[Console] Added formatter style stack.

src/Symfony/Component/Console/Formatter/OutputFormatterStyleStack.php

@@ -0,0 +1,93 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Console\Formatter;
+
+/**
+ * @author Jean-François Simon <contact@jfsimon.fr>
+ */
+class OutputFormatterStyleStack
+{
+    /**
+     * @var OutputFormatterStyle[]
+     */
+    private $styles;
+
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        $this->reset();
+    }
+
+    /**
+     * Resets stack (ie. empty internal arrays).
+     */
+    public function reset()
+    {
+        $this->styles = array();
+    }
+
+    /**
+     * Pushes a style in the stack.
+     *
+     * @param OutputFormatterStyleInterface $style
+     */
+    public function push(OutputFormatterStyleInterface $style)
+    {
+        $this->styles[] = $style;
+    }
+
+    /**
+     * Pops a style from the stack.
+     *
+     * @param OutputFormatterStyleInterface $style
+     *
+     * @return OutputFormatterStyleInterface
+     *
+     * @throws \InvalidArgumentException  When style tags incorrectly nested
+     */
+    public function pop(OutputFormatterStyleInterface $style = null)
+    {
+        if (empty($this->styles)) {
+            return new OutputFormatterStyle();
+        }
+
+        if (null === $style) {
+            return array_pop($this->styles);
+        }
+
+        foreach (array_reverse($this->styles, true) as $index => $stackedStyle) {
+            if ($style->apply('') === $stackedStyle->apply('')) {
+                $this->styles = array_slice($this->styles, 0, $index);
+
+                return $stackedStyle;
+            }
+        }
+
+        throw new \InvalidArgumentException('Incorrectly nested style tag found.');
+    }
+
+    /**
+     * Computes current style with stacks top codes.
+     *
+     * @return OutputFormatterStyle
+     */
+    public function getCurrent()
+    {
+        if (empty($this->styles)) {
+            return new OutputFormatterStyle();
+        }
+
+        return $this->styles[count($this->styles)-1];
+    }
+}