diff options
| -rw-r--r-- | parser.php | 52 |
1 files changed, 41 insertions, 11 deletions
@@ -1139,6 +1139,18 @@ class qtype_algebra_parser_special extends qtype_algebra_parser_term { ); } +/** + * implement math functions that aren't php builtins + */ +function log2($arg) +{ + return log($arg, 2); +} + +function ln($arg) +{ + return log($arg); +} /** * Class representing a function in an algebraic expression. @@ -1158,6 +1170,9 @@ class qtype_algebra_parser_function extends qtype_algebra_parser_term { * @param $text string matching the function's regular expression */ public function __construct($text) { + if ($text == 'log') { + throw new parser_exception(get_string('deprecatedlog', 'qtype_algebra')); + } if (!function_exists($text) and !array_key_exists($text, self::$fnmap)) { throw new parser_exception(get_string('undefinedfunction', 'qtype_algebra', $text)); } @@ -1284,14 +1299,21 @@ class qtype_algebra_parser_function extends qtype_algebra_parser_term { // Static class properties. const NARGS = 1; - public static $fnmap = array ('ln' => 'log', - 'log' => 'log10' - ); - public static $texmap = array('asin' => '\\sin^{-1}', - 'acos' => '\\cos^{-1}', - 'atan' => '\\tan^{-1}', - 'sqrt' => '\\sqrt' + /* fnmap is not needed, since all needed + * functions are implemented without pseudonyms + */ + public static $fnmap = array (); + public static $texmap = array('sqrt' => '\\sqrt', + 'log2' => '\\log_{2}', + 'log10' => '\\log_{10}', + 'asin' => '\\sin^{-1}', + 'acos' => '\\cos^{-1}', + 'atan' => '\\tan^{-1}', + 'asinh' => '\\sinh^{-1}', + 'acosh' => '\\cosh^{-1}', + 'atanh' => '\\tanh^{-1}', ); + // List of functions requiring special brackets. public static $bracketmap = array ('sqrt' ); @@ -1404,18 +1426,26 @@ class qtype_algebra_parser { 'e' ); - // Functions which the parser will understand. These should all be standard PHP math functions. + // Functions which the parser will understand. + // You have to implement any that are not standard PHP math functions. public static $functions = array ('sqrt', + 'exp', + 'log2', 'ln', 'log', - 'cosh', + 'log10', 'sinh', + 'cosh', + 'tanh', 'sin', 'cos', 'tan', 'asin', 'acos', - 'atan' + 'atan', + 'asinh', + 'acosh', + 'atanh', ); // Array to define the priority of the different operations. The parser implements the standard BODMAS priority: @@ -1461,7 +1491,7 @@ class qtype_algebra_parser { } /** - * Parses a given string containing an algebric epxression and returns the corresponding parse tree. + * Parses a given string containing an algebric expression and returns the corresponding parse tree. * * This method loops over the string using the regular expressions in the token map to break down the * string into tokens. These tokens are arranged into a structured stack, taking account of the |