Completed analysis of unsolvable situations and main decision process

src/Composer/DependencyResolver/DefaultPolicy.php

@@ -59,9 +59,41 @@ class DefaultPolicy implements PolicyInterface
         return true;
     }
 
-    public function selectPreferedPackages(array $literals)
+    public function selectPreferedPackages(Solver $solver, Pool $pool, RepositoryInterface $installed, array $literals)
     {
-        // todo: prefer installed, recommended, highest priority repository, ...
-        return array($literals[0]);
+        // prefer installed, newest version, recommended, highest priority repository, ...
+        $newest = $this->selectNewestPackages($installed, $literals);
+
+        $selected = array();
+        foreach ($newest as $literal) {
+            if ($literal->getPackage()->getRepository() === $installed) {
+                $selected[] = $literal;
+            }
+        }
+        if (count($selected)) {
+            return $selected;
+        }
+
+        return $newest;
+    }
+
+    public function selectNewestPackages(RepositoryInterface $installed, array $literals)
+    {
+        $maxLiterals = array($literals[0]);
+        $maxPackage = $literals[0]->getPackage();
+        foreach ($literals as $i => $literal) {
+            if (0 === $i) {
+                continue;
+            }
+
+            if ($this->versionCompare($literal->getPackage(), $maxPackage, '>')) {
+                $maxPackage = $literal->getPackage();
+                $maxLiterals = array($literal);
+            } else if ($this->versionCompare($literal->getPackage(), $maxPackage, '==')) {
+                $maxLiterals[] = $literal;
+            }
+        }
+
+        return $maxLiterals;
     }
 }

src/Composer/DependencyResolver/PolicyInterface.php

@@ -25,5 +25,5 @@ interface PolicyInterface
     function versionCompare(PackageInterface $a, PackageInterface $b, $operator);
     function findUpdatePackages(Solver $solver, Pool $pool, RepositoryInterface $repo, PackageInterface $package, $allowAll);
     function installable(Solver $solver, Pool $pool, RepositoryInterface $repo, PackageInterface $package);
-    function selectPreferedPackages(array $literals);
+    function selectPreferedPackages(Solver $solver, Pool $pool, RepositoryInterface $installed, array $literals);
 }

src/Composer/DependencyResolver/Pool.php

@@ -37,7 +37,7 @@ class Pool
 
         foreach ($repo->getPackages() as $package) {
             $this->packages[] = $package;
-            $package->setId(sizeof($this->packages));
+            $package->setId(sizeof($this->packages) - 1);
 
             foreach ($package->getNames() as $name) {
                 $this->packageByName[$name][] = $package;

src/Composer/DependencyResolver/Rule.php

@@ -20,6 +20,8 @@ class Rule
     protected $disabled;
     protected $literals;
     protected $type;
+    protected $id;
+    protected $weak;
 
     public $watch1;
     public $watch2;
@@ -37,6 +39,7 @@ class Rule
         $this->reasonData = $reasonData;
 
         $this->disabled = false;
+        $this->weak = false;
 
         $this->watch1 = (count($this->literals) > 0) ? $literals[0]->getId() : 0;
         $this->watch2 = (count($this->literals) > 1) ? $literals[1]->getId() : 0;
@@ -44,6 +47,16 @@ class Rule
         $this->type = -1;
     }
 
+    public function setId($id)
+    {
+        $this->id = $id;
+    }
+
+    public function getId()
+    {
+        return $this->id;
+    }
+
     /**
      * Checks if this rule is equal to another one
      *
@@ -97,6 +110,16 @@ class Rule
         return !$this->disabled;
     }
 
+    public function isWeak()
+    {
+        return $this->weak;
+    }
+
+    public function setWeak($weak)
+    {
+        $this->weak = $weak;
+    }
+
     public function getLiterals()
     {
         return $this->literals;

src/Composer/DependencyResolver/RuleSet.php

@@ -15,14 +15,14 @@ namespace Composer\DependencyResolver;
 /**
  * @author Nils Adermann <naderman@naderman.de>
  */
-class RuleSet
+class RuleSet implements \IteratorAggregate, \Countable
 {
     // highest priority => lowest number
     const TYPE_PACKAGE = 0;
     const TYPE_JOB = 1;
     const TYPE_UPDATE = 2;
     const TYPE_FEATURE = 3;
-    const TYPE_WEAK = 4;
+    const TYPE_CHOICE = 4;
     const TYPE_LEARNED = 5;
 
     protected static $types = array(
@@ -31,14 +31,18 @@ class RuleSet
         self::TYPE_FEATURE => 'FEATURE',
         self::TYPE_UPDATE => 'UPDATE',
         self::TYPE_JOB => 'JOB',
-        self::TYPE_WEAK => 'WEAK',
+        self::TYPE_CHOICE => 'CHOICE',
         self::TYPE_LEARNED => 'LEARNED',
     );
 
     protected $rules;
+    protected $ruleById;
+    protected $nextRuleId;
 
     public function __construct()
     {
+        $this->nextRuleId = 0;
+
         foreach ($this->getTypes() as $type) {
             $this->rules[$type] = array();
         }
@@ -46,18 +50,30 @@ class RuleSet
 
     public function add(Rule $rule, $type)
     {
-        if (!isset(self::$types[$type]))
-        {
+        if (!isset(self::$types[$type])) {
             throw OutOfBoundsException('Unknown rule type: ' . $type);
         }
 
-        if (!isset($this->rules[$type]))
-        {
+        if (!isset($this->rules[$type])) {
             $this->rules[$type] = array();
         }
 
         $this->rules[$type][] = $rule;
+        $this->ruleById[$this->nextRuleId] = $rule;
         $rule->setType($type);
+
+        $rule->setId($this->nextRuleId);
+        $this->nextRuleId++;
+    }
+
+    public function count()
+    {
+        return $this->nextRuleId;
+    }
+
+    public function ruleById($id)
+    {
+        return $this->ruleById[$id];
     }
 
     public function getRules()

src/Composer/DependencyResolver/RuleSetIterator.php

@@ -21,7 +21,6 @@ class RuleSetIterator implements \Iterator
     protected $types;
 
     protected $currentOffset;
-    protected $currentTotalOffset;
     protected $currentType;
     protected $currentTypeOffset;
 
@@ -44,14 +43,8 @@ class RuleSetIterator implements \Iterator
         return $this->currentType;
     }
 
-    public function getId()
-    {
-        return $this->currentTotalOffset;
-    }
-
     public function next()
     {
-        $this->currentTotalOffset++;
         $this->currentOffset++;
 
         if (!isset($this->rules[$this->currentType])) {
@@ -77,7 +70,6 @@ class RuleSetIterator implements \Iterator
     public function rewind()
     {
         $this->currentOffset = 0;
-        $this->currentTotalOffset = 0;
 
         $this->currentTypeOffset = -1;
         $this->currentType = -1;

tests/Composer/Test/DependencyResolver/RuleSetTest.php

@@ -29,8 +29,8 @@ class RuleSetTest extends \PHPUnit_Framework_TestCase
                 new Rule(array(), 'update1', null),
             ),
             RuleSet::TYPE_FEATURE => array(),
-            RuleSet::TYPE_WEAK => array(),
             RuleSet::TYPE_LEARNED => array(),
+            RuleSet::TYPE_CHOICE => array(),
         );
 
         $ruleSet = new RuleSet;

tests/Composer/Test/DependencyResolver/SolverTest.php

@@ -13,6 +13,7 @@
 namespace Composer\Test\DependencyResolver;
 
 use Composer\Repository\ArrayRepository;
+use Composer\Repository\PlatformRepository;
 use Composer\DependencyResolver\DefaultPolicy;
 use Composer\DependencyResolver\Pool;
 use Composer\DependencyResolver\Request;
@@ -29,7 +30,7 @@ class SolverTest extends \PHPUnit_Framework_TestCase
 
         $repoInstalled = new ArrayRepository;
         $repoInstalled->addPackage($oldPackage = new MemoryPackage('old', '1.0'));
-        $repoInstalled->addPackage(new MemoryPackage('C', '1.0'));
+        $repoInstalled->addPackage($oldPackageC = new MemoryPackage('C', '1.0'));
 
         $repo = new ArrayRepository;
         $repo->addPackage($packageA = new MemoryPackage('A', '2.0'));
@@ -44,8 +45,8 @@ class SolverTest extends \PHPUnit_Framework_TestCase
 
         $request = new Request($pool);
         $request->install('A');
-        $request->update('C');
-        $request->remove('old');
+        //$request->update('C');
+        //$request->remove('old');
 
         $policy = new DefaultPolicy;
         $solver = new Solver($policy, $pool, $repoInstalled);
@@ -56,15 +57,15 @@ class SolverTest extends \PHPUnit_Framework_TestCase
                 'job' => 'install',
                 'package' => $packageA,
             ),
-            array(
+            /*array(
                 'job' => 'remove',
                 'package' => $oldPackage,
-            ),
+            ),*/
             array(
                 'job' => 'install',
-                'package' => $newPackageB,
-            ),
-/*            array(
+                'package' => $packageB,
+            ),/*
+            array(
                 'job' => 'update',
                 'package' => $packageC,
             ),*/