WP_HTML_Tag_Processor::parse_next_tag() │ private │ WP 6.2.0
Parses the next tag.
This will find and start parsing the next tag, including the opening <, the potential closer /, and the tag name. It does not parse the attributes or scan to the closing >; these are left for other methods.
Method of the class: WP_HTML_Tag_Processor{}
No Hooks.
Return
true|false. Whether a tag was found before the end of the document.
Usage
// private - for code of main (parent) class only $result = $this->parse_next_tag();
Changelog
| Since 6.2.0 | Introduced. |
| Since 6.2.1 | Support abruptly-closed comments, invalid-tag-closer-comments, and empty elements. |
WP_HTML_Tag_Processor::parse_next_tag() WP HTML Tag Processor::parse next tag code WP 6.6.2
private function parse_next_tag() {
$this->after_tag();
$html = $this->html;
$doc_length = strlen( $html );
$was_at = $this->bytes_already_parsed;
$at = $was_at;
while ( false !== $at && $at < $doc_length ) {
$at = strpos( $html, '<', $at );
/*
* This does not imply an incomplete parse; it indicates that there
* can be nothing left in the document other than a #text node.
*/
if ( false === $at ) {
$this->parser_state = self::STATE_TEXT_NODE;
$this->token_starts_at = $was_at;
$this->token_length = strlen( $html ) - $was_at;
$this->text_starts_at = $was_at;
$this->text_length = $this->token_length;
$this->bytes_already_parsed = strlen( $html );
return true;
}
if ( $at > $was_at ) {
/*
* A "<" normally starts a new HTML tag or syntax token, but in cases where the
* following character can't produce a valid token, the "<" is instead treated
* as plaintext and the parser should skip over it. This avoids a problem when
* following earlier practices of typing emoji with text, e.g. "<3". This
* should be a heart, not a tag. It's supposed to be rendered, not hidden.
*
* At this point the parser checks if this is one of those cases and if it is
* will continue searching for the next "<" in search of a token boundary.
*
* @see https://html.spec.whatwg.org/#tag-open-state
*/
if ( strlen( $html ) > $at + 1 ) {
$next_character = $html[ $at + 1 ];
$at_another_node = (
'!' === $next_character ||
'/' === $next_character ||
'?' === $next_character ||
( 'A' <= $next_character && $next_character <= 'Z' ) ||
( 'a' <= $next_character && $next_character <= 'z' )
);
if ( ! $at_another_node ) {
++$at;
continue;
}
}
$this->parser_state = self::STATE_TEXT_NODE;
$this->token_starts_at = $was_at;
$this->token_length = $at - $was_at;
$this->text_starts_at = $was_at;
$this->text_length = $this->token_length;
$this->bytes_already_parsed = $at;
return true;
}
$this->token_starts_at = $at;
if ( $at + 1 < $doc_length && '/' === $this->html[ $at + 1 ] ) {
$this->is_closing_tag = true;
++$at;
} else {
$this->is_closing_tag = false;
}
/*
* HTML tag names must start with [a-zA-Z] otherwise they are not tags.
* For example, "<3" is rendered as text, not a tag opener. If at least
* one letter follows the "<" then _it is_ a tag, but if the following
* character is anything else it _is not a tag_.
*
* It's not uncommon to find non-tags starting with `<` in an HTML
* document, so it's good for performance to make this pre-check before
* continuing to attempt to parse a tag name.
*
* Reference:
* * https://html.spec.whatwg.org/multipage/parsing.html#data-state
* * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
*/
$tag_name_prefix_length = strspn( $html, 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', $at + 1 );
if ( $tag_name_prefix_length > 0 ) {
++$at;
$this->parser_state = self::STATE_MATCHED_TAG;
$this->tag_name_starts_at = $at;
$this->tag_name_length = $tag_name_prefix_length + strcspn( $html, " \t\f\r\n/>", $at + $tag_name_prefix_length );
$this->bytes_already_parsed = $at + $this->tag_name_length;
return true;
}
/*
* Abort if no tag is found before the end of
* the document. There is nothing left to parse.
*/
if ( $at + 1 >= $doc_length ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
/*
* `<!` transitions to markup declaration open state
* https://html.spec.whatwg.org/multipage/parsing.html#markup-declaration-open-state
*/
if ( ! $this->is_closing_tag && '!' === $html[ $at + 1 ] ) {
/*
* `<!--` transitions to a comment state – apply further comment rules.
* https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
*/
if (
$doc_length > $at + 3 &&
'-' === $html[ $at + 2 ] &&
'-' === $html[ $at + 3 ]
) {
$closer_at = $at + 4;
// If it's not possible to close the comment then there is nothing more to scan.
if ( $doc_length <= $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
// Abruptly-closed empty comments are a sequence of dashes followed by `>`.
$span_of_dashes = strspn( $html, '-', $closer_at );
if ( '>' === $html[ $closer_at + $span_of_dashes ] ) {
/*
* @todo When implementing `set_modifiable_text()` ensure that updates to this token
* don't break the syntax for short comments, e.g. `<!--->`. Unlike other comment
* and bogus comment syntax, these leave no clear insertion point for text and
* they need to be modified specially in order to contain text. E.g. to store
* `?` as the modifiable text, the `<!--->` needs to become `<!--?-->`, which
* involves inserting an additional `-` into the token after the modifiable text.
*/
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_ABRUPTLY_CLOSED_COMMENT;
$this->token_length = $closer_at + $span_of_dashes + 1 - $this->token_starts_at;
// Only provide modifiable text if the token is long enough to contain it.
if ( $span_of_dashes >= 2 ) {
$this->comment_type = self::COMMENT_AS_HTML_COMMENT;
$this->text_starts_at = $this->token_starts_at + 4;
$this->text_length = $span_of_dashes - 2;
}
$this->bytes_already_parsed = $closer_at + $span_of_dashes + 1;
return true;
}
/*
* Comments may be closed by either a --> or an invalid --!>.
* The first occurrence closes the comment.
*
* See https://html.spec.whatwg.org/#parse-error-incorrectly-closed-comment
*/
--$closer_at; // Pre-increment inside condition below reduces risk of accidental infinite looping.
while ( ++$closer_at < $doc_length ) {
$closer_at = strpos( $html, '--', $closer_at );
if ( false === $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
if ( $closer_at + 2 < $doc_length && '>' === $html[ $closer_at + 2 ] ) {
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_HTML_COMMENT;
$this->token_length = $closer_at + 3 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 4;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 3;
return true;
}
if (
$closer_at + 3 < $doc_length &&
'!' === $html[ $closer_at + 2 ] &&
'>' === $html[ $closer_at + 3 ]
) {
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_HTML_COMMENT;
$this->token_length = $closer_at + 4 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 4;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 4;
return true;
}
}
}
/*
* `<!DOCTYPE` transitions to DOCTYPE state – skip to the nearest >
* These are ASCII-case-insensitive.
* https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
*/
if (
$doc_length > $at + 8 &&
( 'D' === $html[ $at + 2 ] || 'd' === $html[ $at + 2 ] ) &&
( 'O' === $html[ $at + 3 ] || 'o' === $html[ $at + 3 ] ) &&
( 'C' === $html[ $at + 4 ] || 'c' === $html[ $at + 4 ] ) &&
( 'T' === $html[ $at + 5 ] || 't' === $html[ $at + 5 ] ) &&
( 'Y' === $html[ $at + 6 ] || 'y' === $html[ $at + 6 ] ) &&
( 'P' === $html[ $at + 7 ] || 'p' === $html[ $at + 7 ] ) &&
( 'E' === $html[ $at + 8 ] || 'e' === $html[ $at + 8 ] )
) {
$closer_at = strpos( $html, '>', $at + 9 );
if ( false === $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
$this->parser_state = self::STATE_DOCTYPE;
$this->token_length = $closer_at + 1 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 9;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 1;
return true;
}
/*
* Anything else here is an incorrectly-opened comment and transitions
* to the bogus comment state - skip to the nearest >. If no closer is
* found then the HTML was truncated inside the markup declaration.
*/
$closer_at = strpos( $html, '>', $at + 1 );
if ( false === $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_INVALID_HTML;
$this->token_length = $closer_at + 1 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 2;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 1;
/*
* Identify nodes that would be CDATA if HTML had CDATA sections.
*
* This section must occur after identifying the bogus comment end
* because in an HTML parser it will span to the nearest `>`, even
* if there's no `]]>` as would be required in an XML document. It
* is therefore not possible to parse a CDATA section containing
* a `>` in the HTML syntax.
*
* Inside foreign elements there is a discrepancy between browsers
* and the specification on this.
*
* @todo Track whether the Tag Processor is inside a foreign element
* and require the proper closing `]]>` in those cases.
*/
if (
$this->token_length >= 10 &&
'[' === $html[ $this->token_starts_at + 2 ] &&
'C' === $html[ $this->token_starts_at + 3 ] &&
'D' === $html[ $this->token_starts_at + 4 ] &&
'A' === $html[ $this->token_starts_at + 5 ] &&
'T' === $html[ $this->token_starts_at + 6 ] &&
'A' === $html[ $this->token_starts_at + 7 ] &&
'[' === $html[ $this->token_starts_at + 8 ] &&
']' === $html[ $closer_at - 1 ] &&
']' === $html[ $closer_at - 2 ]
) {
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_CDATA_LOOKALIKE;
$this->text_starts_at += 7;
$this->text_length -= 9;
}
return true;
}
/*
* </> is a missing end tag name, which is ignored.
*
* This was also known as the "presumptuous empty tag"
* in early discussions as it was proposed to close
* the nearest previous opening tag.
*
* See https://html.spec.whatwg.org/#parse-error-missing-end-tag-name
*/
if ( '>' === $html[ $at + 1 ] ) {
// `<>` is interpreted as plaintext.
if ( ! $this->is_closing_tag ) {
++$at;
continue;
}
$this->parser_state = self::STATE_PRESUMPTUOUS_TAG;
$this->token_length = $at + 2 - $this->token_starts_at;
$this->bytes_already_parsed = $at + 2;
return true;
}
/*
* `<?` transitions to a bogus comment state – skip to the nearest >
* See https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
*/
if ( ! $this->is_closing_tag && '?' === $html[ $at + 1 ] ) {
$closer_at = strpos( $html, '>', $at + 2 );
if ( false === $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
$this->parser_state = self::STATE_COMMENT;
$this->comment_type = self::COMMENT_AS_INVALID_HTML;
$this->token_length = $closer_at + 1 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 2;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 1;
/*
* Identify a Processing Instruction node were HTML to have them.
*
* This section must occur after identifying the bogus comment end
* because in an HTML parser it will span to the nearest `>`, even
* if there's no `?>` as would be required in an XML document. It
* is therefore not possible to parse a Processing Instruction node
* containing a `>` in the HTML syntax.
*
* XML allows for more target names, but this code only identifies
* those with ASCII-representable target names. This means that it
* may identify some Processing Instruction nodes as bogus comments,
* but it will not misinterpret the HTML structure. By limiting the
* identification to these target names the Tag Processor can avoid
* the need to start parsing UTF-8 sequences.
*
* > NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] |
* [#x370-#x37D] | [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] |
* [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] |
* [#x10000-#xEFFFF]
* > NameChar ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
*
* @see https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-PITarget
*/
if ( $this->token_length >= 5 && '?' === $html[ $closer_at - 1 ] ) {
$comment_text = substr( $html, $this->token_starts_at + 2, $this->token_length - 4 );
$pi_target_length = strspn( $comment_text, 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ:_' );
if ( 0 < $pi_target_length ) {
$pi_target_length += strspn( $comment_text, 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789:_-.', $pi_target_length );
$this->comment_type = self::COMMENT_AS_PI_NODE_LOOKALIKE;
$this->tag_name_starts_at = $this->token_starts_at + 2;
$this->tag_name_length = $pi_target_length;
$this->text_starts_at += $pi_target_length;
$this->text_length -= $pi_target_length + 1;
}
}
return true;
}
/*
* If a non-alpha starts the tag name in a tag closer it's a comment.
* Find the first `>`, which closes the comment.
*
* This parser classifies these particular comments as special "funky comments"
* which are made available for further processing.
*
* See https://html.spec.whatwg.org/#parse-error-invalid-first-character-of-tag-name
*/
if ( $this->is_closing_tag ) {
// No chance of finding a closer.
if ( $at + 3 > $doc_length ) {
return false;
}
$closer_at = strpos( $html, '>', $at + 2 );
if ( false === $closer_at ) {
$this->parser_state = self::STATE_INCOMPLETE_INPUT;
return false;
}
$this->parser_state = self::STATE_FUNKY_COMMENT;
$this->token_length = $closer_at + 1 - $this->token_starts_at;
$this->text_starts_at = $this->token_starts_at + 2;
$this->text_length = $closer_at - $this->text_starts_at;
$this->bytes_already_parsed = $closer_at + 1;
return true;
}
++$at;
}
return false;
}