<?php
/**
 * jsmin.php - PHP implementation of Douglas Crockford's JSMin.
 *
 * This is pretty much a direct port of jsmin.c to PHP with just a few
 * PHP-specific performance tweaks. Also, whereas jsmin.c reads from stdin and
 * outputs to stdout, this library accepts a string as input and returns another
 * string as output.
 *
 * PHP 5 or higher is required.
 *
 * Permission is hereby granted to use this version of the library under the
 * same terms as jsmin.c, which has the following license:
 *
 * --
 * Copyright (c) 2002 Douglas Crockford  (www.crockford.com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * The Software shall be used for Good, not Evil.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * --
 *
 * @package Prado\Web\Javascripts
 * @author Ryan Grove <ryan@wonko.com>
 * @copyright 2002 Douglas Crockford <douglas@crockford.com> (jsmin.c)
 * @copyright 2008 Ryan Grove <ryan@wonko.com> (PHP port)
 * @license http://opensource.org/licenses/mit-license.php MIT License
 * @link http://code.google.com/p/jsmin-php/
 */

class JSMin {
  const ORD_LF    = 10;
  const ORD_SPACE = 32;

  protected $a           = '';
  protected $b           = '';
  protected $input       = '';
  protected $inputIndex  = 0;
  protected $inputLength = 0;
  protected $lookAhead   = null;
  protected $output      = '';

  // -- Public Static Methods --------------------------------------------------

  public static function minify($js) {
    $jsmin = new JSMin($js);
    return $jsmin->min();
  }

  // -- Public Instance Methods ------------------------------------------------

  public function __construct($input) {
    $this->input       = str_replace("\r\n", "\n", $input);
    $this->inputLength = strlen($this->input);
  }

  // -- Protected Instance Methods ---------------------------------------------

  protected function action($d) {
    switch($d) {
      case 1:
        $this->output .= $this->a;

      case 2:
        $this->a = $this->b;

        if ($this->a === "'" || $this->a === '"') {
          for (;;) {
            $this->output .= $this->a;
            $this->a       = $this->get();

            if ($this->a === $this->b) {
              break;
            }

            if (ord($this->a) <= self::ORD_LF) {
              throw new JSMinException('Unterminated string literal.');
            }

            if ($this->a === '\\') {
              $this->output .= $this->a;
              $this->a       = $this->get();
            }
          }
        }

      case 3:
        $this->b = $this->next();

        if ($this->b === '/' && (
            $this->a === '(' || $this->a === ',' || $this->a === '=' ||
            $this->a === ':' || $this->a === '[' || $this->a === '!' ||
            $this->a === '&' || $this->a === '|' || $this->a === '?')) {

          $this->output .= $this->a . $this->b;

          for (;;) {
            $this->a = $this->get();

            if ($this->a === '/') {
              break;
            } elseif ($this->a === '\\') {
              $this->output .= $this->a;
              $this->a       = $this->get();
            } elseif (ord($this->a) <= self::ORD_LF) {
              throw new JSMinException('Unterminated regular expression '.
                  'literal.');
            }

            $this->output .= $this->a;
          }

          $this->b = $this->next();
        }
    }
  }

  protected function get() {
    $c = $this->lookAhead;
    $this->lookAhead = null;

    if ($c === null) {
      if ($this->inputIndex < $this->inputLength) {
        $c = $this->input[$this->inputIndex];
        $this->inputIndex += 1;
      } else {
        $c = null;
      }
    }

    if ($c === "\r") {
      return "\n";
    }

    if ($c === null || $c === "\n" || ord($c) >= self::ORD_SPACE) {
      return $c;
    }

    return ' ';
  }

  protected function isAlphaNum($c) {
    return ord($c) > 126 || $c === '\\' || preg_match('/^[\w\$]$/', $c) === 1;
  }

  protected function min() {
    $this->a = "\n";
    $this->action(3);

    while ($this->a !== null) {
      switch ($this->a) {
        case ' ':
          if ($this->isAlphaNum($this->b)) {
            $this->action(1);
          } else {
            $this->action(2);
          }
          break;

        case "\n":
          switch ($this->b) {
            case '{':
            case '[':
            case '(':
            case '+':
            case '-':
              $this->action(1);
              break;

            case ' ':
              $this->action(3);
              break;

            default:
              if ($this->isAlphaNum($this->b)) {
                $this->action(1);
              }
              else {
                $this->action(2);
              }
          }
          break;

        default:
          switch ($this->b) {
            case ' ':
              if ($this->isAlphaNum($this->a)) {
                $this->action(1);
                break;
              }

              $this->action(3);
              break;

            case "\n":
              switch ($this->a) {
                case '}':
                case ']':
                case ')':
                case '+':
                case '-':
                case '"':
                case "'":
                  $this->action(1);
                  break;

                default:
                  if ($this->isAlphaNum($this->a)) {
                    $this->action(1);
                  }
                  else {
                    $this->action(3);
                  }
              }
              break;

            default:
              $this->action(1);
              break;
          }
      }
    }

    return $this->output;
  }

  protected function next() {
    $c = $this->get();

    if ($c === '/') {
      switch($this->peek()) {
        case '/':
          for (;;) {
            $c = $this->get();

            if (ord($c) <= self::ORD_LF) {
              return $c;
            }
          }

        case '*':
          $this->get();

          for (;;) {
            switch($this->get()) {
              case '*':
                if ($this->peek() === '/') {
                  $this->get();
                  return ' ';
                }
                break;

              case null:
                throw new JSMinException('Unterminated comment.');
            }
          }

        default:
          return $c;
      }
    }

    return $c;
  }

  protected function peek() {
    $this->lookAhead = $this->get();
    return $this->lookAhead;
  }
}