From 686c269bae7de4d84d4dd241c9b9f9092ece4f01 Mon Sep 17 00:00:00 2001
From: Alex Pott <alex.a.pott@googlemail.com>
Date: Wed, 8 May 2013 00:29:47 +0100
Subject: [PATCH] Issue #1938670 by ParisLiakos, Xano, RobLoach, pp, alexpott:
 Convert unicode.inc to \Drupal\Component\Utility\Unicode.

---
 core/includes/bootstrap.inc                   |  68 +--
 core/includes/theme.maintenance.inc           |   4 +-
 core/includes/unicode.inc                     | 393 ++----------
 core/lib/Drupal/Component/Utility/String.php  |  17 +
 core/lib/Drupal/Component/Utility/Unicode.php | 578 ++++++++++++++++++
 core/modules/search/search.module             |   5 +-
 .../system/Tests/System/UnicodeUnitTest.php   | 312 ----------
 .../Drupal/views/Plugin/views/HandlerBase.php |   5 +-
 .../Tests/Component/Utility/StringTest.php    |  44 +-
 .../Tests/Component/Utility/UnicodeTest.php   | 336 ++++++++++
 core/tests/bootstrap.php                      |   5 +
 11 files changed, 1034 insertions(+), 733 deletions(-)
 create mode 100644 core/lib/Drupal/Component/Utility/Unicode.php
 delete mode 100644 core/modules/system/lib/Drupal/system/Tests/System/UnicodeUnitTest.php
 create mode 100644 core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php

diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 25e9b9ab5087..9cdf41f8a773 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -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';
 
diff --git a/core/includes/theme.maintenance.inc b/core/includes/theme.maintenance.inc
index 578d3544c0fd..33d44ee870c0 100644
--- a/core/includes/theme.maintenance.inc
+++ b/core/includes/theme.maintenance.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')) {
diff --git a/core/includes/unicode.inc b/core/includes/unicode.inc
index 70a8fde186c4..1b9bcf15006c 100644
--- a/core/includes/unicode.inc
+++ b/core/includes/unicode.inc
@@ -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 {
-      // $length == 0, return an empty string.
-      return '';
-    }
-
-    return substr($text, $istart, max(0, $iend - $istart + 1));
-  }
+  return Unicode::substr($text, $start, $length);
 }
diff --git a/core/lib/Drupal/Component/Utility/String.php b/core/lib/Drupal/Component/Utility/String.php
index c79b5af2b1d1..a6df8fe6780f 100644
--- a/core/lib/Drupal/Component/Utility/String.php
+++ b/core/lib/Drupal/Component/Utility/String.php
@@ -31,6 +31,23 @@ public static function checkPlain($text) {
     return htmlspecialchars($text, ENT_QUOTES, 'UTF-8');
   }
 
+  /**
+   * 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 it will revert
+   * previous sanitization efforts (&lt;script&gt; will become <script>).
+   *
+   * @param string $text
+   *   The text to decode entities in.
+   *
+   * @return string
+   *   The input $text, with all HTML entities decoded once.
+   */
+  public static function decodeEntities($text) {
+    return html_entity_decode($text, ENT_QUOTES, 'UTF-8');
+  }
+
   /**
    * Formats a string for HTML display by replacing variable placeholders.
    *
diff --git a/core/lib/Drupal/Component/Utility/Unicode.php b/core/lib/Drupal/Component/Utility/Unicode.php
new file mode 100644
index 000000000000..6ee23d11d6f8
--- /dev/null
+++ b/core/lib/Drupal/Component/Utility/Unicode.php
@@ -0,0 +1,578 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Utility\Unicode.
+ */
+
+namespace Drupal\Component\Utility;
+
+/**
+ * Provides Unicode-related conversions and operations.
+ */
+class Unicode {
+
+  /**
+   * 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
+   */
+  const PREG_CLASS_WORD_BOUNDARY = <<< 'EOD'
+\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}
+EOD;
+
+  /**
+   * Indicates that standard PHP (emulated) unicode support is being used.
+   */
+  const STATUS_SINGLEBYTE = 0;
+
+  /**
+   * Indicates that full unicode support with the PHP mbstring extension is
+   * being used.
+   */
+  const STATUS_MULTIBYTE = 1;
+
+  /**
+   * Indicates an error during check for PHP unicode support.
+   */
+  const STATUS_ERROR = -1;
+
+  /**
+   * Holds the multibyte capabilities of the current enviroment.
+   *
+   * @var int
+   */
+  protected static $status = 0;
+
+  /**
+   * Get the current status of unicode/multibyte support on this enviroment.
+   *
+   * @return int
+   *   The status of multibyte support. It can be one of:
+   *   - \Drupal\Component\Utility\Unicode::STATUS_MULTIBYTE
+   *     Full unicode support using an extension.
+   *   - \Drupal\Component\Utility\Unicode::STATUS_SINGLEBYTE
+   *     Standard PHP (emulated) unicode support.
+   *   - \Drupal\Component\Utility\Unicode::STATUS_ERROR
+   *     An error occured. No unicode support.
+   */
+  public static function getStatus() {
+    return static::$status;
+  }
+
+  /**
+   * Sets the value for multibyte support status for the current enviroment.
+   *
+   * The following status keys are supported:
+   *   - \Drupal\Component\Utility\Unicode::STATUS_MULTIBYTE
+   *     Full unicode support using an extension.
+   *   - \Drupal\Component\Utility\Unicode::STATUS_SINGLEBYTE
+   *     Standard PHP (emulated) unicode support.
+   *   - \Drupal\Component\Utility\Unicode::STATUS_ERROR
+   *     An error occured. No unicode support.
+   *
+   * @param int $status
+   *   The new status of multibyte support.
+   */
+  public static function setStatus($status) {
+    if (!in_array($status, array(static::STATUS_SINGLEBYTE, static::STATUS_MULTIBYTE, static::STATUS_ERROR))) {
+      throw new \InvalidArgumentException('Invalid status value for unicode support.');
+    }
+    static::$status = $status;
+  }
+
+  /**
+   * Checks for Unicode support in PHP and sets the proper settings if possible.
+   *
+   * Because of the need to be able to handle text in various encodings, we do
+   * not support mbstring function overloading. HTTP input/output conversion
+   * must be disabled for similar reasons.
+   *
+   * @return string
+   *   A string identifier of a failed multibyte extension check, if any.
+   *   Otherwise, an empty string.
+   */
+  public static function check() {
+    // Check for mbstring extension.
+    if (!function_exists('mb_strlen')) {
+      static::$status = static::STATUS_SINGLEBYTE;
+      return 'mb_strlen';
+    }
+
+    // Check mbstring configuration.
+    if (ini_get('mbstring.func_overload') != 0) {
+      static::$status = static::STATUS_ERROR;
+      return 'mbstring.func_overload';
+    }
+    if (ini_get('mbstring.encoding_translation') != 0) {
+      static::$status = static::STATUS_ERROR;
+      return 'mbstring.encoding_translation';
+    }
+    if (ini_get('mbstring.http_input') != 'pass') {
+      static::$status = static::STATUS_ERROR;
+      return 'mbstring.http_input';
+    }
+    if (ini_get('mbstring.http_output') != 'pass') {
+      static::$status = static::STATUS_ERROR;
+      return 'mbstring.http_output';
+    }
+
+    // Set appropriate configuration.
+    mb_internal_encoding('utf-8');
+    mb_language('uni');
+    static::$status = static::STATUS_MULTIBYTE;
+    return '';
+  }
+
+  /**
+   * Converts data to UTF-8.
+   *
+   * Requires the iconv, GNU recode or mbstring PHP extension.
+   *
+   * @param string $data
+   *   The data to be converted.
+   * @param string $encoding
+   *   The encoding that the data is in.
+   *
+   * @return string|bool
+   *   Converted data or FALSE.
+   */
+  public static function convertToUtf8($data, $encoding) {
+    if (function_exists('iconv')) {
+      return @iconv($encoding, 'utf-8', $data);
+    }
+    elseif (function_exists('mb_convert_encoding')) {
+      return @mb_convert_encoding($data, 'utf-8', $encoding);
+    }
+    elseif (function_exists('recode_string')) {
+      return @recode_string($encoding . '..utf-8', $data);
+    }
+    // Cannot convert.
+    return FALSE;
+  }
+
+  /**
+   * 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 $string
+   *   The string to truncate.
+   * @param int $len
+   *   An upper limit on the returned string length.
+   *
+   * @return string
+   *   The truncated string.
+   */
+  public static function truncateBytes($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);
+  }
+
+  /**
+   * Counts the number of characters in a UTF-8 string.
+   *
+   * This is less than or equal to the byte count.
+   *
+   * @param string $text
+   *   The string to run the operation on.
+   *
+   * @return int
+   *   The length of the string.
+   */
+  public static function strlen($text) {
+    if (static::getStatus() == static::STATUS_MULTIBYTE) {
+      return mb_strlen($text);
+    }
+    else {
+      // Do not count UTF-8 continuation bytes.
+      return strlen(preg_replace("/[\x80-\xBF]/", '', $text));
+    }
+  }
+
+  /**
+   * Uppercase a UTF-8 string.
+   *
+   * @param string $text
+   *   The string to run the operation on.
+   *
+   * @return string
+   *   The string in uppercase.
+   */
+  public static function strtoupper($text) {
+    if (static::getStatus() == static::STATUS_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]/', '\Drupal\Component\Utility\Unicode::caseFlip', $text);
+      return $text;
+    }
+  }
+
+  /**
+   * Lowercase a UTF-8 string.
+   *
+   * @param string $text
+   *   The string to run the operation on.
+   *
+   * @return string
+   *   The string in lowercase.
+   */
+  public static function strtolower($text) {
+    if (static::getStatus() == static::STATUS_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]/', '\Drupal\Component\Utility\Unicode::caseFlip', $text);
+      return $text;
+    }
+  }
+
+  /**
+   * Capitalizes the first letter of a UTF-8 string.
+   *
+   * @param string $text
+   *   The string to convert.
+   *
+   * @return string
+   *   The string with the first letter as uppercase.
+   */
+  public static function ucfirst($text) {
+    return static::strtoupper(static::substr($text, 0, 1)) . static::substr($text, 1);
+  }
+
+  /**
+   * 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 string $text
+   *   The input string.
+   * @param int $start
+   *   The position at which to start reading.
+   * @param int $length
+   *   The number of characters to read.
+   *
+   * @return string
+   *   The shortened string.
+   */
+  public static function substr($text, $start, $length = NULL) {
+    if (static::getStatus() == static::STATUS_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 {
+        // $length == 0, return an empty string.
+        return '';
+      }
+
+      return substr($text, $istart, max(0, $iend - $istart + 1));
+    }
+  }
+
+  /**
+   * Truncates a UTF-8-encoded string safely to a number of characters.
+   *
+   * @param string $string
+   *   The string to truncate.
+   * @param int $max_length
+   *   An upper limit on the returned string length, including trailing ellipsis
+   *   if $add_ellipsis is TRUE.
+   * @param bool $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 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.
+   * @param bool $add_ellipsis
+   *   If TRUE, add '...' to the end of the truncated string (defaults to
+   *   FALSE). The string length will still fall within $max_length.
+   * @param bool $min_wordsafe_length
+   *   If $wordsafe is TRUE, the minimum acceptable length for truncation (before
+   *   adding an ellipsis, if $add_ellipsis is TRUE). Has no effect if $wordsafe
+   *   is FALSE. This can be used to prevent having a very short resulting string
+   *   that will not be understandable. For instance, if you are truncating the
+   *   string "See myverylongurlexample.com for more information" to a word-safe
+   *   return length of 20, the only available word boundary within 20 characters
+   *   is after the word "See", which wouldn't leave a very informative string. If
+   *   you had set $min_wordsafe_length to 10, though, the function would realise
+   *   that "See" alone is too short, and would then just truncate ignoring word
+   *   boundaries, giving you "See myverylongurl..." (assuming you had set
+   *   $add_ellipses to TRUE).
+   *
+   * @return string
+   *   The truncated string.
+   */
+  public static function truncate($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 (static::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 = static::substr('…', 0, $max_length);
+      $max_length -= static::strlen($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 . '})[' . Unicode::PREG_CLASS_WORD_BOUNDARY . ']/u', $string, $matches);
+      if ($found) {
+        $string = $matches[1];
+      }
+      else {
+        $string = static::substr($string, 0, $max_length);
+      }
+    }
+    else {
+      $string = static::substr($string, 0, $max_length);
+    }
+
+    if ($add_ellipsis) {
+      // If we're adding an ellipsis, remove any trailing periods.
+      $string = rtrim($string, '.');
+
+      $string .= $ellipsis;
+    }
+
+    return $string;
+  }
+
+  /**
+   * Encodes MIME/HTTP headers that contain incorrectly encoded characters.
+   *
+   * For example, Unicode::mimeHeaderEncode('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 self::truncateBytes(). This ensures
+   *   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 $string
+   *   The header to encode.
+   *
+   * @return string
+   *   The mime-encoded header.
+   */
+  public static function mimeHeaderEncode($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) {
+        $chunk = static::truncateBytes($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;
+  }
+
+  /**
+   * Decodes MIME/HTTP encoded header values.
+   *
+   * @param string $header
+   *   The header to decode.
+   *
+   * @return string
+   *   The mime-decoded header.
+   */
+  public static function mimeHeaderDecode($header) {
+    $callback = function ($matches) {
+      $data = ($matches[2] == 'B') ? base64_decode($matches[3]) : str_replace('_', ' ', quoted_printable_decode($matches[3]));
+      if (strtolower($matches[1]) != 'utf-8') {
+        $data = static::convertToUtf8($data, $matches[1]);
+      }
+      return $data;
+    };
+    // First step: encoded chunks followed by other encoded chunks (need to collapse whitespace)
+    $header = preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=\s+(?==\?)/', $callback, $header);
+    // Second step: remaining chunks (do not collapse whitespace)
+    return preg_replace_callback('/=\?([^?]+)\?(Q|B)\?([^?]+|\?(?!=))\?=/', $callback, $header);
+  }
+
+  /**
+   * Flip U+C0-U+DE to U+E0-U+FD and back. Can be used as preg_replace callback.
+   *
+   * @param array $matches
+   *   An array of matches by preg_replace_callback().
+   *
+   * @return string
+   *   The flipped text.
+   */
+  public static function caseFlip($matches) {
+    return $matches[0][0] . chr(ord($matches[0][1]) ^ 32);
+  }
+
+}
diff --git a/core/modules/search/search.module b/core/modules/search/search.module
index 6dd68d952049..6501a854f99a 100644
--- a/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -6,6 +6,7 @@
  */
 
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\Component\Utility\Unicode;
 
 /**
  * Matches all 'N' Unicode character classes (numbers)
@@ -447,7 +448,7 @@ function search_simplify($text, $langcode = NULL) {
 
   // With the exception of the rules above, we consider all punctuation,
   // marks, spacers, etc, to be a word boundary.
-  $text = preg_replace('/[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']+/u', ' ', $text);
+  $text = preg_replace('/[' . Unicode::PREG_CLASS_WORD_BOUNDARY . ']+/u', ' ', $text);
 
   // Truncate everything to 50 characters.
   $words = explode(' ', $text);
@@ -1102,7 +1103,7 @@ function search_data($keys, $module, $conditions = NULL) {
  */
 function search_excerpt($keys, $text, $langcode = NULL) {
   // We highlight around non-indexable or CJK characters.
-  $boundary = '(?:(?<=[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . PREG_CLASS_CJK . '])|(?=[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . PREG_CLASS_CJK . ']))';
+  $boundary = '(?:(?<=[' . Unicode::PREG_CLASS_WORD_BOUNDARY . PREG_CLASS_CJK . '])|(?=[' . Unicode::PREG_CLASS_WORD_BOUNDARY . PREG_CLASS_CJK . ']))';
 
   // Extract positive keywords and phrases
   preg_match_all('/ ("([^"]+)"|(?!OR)([^" ]+))/', ' ' . $keys, $matches);
diff --git a/core/modules/system/lib/Drupal/system/Tests/System/UnicodeUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/System/UnicodeUnitTest.php
deleted file mode 100644
index 58bef1032904..000000000000
--- a/core/modules/system/lib/Drupal/system/Tests/System/UnicodeUnitTest.php
+++ /dev/null
@@ -1,312 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\system\Tests\System\UnicodeUnitTest.
- */
-
-namespace Drupal\system\Tests\System;
-
-use Drupal\simpletest\UnitTestBase;
-
-/**
- * Test unicode handling features implemented in unicode.inc.
- */
-class UnicodeUnitTest extends UnitTestBase {
-
-  /**
-   * Whether to run the extended version of the tests (including non latin1 characters).
-   *
-   * @var boolean
-   */
-  protected $extendedMode = FALSE;
-
-  public static function getInfo() {
-    return array(
-      'name' => 'Unicode handling',
-      'description' => 'Tests Drupal Unicode handling.',
-      'group' => 'System',
-    );
-  }
-
-  /**
-   * Test full unicode features implemented using the mbstring extension.
-   */
-  function testMbStringUnicode() {
-    global $multibyte;
-
-    // mbstring was not detected on this installation, there is no way to test
-    // multibyte features. Treat that as an exception.
-    if ($multibyte == UNICODE_SINGLEBYTE) {
-      $this->error(t('Unable to test Multibyte features: mbstring extension was not detected.'));
-    }
-
-    $multibyte = UNICODE_MULTIBYTE;
-
-    $this->extendedMode = TRUE;
-    $this->pass(t('Testing in mbstring mode'));
-
-    $this->helperTestStrToLower();
-    $this->helperTestStrToUpper();
-    $this->helperTestUcFirst();
-    $this->helperTestStrLen();
-    $this->helperTestSubStr();
-    $this->helperTestTruncate();
-  }
-
-  /**
-   * Test emulated unicode features.
-   */
-  function testEmulatedUnicode() {
-    global $multibyte;
-
-    $multibyte = UNICODE_SINGLEBYTE;
-
-    $this->extendedMode = FALSE;
-
-    $this->pass(t('Testing in emulated (best-effort) mode'));
-
-    $this->helperTestStrToLower();
-    $this->helperTestStrToUpper();
-    $this->helperTestUcFirst();
-    $this->helperTestStrLen();
-    $this->helperTestSubStr();
-    $this->helperTestTruncate();
-  }
-
-  function helperTestStrToLower() {
-    $testcase = array(
-      'tHe QUIcK bRoWn' => 'the quick brown',
-      'FrançAIS is ÜBER-åwesome' => 'français is über-åwesome',
-    );
-    if ($this->extendedMode) {
-      $testcase['ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΣὨ'] = 'αβγδεζηθικλμνξοσὠ';
-    }
-
-    foreach ($testcase as $input => $output) {
-      $this->assertEqual(drupal_strtolower($input), $output, format_string('%input is lowercased as %output', array('%input' => $input, '%output' => $output)));
-    }
-  }
-
-  function helperTestStrToUpper() {
-    $testcase = array(
-      'tHe QUIcK bRoWn' => 'THE QUICK BROWN',
-      'FrançAIS is ÜBER-åwesome' => 'FRANÇAIS IS ÜBER-ÅWESOME',
-    );
-    if ($this->extendedMode) {
-      $testcase['αβγδεζηθικλμνξοσὠ'] = 'ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΣὨ';
-    }
-
-    foreach ($testcase as $input => $output) {
-      $this->assertEqual(drupal_strtoupper($input), $output, format_string('%input is uppercased as %output', array('%input' => $input, '%output' => $output)));
-    }
-  }
-
-  function helperTestUcFirst() {
-    $testcase = array(
-      'tHe QUIcK bRoWn' => 'THe QUIcK bRoWn',
-      'françAIS' => 'FrançAIS',
-      'über' => 'Über',
-      'Ã¥wesome' => 'Ã…wesome'
-    );
-    if ($this->extendedMode) {
-      $testcase['σion'] = 'Σion';
-    }
-
-    foreach ($testcase as $input => $output) {
-      $this->assertEqual(drupal_ucfirst($input), $output, format_string('%input is ucfirst-ed as %output', array('%input' => $input, '%output' => $output)));
-    }
-  }
-
-  function helperTestStrLen() {
-    $testcase = array(
-      'tHe QUIcK bRoWn' => 15,
-      'ÃœBER-Ã¥wesome' => 12,
-    );
-
-    foreach ($testcase as $input => $output) {
-      $this->assertEqual(drupal_strlen($input), $output, format_string('%input length is %output', array('%input' => $input, '%output' => $output)));
-    }
-  }
-
-  function helperTestSubStr() {
-    $testcase = array(
-      //     012345678901234567890123
-      array('frànçAIS is über-åwesome', 0, 0,
-            ''),
-      array('frànçAIS is über-åwesome', 0, 1,
-            'f'),
-      array('frànçAIS is über-åwesome', 0, 8,
-            'frànçAIS'),
-      array('frànçAIS is über-åwesome', 0, 23,
-            'frànçAIS is über-åwesom'),
-      array('frànçAIS is über-åwesome', 0, 24,
-            'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 0, 25,
-            'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 0, 100,
-            'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 4, 4,
-                'çAIS'),
-      array('frànçAIS is über-åwesome', 1, 0,
-            ''),
-      array('frànçAIS is über-åwesome', 100, 0,
-            ''),
-      array('frànçAIS is über-åwesome', -4, 2,
-                                'so'),
-      array('frànçAIS is über-åwesome', -4, 3,
-                                'som'),
-      array('frànçAIS is über-åwesome', -4, 4,
-                                'some'),
-      array('frànçAIS is über-åwesome', -4, 5,
-                                'some'),
-      array('frànçAIS is über-åwesome', -7, 10,
-                             'Ã¥wesome'),
-      array('frànçAIS is über-åwesome', 5, -10,
-                 'AIS is üb'),
-      array('frànçAIS is über-åwesome', 0, -10,
-            'frànçAIS is üb'),
-      array('frànçAIS is über-åwesome', 0, -1,
-        'frànçAIS is über-åwesom'),
-      array('frànçAIS is über-åwesome', -7, -2,
-                             'Ã¥weso'),
-      array('frànçAIS is über-åwesome', -7, -6,
-                             'Ã¥'),
-      array('frànçAIS is über-åwesome', -7, -7,
-                             ''),
-      array('frànçAIS is über-åwesome', -7, -8,
-                             ''),
-      array('...', 0, 2, '..'),
-      array('以呂波耳・ほへとち。リヌルヲ。', 1, 3,
-              '呂波耳'),
-
-    );
-
-    foreach ($testcase as $test) {
-      list($input, $start, $length, $output) = $test;
-      $result = drupal_substr($input, $start, $length);
-      $this->assertEqual($result, $output, format_string('%input substring at offset %offset for %length characters is %output (got %result)', array('%input' => $input, '%offset' => $start, '%length' => $length, '%output' => $output, '%result' => $result)));
-    }
-  }
-
-  /**
-   * Test decode_entities().
-   */
-  function testDecodeEntities() {
-    $testcase = array(
-      'Drupal' => 'Drupal',
-      '<script>' => '<script>',
-      '&lt;script&gt;' => '<script>',
-      '&#60;script&#62;' => '<script>',
-      '&amp;lt;script&amp;gt;' => '&lt;script&gt;',
-      '"' => '"',
-      '&#34;' => '"',
-      '&amp;#34;' => '&#34;',
-      '&quot;' => '"',
-      '&amp;quot;' => '&quot;',
-      "'" => "'",
-      '&#39;' => "'",
-      '&amp;#39;' => '&#39;',
-      '©' => '©',
-      '&copy;' => '©',
-      '&#169;' => '©',
-      '→' => '→',
-      '&#8594;' => '→',
-      'âž¼' => 'âž¼',
-      '&#10172;' => 'âž¼',
-      '&euro;' => '€',
-    );
-    foreach ($testcase as $input => $output) {
-      $this->assertEqual(decode_entities($input), $output, format_string('Make sure the decoded entity of @input is @output', array('@input' => $input, '@output' => $output)));
-    }
-  }
-
-  /**
-   * Tests truncate_utf8().
-   */
-  function helperTestTruncate() {
-    // Each case is an array with input string, length to truncate to, and
-    // expected return value.
-
-    // Test non-wordsafe, non-ellipsis cases.
-    $non_wordsafe_non_ellipsis_cases = array(
-      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über-åwesom'),
-      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über-'),
-      array('以呂波耳・ほへとち。リヌルヲ。', 6, '以呂波耳・ほ'),
-    );
-    $this->runTruncateTests($non_wordsafe_non_ellipsis_cases, FALSE, FALSE);
-
-    // Test non-wordsafe, ellipsis cases.
-    $non_wordsafe_ellipsis_cases = array(
-      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über-åweso…'),
-      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über…'),
-    );
-    $this->runTruncateTests($non_wordsafe_ellipsis_cases, FALSE, TRUE);
-
-    // Test wordsafe, ellipsis cases.
-    $wordsafe_ellipsis_cases = array(
-      array('123', 1, '…'),
-      array('123', 2, '1…'),
-      array('123', 3, '123'),
-      array('1234', 3, '12…'),
-      array('1234567890', 10, '1234567890'),
-      array('12345678901', 10, '123456789…'),
-      array('12345678901', 11, '12345678901'),
-      array('123456789012', 11, '1234567890…'),
-      array('12345 7890', 10, '12345 7890'),
-      array('12345 7890', 9, '12345…'),
-      array('123 567 90', 10, '123 567 90'),
-      array('123 567 901', 10, '123 567…'),
-      array('Stop. Hammertime.', 17, 'Stop. Hammertime.'),
-      array('Stop. Hammertime.', 16, 'Stop…'),
-      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome'),
-      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über…'),
-      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über…'),
-      array('¿Dónde está el niño?', 20, '¿Dónde está el niño?'),
-      array('¿Dónde está el niño?', 19, '¿Dónde está el…'),
-      array('¿Dónde está el niño?', 13, '¿Dónde está…'),
-      array('¿Dónde está el niño?', 10, '¿Dónde…'),
-      array('Help! Help! Help!', 17, 'Help! Help! Help!'),
-      array('Help! Help! Help!', 16, 'Help! Help!…'),
-      array('Help! Help! Help!', 15, 'Help! Help!…'),
-      array('Help! Help! Help!', 14, 'Help! Help!…'),
-      array('Help! Help! Help!', 13, 'Help! Help!…'),
-      array('Help! Help! Help!', 12, 'Help! Help!…'),
-      array('Help! Help! Help!', 11, 'Help! Help…'),
-      array('Help! Help! Help!', 10, 'Help!…'),
-      array('Help! Help! Help!', 9, 'Help!…'),
-      array('Help! Help! Help!', 8, 'Help!…'),
-      array('Help! Help! Help!', 7, 'Help!…'),
-      array('Help! Help! Help!', 6, 'Help!…'),
-      array('Help! Help! Help!', 5, 'Help…'),
-      array('Help! Help! Help!', 4, 'Hel…'),
-      array('Help! Help! Help!', 3, 'He…'),
-      array('Help! Help! Help!', 2, 'H…'),
-    );
-    $this->runTruncateTests($wordsafe_ellipsis_cases, TRUE, TRUE);
-  }
-
-  /**
-   * Runs test cases for helperTestTruncate().
-   *
-   * Runs each test case through truncate_utf8() and compares the output
-   * to the expected output.
-   *
-   * @param $cases
-   *   Cases array. Each case is an array with the input string, length to
-   *   truncate to, and expected output.
-   * @param $wordsafe
-   *   TRUE to use word-safe truncation, FALSE to not use word-safe truncation.
-   * @param $ellipsis
-   *   TRUE to append ... if the input is truncated, FALSE to not append ....
-   */
-  function runTruncateTests($cases, $wordsafe, $ellipsis) {
-    foreach ($cases as $case) {
-      list($input, $max_length, $expected) = $case;
-      $output = truncate_utf8($input, $max_length, $wordsafe, $ellipsis);
-      $this->assertEqual($output, $expected, format_string('%input truncate to %length characters with %wordsafe, %ellipsis is %expected (got %output)', array('%input' => $input, '%length' => $max_length, '%output' => $output, '%expected' => $expected, '%wordsafe' => ($wordsafe ? 'word-safe' : 'not word-safe'), '%ellipsis' => ($ellipsis ? 'ellipsis' : 'not ellipsis'))));
-    }
-  }
-}
diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/HandlerBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/HandlerBase.php
index 71fc789a8268..3f510aa8ce28 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/HandlerBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/HandlerBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\views\Plugin\views;
 
+use Drupal\Component\Utility\Unicode;
 use Drupal\views\Plugin\views\display\DisplayPluginBase;
 use Drupal\views\Plugin\views\PluginBase;
 use Drupal\views\ViewExecutable;
@@ -242,8 +243,6 @@ public function sanitizeValue($value, $type = NULL) {
    *    The transformed string.
    */
   protected function caseTransform($string, $option) {
-    global $multibyte;
-
     switch ($option) {
       default:
         return $string;
@@ -254,7 +253,7 @@ protected function caseTransform($string, $option) {
       case 'ucfirst':
         return drupal_strtoupper(drupal_substr($string, 0, 1)) . drupal_substr($string, 1);
       case 'ucwords':
-        if ($multibyte == UNICODE_MULTIBYTE) {
+        if (Unicode::getStatus() == Unicode::STATUS_MULTIBYTE) {
           return mb_convert_case($string, MB_CASE_TITLE);
         }
         else {
diff --git a/core/tests/Drupal/Tests/Component/Utility/StringTest.php b/core/tests/Drupal/Tests/Component/Utility/StringTest.php
index c1a75292e4e9..10e3af7e200b 100644
--- a/core/tests/Drupal/Tests/Component/Utility/StringTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/StringTest.php
@@ -41,7 +41,7 @@ public static function getInfo() {
    */
   function testCheckPlain($text, $expected, $message, $ignorewarnings = FALSE) {
     $result = $ignorewarnings ? @String::checkPlain($text) : String::checkPlain($text);
-    $this->assertEquals($result, $expected, $message);
+    $this->assertEquals($expected, $result, $message);
   }
 
   /**
@@ -80,7 +80,7 @@ function providerCheckPlain() {
    */
   function testFormat($string, $args, $expected, $message) {
     $result = String::format($string, $args);
-    $this->assertEquals($result, $expected, $message);
+    $this->assertEquals($expected, $result, $message);
   }
 
   /**
@@ -106,4 +106,44 @@ function testPlaceholder() {
     $this->assertEquals('<em class="placeholder">Some text</em>', String::placeholder('Some text'));
   }
 
+  /**
+   * Tests String::decodeEntities().
+   *
+   * @dataProvider providerDecodeEntities
+   */
+  public function testDecodeEntities($text, $expected) {
+    $this->assertEquals($expected, String::decodeEntities($text));
+  }
+
+  /**
+   * Data provider for testDecodeEntities().
+   *
+   * @see testCheckPlain()
+   */
+  public function providerDecodeEntities() {
+    return array(
+      array('Drupal', 'Drupal'),
+      array('<script>', '<script>'),
+      array('&lt;script&gt;', '<script>'),
+      array('&#60;script&#62;', '<script>'),
+      array('&amp;lt;script&amp;gt;', '&lt;script&gt;'),
+      array('"', '"'),
+      array('&#34;', '"'),
+      array('&amp;#34;', '&#34;'),
+      array('&quot;', '"'),
+      array('&amp;quot;', '&quot;'),
+      array("'", "'"),
+      array('&#39;', "'"),
+      array('&amp;#39;', '&#39;'),
+      array('©', '©'),
+      array('&copy;', '©'),
+      array('&#169;', '©'),
+      array('→', '→'),
+      array('&#8594;', '→'),
+      array('âž¼', 'âž¼'),
+      array('&#10172;', 'âž¼'),
+      array('&euro;', '€'),
+    );
+  }
+
 }
diff --git a/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php b/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
new file mode 100644
index 000000000000..5f49a6d3c9b8
--- /dev/null
+++ b/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
@@ -0,0 +1,336 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Component\Utility\UnicodeTest.
+ */
+
+namespace Drupal\Tests\Component\Utility;
+
+use Drupal\Tests\UnitTestCase;
+use Drupal\Component\Utility\Unicode;
+
+/**
+ * Test unicode handling features implemented in Unicode component.
+ */
+class UnicodeTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Unicode handling',
+      'description' => 'Tests Drupal Unicode handling.',
+      'group' => 'System',
+    );
+  }
+
+  public function setUp() {
+    // Initialize unicode component.
+    Unicode::check();
+  }
+
+  /**
+   * Tests Unicode::getStatus() and Unicode::setStatus().
+   *
+   * @dataProvider providerTestStatus
+   */
+  public function testStatus($value, $expected, $invalid = FALSE) {
+    if ($invalid) {
+      $this->setExpectedException('InvalidArgumentException');
+    }
+    Unicode::setStatus($value);
+    $this->assertEquals($expected, Unicode::getStatus());
+  }
+
+  /**
+   * Data provider for testStatus().
+   *
+   * @see testStatus()
+   *
+   * @return array
+   *   An array containing:
+   *     - The status value to set.
+   *     - The status value to expect after setting the new value.
+   *     - (optional) Boolean indicating invalid status. Defaults to FALSE.
+   */
+  public function providerTestStatus() {
+    return array(
+      array(Unicode::STATUS_SINGLEBYTE, Unicode::STATUS_SINGLEBYTE),
+      array(rand(10, 100), Unicode::STATUS_SINGLEBYTE, TRUE),
+      array(rand(10, 100), Unicode::STATUS_SINGLEBYTE, TRUE),
+      array(Unicode::STATUS_MULTIBYTE, Unicode::STATUS_MULTIBYTE),
+      array(rand(10, 100), Unicode::STATUS_MULTIBYTE, TRUE),
+      array(Unicode::STATUS_ERROR, Unicode::STATUS_ERROR),
+      array(Unicode::STATUS_MULTIBYTE, Unicode::STATUS_MULTIBYTE),
+    );
+  }
+
+  /**
+   * Tests Unicode::mimeHeaderEncode() and Unicode::mimeHeaderDecode().
+   *
+   * @dataProvider providerTestMimeHeader
+   */
+  public function testMimeHeader($value, $encoded) {
+    $this->assertEquals($encoded, Unicode::mimeHeaderEncode($value));
+    $this->assertEquals($value, Unicode::mimeHeaderDecode($encoded));
+  }
+
+  /**
+   * Data provider for testMimeHeader().
+   *
+   * @see testMimeHeader()
+   *
+   * @return array
+   *   An array containing a string and its encoded value.
+   */
+  public function providerTestMimeHeader() {
+    return array(
+      array('tést.txt', '=?UTF-8?B?dMOpc3QudHh0?='),
+    );
+  }
+
+
+  /**
+   * Tests Unicode::strtolower().
+   *
+   * @dataProvider providerStrtolower
+   */
+  public function testStrtolower($text, $expected, $multibyte = FALSE) {
+    $status = $multibyte ? Unicode::STATUS_MULTIBYTE : Unicode::STATUS_SINGLEBYTE;
+    Unicode::setStatus($status);
+    $this->assertEquals($expected, Unicode::strtolower($text));
+  }
+
+  /**
+   * Data provider for testStrtolower().
+   *
+   * @see testStrtolower()
+   *
+   * @return array
+   *   An array containing a string, its lowercase version and whether it should
+   *   be processed as multibyte.
+   */
+  public function providerStrtolower() {
+    $cases = array(
+      array('tHe QUIcK bRoWn', 'the quick brown'),
+      array('FrançAIS is ÜBER-åwesome', 'français is über-åwesome'),
+    );
+    foreach ($cases as $case) {
+      // Test the same string both in multibyte and singlebyte conditions.
+      array_push($case, TRUE);
+      $cases[] = $case;
+    }
+    // Add a multibyte string.
+    $cases[] = array('ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΣὨ', 'αβγδεζηθικλμνξοσὠ', TRUE);
+    return $cases;
+  }
+
+  /**
+   * Tests Unicode::strtoupper().
+   *
+   * @dataProvider providerStrtoupper
+   */
+  public function testStrtoupper($text, $expected, $multibyte = FALSE) {
+    $status = $multibyte ? Unicode::STATUS_MULTIBYTE : Unicode::STATUS_SINGLEBYTE;
+    Unicode::setStatus($status);
+    $this->assertEquals($expected, Unicode::strtoupper($text));
+  }
+
+  /**
+   * Data provider for testStrtoupper().
+   *
+   * @see testStrtoupper()
+   *
+   * @return array
+   *   An array containing a string, its uppercase version and whether it should
+   *   be processed as multibyte.
+   */
+  public function providerStrtoupper() {
+    $cases = array(
+      array('tHe QUIcK bRoWn', 'THE QUICK BROWN'),
+      array('FrançAIS is ÜBER-åwesome', 'FRANÇAIS IS ÜBER-ÅWESOME'),
+    );
+    foreach ($cases as $case) {
+      // Test the same string both in multibyte and singlebyte conditions.
+      array_push($case, TRUE);
+      $cases[] = $case;
+    }
+    // Add a multibyte string.
+    $cases[] = array('αβγδεζηθικλμνξοσὠ', 'ΑΒΓΔΕΖΗΘΙΚΛΜΝΞΟΣὨ', TRUE);
+    return $cases;
+  }
+
+  /**
+   * Tests Unicode::ucfirst().
+   *
+   * @dataProvider providerUcfirst
+   */
+  public function testUcfirst($text, $expected) {
+    $this->assertEquals($expected, Unicode::ucfirst($text));
+  }
+
+  /**
+   * Data provider for testUcfirst().
+   *
+   * @see testUcfirst()
+   *
+   * @return array
+   *   An array containing a string and its uppercase first version.
+   */
+  public function providerUcfirst() {
+    return array(
+      array('tHe QUIcK bRoWn', 'THe QUIcK bRoWn'),
+      array('françAIS', 'FrançAIS'),
+      array('über', 'Über'),
+      array('Ã¥wesome', 'Ã…wesome'),
+      // A multibyte string.
+      array('σion', 'Σion'),
+    );
+  }
+
+  /**
+   * Tests Unicode::strlen().
+   *
+   * @dataProvider providerStrlen
+   */
+  public function testStrlen($text, $expected) {
+    $this->assertEquals($expected, Unicode::strlen($text));
+  }
+
+  /**
+   * Data provider for testStrlen().
+   *
+   * @see testStrlen()
+   *
+   * @return array
+   *   An array containing a string and its length.
+   */
+  public function providerStrlen() {
+    return array(
+      array('tHe QUIcK bRoWn', 15),
+      array('ÃœBER-Ã¥wesome', 12),
+    );
+  }
+
+  /**
+   * Tests Unicode::substr().
+   *
+   * @dataProvider providerSubstr
+   */
+  public function testSubstr($text, $start, $length, $expected) {
+    $this->assertEquals($expected, Unicode::substr($text, $start, $length));
+  }
+
+  /**
+   * Data provider for testSubstr().
+   *
+   * @see testSubstr()
+   *
+   * @return array
+   *   An array containing:
+   *     - The string to test.
+   *     - The start number to be processed by substr.
+   *     - The length number to be processed by substr.
+   *     - The expected string result.
+   */
+  public function providerSubstr() {
+    return array(
+      array('frànçAIS is über-åwesome', 0, 0, ''),
+      array('frànçAIS is über-åwesome', 0, 1, 'f'),
+      array('frànçAIS is über-åwesome', 0, 8, 'frànçAIS'),
+      array('frànçAIS is über-åwesome', 0, 23, 'frànçAIS is über-åwesom'),
+      array('frànçAIS is über-åwesome', 0, 24, 'frànçAIS is über-åwesome'),
+      array('frànçAIS is über-åwesome', 0, 25, 'frànçAIS is über-åwesome'),
+      array('frànçAIS is über-åwesome', 0, 100, 'frànçAIS is über-åwesome'),
+      array('frànçAIS is über-åwesome', 4, 4, 'çAIS'),
+      array('frànçAIS is über-åwesome', 1, 0, ''),
+      array('frànçAIS is über-åwesome', 100, 0, ''),
+      array('frànçAIS is über-åwesome', -4, 2, 'so'),
+      array('frànçAIS is über-åwesome', -4, 3, 'som'),
+      array('frànçAIS is über-åwesome', -4, 4, 'some'),
+      array('frànçAIS is über-åwesome', -4, 5, 'some'),
+      array('frànçAIS is über-åwesome', -7, 10, 'åwesome'),
+      array('frànçAIS is über-åwesome', 5, -10, 'AIS is üb'),
+      array('frànçAIS is über-åwesome', 0, -10, 'frànçAIS is üb'),
+      array('frànçAIS is über-åwesome', 0, -1, 'frànçAIS is über-åwesom'),
+      array('frànçAIS is über-åwesome', -7, -2, 'åweso'),
+      array('frànçAIS is über-åwesome', -7, -6, 'å'),
+      array('frànçAIS is über-åwesome', -7, -7, ''),
+      array('frànçAIS is über-åwesome', -7, -8, ''),
+      array('...', 0, 2, '..'),
+      array('以呂波耳・ほへとち。リヌルヲ。', 1, 3, '呂波耳'),
+    );
+  }
+
+  /**
+   * Tests Unicode::truncate().
+   *
+   * @dataProvider providerTruncate
+   */
+  public function testTruncate($text, $max_length, $expected, $wordsafe = FALSE, $add_ellipsis = FALSE) {
+    Unicode::check();
+    $this->assertEquals($expected, Unicode::truncate($text, $max_length, $wordsafe, $add_ellipsis));
+  }
+
+  /**
+   * Data provider for testTruncate().
+   *
+   * @see testTruncate()
+   *
+   * @return array
+   *   An array containing:
+   *     - The string to test.
+   *     - The max length to truncate this string to.
+   *     - The expected string result.
+   *     - (optional) Boolean for the $wordsafe flag. Defaults to FALSE.
+   *     - (optional) Boolean for the $add_ellipsis flag. Defaults to FALSE.
+   */
+  public function providerTruncate() {
+    return array(
+      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome'),
+      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über-åwesom'),
+      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über-'),
+      array('以呂波耳・ほへとち。リヌルヲ。', 6, '以呂波耳・ほ'),
+      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome', FALSE, TRUE),
+      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über-åweso…', FALSE, TRUE),
+      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über…', FALSE, TRUE),
+      array('123', 1, '…', TRUE, TRUE),
+      array('123', 2, '1…', TRUE, TRUE),
+      array('123', 3, '123', TRUE, TRUE),
+      array('1234', 3, '12…', TRUE, TRUE),
+      array('1234567890', 10, '1234567890', TRUE, TRUE),
+      array('12345678901', 10, '123456789…', TRUE, TRUE),
+      array('12345678901', 11, '12345678901', TRUE, TRUE),
+      array('123456789012', 11, '1234567890…', TRUE, TRUE),
+      array('12345 7890', 10, '12345 7890', TRUE, TRUE),
+      array('12345 7890', 9, '12345…', TRUE, TRUE),
+      array('123 567 90', 10, '123 567 90', TRUE, TRUE),
+      array('123 567 901', 10, '123 567…', TRUE, TRUE),
+      array('Stop. Hammertime.', 17, 'Stop. Hammertime.', TRUE, TRUE),
+      array('Stop. Hammertime.', 16, 'Stop…', TRUE, TRUE),
+      array('frànçAIS is über-åwesome', 24, 'frànçAIS is über-åwesome', TRUE, TRUE),
+      array('frànçAIS is über-åwesome', 23, 'frànçAIS is über…', TRUE, TRUE),
+      array('frànçAIS is über-åwesome', 17, 'frànçAIS is über…', TRUE, TRUE),
+      array('¿Dónde está el niño?', 20, '¿Dónde está el niño?', TRUE, TRUE),
+      array('¿Dónde está el niño?', 19, '¿Dónde está el…', TRUE, TRUE),
+      array('¿Dónde está el niño?', 13, '¿Dónde está…', TRUE, TRUE),
+      array('¿Dónde está el niño?', 10, '¿Dónde…', TRUE, TRUE),
+      array('Help! Help! Help!', 17, 'Help! Help! Help!', TRUE, TRUE),
+      array('Help! Help! Help!', 16, 'Help! Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 15, 'Help! Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 14, 'Help! Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 13, 'Help! Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 12, 'Help! Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 11, 'Help! Help…', TRUE, TRUE),
+      array('Help! Help! Help!', 10, 'Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 9, 'Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 8, 'Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 7, 'Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 6, 'Help!…', TRUE, TRUE),
+      array('Help! Help! Help!', 5, 'Help…', TRUE, TRUE),
+      array('Help! Help! Help!', 4, 'Hel…', TRUE, TRUE),
+      array('Help! Help! Help!', 3, 'He…', TRUE, TRUE),
+      array('Help! Help! Help!', 2, 'H…', TRUE, TRUE),
+    );
+  }
+
+}
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index 57e3da621c61..08d887166d93 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -20,3 +20,8 @@
 require __DIR__ . "/../../core/lib/Drupal.php";
 // Look into removing this later.
 define('REQUEST_TIME', (int) $_SERVER['REQUEST_TIME']);
+
+// Set sane locale settings, to ensure consistent string, dates, times and
+// numbers handling.
+// @see drupal_environment_initialize()
+setlocale(LC_ALL, 'C');
-- 
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