Add filter to strip control characters

README.md

@@ -89,6 +89,18 @@ $value = \TraderInteractive\Filter\Strings::redact('a string with some unwanted
 assert($value === 'a string with some ******** *****');
 ```
 
+#### Strings::stripControlCharacters
+
+This filter will strip all ASCII control characters, plus the delete character, including tabs and newlines. 
+It will also strip unicode invisible formatting characters, private use characters, and unused code points.
+
+The second, optional argument specifies a replacement string for the removed characters.
+
+```php
+$value = \TraderInteractive\Filter\Strings::stripControlCharacters("Hello\x00\tWorld\nTest\x7F");
+assert($value === 'HelloWorldTest');
+```
+
 #### Strings::stripEmoji
 
 This filter will strip emoji, pictographs, alphanumeric supplement characters and more from a given string.

src/Filter/Strings.php

@@ -213,6 +213,27 @@ public static function stripEmoji(string $value, string $replacement = ''): stri
         return preg_replace($regexPatterns, $replacement, $value);
     }
 
+    /**
+     * Strip control characters from a given string
+     *
+     * @param string $value       The input string.
+     * @param string $replacement The string to replace the tags with. Defaults to an empty string.
+     *
+     * @return string;
+     */
+    public static function stripControlCharacters(string $value, string $replacement = ''): string
+    {
+        $asciiControlCharacters = '\x00-\x1F\x7F';
+        $unicodeControlCharacters = '\p{C}';
+        $controlCharactersPattern = "/[{$asciiControlCharacters}{$unicodeControlCharacters}]/u";
+        $filtered = preg_replace($controlCharactersPattern, $replacement, $value);
+        if ($filtered === null) {
+            throw new FilterException("Unable to strip control characters from '{$value}'");
+        }
+
+        return $filtered;
+    }
+
     private static function validateMinimumLength(int $minLength)
     {
         if ($minLength < 0) {

tests/Filter/StringsTest.php

@@ -553,6 +553,7 @@ public function provideRedactFailsOnBadInput() : array
      * @param string $expectedValue The expected filtered value.
      *
      * @test
+     * @covers ::stripEmoji
      * @dataProvider provideStripEmoji
      */
     public function stripEmoji(string $input, string $expectedValue): void
@@ -591,4 +592,51 @@ public static function provideStripEmoji(): array
             ],
         ];
     }
+
+    /**
+     * @param string $input         The string value to be filtered.
+     * @param string $expectedValue The expected filtered value.
+     *
+     * @test
+     * @covers ::stripControlCharacters
+     * @dataProvider provideStripControlCharacters
+     */
+    public function stripControlCharacters(string $input, string $expectedValue): void
+    {
+        $actualValue = Strings::stripControlCharacters($input);
+        $this->assertSame($expectedValue, $actualValue);
+    }
+
+    /**
+     * @return array
+     */
+    public static function provideStripControlCharacters(): array
+    {
+        return [
+            'string contains no control characters' => [
+                'input' => 'a b c',
+                'expected' => 'a b c',
+            ],
+            'Contains a null byte, tab,  newline, and delete' => [
+                'input' => "Hello\x00\tWorld\nTest\x7F",
+                'expected' => 'HelloWorldTest',
+            ],
+            'Contains a Zero-Width Space (\u{200B}) and a Soft Hyphen (\u{00AD})' => [
+                'input' => "Uni\u{200B}code\u{00AD}Text",
+                'expected' => 'UnicodeText',
+            ],
+        ];
+    }
+
+    /**
+     * @test
+     * @covers ::stripControlCharacters
+     */
+    public function stripControlCharactersNonUtf8()
+    {
+        $windows1252String = "100 \x80";
+        $this->expectException(FilterException::class);
+        $this->expectExceptionMessage("Unable to strip control characters from '{$windows1252String}'");
+        Strings::stripControlCharacters($windows1252String);
+    }
 }