<?php

/**

 * Classes, which help reading streams of data from files.

 * Based on the classes from Danilo Segan <danilo@kvota.net>

 *

 * @version $Id: streams.php 138 2009-06-23 13:22:09Z nbachiyski $

 * @package pomo

 * @subpackage streams

 */

/**

 * Provides file-like methods for manipulating a string instead

 * of a physical file.

 */

class POMO_StringReader {

  var $_pos;

  var $_str;

	function POMO_StringReader($str = '') {

		$this->_str = $str;

		$this->_pos = 0;

		$this->is_overloaded = ((ini_get("mbstring.func_overload") & 2) != 0) && function_exists('mb_substr');

	}

	function _substr($string, $start, $length) {

		if ($this->is_overloaded) {

			return mb_substr($string,$start,$length,'ascii');

		} else {

			return substr($string,$start,$length);

		}

	}

	function _strlen($string) {

		if ($this->is_overloaded) {

			return mb_strlen($string,'ascii');

		} else {

			return strlen($string);

		}

	}

	function read($bytes) {

		$data = $this->_substr($this->_str, $this->_pos, $bytes);

		$this->_pos += $bytes;

		if ($this->_strlen($this->_str) < $this->_pos) $this->_pos = $this->_strlen($this->_str);

		return $data;

	}

	function seekto($pos) {

		$this->_pos = $pos;

		if ($this->_strlen($this->_str) < $this->_pos) $this->_pos = $this->_strlen($this->_str);

		return $this->_pos;

	}

	function pos() {

		return $this->_pos;

	}

	function length() {

		return $this->_strlen($this->_str);

	}

}

/**

 * Reads the contents of the file in the beginning.

 */

class POMO_CachedFileReader extends POMO_StringReader {

	function POMO_CachedFileReader($filename) {

		parent::POMO_StringReader();

		$this->_str = file_get_contents($filename);

		if (false === $this->_str)

			return false;

		$this->_pos = 0;

	}

}

/**

 * Allows reading integers from a file.

 */

class POMO_CachedIntFileReader extends POMO_CachedFileReader {

	var $endian = 'little';

	/**

	 * Opens a file and caches it.

	 *

	 * @param $filename string name of the file to be opened

	 * @param $endian string endianness of the words in the file, allowed

	 * 	values are 'little' or 'big'. Default value is 'little'

	 */

	function POMO_CachedIntFileReader($filename, $endian = 'little') {

		$this->endian = $endian;

		parent::POMO_CachedFileReader($filename);

	}

	/**

	 * Sets the endianness of the file.

	 *

	 * @param $endian string 'big' or 'little'

	 */

	function setEndian($endian) {

		$this->endian = $endian;

	}

	/**

	 * Reads a 32bit Integer from the Stream

	 *

	 * @return mixed The integer, corresponding to the next 32 bits from

	 * 	the stream of false if there are not enough bytes or on error

	 */

	function readint32() {

		$bytes = $this->read(4);

		if (4 != $this->_strlen($bytes))

			return false;

		$endian_letter = ('big' == $this->endian)? 'N' : 'V';

		$int = unpack($endian_letter, $bytes);

		return array_shift($int);

	}

	/**

	 * Reads an array of 32-bit Integers from the Stream

	 *

	 * @param integer count How many elements should be read

	 * @return mixed Array of integers or false if there isn't

	 * 	enough data or on error

	 */

	function readint32array($count) {

		$bytes = $this->read(4 * $count);

		if (4*$count != $this->_strlen($bytes))

			return false;

		$endian_letter = ('big' == $this->endian)? 'N' : 'V';

		return unpack($endian_letter.$count, $bytes);

	}

}

?>