Commit 686c269b authored by alexpott's avatar alexpott

Issue #1938670 by ParisLiakos, Xano, RobLoach, pp, alexpott: Convert...

Issue #1938670 by ParisLiakos, Xano, RobLoach, pp, alexpott: Convert unicode.inc to \Drupal\Component\Utility\Unicode.
parent 608fa1d5
......@@ -5,6 +5,7 @@
use Drupal\Component\Utility\Settings;
use Drupal\Component\Utility\String;
use Drupal\Component\Utility\Timer;
use Drupal\Component\Utility\Unicode;
use Drupal\Core\DrupalKernel;
use Drupal\Core\Database\Database;
use Drupal\Core\DependencyInjection\ContainerBuilder;
......@@ -270,22 +271,6 @@
*/
const LANGUAGE_RTL = 1;
/**
* Indicates an error during check for PHP unicode support.
*/
const UNICODE_ERROR = -1;
/**
* Indicates that standard PHP (emulated) unicode support is being used.
*/
const UNICODE_SINGLEBYTE = 0;
/**
* Indicates that full unicode support with the PHP mbstring extension is being
* used.
*/
const UNICODE_MULTIBYTE = 1;
/**
* Time of the current request in seconds elapsed since the Unix Epoch.
*
......@@ -667,9 +652,6 @@ function drupal_environment_initialize() {
// Set sane locale settings, to ensure consistent string, dates, times and
// numbers handling.
setlocale(LC_ALL, 'C');
// Detect string handling method.
unicode_check();
}
/**
......@@ -682,51 +664,6 @@ function drupal_valid_http_host($host) {
return preg_match('/^\[?(?:[a-zA-Z0-9-:\]_]+\.?)+$/', $host);
}
/**
* Checks for Unicode support in PHP and sets the proper settings if possible.
*
* Because Drupal needs to be able to handle text in various encodings, we do
* not support mbstring function overloading. HTTP input/output conversion must
* be disabled for similar reasons.
*
* @return string
* A string identifier of a failed multibyte extension check, if any.
* Otherwise, an empty string.
*/
function unicode_check() {
global $multibyte;
// Check for mbstring extension.
if (!function_exists('mb_strlen')) {
$multibyte = UNICODE_SINGLEBYTE;
return 'mb_strlen';
}
// Check mbstring configuration.
if (ini_get('mbstring.func_overload') != 0) {
$multibyte = UNICODE_ERROR;
return 'mbstring.func_overload';
}
if (ini_get('mbstring.encoding_translation') != 0) {
$multibyte = UNICODE_ERROR;
return 'mbstring.encoding_translation';
}
if (ini_get('mbstring.http_input') != 'pass') {
$multibyte = UNICODE_ERROR;
return 'mbstring.http_input';
}
if (ini_get('mbstring.http_output') != 'pass') {
$multibyte = UNICODE_ERROR;
return 'mbstring.http_output';
}
// Set appropriate configuration.
mb_internal_encoding('utf-8');
mb_language('uni');
$multibyte = UNICODE_MULTIBYTE;
return '';
}
/**
* Sets the base URL, cookie domain, and session name from configuration.
*/
......@@ -2165,6 +2102,9 @@ function _drupal_bootstrap_configuration() {
// Start a page timer:
Timer::start('page');
// Detect string handling method.
Unicode::check();
// Load the procedural configuration system helper functions.
require_once DRUPAL_ROOT . '/core/includes/config.inc';
......
......@@ -5,6 +5,8 @@
* Theming for maintenance pages.
*/
use Drupal\Component\Utility\Unicode;
/**
* Sets up the theming system for maintenance page.
*
......@@ -28,7 +30,7 @@ function _drupal_maintenance_theme() {
require_once DRUPAL_ROOT . '/core/includes/unicode.inc';
require_once DRUPAL_ROOT . '/core/includes/file.inc';
require_once DRUPAL_ROOT . '/core/includes/module.inc';
unicode_check();
Unicode::check();
// Install and update pages are treated differently to prevent theming overrides.
if (defined('MAINTENANCE_MODE') && (MAINTENANCE_MODE == 'install' || MAINTENANCE_MODE == 'update')) {
......
......@@ -5,66 +5,8 @@
* Provides Unicode-related conversions and operations.
*/
/**
* Matches Unicode characters that are word boundaries.
*
* Characters with the following General_category (gc) property values are used
* as word boundaries. While this does not fully conform to the Word Boundaries
* algorithm described in http://unicode.org/reports/tr29, as PCRE does not
* contain the Word_Break property table, this simpler algorithm has to do.
* - Cc, Cf, Cn, Co, Cs: Other.
* - Pc, Pd, Pe, Pf, Pi, Po, Ps: Punctuation.
* - Sc, Sk, Sm, So: Symbols.
* - Zl, Zp, Zs: Separators.
*
* Non-boundary characters include the following General_category (gc) property
* values:
* - Ll, Lm, Lo, Lt, Lu: Letters.
* - Mc, Me, Mn: Combining Marks.
* - Nd, Nl, No: Numbers.
*
* Note that the PCRE property matcher is not used because we wanted to be
* compatible with Unicode 5.2.0 regardless of the PCRE version used (and any
* bugs in PCRE property tables).
*
* @see http://unicode.org/glossary
*/
define('PREG_CLASS_UNICODE_WORD_BOUNDARY',
'\x{0}-\x{2F}\x{3A}-\x{40}\x{5B}-\x{60}\x{7B}-\x{A9}\x{AB}-\x{B1}\x{B4}' .
'\x{B6}-\x{B8}\x{BB}\x{BF}\x{D7}\x{F7}\x{2C2}-\x{2C5}\x{2D2}-\x{2DF}' .
'\x{2E5}-\x{2EB}\x{2ED}\x{2EF}-\x{2FF}\x{375}\x{37E}-\x{385}\x{387}\x{3F6}' .
'\x{482}\x{55A}-\x{55F}\x{589}-\x{58A}\x{5BE}\x{5C0}\x{5C3}\x{5C6}' .
'\x{5F3}-\x{60F}\x{61B}-\x{61F}\x{66A}-\x{66D}\x{6D4}\x{6DD}\x{6E9}' .
'\x{6FD}-\x{6FE}\x{700}-\x{70F}\x{7F6}-\x{7F9}\x{830}-\x{83E}' .
'\x{964}-\x{965}\x{970}\x{9F2}-\x{9F3}\x{9FA}-\x{9FB}\x{AF1}\x{B70}' .
'\x{BF3}-\x{BFA}\x{C7F}\x{CF1}-\x{CF2}\x{D79}\x{DF4}\x{E3F}\x{E4F}' .
'\x{E5A}-\x{E5B}\x{F01}-\x{F17}\x{F1A}-\x{F1F}\x{F34}\x{F36}\x{F38}' .
'\x{F3A}-\x{F3D}\x{F85}\x{FBE}-\x{FC5}\x{FC7}-\x{FD8}\x{104A}-\x{104F}' .
'\x{109E}-\x{109F}\x{10FB}\x{1360}-\x{1368}\x{1390}-\x{1399}\x{1400}' .
'\x{166D}-\x{166E}\x{1680}\x{169B}-\x{169C}\x{16EB}-\x{16ED}' .
'\x{1735}-\x{1736}\x{17B4}-\x{17B5}\x{17D4}-\x{17D6}\x{17D8}-\x{17DB}' .
'\x{1800}-\x{180A}\x{180E}\x{1940}-\x{1945}\x{19DE}-\x{19FF}' .
'\x{1A1E}-\x{1A1F}\x{1AA0}-\x{1AA6}\x{1AA8}-\x{1AAD}\x{1B5A}-\x{1B6A}' .
'\x{1B74}-\x{1B7C}\x{1C3B}-\x{1C3F}\x{1C7E}-\x{1C7F}\x{1CD3}\x{1FBD}' .
'\x{1FBF}-\x{1FC1}\x{1FCD}-\x{1FCF}\x{1FDD}-\x{1FDF}\x{1FED}-\x{1FEF}' .
'\x{1FFD}-\x{206F}\x{207A}-\x{207E}\x{208A}-\x{208E}\x{20A0}-\x{20B8}' .
'\x{2100}-\x{2101}\x{2103}-\x{2106}\x{2108}-\x{2109}\x{2114}' .
'\x{2116}-\x{2118}\x{211E}-\x{2123}\x{2125}\x{2127}\x{2129}\x{212E}' .
'\x{213A}-\x{213B}\x{2140}-\x{2144}\x{214A}-\x{214D}\x{214F}' .
'\x{2190}-\x{244A}\x{249C}-\x{24E9}\x{2500}-\x{2775}\x{2794}-\x{2B59}' .
'\x{2CE5}-\x{2CEA}\x{2CF9}-\x{2CFC}\x{2CFE}-\x{2CFF}\x{2E00}-\x{2E2E}' .
'\x{2E30}-\x{3004}\x{3008}-\x{3020}\x{3030}\x{3036}-\x{3037}' .
'\x{303D}-\x{303F}\x{309B}-\x{309C}\x{30A0}\x{30FB}\x{3190}-\x{3191}' .
'\x{3196}-\x{319F}\x{31C0}-\x{31E3}\x{3200}-\x{321E}\x{322A}-\x{3250}' .
'\x{3260}-\x{327F}\x{328A}-\x{32B0}\x{32C0}-\x{33FF}\x{4DC0}-\x{4DFF}' .
'\x{A490}-\x{A4C6}\x{A4FE}-\x{A4FF}\x{A60D}-\x{A60F}\x{A673}\x{A67E}' .
'\x{A6F2}-\x{A716}\x{A720}-\x{A721}\x{A789}-\x{A78A}\x{A828}-\x{A82B}' .
'\x{A836}-\x{A839}\x{A874}-\x{A877}\x{A8CE}-\x{A8CF}\x{A8F8}-\x{A8FA}' .
'\x{A92E}-\x{A92F}\x{A95F}\x{A9C1}-\x{A9CD}\x{A9DE}-\x{A9DF}' .
'\x{AA5C}-\x{AA5F}\x{AA77}-\x{AA79}\x{AADE}-\x{AADF}\x{ABEB}' .
'\x{E000}-\x{F8FF}\x{FB29}\x{FD3E}-\x{FD3F}\x{FDFC}-\x{FDFD}' .
'\x{FE10}-\x{FE19}\x{FE30}-\x{FE6B}\x{FEFF}-\x{FF0F}\x{FF1A}-\x{FF20}' .
'\x{FF3B}-\x{FF40}\x{FF5B}-\x{FF65}\x{FFE0}-\x{FFFD}');
use Drupal\Component\Utility\Unicode;
use Drupal\Component\Utility\String;
/**
* Returns Unicode library status and errors.
......@@ -74,17 +16,17 @@ function unicode_requirements() {
$t = get_t();
$libraries = array(
UNICODE_SINGLEBYTE => $t('Standard PHP'),
UNICODE_MULTIBYTE => $t('PHP Mbstring Extension'),
UNICODE_ERROR => $t('Error'),
Unicode::STATUS_SINGLEBYTE => $t('Standard PHP'),
Unicode::STATUS_MULTIBYTE => $t('PHP Mbstring Extension'),
Unicode::STATUS_ERROR => $t('Error'),
);
$severities = array(
UNICODE_SINGLEBYTE => REQUIREMENT_WARNING,
UNICODE_MULTIBYTE => NULL,
UNICODE_ERROR => REQUIREMENT_ERROR,
Unicode::STATUS_SINGLEBYTE => REQUIREMENT_WARNING,
Unicode::STATUS_MULTIBYTE => NULL,
Unicode::STATUS_ERROR => REQUIREMENT_ERROR,
);
$failed_check = unicode_check();
$library = $GLOBALS['multibyte'];
$failed_check = Unicode::check();
$library = Unicode::getStatus();
$requirements['unicode'] = array(
'title' => $t('Unicode library'),
......@@ -176,29 +118,20 @@ function drupal_xml_parser_create(&$data) {
/**
* Converts data to UTF-8.
*
* Requires the iconv, GNU recode or mbstring PHP extension.
*
* @param $data
* @param string $data
* The data to be converted.
* @param $encoding
* @param string $encoding
* The encoding that the data is in.
*
* @return
* @return string|bool
* Converted data or FALSE.
*
* @see \Drupal\Component\Utility\Unicode::convertToUtf8().
*/
function drupal_convert_to_utf8($data, $encoding) {
if (function_exists('iconv')) {
$out = @iconv($encoding, 'utf-8', $data);
}
elseif (function_exists('mb_convert_encoding')) {
$out = @mb_convert_encoding($data, 'utf-8', $encoding);
}
elseif (function_exists('recode_string')) {
$out = @recode_string($encoding . '..utf-8', $data);
}
else {
$out = Unicode::convertToUtf8($data, $encoding);
if ($out === FALSE) {
watchdog('php', 'Unsupported encoding %s. Please install iconv, GNU recode or mbstring for PHP.', array('%s' => $encoding), WATCHDOG_ERROR);
return FALSE;
}
return $out;
......@@ -207,33 +140,18 @@ function drupal_convert_to_utf8($data, $encoding) {
/**
* Truncates a UTF-8-encoded string safely to a number of bytes.
*
* If the end position is in the middle of a UTF-8 sequence, it scans backwards
* until the beginning of the byte sequence.
*
* Use this function whenever you want to chop off a string at an unsure
* location. On the other hand, if you're sure that you're splitting on a
* character boundary (e.g. after using strpos() or similar), you can safely
* use substr() instead.
*
* @param $string
* @param string $string
* The string to truncate.
* @param $len
* @param int $len
* An upper limit on the returned string length.
*
* @return
* @return string
* The truncated string.
*
* @see \Drupal\Component\Utility\Unicode::truncateBytes().
*/
function drupal_truncate_bytes($string, $len) {
if (strlen($string) <= $len) {
return $string;
}
if ((ord($string[$len]) < 0x80) || (ord($string[$len]) >= 0xC0)) {
return substr($string, 0, $len);
}
// Scan backwards to beginning of the byte sequence.
while (--$len >= 0 && ord($string[$len]) >= 0x80 && ord($string[$len]) < 0xC0);
return substr($string, 0, $len);
return Unicode::truncateBytes($string, $len);
}
/**
......@@ -247,7 +165,7 @@ function drupal_truncate_bytes($string, $len) {
* @param $wordsafe
* If TRUE, attempt to truncate on a word boundary. Word boundaries are
* spaces, punctuation, and Unicode characters used as word boundaries in
* non-Latin languages; see PREG_CLASS_UNICODE_WORD_BOUNDARY for more
* non-Latin languages; see Unicode::PREG_CLASS_WORD_BOUNDARY for more
* information. If a word boundary cannot be found that would make the length
* of the returned string fall within length guidelines (see parameters
* $max_length and $min_wordsafe_length), word boundaries are ignored.
......@@ -269,70 +187,16 @@ function drupal_truncate_bytes($string, $len) {
*
* @return string
* The truncated string.
*
* @see \Drupal\Component\Utility\Unicode::truncate().
*/
function truncate_utf8($string, $max_length, $wordsafe = FALSE, $add_ellipsis = FALSE, $min_wordsafe_length = 1) {
$ellipsis = '';
$max_length = max($max_length, 0);
$min_wordsafe_length = max($min_wordsafe_length, 0);
if (drupal_strlen($string) <= $max_length) {
// No truncation needed, so don't add ellipsis, just return.
return $string;
}
if ($add_ellipsis) {
// Truncate ellipsis in case $max_length is small.
$ellipsis = drupal_substr(t('…'), 0, $max_length);
$max_length -= drupal_strlen($ellipsis);
$max_length = max($max_length, 0);
}
if ($max_length <= $min_wordsafe_length) {
// Do not attempt word-safe if lengths are bad.
$wordsafe = FALSE;
}
if ($wordsafe) {
$matches = array();
// Find the last word boundary, if there is one within $min_wordsafe_length
// to $max_length characters. preg_match() is always greedy, so it will
// find the longest string possible.
$found = preg_match('/^(.{' . $min_wordsafe_length . ',' . $max_length . '})[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']/u', $string, $matches);
if ($found) {
$string = $matches[1];
}
else {
$string = drupal_substr($string, 0, $max_length);
}
}
else {
$string = drupal_substr($string, 0, $max_length);
}
if ($add_ellipsis) {
// If we're adding an ellipsis, remove any trailing periods.
$string = rtrim($string, '.');
$string .= $ellipsis;
}
return $string;
return Unicode::truncate($string, $max_length, $wordsafe, $add_ellipsis, $min_wordsafe_length);
}
/**
* Encodes MIME/HTTP header values that contain incorrectly encoded characters.
*
* For example, mime_header_encode('tést.txt') returns "=?UTF-8?B?dMOpc3QudHh0?=".
*
* See http://www.rfc-editor.org/rfc/rfc2047.txt for more information.
*
* Notes:
* - Only encode strings that contain non-ASCII characters.
* - We progressively cut-off a chunk with truncate_utf8(). This is to ensure
* each chunk starts and ends on a character boundary.
* - Using \n as the chunk separator may cause problems on some systems and may
* have to be changed to \r\n or \r.
*
* @param $string
* The header to encode.
*
......@@ -340,22 +204,10 @@ function truncate_utf8($string, $max_length, $wordsafe = FALSE, $add_ellipsis =
* The mime-encoded header.
*
* @see mime_header_decode()
* @see \Drupal\Component\Utility\Unicode::mimeHeaderEncode().
*/
function mime_header_encode($string) {
if (preg_match('/[^\x20-\x7E]/', $string)) {
$chunk_size = 47; // floor((75 - strlen("=?UTF-8?B??=")) * 0.75);
$len = strlen($string);
$output = '';
while ($len > 0) {
$chunk = drupal_truncate_bytes($string, $chunk_size);
$output .= ' =?UTF-8?B?' . base64_encode($chunk) . "?=\n";
$c = strlen($chunk);
$string = substr($string, $c);
$len -= $c;
}
return trim($output);
}
return $string;
return Unicode::mimeHeaderEncode($string);
}
/**
......@@ -368,78 +220,41 @@ function mime_header_encode($string) {
* The mime-decoded header.
*
* @see mime_header_encode()
* @see \Drupal\Component\Utility\Unicode::mimeHeaderDecode().
*/
function mime_header_decode($header) {
// First step: encoded chunks followed by other encoded chunks (need to collapse whitespace)
$header = preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=\s+(?==\?)/', '_mime_header_decode', $header);
// Second step: remaining chunks (do not collapse whitespace)
return preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=/', '_mime_header_decode', $header);
}
/**
* Decodes encoded header data passed from mime_header_decode().
*
* Callback for preg_replace_callback() within mime_header_decode().
*
* @param $matches
* The array of matches from preg_replace_callback().
*
* @return string
* The mime-decoded string.
*
* @see mime_header_decode()
*/
function _mime_header_decode($matches) {
// Regexp groups:
// 1: Character set name
// 2: Escaping method (Q or B)
// 3: Encoded data
$data = ($matches[2] == 'B') ? base64_decode($matches[3]) : str_replace('_', ' ', quoted_printable_decode($matches[3]));
if (strtolower($matches[1]) != 'utf-8') {
$data = drupal_convert_to_utf8($data, $matches[1]);
}
return $data;
return Unicode::mimeHeaderDecode($header);
}
/**
* Decodes all HTML entities (including numerical ones) to regular UTF-8 bytes.
*
* Double-escaped entities will only be decoded once ("&amp;lt;" becomes "&lt;"
* , not "<"). Be careful when using this function, as decode_entities can
* revert previous sanitization efforts (&lt;script&gt; will become <script>).
*
* @param $text
* The text to decode entities in.
*
* @return
* The input $text, with all HTML entities decoded once.
*
* @see \Drupal\Component\Utility\String::decodeEntities().
*/
function decode_entities($text) {
return html_entity_decode($text, ENT_QUOTES, 'UTF-8');
return String::decodeEntities($text);
}
/**
* Counts the number of characters in a UTF-8 string.
*
* This is less than or equal to the byte count.
*
* @param $text
* The string to run the operation on.
*
* @return integer
* The length of the string.
*
* @see \Drupal\Component\Utility\Unicode::strlen().
* @ingroup php_wrappers
*/
function drupal_strlen($text) {
global $multibyte;
if ($multibyte == UNICODE_MULTIBYTE) {
return mb_strlen($text);
}
else {
// Do not count UTF-8 continuation bytes.
return strlen(preg_replace("/[\x80-\xBF]/", '', $text));
}
return Unicode::strlen($text);
}
/**
......@@ -451,20 +266,11 @@ function drupal_strlen($text) {
* @return string
* The string in uppercase.
*
* @see \Drupal\Component\Utility\Unicode::strtoupper().
* @ingroup php_wrappers
*/
function drupal_strtoupper($text) {
global $multibyte;
if ($multibyte == UNICODE_MULTIBYTE) {
return mb_strtoupper($text);
}
else {
// Use C-locale for ASCII-only uppercase
$text = strtoupper($text);
// Case flip Latin-1 accented letters
$text = preg_replace_callback('/\xC3[\xA0-\xB6\xB8-\xBE]/', '_unicode_caseflip', $text);
return $text;
}
return Unicode::strtoupper($text);
}
/**
......@@ -476,35 +282,11 @@ function drupal_strtoupper($text) {
* @return string
* The string in lowercase.
*
* @see \Drupal\Component\Utility\Unicode::strtolower().
* @ingroup php_wrappers
*/
function drupal_strtolower($text) {
global $multibyte;
if ($multibyte == UNICODE_MULTIBYTE) {
return mb_strtolower($text);
}
else {
// Use C-locale for ASCII-only lowercase
$text = strtolower($text);
// Case flip Latin-1 accented letters
$text = preg_replace_callback('/\xC3[\x80-\x96\x98-\x9E]/', '_unicode_caseflip', $text);
return $text;
}
}
/**
* Flips U+C0-U+DE to U+E0-U+FD and back.
*
* @param $matches
* An array of matches.
*
* @return array
* The Latin-1 version of the array of matches.
*
* @see drupal_strtolower()
*/
function _unicode_caseflip($matches) {
return $matches[0][0] . chr(ord($matches[0][1]) ^ 32);
return Unicode::strtolower($text);
}
/**
......@@ -516,20 +298,16 @@ function _unicode_caseflip($matches) {
* @return
* The string with the first letter as uppercase.
*
* @see \Drupal\Component\Utility\Unicode::ucfirst().
* @ingroup php_wrappers
*/
function drupal_ucfirst($text) {
// Note: no mbstring equivalent!
return drupal_strtoupper(drupal_substr($text, 0, 1)) . drupal_substr($text, 1);
return Unicode::ucfirst($text);
}
/**
* Cuts off a piece of a string based on character indices and counts.
*
* Follows the same behavior as PHP's own substr() function. Note that for
* cutting off a string at a known character/substring location, the usage of
* PHP's normal strpos/substr is safe and much faster.
*
* @param $text
* The input string.
* @param $start
......@@ -540,92 +318,9 @@ function drupal_ucfirst($text) {
* @return
* The shortened string.
*
* @see \Drupal\Component\Utility\Unicode::substr().
* @ingroup php_wrappers
*/
function drupal_substr($text, $start, $length = NULL) {
global $multibyte;
if ($multibyte == UNICODE_MULTIBYTE) {
return $length === NULL ? mb_substr($text, $start) : mb_substr($text, $start, $length);
}
else {
$strlen = strlen($text);
// Find the starting byte offset.
$bytes = 0;
if ($start > 0) {
// Count all the continuation bytes from the start until we have found
// $start characters or the end of the string.
$bytes = -1; $chars = -1;
while ($bytes < $strlen - 1 && $chars < $start) {
$bytes++;
$c = ord($text[$bytes]);
if ($c < 0x80 || $c >= 0xC0) {
$chars++;
}
}
}
elseif ($start < 0) {
// Count all the continuation bytes from the end until we have found
// abs($start) characters.
$start = abs($start);
$bytes = $strlen; $chars = 0;
while ($bytes > 0 && $chars < $start) {
$bytes--;
$c = ord($text[$bytes]);
if ($c < 0x80 || $c >= 0xC0) {
$chars++;
}
}
}
$istart = $bytes;
// Find the ending byte offset.
if ($length === NULL) {
$iend = $strlen;
}
elseif ($length > 0) {
// Count all the continuation bytes from the starting index until we have
// found $length characters or reached the end of the string, then
// backtrace one byte.
$iend = $istart - 1;
$chars = -1;
$last_real = FALSE;
while ($iend < $strlen - 1 && $chars < $length) {
$iend++;
$c = ord($text[$iend]);
$last_real = FALSE;
if ($c < 0x80 || $c >= 0xC0) {
$chars++;
$last_real = TRUE;
}
}
// Backtrace one byte if the last character we found was a real character
// and we don't need it.
if ($last_real && $chars >= $length) {
$iend--;
}
}
elseif ($length < 0) {
// Count all the continuation bytes from the end until we have found
// abs($start) characters, then backtrace one byte.
$length = abs($length);
$iend = $strlen; $chars = 0;
while ($iend > 0 && $chars < $length) {
$iend--;
$c = ord($text[$iend]);
if ($c < 0x80 || $c >= 0xC0) {
$chars++;
}
}
// Backtrace one byte if we are not at the beginning of the string.
if ($iend > 0) {
$iend--;
}
}
else {
// $length == 0, return an empty string.
return '';
}