<?php
/*
 * Limb PHP Framework
 *
 * @link http://limb-project.com 
 * @copyright  Copyright &copy; 2004-2007 BIT(http://bit-creative.com)
 * @license    LGPL http://www.gnu.org/copyleft/lesser.html 
 */

/**
 * The scanner tokenizes input content ({@link input()})
 * and provides a "scanner" interface which can go forward
 * ({@link next()}) and backward (({@link back()}) )
 * along the tokens. It also correlates the toekens with line
 * number ({@link line()}).
 *
 * Part of the credits for this scanner is due to phpDocumentor,
 * from which I borrowed some ideas to make it work.
 *
 * @author Oak Nauhygon <ezpdo4php@gmail.com>
 * @package core
 * @version $Id$
 */
class lmbPHPTokenizer
{
  /**
   * List of tokens that can contain a newline
   * @var array
   */
  static public $newline_tokens = array(
      T_WHITESPACE,
      T_ENCAPSED_AND_WHITESPACE,
      T_COMMENT,
      T_DOC_COMMENT,
      T_OPEN_TAG,
      T_CLOSE_TAG,
      T_INLINE_HTML
      );

  /**
   * The input content
   * @var string
   */
  protected $input;

  /**
   * tokenized array from {@link token_get_all()}
   * @var array
   */
  protected $tokens;

  /**
   * current token position
   * @var integer
   */
  protected $pos = 0;

  /**
   * current source line number
   * @var integer
   */
  protected $line = 0;

  /**
   * Constructor
   * @param string input content
   */
  public function __construct($input = '') {
      if (!empty($input)) {
          $this->input($input);
      }
  }

  /**
   * get input if no param supplied or set input if param is a non-empty string
   * @param string input content
   * @return string|bool
   */
  public function input($input = false) {

      // if input is false, return
      if ($input === false) {
          return $this->input;
      }

      // trim the \r\n input content
      $input = rtrim(ltrim($input, "\r\n"));
      if (empty($input)) {
          return false;
      }

      // use reference to save memory
      $this->input = & $input;

      // unset the tokens so when next() is called the frist
      // time, it will call reset()
      unset($this->tokens);

      return true;
  }

  /**
   * Tokenize input content and reset current
   * token position and line number
   * @return void
   */
  public function reset() {
      $this->tokens = @token_get_all($this->input);
      $this->pos = 0;
      $this->line = 0;
  }

  /**
   * Fetch the next token
   * @return string|array token from tokenizer
   */
  function next() {

      // check if we need to reset (tokenize input)
      if (empty($this->tokens)) {
          $this->reset();
      }

      // check if token at the cur position set
      if ( !isset($this->tokens[$this->pos]) ) {
          return false;
      }

      // keep track of the old line
      $oldline = $this->line;

      // now get the current token
      $word = $this->tokens[$this->pos++];

      // correlate line and token
      if ( is_array($word) ) {

          // count line num for special tokens ({@link $newline_tokens})
          if ( in_array($word[0], lmbPHPTokenizer::$newline_tokens) ) {
              $this->line += substr_count($word[1], "\n");
          }

          // always skip whitespace
          if ( $word[0] == T_WHITESPACE )    {
              return $this->next();
          }
      }

      return $word;
  }

  /**
   * Go back one token (reverse of {@link next()})
   * @return false|string|array
   */
  public function back() {

      $this->pos --;

      // check if it's the beginning
      if ($this->pos < 0) {
          $this->pos = 0;
          return false;
      }

      $word = $this->tokens[$this->pos];

      if ( is_array($word) ) {

          if ( $word[0] == T_WHITESPACE )
              return $this->next();

          if ( in_array($word[0], lmbPHPTokenizer::$newline_tokens) ) {
              $this->line -= substr_count($word[1], "\n");
          }
      }
  }

  /**
   * Get the current line number
   * @return integer
   */
  public function line() {
      return $this->line;
  }
}

?>