$replacement ) {
			return null;
		}

		$after_name = $name_at + $name_length;

		/**
		 * For historical reasons, a matched named character reference is left as literal
		 * text (its decoded replacement is not used) when all of the following hold:
		 *
		 * 1. It was matched in attribute context.
		 * 2. The match does not end in U+003B SEMICOLON (;) — i.e. it is one of the
		 *    legacy forms recognized without a trailing semicolon.
		 * 3. The next input character is U+003D EQUALS SIGN (=) or an ASCII alphanumeric.
		 *
		 * Some illustrative examples follow. Note that both `not` and `not;` appear in the
		 * named character references list. References start with `&` and typically end with
		 * `;`, but the legacy forms are recognized without one.
		 *
		 * - In _data context_, "&notme" is decoded to "¬me": condition 1 fails (not an
		 *   attribute), so the reference is decoded.
		 * - In _attribute context_, "¬me" is decoded to "¬me": the longest match is
		 *   "not;", which ends in a semicolon, so condition 2 fails.
		 * - In _attribute context_, "&not己" is decoded to "¬己": the following character
		 *   "己" is a letter but not an ASCII alphanumeric (nor "="), so condition 3 fails.
		 * - In _attribute context_, "&not" is decoded to "¬": there is no next input
		 *   character, so condition 3 fails.
		 * - In _attribute context_, "&not=me" is left as the literal text "&not=me": all
		 *   three conditions hold.
		 * - In _attribute context_, "&notme" is left as the literal text "&notme": all
		 *   three conditions hold.
		 *
		 * Without these special rules, ordinary URL query strings could have surprising
		 * replacements applied. Consider:
		 *
		 *     <a href="/?random&degree&gt=0&lt=360&not=90">
		 *
		 * The literal attribute value `/?random&degree&gt=0&lt=360&not=90` is preserved
		 * by the special handling. Otherwise, the value would decode to
		 * `/?random°ree>=0<=360¬=90`, which is unlikely to be the author's intent.
		 *
		 * (Authors should not rely on this. Escaping the example as
		 * `/?random&amp;degree&amp;gt=0&amp;lt=360&amp;not=90` produces the intended
		 * value regardless of the following character.)
		 *
		 * @see https://html.spec.whatwg.org/multipage/parsing.html#named-character-reference-state
		 * @see https://html.spec.whatwg.org/multipage/named-characters.html#named-character-references
		 */
		if ( 'attribute' !== $context || ';' === $text[ $after_name - 1 ] || $after_name >= $length ) {
			$match_byte_length = $after_name - $at;
			return $replacement;
		}

		$follower_byte = ord( $text[ $after_name ] );
		if (
			0x3D === $follower_byte || //                              EQUALS SIGN
			( $follower_byte >= 0x30 && $follower_byte <= 0x39 ) || // ASCII digits 0-9
			( $follower_byte >= 0x41 && $follower_byte <= 0x5A ) || // ASCII upper alpha A-Z
			( $follower_byte >= 0x61 && $follower_byte <= 0x7A )    // ASCII lower alpha a-z
		) {
			return null;
		}

		$match_byte_length = $after_name - $at;
		return $replacement;
	}

	/**
	 * Encode a code point number into the UTF-8 encoding.
	 *
	 * This encoder implements the UTF-8 encoding algorithm for converting
	 * a code point into a byte sequence. If it receives an invalid code
	 * point it will return the Unicode Replacement Character U+FFFD `�`.
	 *
	 * Example:
	 *
	 *     '🅰' === WP_HTML_Decoder::code_point_to_utf8_bytes( 0x1f170 );
	 *
	 *     // Half of a surrogate pair is an invalid code point.
	 *     '�' === WP_HTML_Decoder::code_point_to_utf8_bytes( 0xd83c );
	 *
	 * @since 6.6.0
	 *
	 * @see https://www.rfc-editor.org/rfc/rfc3629 For the UTF-8 standard.
	 *
	 * @param int $code_point Which code point to convert.
	 * @return string Converted code point, or `�` if invalid.
	 */
	public static function code_point_to_utf8_bytes( $code_point ): string {
		$string = mb_chr( $code_point, 'UTF-8' );

		return false !== $string ? $string : '�';
	}
}