/**

 * Returns whether PCRE/u (PCRE_UTF8 modifier) is available for use.

 *

 * @ignore

 * @since 4.2.2

 * @access private

 *

 * @param bool $set - Used for testing only

 *             null   : default - get PCRE/u capability

 *             false  : Used for testing - return false for future calls to this function

 *             'reset': Used for testing - restore default behavior of this function

 */

function _wp_can_use_pcre_u( $set = null ) {

	static $utf8_pcre = 'reset';

	if ( null !== $set ) {

		$utf8_pcre = $set;

	}

	if ( 'reset' === $utf8_pcre ) {

		$utf8_pcre = @preg_match( '/^./u', 'a' );

	}

	return $utf8_pcre;

}

if ( ! function_exists( 'mb_substr' ) ) :

	function mb_substr( $str, $start, $length = null, $encoding = null ) {

		return _mb_substr( $str, $start, $length, $encoding );

/*

 * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.

 * For $encoding === UTF-8, the $str input is expected to be a valid UTF-8 byte sequence.

 * The behavior of this function for invalid inputs is undefined.

 */

function _mb_substr( $str, $start, $length = null, $encoding = null ) {

	if ( null === $encoding ) {

		$encoding = get_option( 'blog_charset' );

	}

	// The solution below works only for UTF-8,

	// so in case of a different charset just use built-in substr()

	if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) ) ) {

		return is_null( $length ) ? substr( $str, $start ) : substr( $str, $start, $length );

	}

	if ( _wp_can_use_pcre_u() ) {

		// Use the regex unicode support to separate the UTF-8 characters into an array

		preg_match_all( '/./us', $str, $match );

		$chars = is_null( $length ) ? array_slice( $match[0], $start ) : array_slice( $match[0], $start, $length );

		return implode( '', $chars );

	$regex = '/(

		  [\x00-\x7F]                  # single-byte sequences   0xxxxxxx

		| [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx

		| \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2

		| [\xE1-\xEC][\x80-\xBF]{2}

		| \xED[\x80-\x9F][\x80-\xBF]

		| [\xEE-\xEF][\x80-\xBF]{2}

		| \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3

		| [\xF1-\xF3][\x80-\xBF]{3}

		| \xF4[\x80-\x8F][\x80-\xBF]{2}

	)/x';

	$chars = array( '' ); // Start with 1 element instead of 0 since the first thing we do is pop

	do {

		// We had some string left over from the last round, but we counted it in that last round.

		array_pop( $chars );

		// Split by UTF-8 character, limit to 1000 characters (last array element will contain the rest of the string)

		$pieces = preg_split( $regex, $str, 1000, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );

		$chars = array_merge( $chars, $pieces );

	} while ( count( $pieces ) > 1 && $str = array_pop( $pieces ) ); // If there's anything left over, repeat the loop.

	return join( '', array_slice( $chars, $start, $length ) );

}

if ( ! function_exists( 'mb_strlen' ) ) :

	function mb_strlen( $str, $encoding = null ) {

		return _mb_strlen( $str, $encoding );

	}

endif;

/*

 * Only understands UTF-8 and 8bit.  All other character sets will be treated as 8bit.

 * For $encoding === UTF-8, the $str input is expected to be a valid UTF-8 byte sequence.

 * The behavior of this function for invalid inputs is undefined.

 */

function _mb_strlen( $str, $encoding = null ) {

	if ( null === $encoding ) {

		$encoding = get_option( 'blog_charset' );

	}

	// The solution below works only for UTF-8,

	// so in case of a different charset just use built-in strlen()

	if ( ! in_array( $encoding, array( 'utf8', 'utf-8', 'UTF8', 'UTF-8' ) ) ) {

		return strlen( $str );

	}

	if ( _wp_can_use_pcre_u() ) {

		// Use the regex unicode support to separate the UTF-8 characters into an array

		preg_match_all( '/./us', $str, $match );

		return count( $match[0] );

	}

	$regex = '/(?:

		  [\x00-\x7F]                  # single-byte sequences   0xxxxxxx

		| [\xC2-\xDF][\x80-\xBF]       # double-byte sequences   110xxxxx 10xxxxxx

		| \xE0[\xA0-\xBF][\x80-\xBF]   # triple-byte sequences   1110xxxx 10xxxxxx * 2

		| [\xE1-\xEC][\x80-\xBF]{2}

		| \xED[\x80-\x9F][\x80-\xBF]

		| [\xEE-\xEF][\x80-\xBF]{2}

		| \xF0[\x90-\xBF][\x80-\xBF]{2} # four-byte sequences   11110xxx 10xxxxxx * 3

		| [\xF1-\xF3][\x80-\xBF]{3}

		| \xF4[\x80-\x8F][\x80-\xBF]{2}

	)/x';

	$count = 1; // Start at 1 instead of 0 since the first thing we do is decrement

	do {

		// We had some string left over from the last round, but we counted it in that last round.

		$count--;

		// Split by UTF-8 character, limit to 1000 characters (last array element will contain the rest of the string)

		$pieces = preg_split( $regex, $str, 1000 );

		// Increment

		$count += count( $pieces );

	} while ( $str = array_pop( $pieces ) ); // If there's anything left over, repeat the loop.

	// Fencepost: preg_split() always returns one extra item in the array

	return --$count;

		if ( ! ( $wp_json instanceof Services_JSON ) ) {

		if ( ! ($wp_json instanceof Services_JSON ) ) {

if ( ! function_exists( 'hash_equals' ) ) :

/**

 * Compare two strings in constant time.

 *

 * This function was added in PHP 5.6.

 * It can leak the length of a string.

 *

 * @since 3.9.2

 *

 * @param string $a Expected string.

 * @param string $b Actual string.

 * @return bool Whether strings are equal.

 */

function hash_equals( $a, $b ) {

	$a_length = strlen( $a );

	if ( $a_length !== strlen( $b ) ) {

		return false;

	}

	$result = 0;

	// Do not attempt to "optimize" this.

	for ( $i = 0; $i < $a_length; $i++ ) {

		$result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );

	}

	return $result === 0;

}

endif;

// JSON_PRETTY_PRINT was introduced in PHP 5.4

// Defined here to prevent a notice when using it with wp_json_encode()

if ( ! defined( 'JSON_PRETTY_PRINT' ) ) {

	define( 'JSON_PRETTY_PRINT', 128 );

}