diff options
Diffstat (limited to 'question.php')
| -rw-r--r-- | question.php | 227 |
1 files changed, 113 insertions, 114 deletions
diff --git a/question.php b/question.php index a3c7dfa..e9dffcf 100644 --- a/question.php +++ b/question.php @@ -17,9 +17,8 @@ /** * algebra answer question definition class. * - * @package qtype - * @subpackage algebra - * @author Roger Moore <rwmoore 'at' ualberta.ca> + * @package qtype_algebra + * @author Roger Moore <rwmoore@ualberta.ca> * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ @@ -41,14 +40,14 @@ class qtype_algebra_question extends question_graded_by_strategy /** @var array of question_answer. */ public $answers = array(); - /** @var array of question_answer. */ - public $variables = array(); - public $compareby; - public $nchecks; - public $tolerance; - public $allowedfuncs; - public $disallow; - public $answerprefix; + /** @var array of question_answer. */ + public $variables = array(); + public $compareby; + public $nchecks; + public $tolerance; + public $allowedfuncs; + public $disallow; + public $answerprefix; public function __construct() { parent::__construct(new question_first_matching_answer_grading_strategy($this)); @@ -77,17 +76,17 @@ class qtype_algebra_question extends question_graded_by_strategy } return get_string('pleaseenterananswer', 'qtype_algebra'); } - - /** - * Parses the given expression with the parser if required. - * - * This method will check to see if the argument it is given is already a parsed - * expression and if not will attempt to parse it. - * + + /** + * Parses the given expression with the parser if required. + * + * This method will check to see if the argument it is given is already a parsed + * expression and if not will attempt to parse it. + * * @param $expr expression which will be parsed - * @return top term of the parse tree or a string if an exception is thrown - */ - public function parse_expression($expr) { + * @return top term of the parse tree or a string if an exception is thrown + */ + public function parse_expression($expr) { // Check to see if this is already a parsed expression if(is_a($expr,'qtype_algebra_parser_term')) { // It is a parsed expression so simply return it @@ -101,32 +100,32 @@ class qtype_algebra_question extends question_graded_by_strategy $varnames[]=$var->name; } } - // We now assume that we have a string to parse. Create a parser instance to + // We now assume that we have a string to parse. Create a parser instance to // to this and return the parser expression at the top of the parse tree - $p=new qtype_algebra_parser; + $p=new qtype_algebra_parser; // Perform the actual parsing inside a try-catch block so that any exceptions // can be caught and converted into errors - try { - return $p->parse($expr,$varnames); - } catch(Exception $e) { - // If the expression cannot be parsed then return a null term. This will + try { + return $p->parse($expr,$varnames); + } catch(Exception $e) { + // If the expression cannot be parsed then return a null term. This will // make Moodle treat the answer as wrong. // TODO: Would be nice to have support for 'invalid answer' in the quiz // engine since an unparseable response is usually caused by a silly typo - return new qtype_algebra_parser_nullterm; - } - } + return new qtype_algebra_parser_nullterm; + } + } - /** - * Parses the given expression with the parser if required. - * - * This method will parse the expression and return a TeX string - * or empty string - * + /** + * Parses the given expression with the parser if required. + * + * This method will parse the expression and return a TeX string + * or empty string + * * @param $expr expression which will be parsed - * @return top term of the parse tree or a string if an exception is thrown - */ - public function formated_expression($text) { + * @return top term of the parse tree or a string if an exception is thrown + */ + public function formated_expression($text) { // Create an array of variable names for the parser from the question if defined $varnames=array(); @@ -135,18 +134,18 @@ class qtype_algebra_question extends question_graded_by_strategy $varnames[]=$var->name; } } - // We now assume that we have a string to parse. Create a parser instance to + // We now assume that we have a string to parse. Create a parser instance to // to this and return the parser expression at the top of the parse tree - $p=new qtype_algebra_parser; + $p=new qtype_algebra_parser; // Perform the actual parsing inside a try-catch block so that any exceptions // can be caught and converted into errors - try { + try { $exp = $p->parse($text, $varnames); - return '$$'.$exp->tex().'$$'; - } catch(Exception $e) { - return ''; - } - } + return '$$'.$exp->tex().'$$'; + } catch(Exception $e) { + return ''; + } + } public function is_same_response(array $prevresponse, array $newresponse) { // Check that both states have valid responses @@ -154,11 +153,11 @@ class qtype_algebra_question extends question_graded_by_strategy // At last one of the states did not have a response set so return false by default return false; } - // Parse the previous response + // Parse the previous response $expr=$this->parse_expression($prevresponse['answer']); // Parse the new response $testexpr=$this->parse_expression($newresponse['answer']); - // The type of comparison done depends on the comparision algorithm selected by + // The type of comparison done depends on the comparision algorithm selected by // the question. Use the defined algorithm to select which comparison function // to call... if($this->compareby == 'sage') { @@ -182,68 +181,68 @@ class qtype_algebra_question extends question_graded_by_strategy if ($answer->answer == '*') { return true; } - $expr=$this->parse_expression($response['answer']); + $expr=$this->parse_expression($response['answer']); // Check that there is a response and if not return false. We do this here // because even an empty response should match a widlcard answer. if(is_a($expr,'qtype_algebra_parser_nullterm')) { return false; } - - // Now parse the answer + + // Now parse the answer $ansexpr=$this->parse_expression($answer->answer); - // The type of comparison done depends on the comparision algorithm selected by - // the question. Use the defined algorithm to select which comparison function - // to call... - if($this->compareby == 'sage') { - // Uses an XML-RPC server with SAGE to perform a full symbollic comparision - return self::test_response_by_sage($expr,$ansexpr); - } else if($this->compareby == 'eval') { - // Tests the response by evaluating it for a certain range of each variable - return self::test_response_by_evaluation($expr,$ansexpr); - } else { - // Tests the response by performing a simple parse tree equivalence algorithm - return self::test_response_by_equivalence($expr,$ansexpr); - } + // The type of comparison done depends on the comparision algorithm selected by + // the question. Use the defined algorithm to select which comparison function + // to call... + if($this->compareby == 'sage') { + // Uses an XML-RPC server with SAGE to perform a full symbollic comparision + return self::test_response_by_sage($expr,$ansexpr); + } else if($this->compareby == 'eval') { + // Tests the response by evaluating it for a certain range of each variable + return self::test_response_by_evaluation($expr,$ansexpr); + } else { + // Tests the response by performing a simple parse tree equivalence algorithm + return self::test_response_by_equivalence($expr,$ansexpr); + } } - + /** - * Checks whether a response matches a given answer using SAGE - * - * This method will compare the given response to the given answer using the SAGE - * open source algebra computation software. The software is run by a remote - * XML-RPC server which is called with both the asnwer and the response and told to - * compare the two algebraic expressions. - * - * @return boolean true if the response matches the answer, false otherwise - */ - function test_response_by_sage($response, $answer) { - $request=array( - 'host' => $CFG->qtype_algebra_host, - 'port' => $CFG->qtype_algebra_port, - 'uri' => $CFG->qtype_algebra_uri, - ); - // Sets the name of the method to call to full_symbolic_compare - $request['method']='full_symbolic_compare'; + * Checks whether a response matches a given answer using SAGE + * + * This method will compare the given response to the given answer using the SAGE + * open source algebra computation software. The software is run by a remote + * XML-RPC server which is called with both the asnwer and the response and told to + * compare the two algebraic expressions. + * + * @return boolean true if the response matches the answer, false otherwise + */ + function test_response_by_sage($response, $answer) { + $request=array( + 'host' => $CFG->qtype_algebra_host, + 'port' => $CFG->qtype_algebra_port, + 'uri' => $CFG->qtype_algebra_uri, + ); + // Sets the name of the method to call to full_symbolic_compare + $request['method']='full_symbolic_compare'; // Get a list of all the variables to declare $vars=$response->get_variables(); $vars=array_merge($vars,array_diff($vars,$answer->get_variables())); - // Sets the arguments to the sage string of the response and the list of variables - $request['args']=array($answer->sage(),$response->sage(),$vars); - // Calls the XML-RPC method on the server and returns the response - return xu_rpc_http_concise($request)==0; + // Sets the arguments to the sage string of the response and the list of variables + $request['args']=array($answer->sage(),$response->sage(),$vars); + // Calls the XML-RPC method on the server and returns the response + return xu_rpc_http_concise($request)==0; } - + /** - * Checks whether a response matches a given answer using an evaluation method - * - * This method will compare the given response to the given answer by evaluating both - * for given values of the variables. Each variable must have a predefined range over - * which it can be checked and then both expressions will be evalutated several times - * using values randomly chosen to be within the range. - * - * @return boolean true if the response matches the answer, false otherwise - */ - function test_response_by_evaluation($response, $answer) { + * Checks whether a response matches a given answer using an evaluation method + * + * This method will compare the given response to the given answer by evaluating both + * for given values of the variables. Each variable must have a predefined range over + * which it can be checked and then both expressions will be evalutated several times + * using values randomly chosen to be within the range. + * + * @return boolean true if the response matches the answer, false otherwise + */ + function test_response_by_evaluation($response, $answer) { // Flag used to denote mismatch in response and answer $same=true; // Run the evaluation loop 10 times with different random variables... @@ -283,23 +282,23 @@ class qtype_algebra_question extends question_graded_by_strategy } } // We made it through the loop so now return true - return true; - } + return true; + } /** - * Checks whether a response matches a given answer using a simple equivalence algorithm - * - * This method will compare the given response to the given answer by simply checking to - * see if the two parse trees are equivalent. This allows for a slightly more sophisticated - * check than a simple text compare but will not, neccessarily, catch two equivalent but - * different algebraic expressions. - * - * @return boolean true if the response matches the answer, false otherwise - */ - public function test_response_by_equivalence($response, $answer) { - // Use the parser's equivalent method to see if the response is the same as the answer - return $response->equivalent($answer); - } + * Checks whether a response matches a given answer using a simple equivalence algorithm + * + * This method will compare the given response to the given answer by simply checking to + * see if the two parse trees are equivalent. This allows for a slightly more sophisticated + * check than a simple text compare but will not, neccessarily, catch two equivalent but + * different algebraic expressions. + * + * @return boolean true if the response matches the answer, false otherwise + */ + public function test_response_by_equivalence($response, $answer) { + // Use the parser's equivalent method to see if the response is the same as the answer + return $response->equivalent($answer); + } public function check_file_access($qa, $options, $component, $filearea, $args, $forcedownload) { @@ -320,7 +319,7 @@ class qtype_algebra_question extends question_graded_by_strategy } /** - * Class to represent an algebra question variable, loaded from the question_algebra_variables table + * Class to represent an algebra question variable, loaded from the qtype_algebra_variables table * in the database. * * @copyright 2009 The Open University |