Add a MessageFormatter Phrase renderer

This gives us the ability to use ICU MessageFormatter formatting strings
for better support of internationalization.

Author: navarr

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

@@ -44,6 +44,7 @@
             <argument name="renderers" xsi:type="array">
                 <item name="translation" xsi:type="object">Magento\Framework\Phrase\Renderer\Translate</item>
                 <item name="placeholder" xsi:type="object">Magento\Framework\Phrase\Renderer\Placeholder</item>
+                <item name="messageFormatter" xsi:type="object">Magento\Framework\Phrase\Renderer\MessageFormatter</item>
                 <item name="inline" xsi:type="object">Magento\Framework\Phrase\Renderer\Inline</item>
             </argument>
         </arguments>

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

@@ -0,0 +1,41 @@
+<?php
+
+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) {
+            // Definitely nothing to process with MessageFormatter
+            return $text;
+        }
+
+        $result = \MessageFormatter::formatMessage($this->translate->getLocale(), $text, $arguments);
+
+        // Return $text if MessageFormatter fails (for backwards-compatibility)
+        return $result !== false ? $result : $text;
+    }
+}

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

@@ -0,0 +1,87 @@
+<?php
+
+namespace Magento\Framework\Phrase\Test\Unit\Renderer;
+
+use Magento\Framework\Phrase\Renderer\MessageFormatter;
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
+use Magento\Framework\Translate;
+
+class MessageFormatterTest extends \PHPUnit\Framework\TestCase
+{
+    /** @var ObjectManager */
+    private $objectManager;
+
+    protected function setUp()
+    {
+        $this->objectManager = new \Magento\Framework\TestFramework\Unit\Helper\ObjectManager($this);
+    }
+
+    private function getMessageFormatter($locale)
+    {
+        $translateMock = $this->getMockBuilder(Translate::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['getLocale'])
+            ->getMock();
+        $translateMock->method('getLocale')
+            ->willReturn($locale);
+
+        return $this->objectManager->getObject(MessageFormatter::class, ['translate' => $translateMock]);
+    }
+
+    /**
+     * @param string $text The text with MessageFormat markers
+     * @param string $locale
+     * @param array $arguments The arguments supplying values for the variables
+     * @param string $result The result of Phrase rendering
+     *
+     * @dataProvider renderMessageFormatterDataProvider
+     */
+    public function testRenderMessageFormatter($text, $locale, array $arguments, $result)
+    {
+        $renderer = $this->getMessageFormatter($locale);
+
+        $this->assertEquals($result, $renderer->render([$text], $arguments));
+    }
+
+    /**
+     * @return array
+     */
+    public function renderMessageFormatterDataProvider()
+    {
+        $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.'
+            ],
+        ];
+    }
+}

lib/internal/Magento/Framework/composer.json

@@ -21,6 +21,7 @@
         "ext-spl": "*",
         "ext-xsl": "*",
         "ext-bcmath": "*",
+        "ext-intl": "*",
         "lib-libxml": "*",
         "colinmollenhour/php-redis-session-abstract": "~1.4.0",
         "composer/composer": "^1.6",