Add a MessageFormatter Phrase renderer

app/code/Magento/Translation/etc/di.xml

@@ -43,6 +43,7 @@
         <arguments>
             <argument name="renderers" xsi:type="array">
                 <item name="translation" xsi:type="object">Magento\Framework\Phrase\Renderer\Translate</item>
+                <item name="messageFormatter" xsi:type="object">Magento\Framework\Phrase\Renderer\MessageFormatter</item>
                 <item name="placeholder" xsi:type="object">Magento\Framework\Phrase\Renderer\Placeholder</item>
                 <item name="inline" xsi:type="object">Magento\Framework\Phrase\Renderer\Inline</item>
             </argument>

lib/internal/Magento/Framework/Phrase/Renderer/MessageFormatter.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+declare(strict_types=1);
+
+namespace Magento\Framework\Phrase\Renderer;
+
+use Magento\Framework\Phrase\RendererInterface;
+use Magento\Framework\TranslateInterface;
+
+/**
+ * Process texts to resolve ICU MessageFormat
+ */
+class MessageFormatter implements RendererInterface
+{
+    /** @var TranslateInterface */
+    private $translate;
+
+    /**
+     * @param TranslateInterface $translate
+     */
+    public function __construct(TranslateInterface $translate)
+    {
+        $this->translate = $translate;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function render(array $source, array $arguments)
+    {
+        $text = end($source);
+
+        if (strpos($text, '{') === false) {
+            // About 5x faster for non-MessageFormatted strings
+            // Only slightly slower for MessageFormatted strings (~0.3x)
+            return $text;
+        }
+
+        $result = \MessageFormatter::formatMessage($this->translate->getLocale(), $text, $arguments);
+        return $result !== false ? $result : $text;
+    }
+}

lib/internal/Magento/Framework/Phrase/Test/Unit/Renderer/MessageFormatterTest.php

@@ -0,0 +1,115 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+declare(strict_types=1);
+
+namespace Magento\Framework\Phrase\Test\Unit\Renderer;
+
+use Magento\Framework\Phrase\Renderer\MessageFormatter;
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
+use Magento\Framework\Translate;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests that messages sent through the MessageFormatter phrase renderer result in what would be expected when sent
+ * through PHP's native MessageFormatter, and that the locale is pulled from the Translate dependency
+ */
+class MessageFormatterTest extends TestCase
+{
+    /** @var ObjectManager */
+    private $objectManager;
+
+    /**
+     * @inheritdoc
+     */
+    protected function setUp()
+    {
+        $this->objectManager = new ObjectManager($this);
+    }
+
+    /**
+     * Retrieve test cases
+     *
+     * @return array [Raw Phrase, Locale, Arguments, Expected Result]
+     * @throws \Exception
+     */
+    public function renderMessageFormatterDataProvider(): array
+    {
+        $twentynineteenJuneTwentyseven = new \DateTime('2019-06-27');
+
+        return [
+            [
+                'A table has {legs, plural, =0 {no legs} =1 {one leg} other {# legs}}.',
+                'en_US',
+                ['legs' => 4],
+                'A table has 4 legs.'
+            ],
+            [
+                'A table has {legs, plural, =0 {no legs} =1 {one leg} other {# legs}}.',
+                'en_US',
+                ['legs' => 0],
+                'A table has no legs.'
+            ],
+            [
+                'A table has {legs, plural, =0 {no legs} =1 {one leg} other {# legs}}.',
+                'en_US',
+                ['legs' => 1],
+                'A table has one leg.'
+            ],
+            ['The table costs {price, number, currency}.', 'en_US', ['price' => 23.4], 'The table costs $23.40.'],
+            [
+                'Today is {date, date, long}.',
+                'en_US',
+                ['date' => $twentynineteenJuneTwentyseven],
+                'Today is June 27, 2019.'
+            ],
+            [
+                'Today is {date, date, long}.',
+                'ja_JP',
+                ['date' => $twentynineteenJuneTwentyseven],
+                'Today is 2019年6月27日.'
+            ],
+        ];
+    }
+
+    /**
+     * Test MessageFormatter
+     *
+     * @param string $text The text with MessageFormat markers
+     * @param string $locale
+     * @param array $arguments The arguments supplying values for the variables
+     * @param string $result The expected result of Phrase rendering
+     *
+     * @dataProvider renderMessageFormatterDataProvider
+     */
+    public function testRenderMessageFormatter(string $text, string $locale, array $arguments, string $result): void
+    {
+        $renderer = $this->getMessageFormatter($locale);
+
+        $this->assertEquals($result, $renderer->render([$text], $arguments));
+    }
+
+    /**
+     * Create a MessageFormatter object provided a locale
+     *
+     * Automatically sets up the Translate dependency to return the provided locale and returns a MessageFormatter
+     * that has been provided that dependency
+     *
+     * @param string $locale
+     * @return MessageFormatter
+     */
+    private function getMessageFormatter(string $locale): MessageFormatter
+    {
+        $translateMock = $this->getMockBuilder(Translate::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['getLocale'])
+            ->getMock();
+        $translateMock->method('getLocale')
+            ->willReturn($locale);
+
+        return $this->objectManager->getObject(MessageFormatter::class, ['translate' => $translateMock]);
+    }
+}

lib/internal/Magento/Framework/composer.json

@@ -16,6 +16,7 @@
         "ext-gd": "*",
         "ext-hash": "*",
         "ext-iconv": "*",
+        "ext-intl": "*",
         "ext-openssl": "*",
         "ext-simplexml": "*",
         "ext-spl": "*",