feat(directives): add '@calc' directive

composer.json

@@ -62,7 +62,8 @@
         "symfony/var-exporter": "^5.4.3",
         "thermage/thermage": "^0.19.0",
         "colinodell/json5": "^2.2",
-        "netcarver/textile": "^3.7"
+        "netcarver/textile": "^3.7",
+        "chriskonnertz/string-calc": "^1.0"
     },
     "suggest": {
         "ext-zend-opcache": "Recommended for better performance",

src/flextype/core/Entries/Directives/CalcDirective.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+ /**
+ * Flextype - Hybrid Content Management System with the freedom of a headless CMS 
+ * and with the full functionality of a traditional CMS!
+ * 
+ * Copyright (c) Sergey Romanenko (https://awilum.github.io)
+ *
+ * Licensed under The MIT License.
+ *
+ * For full copyright and license information, please see the LICENSE
+ * Redistributions of files must retain the above copyright notice.
+ */
+
+use Glowy\Arrays\Arrays as Collection;
+use ChrisKonnertz\StringCalc\StringCalc;
+
+emitter()->addListener('onEntriesFetchSingleField', static function (): void {
+
+    if (! registry()->get('flextype.settings.entries.directives.calc.enabled')) {
+        return;
+    }
+    
+    $field  = entries()->registry()->get('methods.fetch.field');
+    $result = entries()->registry()->get('methods.fetch.result');
+
+    if (is_string($field['value'])) {
+        $field['value'] = preg_replace_callback('/@calc\((.*?)\)/', function($matches) use ($result) {
+            return (new StringCalc())->calculate($matches[1]); 
+        }, $field['value']);
+    }
+
+    entries()->registry()->set('methods.fetch.field.key', $field['key']);
+    entries()->registry()->set('methods.fetch.field.value', $field['value']);
+});

src/flextype/settings.yaml

@@ -80,12 +80,6 @@ entries:
   vars:
     debug: false
   directives:
-    markdown:
-      enabled: true
-      path: "/src/flextype/core/Entries/Directives/MarkdownDirective.php"
-    textile:
-      enabled: true
-      path: "/src/flextype/core/Entries/Directives/TextileDirective.php"
     shortcodes:
       enabled: true
       path: "/src/flextype/core/Entries/Directives/ShortcodesDirective.php"
@@ -101,6 +95,15 @@ entries:
     vars:
       enabled: true
       path: "/src/flextype/core/Entries/Directives/VarsDirective.php"
+    calc:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/CalcDirective.php"
+    markdown:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/MarkdownDirective.php"
+    textile:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/TextileDirective.php"
   macros:
     debug: false
     vars:

tests/fixtures/settings/settings.yaml

@@ -76,12 +76,6 @@ entries:
   vars:
     debug: false
   directives:
-    markdown:
-      enabled: true
-      path: "/src/flextype/core/Entries/Directives/MarkdownDirective.php"
-    textile:
-      enabled: true
-      path: "/src/flextype/core/Entries/Directives/TextileDirective.php"
     shortcodes:
       enabled: true
       path: "/src/flextype/core/Entries/Directives/ShortcodesDirective.php"
@@ -97,6 +91,15 @@ entries:
     vars:
       enabled: true
       path: "/src/flextype/core/Entries/Directives/VarsDirective.php"
+    calc:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/CalcDirective.php"
+    markdown:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/MarkdownDirective.php"
+    textile:
+      enabled: true
+      path: "/src/flextype/core/Entries/Directives/TextileDirective.php"
   macros:
     debug: false
     vars:

tests/src/flextype/core/Entries/Directives/CalcDirectiveTest.php

@@ -0,0 +1,16 @@
+<?php
+
+use Flextype\Component\Filesystem\Filesystem;
+
+beforeEach(function() {
+    filesystem()->directory(PATH['project'] . '/entries')->create();
+});
+
+afterEach(function (): void {
+    filesystem()->directory(PATH['project'] . '/entries')->delete();
+});
+
+test('calc directive', function () {
+    entries()->create('field', ['foo' => '@calc(2+2)']);
+    $this->assertEquals(4, entries()->fetch('field')['foo']);
+});