From 94a67b3992bf658e3bc42e944ab919dbddfdcd64 Mon Sep 17 00:00:00 2001
From: jamiepratt <me@jamiep.org>
Date: Tue, 12 Apr 2011 14:08:41 +0700
Subject: [PATCH] Make changes in functionality, originally implemented by Petr
 to make maths class suitable for use in grade book, dependent on boolean
 switches in constructor which default to having the changes 'on'.

---
 lib/evalmath/evalmath.class.php | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/lib/evalmath/evalmath.class.php b/lib/evalmath/evalmath.class.php
index ae398715e4e..6355210ff3e 100644
--- a/lib/evalmath/evalmath.class.php
+++ b/lib/evalmath/evalmath.class.php
@@ -111,7 +111,14 @@ class EvalMath {
         'mod'=>array(2),      'pi'=>array(0),    'power'=>array(2),
         'round'=>array(1, 2), 'sum'=>array(-1));
 
-    function EvalMath() {
+    var $allowimplicitmultiplication;
+
+    function EvalMath($allowconstants = false, $allowimplicitmultiplication = false) {
+        if ($allowconstants){
+            $this->v['pi'] = pi();
+            $this->v['e'] = exp(1);
+        }
+        $this->allowimplicitmultiplication = $allowimplicitmultiplication;
     }
 
     function e($expr) {
@@ -203,8 +210,12 @@ class EvalMath {
             //===============
             } elseif ((in_array($op, $ops) or $ex) and $expecting_op) { // are we putting an operator on the stack?
                 if ($ex) { // are we expecting an operator but have a number/variable/function/opening parethesis?
-                    return $this->trigger("expecting operand");
-                    //$op = '*'; $index--; // it's an implicit multiplication
+                    if (!$this->allowimplicitmultiplication){
+                        return $this->trigger("expecting operator, implicit multiplication not allowed.");
+                    } else {// it's an implicit multiplication
+                        $op = '*';
+                        $index--;
+                    }
                 }
                 // heart of the algorithm:
                 while($stack->count > 0 and ($o2 = $stack->last()) and in_array($o2, $ops) and ($ops_r[$op] ? $ops_p[$op] < $ops_p[$o2] : $ops_p[$op] <= $ops_p[$o2])) {