;
+
+ /*
+ * In this state, the doctype token has been found and its "content" optionally including the
+ * name, public identifier, and system identifier is between the current position and the end.
+ *
+ * "<!DOCTYPE...declaration...>"
+ * ╰─ $at ╰─ $end
+ *
+ * It's also possible that the declaration part is empty.
+ *
+ * ╭─ $at
+ * "<!DOCTYPE>"
+ * ╰─ $end
+ *
+ * Rules for parsing ">" which terminates the DOCTYPE do not need to be considered as they
+ * have been handled above in the condition that the provided DOCTYPE HTML must contain
+ * exactly one ">" character in the final position.
+ */
+
+ /*
+ *
+ * Parsing effectively begins in "Before DOCTYPE name state". Ignore whitespace and
+ * proceed to the next state.
+ *
+ * @see https://html.spec.whatwg.org/#before-doctype-name-state
+ */
+ $at += strspn( $doctype_html, " \t\n\f\r", $at );
+
+ if ( $at >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ $name_length = strcspn( $doctype_html, " \t\n\f\r", $at, $end - $at );
+ $doctype_name = str_replace( "\0", "\u{FFFD}", strtolower( substr( $doctype_html, $at, $name_length ) ) );
+
+ $at += $name_length;
+ $at += strspn( $doctype_html, " \t\n\f\r", $at, $end - $at );
+ if ( $at >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, false );
+ }
+
+ /*
+ * "After DOCTYPE name state"
+ *
+ * Find a case-insensitive match for "PUBLIC" or "SYSTEM" at this point.
+ * Otherwise, set force-quirks and enter bogus DOCTYPE state (skip the rest of the doctype).
+ *
+ * @see https://html.spec.whatwg.org/#after-doctype-name-state
+ */
+ if ( $at + 6 >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ /*
+ * > If the six characters starting from the current input character are an ASCII
+ * > case-insensitive match for the word "PUBLIC", then consume those characters
+ * > and switch to the after DOCTYPE public keyword state.
+ */
+ if ( 0 === substr_compare( $doctype_html, 'PUBLIC', $at, 6, true ) ) {
+ $at += 6;
+ $at += strspn( $doctype_html, " \t\n\f\r", $at, $end - $at );
+ if ( $at >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+ goto parse_doctype_public_identifier;
+ }
+
+ /*
+ * > Otherwise, if the six characters starting from the current input character are an ASCII
+ * > case-insensitive match for the word "SYSTEM", then consume those characters and switch
+ * > to the after DOCTYPE system keyword state.
+ */
+ if ( 0 === substr_compare( $doctype_html, 'SYSTEM', $at, 6, true ) ) {
+ $at += 6;
+ $at += strspn( $doctype_html, " \t\n\f\r", $at, $end - $at );
+ if ( $at >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+ goto parse_doctype_system_identifier;
+ }
+
+ /*
+ * > Otherwise, this is an invalid-character-sequence-after-doctype-name parse error.
+ * > Set the current DOCTYPE token's force-quirks flag to on. Reconsume in the bogus
+ * > DOCTYPE state.
+ */
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+
+ parse_doctype_public_identifier:
+ /*
+ * The parser should enter "DOCTYPE public identifier (double-quoted) state" or
+ * "DOCTYPE public identifier (single-quoted) state" by finding one of the valid quotes.
+ * Anything else forces quirks mode and ignores the rest of the contents.
+ *
+ * @see https://html.spec.whatwg.org/#doctype-public-identifier-(double-quoted)-state
+ * @see https://html.spec.whatwg.org/#doctype-public-identifier-(single-quoted)-state
+ */
+ $closer_quote = $doctype_html[ $at ];
+
+ /*
+ * > This is a missing-quote-before-doctype-public-identifier parse error. Set the
+ * > current DOCTYPE token's force-quirks flag to on. Reconsume in the bogus DOCTYPE state.
+ */
+ if ( '"' !== $closer_quote && "'" !== $closer_quote ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ ++$at;
+
+ $identifier_length = strcspn( $doctype_html, $closer_quote, $at, $end - $at );
+ $doctype_public_id = str_replace( "\0", "\u{FFFD}", substr( $doctype_html, $at, $identifier_length ) );
+
+ $at += $identifier_length;
+ if ( $at >= $end || $closer_quote !== $doctype_html[ $at ] ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ ++$at;
+
+ /*
+ * "Between DOCTYPE public and system identifiers state"
+ *
+ * Advance through whitespace between public and system identifiers.
+ *
+ * @see https://html.spec.whatwg.org/#between-doctype-public-and-system-identifiers-state
+ */
+ $at += strspn( $doctype_html, " \t\n\f\r", $at, $end - $at );
+ if ( $at >= $end ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, false );
+ }
+
+ parse_doctype_system_identifier:
+ /*
+ * The parser should enter "DOCTYPE system identifier (double-quoted) state" or
+ * "DOCTYPE system identifier (single-quoted) state" by finding one of the valid quotes.
+ * Anything else forces quirks mode and ignores the rest of the contents.
+ *
+ * @see https://html.spec.whatwg.org/#doctype-system-identifier-(double-quoted)-state
+ * @see https://html.spec.whatwg.org/#doctype-system-identifier-(single-quoted)-state
+ */
+ $closer_quote = $doctype_html[ $at ];
+
+ /*
+ * > This is a missing-quote-before-doctype-system-identifier parse error. Set the
+ * > current DOCTYPE token's force-quirks flag to on. Reconsume in the bogus DOCTYPE state.
+ */
+ if ( '"' !== $closer_quote && "'" !== $closer_quote ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ ++$at;
+
+ $identifier_length = strcspn( $doctype_html, $closer_quote, $at, $end - $at );
+ $doctype_system_id = str_replace( "\0", "\u{FFFD}", substr( $doctype_html, $at, $identifier_length ) );
+
+ $at += $identifier_length;
+ if ( $at >= $end || $closer_quote !== $doctype_html[ $at ] ) {
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, true );
+ }
+
+ return new self( $doctype_name, $doctype_public_id, $doctype_system_id, false );
+ }
+}