added findPackage() method to the RepositoryManager and RepositoryInterface

src/Composer/Repository/ArrayRepository.php

@@ -23,6 +23,23 @@ class ArrayRepository implements RepositoryInterface
 {
     protected $packages;
 
+    /**
+     * Searches for a package by it's name and version (if has one).
+     *
+     * @param   string  $name       package name
+     * @param   string  $version    package version
+     *
+     * @return  PackageInterface|null
+     */
+    public function findPackage($name, $version)
+    {
+        foreach ($this->getPackages() as $package) {
+            if ($name === $package->getName() && $version === $package->getVersion()) {
+                return $package;
+            }
+        }
+    }
+
     /**
      * Checks if specified package in this repository.
      *

src/Composer/Repository/RepositoryInterface.php

@@ -31,6 +31,16 @@ interface RepositoryInterface extends \Countable
      */
     function hasPackage(PackageInterface $package);
 
+    /**
+     * Searches for a package by it's name and version (if has one).
+     *
+     * @param   string  $name       package name
+     * @param   string  $version    package version
+     *
+     * @return  PackageInterface|null
+     */
+    function findPackage($name, $version);
+
     /**
      * Returns list of registered packages.
      *

src/Composer/Repository/RepositoryManager.php

@@ -22,6 +22,23 @@ class RepositoryManager
     private $localRepository;
     private $repositories = array();
 
+    /**
+     * Searches for a package by it's name and version in managed repositories.
+     *
+     * @param   string  $name       package name
+     * @param   string  $version    package version
+     *
+     * @return  PackageInterface|null
+     */
+    public function findPackage($name, $version)
+    {
+        foreach ($this->repositories as $repository) {
+            if ($package = $repository->findPackage($name, $version)) {
+                return $package;
+            }
+        }
+    }
+
     /**
      * Sets repository with specific name.
      *