+/**
+ * This is a replacement for PHP's substr_replace() that is
+ * multibyte-aware.
+ *
+ * @param string $string The string to operate upon
+ * @param string $replacement The string to be inserted
+ * @param int $start The offset at which to begin substring replacement
+ * @param int $length The number of characters after $start to remove
+ * NOTE that if you need to specify a charset but
+ * want to achieve normal substr_replace() behavior
+ * where $length is not specified, use NULL (OPTIONAL;
+ * default from $start to end of string)
+ * @param string $charset The charset of the given string. A value of NULL
+ * here will force the use of PHP's standard substr().
+ * (OPTIONAL; default is "auto", which indicates that
+ * the user's current charset should be used).
+ *
+ * @return string The manipulated string
+ *
+ * Of course, you can use more advanced (e.g., negative) values
+ * for $start and $length as needed - see the PHP manual for more
+ * information: http://www.php.net/manual/function.substr-replace.php
+ *
+ */
+function sq_substr_replace($string, $replacement, $start, $length=NULL,
+ $charset='auto')
+{
+
+ // NULL charset? Just use substr_replace()
+ //
+ if (is_null($charset))
+ return is_null($length) ? substr_replace($string, $replacement, $start)
+ : substr_replace($string, $replacement, $start, $length);
+
+
+ // use current character set?
+ //
+ if ($charset == 'auto')
+ {
+//FIXME: is there any reason why this cannot be a global flag used by all string wrapper functions?
+ static $auto_charset;
+ if (!isset($auto_charset))
+ {
+ global $default_charset;
+//FIXME - do we need this?
+global $squirrelmail_language;
+ set_my_charset();
+ $auto_charset = $default_charset;
+//FIXME - do we need this?
+if ($squirrelmail_language == 'ja_JP') $auto_charset = 'euc-jp';
+ }
+ $charset = $auto_charset;
+ }
+
+
+ // standardize character set name
+ //
+ $charset = strtolower($charset);
+
+
+/* ===== FIXME: this list is not used in 1.5.x, but if we need it, unless this differs between all our string function wrappers, we should store this info in the session
+ // only use mbstring with the following character sets
+ //
+ $sq_substr_replace_mb_charsets = array(
+ 'utf-8',
+ 'big5',
+ 'gb2312',
+ 'gb18030',
+ 'euc-jp',
+ 'euc-cn',
+ 'euc-tw',
+ 'euc-kr'
+ );
+
+
+ // now we can use our own implementation using
+ // mb_substr() and mb_strlen() if needed
+ //
+ if (in_array($charset, $sq_substr_replace_mb_charsets)
+ && in_array($charset, sq_mb_list_encodings()))
+===== */
+//FIXME: is there any reason why this cannot be a global array used by all string wrapper functions?
+ if (in_array($charset, sq_mb_list_encodings()))
+ {
+
+ $string_length = mb_strlen($string, $charset);
+
+ if ($start < 0)
+ $start = max(0, $string_length + $start);
+
+ else if ($start > $string_length)
+ $start = $string_length;
+
+ if ($length < 0)
+ $length = max(0, $string_length - $start + $length);
+
+ else if (is_null($length) || $length > $string_length)
+ $length = $string_length;
+
+ if ($start + $length > $string_length)
+ $length = $string_length - $start;
+
+ return mb_substr($string, 0, $start, $charset)
+ . $replacement
+ . mb_substr($string,
+ $start + $length,
+ $string_length, // FIXME: I can't see why this is needed: - $start - $length,
+ $charset);
+
+ }
+
+
+ // else use normal substr_replace()
+ //
+ return is_null($length) ? substr_replace($string, $replacement, $start)
+ : substr_replace($string, $replacement, $start, $length);
+
+}
+