formula null coalescing

application/Espo/Core/Formula/Functions/ComparisonGroup/NullCoalescingType.php

@@ -0,0 +1,59 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM - Open Source CRM application.
+ * Copyright (C) 2014-2021 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
+ * Website: https://www.espocrm.com
+ *
+ * EspoCRM is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EspoCRM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Formula\Functions\ComparisonGroup;
+
+use Espo\Core\Formula\Functions\BaseFunction;
+use Espo\Core\Formula\ArgumentList;
+
+class NullCoalescingType extends BaseFunction
+{
+    public function process(ArgumentList $args)
+    {
+        if (count($args) < 2) {
+            $this->throwTooFewArguments();
+        }
+
+        $array = [];
+
+        foreach ($args as $arg) {
+            $array[] = $arg;
+        }
+
+        foreach (array_slice($array, 0, -1) as $arg) {
+            $value = $this->evaluate($arg);
+
+            if ($value !== null) {
+                return $value;
+            }
+        }
+
+        return $this->evaluate($array[count($array) - 1]);
+    }
+}

application/Espo/Core/Formula/Parser.php

@@ -40,6 +40,7 @@ class Parser
 {
     private $priorityList = [
         ['='],
+        ['??'],
         ['||'],
         ['&&'],
         ['==', '!=', '>', '<', '>=', '<='],
@@ -49,6 +50,7 @@ class Parser
 
     private $operatorMap = [
         '=' => 'assign',
+        '??' => 'comparison\\nullCoalescing',
         '||' => 'logical\\or',
         '&&' => 'logical\\and',
         '+' => 'numeric\\summation',

tests/unit/Espo/Core/Formula/EvaluatorTest.php

@@ -704,4 +704,64 @@ class EvaluatorTest extends \PHPUnit\Framework\TestCase
             $this->evaluator->process($expression, null)
         );
     }
+
+    public function testNullCoalescing1(): void
+    {
+        $expression = "null ?? 1";
+
+        $this->assertSame(
+            1,
+            $this->evaluator->process($expression, null)
+        );
+    }
+
+    public function testNullCoalescing2(): void
+    {
+        $expression = "(null) ?? 1 ?? 0";
+
+        $this->assertSame(
+            1,
+            $this->evaluator->process($expression, null)
+        );
+    }
+
+    public function testNullCoalescing3(): void
+    {
+        $expression = "(null) ?? ifThenElse(false, 1, null) ?? 0";
+
+        $this->assertSame(
+            0,
+            $this->evaluator->process($expression, null)
+        );
+    }
+
+    public function testNullCoalescing4(): void
+    {
+        $expression = "null ?? (1 ?? 0)";
+
+        $this->assertSame(
+            1,
+            $this->evaluator->process($expression, null)
+        );
+    }
+
+    public function testNullCoalescing5(): void
+    {
+        $expression = "null ?? 1 + 2";
+
+        $this->assertSame(
+            3,
+            $this->evaluator->process($expression, null)
+        );
+    }
+
+    public function testNullCoalescing6(): void
+    {
+        $expression = "null ?? true || false";
+
+        $this->assertSame(
+            true,
+            $this->evaluator->process($expression, null)
+        );
+    }
 }