protected function stripWhitespace($content)
{
// uniform line endings, make them all line feed
$content = str_replace(array("\r\n", "\r"), "\n", $content);
// collapse all non-line feed whitespace into a single space
$content = preg_replace('/[^\\S\\n]+/', ' ', $content);
// strip leading & trailing whitespace
$content = str_replace(array(" \n", "\n "), "\n", $content);
// collapse consecutive line feeds into just 1
$content = preg_replace('/\\n+/', "\n", $content);
$operatorsBefore = $this->getOperatorsForRegex($this->operatorsBefore, '/');
$operatorsAfter = $this->getOperatorsForRegex($this->operatorsAfter, '/');
$operators = $this->getOperatorsForRegex($this->operators, '/');
$keywordsBefore = $this->getKeywordsForRegex($this->keywordsBefore, '/');
$keywordsAfter = $this->getKeywordsForRegex($this->keywordsAfter, '/');
// strip whitespace that ends in (or next line begin with) an operator
// that allows statements to be broken up over multiple lines
unset($operatorsBefore['+'], $operatorsBefore['-'], $operatorsAfter['+'], $operatorsAfter['-']);
$content = preg_replace(array('/(' . implode('|', $operatorsBefore) . ')\\s+/', '/\\s+(' . implode('|', $operatorsAfter) . ')/'), '\\1', $content);
// make sure + and - can't be mistaken for, or joined into ++ and --
$content = preg_replace(array('/(?<![\\+\\-])\\s*([\\+\\-])(?![\\+\\-])/', '/(?<![\\+\\-])([\\+\\-])\\s*(?![\\+\\-])/'), '\\1', $content);
// collapse whitespace around reserved words into single space
$content = preg_replace('/(^|[;\\}\\s])\\K(' . implode('|', $keywordsBefore) . ')\\s+/', '\\2 ', $content);
$content = preg_replace('/\\s+(' . implode('|', $keywordsAfter) . ')(?=([;\\{\\s]|$))/', ' \\1', $content);
/*
* We didn't strip whitespace after a couple of operators because they
* could be used in different contexts and we can't be sure it's ok to
* strip the newlines. However, we can safely strip any non-line feed
* whitespace that follows them.
*/
$operatorsDiffBefore = array_diff($operators, $operatorsBefore);
$operatorsDiffAfter = array_diff($operators, $operatorsAfter);
$content = preg_replace('/(' . implode('|', $operatorsDiffBefore) . ')[^\\S\\n]+/', '\\1', $content);
$content = preg_replace('/[^\\S\\n]+(' . implode('|', $operatorsDiffAfter) . ')/', '\\1', $content);
/*
* Get rid of double semicolons, except where they can be used like:
* "for(v=1,_=b;;)", "for(v=1;;v++)" or "for(;;ja||(ja=true))".
* I'll safeguard these double semicolons inside for-loops by
* temporarily replacing them with an invalid condition: they won't have
* a double semicolon and will be easy to spot to restore afterwards.
*/
$content = preg_replace('/\\bfor\\(([^;]*);;([^;]*)\\)/', 'for(\\1;-;\\2)', $content);
$content = preg_replace('/;+/', ';', $content);
$content = preg_replace('/\\bfor\\(([^;]*);-;([^;]*)\\)/', 'for(\\1;;\\2)', $content);
/*
* Next, we'll be removing all semicolons where ASI kicks in.
* for-loops however, can have an empty body (ending in only a
* semicolon), like: `for(i=1;i<3;i++);`
* Here, nothing happens during the loop; it's just used to keep
* increasing `i`. With that ; omitted, the next line would be expected
* to be the for-loop's body...
* I'm going to double that semicolon (if any) so after the next line,
* which strips semicolons here & there, we're still left with this one.
*/
$content = preg_replace('/(for\\([^;]*;[^;]*;[^;\\{]*\\));(\\}|$)/s', '\\1;;\\2', $content);
/*
* We also can't strip empty else-statements. Even though they're
* useless and probably shouldn't be in the code in the first place, we
* shouldn't be stripping the `;` that follows it as it breaks the code.
* We can just remove those useless else-statements completely.
*
* @see https://github.com/matthiasmullie/minify/issues/91
*/
$content = preg_replace('/else;/s', '', $content);
/*
* We also don't really want to terminate statements followed by closing
* curly braces (which we've ignored completely up until now) or end-of-
* script: ASI will kick in here & we're all about minifying.
* Semicolons at beginning of the file don't make any sense either.
*/
$content = preg_replace('/;(\\}|$)/s', '\\1', $content);
$content = ltrim($content, ';');
// get rid of remaining whitespace af beginning/end
return trim($content);
}
