1 unicode.inc | backdrop_substr($text, $start, $length = NULL) |
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.
Parameters
string $text: The input string.
int $start: The position at which to start reading.
int $length: The number of characters to read.
Return value
string: The shortened string.
Related topics
File
- core/
includes/ unicode.inc, line 609 - Provides Unicode-related conversions and operations.
Code
function backdrop_substr($text, $start, $length = NULL) {
// Bail early if $text is NULL.
// @todo Remove this in 2.x.
if (is_null($text)) {
return "";
}
global $multibyte;
$text = (string) $text;
if ($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));
}
}