Improve URI parsing for connection parameters.

Using PHP's "parse_str()" to parse the query string is slightly more
efficient then our own code especially when the number of fields in
the query string grows, with the additional benefit of supporting
arrays for values when brackets are present in fieldnames.

So after this commit, providing this URI string:

  $string = 'tcp://127.0.0.1?metavars[]=foo&metavars[]=hoge';

Is equivalent to providing the following named array:

  $array = [
    'scheme' => 'tcp',
    'host' => '127.0.0.1',
    'metavars' => ['foo', 'hoge'],
  ];

Aside from this improvement, the URI parsing behavior has not changed.

lib/Predis/Connection/ConnectionParameters.php

@@ -99,14 +99,10 @@ class ConnectionParameters implements ConnectionParametersInterface
         }
 
         if (isset($parsed['query'])) {
-            foreach (explode('&', $parsed['query']) as $kv) {
-                $kv = explode('=', $kv, 2);
-                if (isset($kv[0], $kv[1])) {
-                    $parsed[$kv[0]] = $kv[1];
-                }
-            }
-
+            parse_str($parsed['query'], $queryarray);
             unset($parsed['query']);
+
+            $parsed = array_merge($parsed, $queryarray);
         }
 
         return $parsed;

tests/Predis/Connection/ConnectionParametersTest.php

@@ -182,6 +182,7 @@ class ConnectionParametersTest extends PredisTestCase
             'host' => '10.10.10.10',
             'persistent' => '1',
             'foo' => '',
+            'bar' => '',
         );
 
         $this->assertSame($expected, ConnectionParameters::parse($uri));
@@ -204,6 +205,23 @@ class ConnectionParametersTest extends PredisTestCase
         $this->assertSame($expected, ConnectionParameters::parse($uri));
     }
 
+    /**
+     * @group disconnected
+     */
+    public function testParsingURIWhenQueryStringHasBracketsInFieldnames()
+    {
+        $uri = 'tcp://10.10.10.10?persistent=1&metavars[]=foo&metavars[]=hoge';
+
+        $expected = array(
+            'scheme' => 'tcp',
+            'host' => '10.10.10.10',
+            'persistent' => '1',
+            'metavars' => array('foo', 'hoge'),
+        );
+
+        $this->assertSame($expected, ConnectionParameters::parse($uri));
+    }
+
     /**
      * @group disconnected
      * @expectedException InvalidArgumentException