Added installer for metapackages

src/Composer/Installer/MetapackageInstaller.php

@@ -0,0 +1,97 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *     Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Installer;
+
+use Composer\IO\IOInterface;
+use Composer\Repository\WritableRepositoryInterface;
+use Composer\Package\PackageInterface;
+
+/**
+ * Metapackage installation manager.
+ *
+ * @author Martin Hasoň <martin.hason@gmail.com>
+ */
+class MetapackageInstaller implements InstallerInterface
+{
+    protected $repository;
+    protected $io;
+
+    /**
+     * @param   WritableRepositoryInterface $repository repository controller
+     * @param   IOInterface                 $io         io instance
+     */
+    public function __construct(WritableRepositoryInterface $repository, IOInterface $io)
+    {
+        $this->repository = $repository;
+        $this->io = $io;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function supports($packageType)
+    {
+        return $packageType === 'metapackage';
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function isInstalled(PackageInterface $package)
+    {
+        return $this->repository->hasPackage($package);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function install(PackageInterface $package)
+    {
+        $this->repository->addPackage(clone $package);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function update(PackageInterface $initial, PackageInterface $target)
+    {
+        if (!$this->repository->hasPackage($initial)) {
+            throw new \InvalidArgumentException('Package is not installed: '.$initial);
+        }
+
+        $this->repository->removePackage($initial);
+        $this->repository->addPackage(clone $target);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function uninstall(PackageInterface $package)
+    {
+        if (!$this->repository->hasPackage($package)) {
+            // TODO throw exception again here, when update is fixed and we don't have to remove+install (see #125)
+            return;
+            throw new \InvalidArgumentException('Package is not installed: '.$package);
+        }
+
+        $this->repository->removePackage($package);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getInstallPath(PackageInterface $package)
+    {
+        return '';
+    }
+}