merged branch bamarni/date-format-regex (PR #8198)

This PR was submitted for the 2.1 branch but it was merged into the 2.2 branch instead (closes #8198).

Discussion
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[Form] fixed date type format pattern regex

| Q             | A
| ------------- | ---
| Bug fix?      | [yes]
| New feature?  | [no]
| BC breaks?    | [no]
| Deprecations? | [no]
| Tests pass?   | [yes]
| License       | MIT

I don't understand what is the rationale behind the current regex, why is there mandatory in-between characters?

The current regex passes with the format option set to ```dMyyyy``` while it doesn't with ```dMy```, on the linked icu documentation it is stated that ```y``` is equivalent to ```yyyy```.

So when setting this format option to dMy, fields are rendered in a wrong order because of the fallback (year, month, day).

Commits
-------

6a91bbb [Form] fixed date type format pattern regex

src/Symfony/Component/Form/Extension/Core/Type/DateType.php

@@ -144,7 +144,7 @@ class DateType extends AbstractType
 
             // set right order with respect to locale (e.g.: de_DE=dd.MM.yy; en_US=M/d/yy)
             // lookup various formats at http://userguide.icu-project.org/formatparse/datetime
-            if (preg_match('/^([yMd]+).+([yMd]+).+([yMd]+)$/', $pattern)) {
+            if (preg_match('/^([yMd]+)[^yMd]*([yMd]+)[^yMd]*([yMd]+)$/', $pattern)) {
                 $pattern = preg_replace(array('/y+/', '/M+/', '/d+/'), array('{{ year }}', '{{ month }}', '{{ day }}'), $pattern);
             } else {
                 // default fallback

src/Symfony/Component/Form/Tests/Extension/Core/Type/DateTypeTest.php

@@ -267,6 +267,29 @@ class DateTypeTest extends LocalizedTestCase
         $this->assertEquals('06*2010*02', $form->getViewData());
     }
 
+    /**
+     * @dataProvider provideDateFormats
+     */
+    public function testDatePatternWithFormatOption($format, $pattern)
+    {
+        $form = $this->factory->create('date', null, array(
+            'format' => $format,
+        ));
+
+        $view = $form->createView();
+
+        $this->assertEquals($pattern, $view->vars['date_pattern']);
+    }
+
+    public function provideDateFormats()
+    {
+        return array(
+            array('dMy', '{{ day }}{{ month }}{{ year }}'),
+            array('d-M-yyyy', '{{ day }}-{{ month }}-{{ year }}'),
+            array('M d y', '{{ month }} {{ day }} {{ year }}'),
+        );
+    }
+
     /**
      * This test is to check that the strings '0', '1', '2', '3' are no accepted
      * as valid IntlDateFormatter constants for FULL, LONG, MEDIUM or SHORT respectively.