Support for unary positive expressions (#85)

* Support for unary positive operator

src/NXP/Classes/Tokenizer.php

@@ -150,11 +150,11 @@ class Tokenizer
                     $this->tokens[] = new Token(Token::ParamSeparator, '');
                     break;
                 default:
-                    // special case for unary minus
+                    // special case for unary operations
-                    if ($ch == '-') {
+                    if ($ch == '-' || $ch == '+') {
                         if ($this->allowNegative) {
                             $this->allowNegative = false;
-                            $this->tokens[] = new Token(Token::Operator, '`');
+                            $this->tokens[] = new Token(Token::Operator, $ch == '-' ? 'uNeg' : 'uPos');
                             continue 2;
                         }
                         // could be in exponent, in which case negative should be added to the numberBuffer

src/NXP/MathExecutor.php

@@ -16,8 +16,8 @@ use NXP\Classes\CustomFunction;
 use NXP\Classes\Operator;
 use NXP\Classes\Tokenizer;
 use NXP\Exception\DivisionByZeroException;
-use NXP\Exception\UnknownVariableException;
 use NXP\Exception\MathExecutorException;
+use NXP\Exception\UnknownVariableException;
 use ReflectionException;
 
 /**
@@ -99,7 +99,14 @@ class MathExecutor
                 170,
                 false
             ],
-            '`' => [ // unary minus token
+            'uPos' => [ // unary positive token
+                        function ($a) {
+                            return $a;
+                        },
+                        200,
+                        false
+            ],
+            'uNeg' => [ // unary minus token
                         function ($a) {
                             return 0 - $a;
                         },

tests/MathTest.php

@@ -252,6 +252,17 @@ class MathTest extends TestCase
         $this->assertEquals(0, $calculator->execute('10 / 0'));
     }
 
+    public function testUnaryOperators()
+    {
+        $calculator = new MathExecutor();
+        $this->assertEquals(5, $calculator->execute('+5'));
+        $this->assertEquals(5, $calculator->execute('+(3+2)'));
+        $this->assertEquals(-5, $calculator->execute('-5'));
+        $this->assertEquals(5, $calculator->execute('-(-5)'));
+        $this->assertEquals(-5, $calculator->execute('+(-5)'));
+        $this->assertEquals(-5, $calculator->execute('-(3+2)'));
+    }
+
     public function testZeroDivisionException()
     {
         $calculator = new MathExecutor();