- Patch #768040 by jhodgdon, janusman, codycraven: truncate_utf8() only works for latin languages and drupal_substr() had a bug.

1 files changed, 123 insertions, 21 deletions

diff --git a/includes/unicode.inc b/includes/unicode.inc
index c3638c9a8..2813a5739 100644
--- a/includes/unicode.inc
+++ b/includes/unicode.inc
@@ -18,6 +18,67 @@ define('UNICODE_SINGLEBYTE', 0);
 define('UNICODE_MULTIBYTE', 1);
 
 /**
+ * Matches Unicode characters that are word boundaries.
+ *
+ * @see http://unicode.org/glossary
+ *
+ * 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).
+ */
+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{D800}-\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}');
+
+/**
  * Wrapper around _unicode_check().
  */
 function unicode_check() {
@@ -213,44 +274,80 @@ function drupal_truncate_bytes($string, $len) {
 }
 
 /**
- * Truncate a UTF-8-encoded string safely to a number of characters.
+ * Truncates a UTF-8-encoded string safely to a number of characters.
  *
  * @param $string
  *   The string to truncate.
- * @param $len
- *   An upper limit on the returned string length.
+ * @param $max_length
+ *   An upper limit on the returned string length, including trailing ellipsis
+ *   if $add_ellipsis is TRUE.
  * @param $wordsafe
- *   Flag to truncate at last space within the upper limit. Defaults to FALSE.
- * @param $dots
- *   Flag to add trailing dots. Defaults to FALSE.
+ *   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
+ *   information.  If a word boundary cannot be found that would make the length
+ *   of the returned string fall within length guidelines (see parameters
+ *   $max_return_length and $min_wordsafe_length), word boundaries are ignored.
+ * @param $add_ellipsis
+ *   If TRUE, add t('...') to the end of the truncated string (defaults to
+ *   FALSE). The string length will still fall within $max_return_length.
+ * @param $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
+ *   $add_ellipses to TRUE).
+ *
  * @return
  *   The truncated string.
  */
-function truncate_utf8($string, $len, $wordsafe = FALSE, $dots = FALSE) {
+function truncate_utf8($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) <= $len) {
+  if (drupal_strlen($string) <= $max_length) {
+    // No truncation needed, so don't add ellipsis, just return.
     return $string;
   }
 
-  if ($dots) {
-    $len -= 4;
+  if ($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) {
-    $string = drupal_substr($string, 0, $len + 1); // leave one more character
-    if ($last_space = strrpos($string, ' ')) { // space exists AND is not on position 0
-      $string = substr($string, 0, $last_space);
+    $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, $len);
+      $string = drupal_substr($string, 0, $max_length);
     }
   }
   else {
-    $string = drupal_substr($string, 0, $len);
+    $string = drupal_substr($string, 0, $max_length);
   }
 
-  if ($dots) {
-    $string .= ' ...';
+  if ($add_ellipsis) {
+    $string .= $ellipsis;
   }
 
   return $string;
@@ -516,16 +613,21 @@ function drupal_substr($text, $start, $length = NULL) {
       // 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;
+      $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++;
+          $last_real = TRUE;
         }
       }
-      // Backtrace one byte if the end of the string was not reached.
-      if ($iend < $strlen - 1) {
+      // Backtrace one byte if the last character we found was a real character
+      // and we don't need it.
+      if ($last_real && $chars >= $length) {
         $iend--;
       }
     }
@@ -548,7 +650,7 @@ function drupal_substr($text, $start, $length = NULL) {
     }
     else {
       // $length == 0, return an empty string.
-      $iend = $istart - 1;
+      return '';
     }
 
     return substr($text, $istart, max(0, $iend - $istart + 1));