<?php
/**
* JShrink
*
* Copyright (c) 2009-2012, Robert Hafner <tedivm@tedivm.com>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of Robert Hafner nor the names of his
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @package JShrink
* @author Robert Hafner <tedivm@tedivm.com>
* @copyright 2009-2012 Robert Hafner <tedivm@tedivm.com>
* @license http://www.opensource.org/licenses/bsd-license.php BSD License
* @link https://github.com/tedivm/JShrink
* @version Release: 0.5.1
*/


/**
* JShrink_Minifier
*
* Usage - JShrink_Minifier::minify($js);
* Usage - JShrink_Minifier::minify($js, $options);
* Usage - JShrink_Minifier::minify($js, array('flaggedComments' => false));
*
* @package JShrink
* @author Robert Hafner <tedivm@tedivm.com>
* @license http://www.opensource.org/licenses/bsd-license.php BSD License
*/
class JShrink_Minifier
{
/**
* The input javascript to be minified.
*
* @var string
*/
protected $input;

/**
* The location of the character (in the input string) that is next to be
* processed.
*
* @var int
*/
protected $index = 0;

/**
* The first of the characters currently being looked at.
*
* @var string
*/
protected $a = '';


/**
* The next character being looked at (after a);
*
* @var string
*/
protected $b = '';

/**
* This character is only active when certain look ahead actions take place.
*
* @var string
*/
protected $c;

/**
* Contains the options for the current minification process.
*
* @var array
*/
protected $options;

/**
* Contains the default options for minification. This array is merged with
* the one passed in by the user to create the request specific set of
* options (stored in the $options attribute).
*
* @var array
*/
static protected $defaultOptions = array('flaggedComments' => true);

/**
* Contains a copy of the JShrink object used to run minification. This is
* only used internally, and is only stored for performance reasons. There
* is no internal data shared between minification requests.
*/
static protected $jshrink;

/**
* Minifier::minify takes a string containing javascript and removes
* unneeded characters in order to shrink the code without altering it's
* functionality.
*/
static public function minify($js, $options = array())
{
try{
ob_start();
$currentOptions = array_merge(self::$defaultOptions, $options);

if(!isset(self::$jshrink))
self::$jshrink = new JShrink_Minifier();

self::$jshrink->breakdownScript($js, $currentOptions);
return ob_get_clean();

}catch(Exception $e){
if(isset(self::$jshrink))
self::$jshrink->clean();

ob_end_clean();
throw $e;
}
}

/**
* Processes a javascript string and outputs only the required characters,
* stripping out all unneeded characters.
*
* @param string $js The raw javascript to be minified
* @param array $currentOptions Various runtime options in an associative array
*/
protected function breakdownScript($js, $currentOptions)
{
// reset work attributes in case this isn't the first run.
$this->clean();

$this->options = $currentOptions;

$js = str_replace("\r\n", "\n", $js);
$this->input = str_replace("\r", "\n", $js);


$this->a = $this->getReal();

// the only time the length can be higher than 1 is if a conditional
// comment needs to be displayed and the only time that can happen for
// $a is on the very first run
while(strlen($this->a) > 1)
{
echo $this->a;
$this->a = $this->getReal();
}

$this->b = $this->getReal();

while($this->a !== false && !is_null($this->a) && $this->a !== '')
{

// now we give $b the same check for conditional comments we gave $a
// before we began looping
if(strlen($this->b) > 1)
{
echo $this->a . $this->b;
$this->a = $this->getReal();
$this->b = $this->getReal();
continue;
}

switch($this->a)
{
// new lines
case "\n":
// if the next line is something that can't stand alone
// preserve the newline
if(strpos('(-+{[@', $this->b) !== false)
{
echo $this->a;
$this->saveString();
break;
}

// if its a space we move down to the string test below
if($this->b === ' ')
break;

// otherwise we treat the newline like a space

case ' ':
if(self::isAlphaNumeric($this->b))
echo $this->a;

$this->saveString();
break;

default:
switch($this->b)
{
case "\n":
if(strpos('}])+-"\'', $this->a) !== false)
{
echo $this->a;
$this->saveString();
break;
}else{
if(self::isAlphaNumeric($this->a))
{
echo $this->a;
$this->saveString();
}
}
break;

case ' ':
if(!self::isAlphaNumeric($this->a))
break;

default:
// check for some regex that breaks stuff
if($this->a == '/' && ($this->b == '\'' || $this->b == '"'))
{
$this->saveRegex();
continue;
}

echo $this->a;
$this->saveString();
break;
}
}

// do reg check of doom
$this->b = $this->getReal();

if(($this->b == '/' && strpos('(,=:[!&|?', $this->a) !== false))
$this->saveRegex();
}
$this->clean();
}

/**
* Returns the next string for processing based off of the current index.
*
* @return string
*/
protected function getChar()
{
if(isset($this->c))
{
$char = $this->c;
unset($this->c);
}else{
$tchar = substr($this->input, $this->index, 1);
if(isset($tchar) && $tchar !== false)
{
$char = $tchar;
$this->index++;
}else{
return false;
}
}

if($char !== "\n" && ord($char) < 32)
return ' ';

return $char;
}

/**
* This function gets the next "real" character. It is essentially a wrapper
* around the getChar function that skips comments. This has significant
* performance benefits as the skipping is done using native functions (ie,
* c code) rather than in script php.
*
* @return string Next 'real' character to be processed.
*/
protected function getReal()
{
$startIndex = $this->index;
$char = $this->getChar();

if($char == '/')
{
$this->c = $this->getChar();

if($this->c == '/')
{
$thirdCommentString = substr($this->input, $this->index, 1);

// kill rest of line
$char = $this->getNext("\n");

if($thirdCommentString == '@')
{
$endPoint = ($this->index) - $startIndex;
unset($this->c);
$char = "\n" . substr($this->input, $startIndex, $endPoint);
}else{
$char = $this->getChar();
$char = $this->getChar();
}

}elseif($this->c == '*'){

$this->getChar(); // current C
$thirdCommentString = $this->getChar();

if($thirdCommentString == '@')
{
// conditional comment

// we're gonna back up a bit and and send the comment back,
// where the first char will be echoed and the rest will be
// treated like a string
$this->index = $this->index-2;
return '/';

}elseif($this->getNext('*/')){
// kill everything up to the next */

$this->getChar(); // get *
$this->getChar(); // get /

$char = $this->getChar(); // get next real character

// if YUI-style comments are enabled we reinsert it into the stream
if($this->options['flaggedComments'] && $thirdCommentString == '!')
{
$endPoint = ($this->index - 1) - $startIndex;
echo "\n" . substr($this->input, $startIndex, $endPoint) . "\n";
}

}else{
$char = false;
}

if($char === false)
throw new RuntimeException('Stray comment. ' . $this->index);

// if we're here c is part of the comment and therefore tossed
if(isset($this->c))
unset($this->c);
}
}
return $char;
}

/**
* Pushes the index ahead to the next instance of the supplied string. If it
* is found the first character of the string is returned.
*
* @return string|false Returns the first character of the string or false.
*/
protected function getNext($string)
{
$pos = strpos($this->input, $string, $this->index);

if($pos === false)
return false;

$this->index = $pos;
return substr($this->input, $this->index, 1);
}

/**
* When a javascript string is detected this function crawls for the end of
* it and saves the whole string.
*
*/
protected function saveString()
{
$this->a = $this->b;
if($this->a == "'" || $this->a == '"') // is the character a quote
{
// save literal string
$stringType = $this->a;

while(1)
{
echo $this->a;
$this->a = $this->getChar();

switch($this->a)
{
case $stringType:
break 2;

case "\n":
throw new RuntimeException('Unclosed string. ' . $this->index);
break;

case '\\':
echo $this->a;
$this->a = $this->getChar();
}
}
}
}

/**
* When a regular expression is detected this funcion crawls for the end of
* it and saves the whole regex.
*/
protected function saveRegex()
{
echo $this->a . $this->b;

while(($this->a = $this->getChar()) !== false)
{
if($this->a == '/')
break;

if($this->a == '\\')
{
echo $this->a;
$this->a = $this->getChar();
}

if($this->a == "\n")
throw new RuntimeException('Stray regex pattern. ' . $this->index);

echo $this->a;
}
$this->b = $this->getReal();
}

/**
* Resets attributes that do not need to be stored between requests so that
* the next request is ready to go.
*/
protected function clean()
{
unset($this->input);
$this->index = 0;
$this->a = $this->b = '';
unset($this->c);
unset($this->options);
}

/**
* Checks to see if a character is alphanumeric.
*
* @return bool
*/
static protected function isAlphaNumeric($char)
{
return preg_match('/^[\w\$]$/', $char) === 1 || $char == '/';
}

}