Collect solver problems in Problem objects with human readable output.

src/Composer/DependencyResolver/Problem.php

@@ -0,0 +1,149 @@
+<?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\DependencyResolver;
+
+/**
+ * Represents a problem detected while solving dependencies
+ *
+ * @author Nils Adermann <naderman@naderman.de>
+ */
+class Problem
+{
+    /**
+     * A set of reasons for the problem, each is a rule or a job and a rule
+     * @var array
+     */
+    protected $reasons;
+
+    /**
+     * Add a job as a reason
+     *
+     * @param   array   $job    A job descriptor which is a reason for this problem
+     * @param   Rule    $rule   An optional rule associated with the job
+     */
+    public function addJobRule($job, Rule $rule = null)
+    {
+        $this->addReason(serialize($job), array(
+            'rule' => $rule,
+            'job' => $job,
+        ));
+    }
+
+    /**
+     * Add a rule as a reason
+     *
+     * @param   Rule    $rule   A rule which is a reason for this problem
+     */
+    public function addRule(Rule $rule)
+    {
+        $this->addReason($rule->getId(), array(
+            'rule' => $rule,
+            'job' => null,
+        ));
+    }
+
+    /**
+     * Retrieve all reasons for this problem
+     *
+     * @return  array   The problem's reasons
+     */
+    public function getReasons()
+    {
+        return $this->reasons;
+    }
+
+    /**
+     * A human readable textual representation of the problem's reasons
+     */
+    public function __toString()
+    {
+        if (count($this->reasons) === 1) {
+            reset($this->reasons);
+            $reason = current($this->reasons);
+
+            $rule = $reason['rule'];
+            $job = $reason['job'];
+
+            if ($job && $job['cmd'] === 'install' && empty($job['packages'])) {
+                return 'The requested package "'.$job['packageName'].'" '.$this->constraintToText($job['constraint']).'could not be found.';
+            }
+        }
+
+        $messages = array("Problem caused by:");
+
+        foreach ($this->reasons as $reason) {
+
+            $rule = $reason['rule'];
+            $job = $reason['job'];
+
+            if ($job) {
+                $messages[] = $this->jobToText($job);
+            } elseif ($rule) {
+                if ($rule instanceof Rule) {
+                    $message = '';
+                    if ($rule->getType() == RuleSet::TYPE_LEARNED) {
+                        $message .= 'learned:';
+                    }
+
+                    $messages[] = $message.$rule;
+                }
+            }
+        }
+
+        return implode("\n\t\t\t- ", $messages);
+    }
+
+    /**
+     * Store a reason descriptor but ignore duplicates
+     *
+     * @param   string  $id         A canonical identifier for the reason
+     * @param   string  $reason     The reason descriptor
+     */
+    protected function addReason($id, $reason)
+    {
+        if (!isset($this->reasons[$id])) {
+            $this->reasons[$id] = $reason;
+        }
+    }
+
+    /**
+     * Turns a job into a human readable description
+     *
+     * @param   array   $job
+     * @return  string
+     */
+    protected function jobToText($job)
+    {
+        switch ($job['cmd']) {
+            case 'install':
+                return 'Installation of package "'.$job['packageName'].'" '.$this->constraintToText($job['constraint']).'was requested. Satisfiable by packages ['.implode(', ', $job['packages']).'].';
+            case 'update':
+                return 'Update of package "'.$job['packageName'].'" '.$this->constraintToText($job['constraint']).'was requested.';
+            case 'remove':
+                return 'Removal of package "'.$job['packageName'].'" '.$this->constraintToText($job['constraint']).'was requested.';
+        }
+
+        return 'Job(cmd='.$job['cmd'].', target='.$job['packageName'].', packages=['.implode(', ', $job['packages']).'])';
+    }
+
+    /**
+     * Turns a constraint into text usable in a sentence describing a job
+     *
+     * @param   LinkConstraint  $constraint
+     * @return  string
+     */
+    protected function constraintToText($constraint)
+    {
+        return ($constraint) ? 'with constraint '.$constraint.' ' : '';
+    }
+}

src/Composer/DependencyResolver/Request.php

@@ -52,6 +52,7 @@ class Request
             'packages' => $packages,
             'cmd' => $cmd,
             'packageName' => $packageName,
+            'constraint' => $constraint,
         );
     }
 

src/Composer/DependencyResolver/Solver.php

@@ -466,24 +466,29 @@ class Solver
             $conflict = $this->findDecisionRule($literal->getPackage());
             /** TODO: handle conflict with systemsolvable? */
 
-            $this->learnedPool[] = array($rule, $conflict);
-
             if ($conflict && RuleSet::TYPE_PACKAGE === $conflict->getType()) {
 
+                $problem = new Problem;
+
                 if ($rule->getType() == RuleSet::TYPE_JOB) {
-                    $why = $this->ruleToJob[$rule->getId()];
+                    $job = $this->ruleToJob[$rule->getId()];
+
+                    $problem->addJobRule($job, $rule);
+                    $problem->addRule($conflict);
+                    $this->disableProblem($job);
                 } else {
-                    $why = $rule;
+                    $problem->addRule($rule);
+                    $problem->addRule($conflict);
+                    $this->disableProblem($rule);
                 }
-                $this->problems[] = array($why);
-
-                $this->disableProblem($why);
+                $this->problems[] = $problem;
                 continue;
             }
 
             // conflict with another job or update/feature rule
-
-            $this->problems[] = array();
+            $problem = new Problem;
+            $problem->addRule($rule);
+            $problem->addRule($conflict);
 
             // push all of our rules (can only be feature or job rules)
             // asserting this literal on the problem stack
@@ -500,14 +505,16 @@ class Solver
                 }
 
                 if ($assertRule->getType() === RuleSet::TYPE_JOB) {
-                    $why = $this->ruleToJob[$assertRule->getId()];
+                    $job = $this->ruleToJob[$assertRule->getId()];
+
+                    $problem->addJobRule($job, $assertRule);
+                    $this->disableProblem($job);
                 } else {
-                    $why = $assertRule;
+                    $problem->addRule($assertRule);
+                    $this->disableProblem($assertRule);
                 }
-                $this->problems[count($this->problems) - 1][] = $why;
-
-                $this->disableProblem($why);
             }
+            $this->problems[] = $problem;
 
             // start over
             while (count($this->decisionQueue) > $decisionStart) {
@@ -977,7 +984,9 @@ class Solver
             switch ($job['cmd']) {
                 case 'install':
                     if (empty($job['packages'])) {
-                        $this->problems[] = array($job);
+                        $problem = new Problem();
+                        $problem->addJobRule($job);
+                        $this->problems[] = $problem;
                     } else {
                         $rule = $this->createInstallOneOfRule($job['packages'], self::RULE_JOB_INSTALL, $job['packageName']);
                         $this->addRule(RuleSet::TYPE_JOB, $rule);
@@ -1028,7 +1037,7 @@ class Solver
         //solver_prepare_solutions(solv);
 
         if ($this->problems) {
-            throw new SolverProblemsException($this->problems, $this->learnedPool);
+            throw new SolverProblemsException($this->problems);
         }
 
         return $this->createTransaction();
@@ -1492,17 +1501,16 @@ class Solver
         return array($ruleLevel, $newRule, $why);
     }
 
-    private function analyzeUnsolvableRule($conflictRule, &$lastWeakWhy)
+    private function analyzeUnsolvableRule($problem, $conflictRule, &$lastWeakWhy)
     {
         $why = $conflictRule->getId();
 
         if ($conflictRule->getType() == RuleSet::TYPE_LEARNED) {
-
             $learnedWhy = $this->learnedWhy[$why];
-            $problem = $this->learnedPool[$learnedWhy];
+            $problemRules = $this->learnedPool[$learnedWhy];
 
-            foreach ($problem as $problemRule) {
-                $this->analyzeUnsolvableRule($problemRule, $lastWeakWhy);
+            foreach ($problemRules as $problemRule) {
+                $this->analyzeUnsolvableRule($problem, $problemRule, $lastWeakWhy);
             }
             return;
         }
@@ -1520,24 +1528,22 @@ class Solver
         }
 
         if ($conflictRule->getType() == RuleSet::TYPE_JOB) {
-            $why = $this->ruleToJob[$conflictRule->getId()];
-        }
-
-        // if this problem was already found skip it
-        if (in_array($why, $this->problems[count($this->problems) - 1], true)) {
-            return;
+            $job = $this->ruleToJob[$conflictRule->getId()];
+            $problem->addJobRule($job, $conflictRule);
+        } else {
+            $problem->addRule($conflictRule);
         }
-
-        $this->problems[count($this->problems) - 1][] = $why;
     }
 
     private function analyzeUnsolvable($conflictRule, $disableRules)
     {
         $lastWeakWhy = null;
-        $this->problems[] = array();
-        $this->learnedPool[] = array($conflictRule);
+        $problem = new Problem;
+        $problem->addRule($conflictRule);
+
+        $this->analyzeUnsolvableRule($problem, $conflictRule, $lastWeakWhy);
 
-        $this->analyzeUnsolvableRule($conflictRule, $lastWeakWhy);
+        $this->problems[] = $problem;
 
         $seen = array();
         $literals = $conflictRule->getLiterals();
@@ -1569,9 +1575,9 @@ class Solver
             }
 
             $why = $this->decisionQueueWhy[$decisionId];
-            $this->learnedPool[count($this->learnedPool) - 1][] = $why;
+            $problem->addRule($why);
 
-            $this->analyzeUnsolvableRule($why, $lastWeakWhy);
+            $this->analyzeUnsolvableRule($problem, $why, $lastWeakWhy);
 
             $literals = $why->getLiterals();
 /* unnecessary because unlike rule.d, watch2 == 2nd literal, unless watch2 changed
@@ -1591,7 +1597,6 @@ class Solver
 
         if ($lastWeakWhy) {
             array_pop($this->problems);
-            array_pop($this->learnedPool);
 
             if ($lastWeakWhy->getType() === RuleSet::TYPE_JOB) {
                 $why = $this->ruleToJob[$lastWeakWhy];
@@ -1616,8 +1621,12 @@ class Solver
         }
 
         if ($disableRules) {
-            foreach ($this->problems[count($this->problems) - 1] as $why) {
-                $this->disableProblem($why);
+            foreach ($this->problems[count($this->problems) - 1] as $reason) {
+                if ($reason['job']) {
+                    $this->disableProblem($reason['job']);
+                } else {
+                    $this->disableProblem($reason['rule']);
+                }
             }
 
             $this->resetSolver();
@@ -1670,10 +1679,10 @@ class Solver
     {
         foreach ($this->rules->getIteratorFor(RuleSet::TYPE_LEARNED) as $rule) {
             $why = $this->learnedWhy[$rule->getId()];
-            $problem = $this->learnedPool[$why];
+            $problemRules = $this->learnedPool[$why];
 
             $foundDisabled = false;
-            foreach ($problem as $problemRule) {
+            foreach ($problemRules as $problemRule) {
                 if ($problemRule->disabled()) {
                     $foundDisabled = true;
                     break;

src/Composer/DependencyResolver/SolverProblemsException.php

@@ -19,47 +19,26 @@ class SolverProblemsException extends \RuntimeException
 {
     protected $problems;
 
-    public function __construct(array $problems, array $learnedPool)
+    public function __construct(array $problems)
     {
-        $message = '';
-        foreach ($problems as $i => $problem) {
-            $message .= '[';
-            foreach ($problem as $why) {
+        $this->problems = $problems;
 
-                if (is_int($why) && isset($learnedPool[$why])) {
-                    $rules = $learnedPool[$why];
-                } else {
-                    $rules = $why;
-                }
+        parent::__construct($this->createMessage());
+    }
+
+    protected function createMessage()
+    {
+        $messages = array();
 
-                if (isset($rules['packages'])) {
-                    $message .= $this->jobToText($rules);
-                } else {
-                    $message .= '(';
-                    foreach ($rules as $rule) {
-                        if ($rule instanceof Rule) {
-                            if ($rule->getType() == RuleSet::TYPE_LEARNED) {
-                                $message .= 'learned: ';
-                            }
-                            $message .= $rule . ', ';
-                        } else {
-                            $message .= 'String(' . $rule . '), ';
-                        }
-                    }
-                    $message .= ')';
-                }
-                $message .= ', ';
-            }
-            $message .= "]\n";
+        foreach ($this->problems as $problem) {
+            $messages[] = (string) $problem;
         }
 
-        parent::__construct($message);
+        return "\n\tProblems:\n\t\t- ".implode("\n\t\t- ", $messages);
     }
 
-    public function jobToText($job)
+    public function getProblems()
     {
-        //$output = serialize($job);
-        $output = 'Job(cmd='.$job['cmd'].', target='.$job['packageName'].', packages=['.implode(', ', $job['packages']).'])';
-        return $output;
+        return $this->problems;
     }
 }

tests/Composer/Test/DependencyResolver/RequestTest.php

@@ -40,9 +40,9 @@ class RequestTest extends TestCase
 
         $this->assertEquals(
             array(
-                array('packages' => array($foo), 'cmd' => 'install', 'packageName' => 'foo'),
-                array('packages' => array($bar), 'cmd' => 'install', 'packageName' => 'bar'),
-                array('packages' => array($foobar), 'cmd' => 'remove', 'packageName' => 'foobar'),
+                array('packages' => array($foo), 'cmd' => 'install', 'packageName' => 'foo', 'constraint' => null),
+                array('packages' => array($bar), 'cmd' => 'install', 'packageName' => 'bar', 'constraint' => null),
+                array('packages' => array($foobar), 'cmd' => 'remove', 'packageName' => 'foobar', 'constraint' => null),
             ),
             $request->getJobs());
     }
@@ -63,11 +63,11 @@ class RequestTest extends TestCase
         $pool->addRepository($repo2);
 
         $request = new Request($pool);
-        $request->install('foo', $this->getVersionConstraint('=', '1'));
+        $request->install('foo', $constraint = $this->getVersionConstraint('=', '1'));
 
         $this->assertEquals(
             array(
-                    array('packages' => array($foo1, $foo2), 'cmd' => 'install', 'packageName' => 'foo'),
+                    array('packages' => array($foo1, $foo2), 'cmd' => 'install', 'packageName' => 'foo', 'constraint' => $constraint),
             ),
             $request->getJobs()
         );

tests/Composer/Test/DependencyResolver/SolverTest.php

@@ -59,13 +59,15 @@ class SolverTest extends TestCase
         $this->repo->addPackage($this->getPackage('A', '1.0'));
         $this->reposComplete();
 
-        $this->request->install('B');
+        $this->request->install('B', $this->getVersionConstraint('=', '1'));
 
         try {
             $transaction = $this->solver->solve($this->request);
-            $this->fail('Unsolvable conflict did not resolve in exception.');
+            $this->fail('Unsolvable conflict did not result in exception.');
         } catch (SolverProblemsException $e) {
-            // TODO assert problem properties
+            $problems = $e->getProblems();
+            $this->assertEquals(1, count($problems));
+            $this->assertEquals('The requested package "b" with constraint == 1.0.0.0 could not be found.', (string) $problems[0]);
         }
     }
 
@@ -589,8 +591,10 @@ class SolverTest extends TestCase
 
         try {
             $transaction = $this->solver->solve($this->request);
-            $this->fail('Unsolvable conflict did not resolve in exception.');
+            $this->fail('Unsolvable conflict did not result in exception.');
         } catch (SolverProblemsException $e) {
+            $problems = $e->getProblems();
+            $this->assertEquals(1, count($problems));
             // TODO assert problem properties
         }
     }
@@ -610,8 +614,10 @@ class SolverTest extends TestCase
 
         try {
             $transaction = $this->solver->solve($this->request);
-            $this->fail('Unsolvable conflict did not resolve in exception.');
+            $this->fail('Unsolvable conflict did not result in exception.');
         } catch (SolverProblemsException $e) {
+            $problems = $e->getProblems();
+            $this->assertEquals(1, count($problems));
             // TODO assert problem properties
         }
     }