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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* @package core
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* @subpackage lib
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* @copyright Petr Skoda (skodak)
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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defined('MOODLE_INTERNAL') || die();
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/** @see evalmath/evalmath.class.php */
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require_once $CFG->dirroot.'/lib/evalmath/evalmath.class.php';
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/**
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* This class abstracts evaluation of spreadsheet formulas.
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* See unit tests in lib/tests/mathslib_test.php for sample usage.
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*
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* @package moodlecore
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* @copyright Petr Skoda (skodak)
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class calc_formula {
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// private properties
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var $_em;
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var $_nfx = false; // postfix notation
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var $_error = false; // last error
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/**
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* Constructor for spreadsheet formula with optional parameters
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*
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* @param string $formula with leading =
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* @param array $params associative array of parameters used in formula. All parameter names must be lowercase!
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*/
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public function __construct($formula, $params=false) {
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$this->_em = new EvalMath();
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$this->_em->suppress_errors = true; // no PHP errors!
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if (strpos($formula, '=') !== 0) {
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$this->_error = "missing leading '='";
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return;
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}
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$formula = substr($formula, 1);
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$this->_nfx = $this->_em->nfx($formula);
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if ($this->_nfx == false) {
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$this->_error = $this->_em->last_error;
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return;
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}
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if ($params != false) {
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$this->set_params($params);
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}
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}
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/**
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* Old syntax of class constructor. Deprecated in PHP7.
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*
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* @deprecated since Moodle 3.1
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*/
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public function calc_formula($formula, $params=false) {
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debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
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self::__construct($formula, $params);
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}
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/**
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* Raplace parameters used in existing formula,
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* parameter names must contain only lowercase [a-z] letters, no other characters are allowed!
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*
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* @param array $params associative array of parameters used in formula
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*/
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function set_params($params) {
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$this->_em->v = $params;
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}
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/**
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* Evaluate formula
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*
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* @return mixed number if ok, false if error
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*/
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function evaluate() {
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if ($this->_nfx == false) {
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return false;
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}
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$res = $this->_em->pfx($this->_nfx);
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if ($res === false) {
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$this->_error = $this->_em->last_error;
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return false;
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} else {
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$this->_error = false;
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return $res;
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}
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}
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/**
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* Get last error.
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* TODO: localize the strings from contructor and EvalMath library
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*
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* @return mixed string with last error description or false if ok
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*/
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function get_error() {
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return $this->_error;
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}
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/**
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* Similar to format_float, formats the numbers and list separators
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* according to locale specifics.
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* @param string $formula
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* @return string localised formula
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*/
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public static function localize($formula) {
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$formula = str_replace('.', '$', $formula ?? ''); // Temp placeholder.
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$formula = str_replace(',', get_string('listsep', 'langconfig'), $formula);
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$formula = str_replace('$', get_string('decsep', 'langconfig'), $formula);
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return $formula;
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}
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/**
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* Similar to unformat_float, converts floats and lists to PHP standards.
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* @param string $formula localised formula
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* @return string
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*/
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public static function unlocalize($formula) {
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$formula = str_replace(get_string('decsep', 'langconfig'), '$', $formula);
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$formula = str_replace(get_string('listsep', 'langconfig'), ',', $formula);
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$formula = str_replace('$', '.', $formula); // temp placeholder
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return $formula;
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}
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}
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