<?php
namespace splitbrain\JSStrip;
/**
* Strip comments and whitespaces from given JavaScript Code
*
* This is a port of Nick Galbreath's python tool jsstrip.py which is
* released under BSD license. See link for original code.
*
* @author Nick Galbreath <nickg@modp.com>
* @author Andreas Gohr <andi@splitbrain.org>
* @link http://code.google.com/p/jsstrip/
*/
class JSStrip
{
const REGEX_STARTERS = [
'(', '=', '<', '>', '?', '[', '{', ',', ';', ':', '!', '&', '|', '+', '-', '%', '~', '^',
'return', 'yield', 'else', 'throw', 'await'
];
const WHITESPACE_CHARS = [" ", "\t", "\n", "\r", "\0", "\x0B"];
/** items that don't need spaces next to them */
const CHARS = "^&|!+\-*\/%=\?:;,{}()<>% \t\n\r'\"`[]~^";
/**
* items which need a space if the sign before and after whitespace is equal.
* E.g. '+ ++' may not be compressed to '+++' --> syntax error.
*/
const OPS = "+-/";
protected $source;
protected $idx = 0;
protected $line = 0;
/**
* Compress the given code
*
* @param string $source The JavaScript code to compress
* @return string
* @throws Exception if parsing fails
*/
function compress($source)
{
$source = ltrim($source); // strip all initial whitespace
$source .= "\n";
$idx = 0; // char index for input string
// track these as member variables
$this->source = $source;
$this->line = 1;
$this->idx = &$idx;
$j = 0; // char forward index for input string
$slen = strlen($source); // size of input string
$lch = ''; // last char added
$result = ''; // we store the final result here
while ($idx < $slen) {
// skip all "boring" characters. This is either
// reserved word (e.g. "for", "else", "if") or a
// variable/object/method (e.g. "foo.color")
while ($idx < $slen && (strpos(self::CHARS, $source[$idx]) === false)) {
$result .= $source[$idx];
$idx = $idx + 1;
}
$ch = $source[$idx];
// multiline comments (keeping IE conditionals)
if ($ch == '/' && $source[$idx + 1] == '*' && $source[$idx + 2] != '@') {
$endC = strpos($source, '*/', $idx + 2);
if ($endC === false) $this->fatal('Found invalid /*..*/ comment');
// check if this is a NOCOMPRESS comment
if (substr($source, $idx, $endC + 2 - $idx) == '/* BEGIN NOCOMPRESS */') {
// take nested NOCOMPRESS comments into account
$depth = 0;
$nextNC = $endC;
do {
$beginNC = strpos($source, '/* BEGIN NOCOMPRESS */', $nextNC + 2);
$endNC = strpos($source, '/* END NOCOMPRESS */', $nextNC + 2);
if ($endNC === false) $this->fatal('Found invalid NOCOMPRESS comment');
if ($beginNC !== false && $beginNC < $endNC) {
$depth++;
$nextNC = $beginNC;
} else {
$depth--;
$nextNC = $endNC;
}
} while ($depth >= 0);
// verbatim copy contents, trimming but putting it on its own line
$result .= "\n" . trim(substr($source, $idx + 22, $endNC - ($idx + 22))) . "\n"; // BEGIN comment = 22 chars
$idx = $endNC + 20; // END comment = 20 chars
} else {
$idx = $endC + 2;
}
continue;
}
// singleline
if ($ch == '/' && $source[$idx + 1] == '/') {
$endC = strpos($source, "\n", $idx + 2);
if ($endC === false) $this->fatal('Invalid comment'); // not sure this can happen
$idx = $endC;
continue;
}
// tricky. might be an RE
if ($ch == '/') {
// rewind, skip white space
$j = 1;
while (in_array($source[$idx - $j], self::WHITESPACE_CHARS)) {
$j = $j + 1;
}
if (current(array_filter(
self::REGEX_STARTERS,
function ($e) use ($source, $idx, $j) {
$len = strlen($e);
$idx = $idx - $j + 1 - $len;
return substr($source, $idx, $len) === $e;
}
))) {
// yes, this is an re
// now move forward and find the end of it
$j = 1;
// we set this flag when inside a character class definition, enclosed by brackets [] where '/' does not terminate the re
$ccd = false;
while ($ccd || $source[$idx + $j] != '/') {
if ($source[$idx + $j] == '\\') $j = $j + 2;
else {
$j++;
// check if we entered/exited a character class definition and set flag accordingly
if ($source[$idx + $j - 1] == '[') $ccd = true;
else if ($source[$idx + $j - 1] == ']') $ccd = false;
}
}
$result .= substr($source, $idx, $j + 1);
$idx = $idx + $j + 1;
continue;
}
}
// double quote strings
if ($ch == '"') {
$j = 1;
while (($idx + $j < $slen) && $source[$idx + $j] != '"') {
if ($source[$idx + $j] == '\\' && ($source[$idx + $j + 1] == '"' || $source[$idx + $j + 1] == '\\')) {
$j += 2;
} else {
$j += 1;
}
}
$string = substr($source, $idx, $j + 1);
// remove multiline markers:
$string = str_replace("\\\n", '', $string);
$result .= $string;
$idx = $idx + $j + 1;
continue;
}
// single quote strings
if ($ch == "'") {
$j = 1;
while (($idx + $j < $slen) && $source[$idx + $j] != "'") {
if ($source[$idx + $j] == '\\' && ($source[$idx + $j + 1] == "'" || $source[$idx + $j + 1] == '\\')) {
$j += 2;
} else {
$j += 1;
}
}
$string = substr($source, $idx, $j + 1);
// remove multiline markers:
$string = str_replace("\\\n", '', $string);
$result .= $string;
$idx = $idx + $j + 1;
continue;
}
// backtick strings
if ($ch == "`") {
$j = 1;
while (($idx + $j < $slen) && $source[$idx + $j] != "`") {
if ($source[$idx + $j] == '\\' && ($source[$idx + $j + 1] == "`" || $source[$idx + $j + 1] == '\\')) {
$j += 2;
} else {
$j += 1;
}
}
$string = substr($source, $idx, $j + 1);
// remove multiline markers:
$string = str_replace("\\\n", '', $string);
$result .= $string;
$idx = $idx + $j + 1;
continue;
}
// whitespaces
if ($ch == ' ' || $ch == "\r" || $ch == "\n" || $ch == "\t") {
$lch = substr($result, -1);
if ($ch == "\n") $this->line++;
// Only consider deleting whitespace if the signs before and after
// are not equal and are not an operator which may not follow itself.
if ($idx + 1 < $slen && ((!$lch || $source[$idx + 1] == ' ')
|| $lch != $source[$idx + 1]
|| strpos(self::OPS, $source[$idx + 1]) === false)) {
// leading spaces
if ($idx + 1 < $slen && (strpos(self::CHARS, $source[$idx + 1]) !== false)) {
$idx = $idx + 1;
continue;
}
// trailing spaces
// if this ch is space AND the last char processed
// is special, then skip the space
if ($lch && (strpos(self::CHARS, $lch) !== false)) {
$idx = $idx + 1;
continue;
}
}
// else after all of this convert the "whitespace" to
// a single space. It will get appended below
$ch = ' ';
}
// other chars
$result .= $ch;
$idx = $idx + 1;
}
return trim($result);
}
/**
* Helper to throw a fatal error
*
* Tries to give some context to locate the error
*
* @param string $msg
* @throws Exception
*/
protected function fatal($msg)
{
$before = substr($this->source, max(0, $this->idx - 15), $this->idx);
$after = substr($this->source, $this->idx, 15);
$msg = "$msg on line {$this->line}: '{$before}â—Ž{$after}'";
throw new Exception($msg);
}
}