Add fix for when the buffer starts with a BOM

Add fix for when the buffer starts with a BOM and change the offset to
ignore. Added additional test to cover the improved functionality.

src/Csv.php

@@ -292,12 +292,21 @@ protected function fetchLine(StreamInterface $stream, &$buffer)
             return false;
         }
 
+        // Check for UTF-8 BOM and remove
+        // > The Unicode Standard permits the BOM in UTF-8, but does not require or recommend its use.
+        // > Byte order has no meaning in UTF-8, so its only use in UTF-8 is to
+        // > signal at the start that the text stream is encoded in UTF-8.
+        // > https://en.wikipedia.org/wiki/Byte_order_mark#UTF-8
+        $offset = 0;
+        if (substr($buffer, 0, 3) == "\xEF\xBB\xBF") {
+            $offset = 3;
+        }
+
         // prepare the regex
         $regex = $this->getRegex();
 
-        $idx    = 0;
-        $row    = array();
-        $offset = 0;
+        $idx = 0;
+        $row = array();
         while ($offset < $bufferSize) {
 
             // use the regex to pull out matches
@@ -349,4 +358,4 @@ protected function fetchLine(StreamInterface $stream, &$buffer)
         // return the row
         return $row;
     }
-}
+}

tests/CsvTest.php

@@ -1,7 +1,6 @@
 <?php
 namespace Phlib\Csv\Tests;
 
-use Phlib\Csv\Adapter\AdapterInterface;
 use Phlib\Csv\Csv;
 use Psr\Http\Message\StreamInterface;
 
@@ -208,6 +207,23 @@ public function testMoreRowColumnsThanHeaders()
         $csv->current();
     }
 
+    public function testStartsWithBomb()
+    {
+        // Additional fields than the headers will be ignored
+        $csvData = <<<CSV
+\xEF\xBB\xBFemail,name
+aw@example.com,Adam
+lr@example.com,Luke
+CSV;
+        $csv = new Csv($this->getStreamInterface($csvData), true);
+
+        $expected = [
+            'email' => 'aw@example.com',
+            'name'  => 'Adam'
+        ];
+        $this->assertSame($expected, $csv->current());
+    }
+
     /**
      * @return StreamInterface
      */