Subversion-Projekte lars-tiefland.php_share

<?php

/**

 *  Equation driver for Text_CAPTCHA.

 *  Returns simple equations as string, e.g. "9 - 2"

 *

 *  @author  Christian Weiske <cweiske@php.net>

 *  @author  Christian Wenz <wenz@php.net>

 *  @license BSD License

 */

require_once 'Text/CAPTCHA.php';

class Text_CAPTCHA_Driver_Equation extends Text_CAPTCHA

{

    /**

     * Operators that may be used in the equation.

     * Two numbers have to be filled in, and

     *  %s is needed since number2text conversion

     *  may be applied and strings filled in.

     *

     * @access protected

     * @var array

     */

    var $_operators = array(

        '%s * %s',

        '%s + %s',

        '%s - %s',

        'min(%s, %s)',

        'max(%s, %s)'

    );

    /**

     * The equation to solve.

     *

     * @access protected

     * @var string

     */

    var $_equation = null;

    /**

     * Minimal number to use in an equation.

     *

     * @access protected

     * @var int

     */

    var $_min = 1;

    /**

     * Maximum number to use in an equation.

     *

     * @access protected

     * @var int

     */

    var $_max = 10;

    /**

     * Whether numbers shall be converted to text

     *

     * @access protected

     * @var bool

     */

    var $_numbersToText = false;

    /**

     * Complexity of the generated equations.

     * 1 - simple ones such as "1 + 10"

     * 2 - harder ones such as "(3-2)*(min(5,6))"

     *

     * @access protected

     * @var int

     */

    var $_severity = 1;

    /**

     * Last error

     *

     * @access protected

     * @var PEAR_Error

     */

    var $_error = null;

    /**

     * Initialize the driver.

     *

     * @param array $options Optionally supply options for the initialization phase

     *

     * @access public

     * @return true on success, PEAR_Error on error.

     */

    function init($options = array())

    {

        if (isset($options['min'])) {

            $this->_min = (int)$options['min'];

        } else {

            $this->_min = 1;

        }

        if (isset($options['max'])) {

            $this->_max = (int)$options['max'];

        } else {

            $this->_max = 10;

        }

        if (isset($options['numbersToText'])) {

            $this->_numbersToText = (bool)$options['numbersToText'];

        } else {

            $this->_numbersToText = false;

        }

        if (isset($options['severity'])) {

            $this->_severity = (int)$options['severity'];

        } else {

            $this->_severity = 1;

        }

        if ($this->_numbersToText) {

            include_once 'Numbers/Words.php';

            if (!class_exists('Numbers_Words')) {

                $this->_error = PEAR::raiseError('Number_Words package required', true);

                return $this->_error;

            }

        }

        return $this->_createPhrase();

    }

    /**

     * Create random CAPTCHA equation.

     *

     * This method creates a random equation. The equation is

     * stored in $this->_equation, the solution in $this->_phrase.

     *

     * @access protected

     * @return mixed    true on success, PEAR_Error on error

     */

    function _createPhrase()

    {

        switch ($this->_severity) {

            case 1:

                list($this->_equation, $this->_phrase) = $this->_createSimpleEquation();

                break;

            case 2:

                list($eq1, $sol1) = $this->_createSimpleEquation();

                list($eq2, $sol2) = $this->_createSimpleEquation();

                $op3 = $this->_operators[rand(0, count($this->_operators) - 1)];

                list($eq3, $this->_phrase) = $this->_solveSimpleEquation($sol1, $sol2, $op3);

                $this->_equation = sprintf($op3, '(' . $eq1 . ')', '(' . $eq2 . ')');

                break;

            default:

                $this->_error = PEAR::raiseError('Equation complexity of ' . $this->_severity . ' not supported', true);

                return $this->_error;

        }

        return true;

    }

    /**

     * Creates a simple equation of type (number operator number)

     *

     * @access protected

     * @return array    Array with equation and solution

     */

    function _createSimpleEquation()

    {

        $one = rand($this->_min, $this->_max);

        $two = rand($this->_min, $this->_max);

        $operator = $this->_operators[rand(0, count($this->_operators) - 1)];

        return $this->_solveSimpleEquation($one, $two, $operator);

    }

    /**

     * Solves a simple equation with two given numbers

     * and one operator as defined in $this->_operators.

     *

     * Also converts the numbers to words if required.

     *

     * @param int    $one      First number

     * @param int    $two      Second number

     * @param string $operator Operator

     *

     * @access protected

     * @return array    Array with equation and solution

     */

    function _solveSimpleEquation($one, $two, $operator)

    {

        $equation = sprintf($operator, $one, $two);

        $code = '$solution=' . $equation . ';';

        eval($code);

        if ($this->_numbersToText) {

            $equation = sprintf($operator, Numbers_Words::toWords($one), Numbers_Words::toWords($two));

        }

        return array($equation, $solution);

    }

    /**

     * Return the solution to the equation.

     *

     * This method returns the CAPTCHA phrase, which is

     *  the solution to the equation.

     *

     * @access  public

     * @return  string   secret phrase

     */

    function getPhrase()

    {

        return $this->_phrase;

    }

    /**

     * Creates the captcha. This method is a placeholder,

     *  since the equation is created in _createPhrase()

     *

     * @access protected

     * @return PEAR_Error

     */

    function _createCAPTCHA()

    {

        //is already done in _createPhrase();

    }

    /**

     * Returns the CAPTCHA (as a string)

     *

     * @access public

     * @return string

     */

    function getCAPTCHA()

    {

        return $this->_equation;

    }

}//class Text_CAPTCHA_Driver_TextEquation extends Text_CAPTCHA