[http-foudation] Better accept header parsing

UPGRADE-2.2.md

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+UPGRADE FROM 2.1 to 2.2
+=======================
+
+#### Deprecations
+
+ * The `Request::splitHttpAcceptHeader()` is deprecated and will be removed in 2.3.
+
+   You should now use the `AcceptHeader` class which give you fluent methods to
+   parse request accept-* headers. Some examples:
+
+   ```
+   $accept = AcceptHeader::fromString($request->headers->get('Accept'));
+   if ($accept->has('text/html') {
+       $item = $accept->get('html');
+       $charset = $item->getAttribute('charset', 'utf-8');
+       $quality = $item->getQuality();
+   }
+
+   // accepts items are sorted by descending quality
+   $accepts = AcceptHeader::fromString($request->headers->get('Accept'))->all();
+
+   ```

src/Symfony/Component/HttpFoundation/AcceptHeader.php

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+<?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 Symfony\Component\HttpFoundation;
+
+/**
+ * Represents an Accept-* header.
+ *
+ * An accept header is compound with a list of items,
+ * sorted by descending quality.
+ *
+ * @author Jean-François Simon <[email protected]>
+ */
+class AcceptHeader
+{
+    /**
+     * @var AcceptHeaderItem[]
+     */
+    private $items = array();
+
+    /**
+     * @var bool
+     */
+    private $sorted = true;
+
+    /**
+     * Constructor.
+     *
+     * @param AcceptHeaderItem[] $items
+     */
+    public function __construct(array $items)
+    {
+        foreach ($items as $item) {
+            $this->add($item);
+        }
+    }
+
+    /**
+     * Builds an AcceptHeader instance from a string.
+     *
+     * @param string $headerValue
+     *
+     * @return AcceptHeader
+     */
+    public static function fromString($headerValue)
+    {
+        $index = 0;
+
+        return new self(array_map(function ($itemValue) use (&$index) {
+            $item = AcceptHeaderItem::fromString($itemValue);
+            $item->setIndex($index++);
+
+            return $item;
+        }, preg_split('/\s*(?:,*("[^"]+"),*|,*(\'[^\']+\'),*|,+)\s*/', $headerValue, 0, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE)));
+    }
+
+    /**
+     * Returns header value's string representation.
+     *
+     * @return string
+     */
+    public function __toString()
+    {
+        return implode(',', $this->items);
+    }
+
+    /**
+     * Tests if header has given value.
+     *
+     * @param string $value
+     *
+     * @return Boolean
+     */
+    public function has($value)
+    {
+        return isset($this->items[$value]);
+    }
+
+    /**
+     * Returns given value's item, if exists.
+     *
+     * @param string $value
+     *
+     * @return AcceptHeaderItem|null
+     */
+    public function get($value)
+    {
+        return isset($this->items[$value]) ? $this->items[$value] : null;
+    }
+
+    /**
+     * Adds an item.
+     *
+     * @param AcceptHeaderItem $item
+     *
+     * @return AcceptHeader
+     */
+    public function add(AcceptHeaderItem $item)
+    {
+        $this->items[$item->getValue()] = $item;
+        $this->sorted = false;
+
+        return $this;
+    }
+
+    /**
+     * Returns all items.
+     *
+     * @return AcceptHeaderItem[]
+     */
+    public function all()
+    {
+        $this->sort();
+
+        return $this->items;
+    }
+
+    /**
+     * Filters items on their value using given regex.
+     *
+     * @param string $pattern
+     *
+     * @return AcceptHeader
+     */
+    public function filter($pattern)
+    {
+        return new self(array_filter($this->items, function (AcceptHeaderItem $item) use ($pattern) {
+            return preg_match($pattern, $item->getValue());
+        }));
+    }
+
+    /**
+     * Returns first item.
+     *
+     * @return AcceptHeaderItem|null
+     */
+    public function first()
+    {
+        $this->sort();
+
+        return !empty($this->items) ? current($this->items) : null;
+    }
+
+    /**
+     * Sorts items by descending quality
+     */
+    private function sort()
+    {
+        if (!$this->sorted) {
+            uasort($this->items, function ($a, $b) {
+                $qA = $a->getQuality();
+                $qB = $b->getQuality();
+
+                if ($qA === $qB) {
+                    return $a->getIndex() > $b->getIndex() ? 1 : -1;
+                }
+
+                return $qA > $qB ? -1 : 1;
+            });
+
+            $this->sorted = true;
+        }
+    }
+}