Draft: [FEATURE] Allow null coalesce operator in evaluation (#522)

src/ViewHelpers/Expression/CastViewHelper.php

@@ -13,7 +13,7 @@
 use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
 
 /**
- * Math Expression ViewHelper, seconds as expression type
+ * Cast Expression ViewHelper, seconds as expression type
  */
 class CastViewHelper extends AbstractViewHelper implements ExpressionComponentInterface
 {
@@ -31,7 +31,7 @@ public function __construct(iterable $parts = [])
     protected function initializeArguments()
     {
         $this->registerArgument('subject', 'mixed', 'Numeric first value to calculate', true);
-        $this->registerArgument('as', 'string', 'Type to cast, valid values are: integer, boolean, string, float and array', true);
+        $this->registerArgument('as', 'string', 'Type to cast, valid values are: integer, boolean, string, float, array and DateTime', true);
     }
 
     public function evaluate(RenderingContextInterface $renderingContext)

src/ViewHelpers/Expression/NullcoalescingViewHelper.php

@@ -0,0 +1,85 @@
+<?php
+namespace TYPO3Fluid\Fluid\ViewHelpers\Expression;
+
+/*
+ * This file belongs to the package "TYPO3 Fluid".
+ * See LICENSE.txt that was shipped with this package.
+ */
+
+use TYPO3Fluid\Fluid\Component\ExpressionComponentInterface;
+use TYPO3Fluid\Fluid\Core\Rendering\RenderingContextInterface;
+use TYPO3Fluid\Fluid\Core\ViewHelper\AbstractViewHelper;
+
+/**
+ * Ternary Condition Node - allows the shorthand version
+ * of a condition to be written as `{var ? thenvar : elsevar}`
+ */
+class NullcoalescingViewHelper extends AbstractViewHelper implements ExpressionComponentInterface
+{
+    protected $parts = [];
+
+    public function __construct(iterable $parts = [])
+    {
+        $this->parts = $parts;
+    }
+
+    protected function initializeArguments()
+    {
+        $this->registerArgument('a', 'mixed', 'Anythong that can have a value or null', true);
+        $this->registerArgument('b', 'mixed', 'Fallback value', true);
+    }
+
+    public static function matches(array $parts): bool
+    {
+        var_dump('matches');
+        return isset($parts[2]) && strpos('??', $parts[1]) !== false;
+    }
+
+    /**
+     * @param RenderingContextInterface $renderingContext
+     * @param string $expression
+     * @param array $matches
+     * @return mixed
+     */
+    public function evaluate(RenderingContextInterface $renderingContext)
+    {
+        $arguments = $this->getArguments()->setRenderingContext($renderingContext)->getArrayCopy();
+        $parts = empty($this->parts) ? [$arguments['a'], $arguments['b']] : $this->parts;
+
+        var_dump($parts);
+        var_dump($renderingContext->getVariableProvider()->getAll());
+
+        foreach($parts as $part) {
+            $value = static::getTemplateVariableOrValueItself($part, $renderingContext);
+            var_dump($value);
+            if(!is_null($value)) {
+                return $value;
+            }
+        }
+
+        return null;
+    }
+
+
+    /**
+     * @param mixed $candidate
+     * @param RenderingContextInterface $renderingContext
+     * @return mixed
+     */
+    protected static function getTemplateVariableOrValueItself($candidate, RenderingContextInterface $renderingContext)
+    {
+        if(is_null($candidate)) {
+            return null;
+        }
+        if (is_numeric($candidate)) {
+            return $candidate;
+        }
+
+        if (mb_strpos($candidate, '\'') === 0) {
+            return trim($candidate, '\'');
+        } elseif (mb_strpos($candidate, '"') === 0) {
+            return trim($candidate, '"');
+        }
+        return $renderingContext->getVariableProvider()->get($candidate);
+    }
+}

tests/Unit/Core/Rendering/RenderingContextFixture.php

@@ -11,6 +11,7 @@
 use TYPO3Fluid\Fluid\Core\ErrorHandler\ErrorHandlerInterface;
 use TYPO3Fluid\Fluid\Core\ErrorHandler\StandardErrorHandler;
 use TYPO3Fluid\Fluid\Core\Parser\Configuration;
+use TYPO3Fluid\Fluid\ViewHelpers\Expression\NullcoalescingViewHelper;
 use TYPO3Fluid\Fluid\Core\Parser\TemplateParser;
 use TYPO3Fluid\Fluid\Core\Rendering\FluidRenderer;
 use TYPO3Fluid\Fluid\Core\Rendering\FluidRendererInterface;
@@ -71,6 +72,7 @@ class RenderingContextFixture implements RenderingContextInterface
         MathViewHelper::class,
         CastViewHelper::class,
         IfViewHelper::class,
+        NullcoalescingViewHelper::class,
     ];
 
     /**

tests/Unit/ViewHelpers/Expression/NullcoalescingViewHelperTest.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace TYPO3Fluid\Fluid\Tests\Unit\ViewHelpers\Expression;
+
+
+/*
+ * This file belongs to the package "TYPO3 Fluid".
+ * See LICENSE.txt that was shipped with this package.
+ */
+
+use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\TextNode;
+use TYPO3Fluid\Fluid\Core\Rendering\RenderingContext;
+use TYPO3Fluid\Fluid\Core\Variables\StandardVariableProvider;
+use TYPO3Fluid\Fluid\Tests\Unit\Core\Rendering\RenderingContextFixture;
+use TYPO3Fluid\Fluid\Tests\Unit\ViewHelpers\ViewHelperBaseTestCase;
+use TYPO3Fluid\Fluid\ViewHelpers\Expression\NullcoalescingViewHelper;
+
+/**
+ * Class TernaryExpressionNodeTest
+ */
+class NullcoalescingViewHelperTest extends ViewHelperBaseTestCase
+{
+
+
+    /**
+     * @dataProvider getEvaluateExpressionTestValues
+     * @param string $expression
+     * @param array $variables
+     * @param mixed $expected
+     */
+    public function testEvaluateExpression($expression, array $variables, $expected)
+    {
+        $renderingContext = new RenderingContext();
+        $renderingContext->setVariableProvider(new StandardVariableProvider($variables));
+        $result = NullcoalescingViewHelper::evaluateExpression($renderingContext, $expression, []);
+        $this->assertEquals($expected, $result);
+    }
+
+    public function getStandardTestValues(): array
+    {
+
+        $context = new RenderingContextFixture();
+        foreach(['a' => 'a', 'b' => 'b', 'c' => 'c'] as $key => $value) {
+            $context->getVariableProvider()->add($key, $value);
+        }
+
+        return [
+            'value not null, default integer' => ['a', $context, ['a' => 'a', 'b' => 1]],
+            'value null, default to 1' => [1, $context, ['d' => null, 'b' => 1]],
+            'value not null, default other value' => ['a', $context, ['a' => 'a', 'b' => 'b']],
+            'value null, default to other value' => ['b', $context, ['d' => null, 'b' => 'b']],
+            'value not null, default other value with additional fallback object' => ['a', $context, ['a' => 'a', 'b' => 'b', 'c' => 'c']],
+            'value null, default other value with additional fallback object' => ['b', $context, ['d' => null, 'b' => 'b', 'c' => 'c']],
+            'value null, default other value also null, with additional fallback object' => ['c', $context, ['d' => null, ['e' => null, 'c' => 'c']]],
+            'value null, default other value also null, with additional fallback string (single quote)' => ['test', $context, ['d' => null, 'e' => null], [new TextNode('\'test\'')]],
+            'value null, default other value also null, with additional fallback string (double quote)' => ['test', $context, ['d' => null, 'e' => null], [new TextNode('"test"')]],
+        ];
+    }
+}