Fix support for partial provider repos

src/Composer/Repository/ComposerRepository.php

@@ -59,6 +59,8 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
     protected $distMirrors;
     private $degradedMode = false;
     private $rootData;
+    private $hasPartialPackages;
+    private $partialPackagesByName;
 
     public function __construct(array $repoConfig, IOInterface $io, Config $config, EventDispatcher $eventDispatcher = null, RemoteFilesystem $rfs = null)
     {
@@ -280,6 +282,11 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
             return $this->providers[$name];
         }
 
+        if ($this->hasPartialPackages && null === $this->partialPackagesByName) {
+            $this->initializePartialPackages();
+        }
+
+        if (!$this->hasPartialPackages || !isset($this->partialPackagesByName[$name])) {
             // skip platform packages, root package and composer-plugin-api
             if (preg_match(PlatformRepository::PLATFORM_PACKAGE_REGEX, $name) || '__root__' === $name || 'composer-plugin-api' === $name) {
                 return array();
@@ -340,9 +347,19 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
                 }
             }
 
+            $loadingPartialPackage = false;
+        } else {
+            $packages = array('packages' => array('versions' => $this->partialPackagesByName[$name]));
+            $loadingPartialPackage = true;
+        }
+
         $this->providers[$name] = array();
         foreach ($packages['packages'] as $versions) {
             foreach ($versions as $version) {
+                if (!$loadingPartialPackage && $this->hasPartialPackages && isset($this->partialPackagesByName[$version['name']])) {
+                    continue;
+                }
+
                 // avoid loading the same objects twice
                 if (isset($this->providersByUid[$version['uid']])) {
                     // skip if already assigned
@@ -492,6 +509,8 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
         if (!empty($data['providers-lazy-url'])) {
             $this->lazyProvidersUrl = $this->canonicalizeUrl($data['providers-lazy-url']);
             $this->hasProviders = true;
+
+            $this->hasPartialPackages = !empty($data['packages']) && is_array($data['packages']);
         }
 
         if ($this->allowSslDowngrade) {
@@ -754,4 +773,22 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
             }
         }
     }
+
+    /**
+     * This initializes the packages key of a partial packages.json that contain some packages inlined + a providers-lazy-url
+     *
+     * This should only be called once
+     */
+    private function initializePartialPackages()
+    {
+        $rootData = $this->loadRootServerFile();
+
+        $this->partialPackagesByName = array();
+        foreach ($rootData['packages'] as $package => $versions) {
+            $this->partialPackagesByName[strtolower($package)] = $versions;
+        }
+
+        // wipe rootData as it is fully consumed at this point and this saves some memory
+        $this->rootData = true;
+    }
 }