feature symfony#16652 [console] Add truncate method to FormatterHelper (mheki)

This PR was submitted for the 2.8 branch but it was merged into the 3.1-dev branch instead (closes symfony#16652).

Discussion
----------

[console] Add truncate method to FormatterHelper

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#11977
| License       | MIT
| Doc PR        | -

This PR adds a `truncate` method to `FormatterHelper`.
Message is truncated to the given length, then the suffix is appended to end of that string.
If the length is negative, number of letters to truncate is counted from the end of the message.
Suffix is always appended, unless truncate length is longer than message and suffix length.

Commits
-------

a16b1a0 [console] Add truncate method to FormatterHelper

Author: fabpot

src/Symfony/Component/Console/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+3.1.0
+-----
+
+ * added truncate method to FormatterHelper
+
 2.8.0
 -----
 

src/Symfony/Component/Console/Helper/FormatterHelper.php

@@ -72,6 +72,30 @@ public function formatBlock($messages, $style, $large = false)
         return implode("\n", $messages);
     }
 
+    /**
+     * Truncates a message to the given length.
+     *
+     * @param string $message
+     * @param int    $length
+     * @param string $suffix
+     *
+     * @return string
+     */
+    public function truncate($message, $length, $suffix = '...')
+    {
+        $computedLength = $length - $this->strlen($suffix);
+
+        if ($computedLength > $this->strlen($message)) {
+            return $message;
+        }
+
+        if (false === $encoding = mb_detect_encoding($message, null, true)) {
+            return substr($message, 0, $length).$suffix;
+        }
+
+        return mb_substr($message, 0, $length, $encoding).$suffix;
+    }
+
     /**
      * {@inheritdoc}
      */

src/Symfony/Component/Console/Tests/Helper/FormatterHelperTest.php

@@ -89,4 +89,40 @@ public function testFormatBlockLGEscaping()
             '::formatBlock() escapes \'<\' chars'
         );
     }
+
+    public function testTruncatingWithShorterLengthThanMessageWithSuffix()
+    {
+        $formatter = new FormatterHelper();
+        $message = 'testing truncate';
+
+        $this->assertSame('test...', $formatter->truncate($message, 4));
+        $this->assertSame('testing truncat...', $formatter->truncate($message, 15));
+        $this->assertSame('testing truncate...', $formatter->truncate($message, 16));
+        $this->assertSame('zażółć gęślą...', $formatter->truncate('zażółć gęślą jaźń', 12));
+    }
+
+    public function testTruncatingMessageWithCustomSuffix()
+    {
+        $formatter = new FormatterHelper();
+        $message = 'testing truncate';
+
+        $this->assertSame('test!', $formatter->truncate($message, 4, '!'));
+    }
+
+    public function testTruncatingWithLongerLengthThanMessageWithSuffix()
+    {
+        $formatter = new FormatterHelper();
+        $message = 'test';
+
+        $this->assertSame($message, $formatter->truncate($message, 10));
+    }
+
+    public function testTruncatingWithNegativeLength()
+    {
+        $formatter = new FormatterHelper();
+        $message = 'testing truncate';
+
+        $this->assertSame('testing tru...', $formatter->truncate($message, -5));
+        $this->assertSame('...', $formatter->truncate($message, -100));
+    }
 }