Copy ValueExporter to this package for 4.0 compat

See #225
Symfony 2.3 doesn't have this yet, copy it here for now.

src/DataCollector/Util/ValueExporter.php

@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * This file is a copy of Symfony\Component\HttpKernel\DataCollector\Util\ValueExporter
+ * https://github.com/symfony/symfony/blob/2.7/src/Symfony/Component/HttpKernel/DataCollector/Util/ValueExporter.php
+ *
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Barryvdh\Debugbar\DataCollector\Util;
+
+/**
+ * @author Bernhard Schussek <[email protected]>
+ */
+class ValueExporter
+{
+    /**
+     * Converts a PHP value to a string.
+     *
+     * @param mixed   $value The PHP value
+     * @param int     $depth only for internal usage
+     * @param bool    $deep  only for internal usage
+     *
+     * @return string The string representation of the given value
+     */
+    public function exportValue($value, $depth = 1, $deep = false)
+    {
+        if (is_object($value)) {
+            if ($value instanceof \DateTime || $value instanceof \DateTimeInterface) {
+                return sprintf('Object(%s) - %s', get_class($value), $value->format(\DateTime::ISO8601));
+            }
+
+            return sprintf('Object(%s)', get_class($value));
+        }
+
+        if (is_array($value)) {
+            if (empty($value)) {
+                return '[]';
+            }
+
+            $indent = str_repeat('  ', $depth);
+
+            $a = array();
+            foreach ($value as $k => $v) {
+                if (is_array($v)) {
+                    $deep = true;
+                }
+                $a[] = sprintf('%s => %s', $k, $this->exportValue($v, $depth + 1, $deep));
+            }
+
+            if ($deep) {
+                return sprintf("[\n%s%s\n%s]", $indent, implode(sprintf(", \n%s", $indent), $a), str_repeat('  ', $depth - 1));
+            }
+
+            return sprintf("[%s]", implode(', ', $a));
+        }
+
+        if (is_resource($value)) {
+            return sprintf('Resource(%s#%d)', get_resource_type($value), $value);
+        }
+
+        if (null === $value) {
+            return 'null';
+        }
+
+        if (false === $value) {
+            return 'false';
+        }
+
+        if (true === $value) {
+            return 'true';
+        }
+
+        return (string) $value;
+    }
+}

src/DataCollector/ViewCollector.php

@@ -2,9 +2,9 @@
 
 namespace Barryvdh\Debugbar\DataCollector;
 
+use Barryvdh\Debugbar\DataCollector\Util\ValueExporter;
 use DebugBar\Bridge\Twig\TwigCollector;
 use Illuminate\View\View;
-use Symfony\Component\HttpKernel\DataCollector\Util\ValueExporter;
 
 class ViewCollector extends TwigCollector
 {