Detect cycles by default, with an option to run unsafely

Instead of requiring the user specify -C/--cycles to run cycle detection, we run detection on every invocation. If any cycles are
detected, they are displayed, an exception is thrown, and the current invocation is aborted.

Should the user want to run Phake without cycle detection, they can specify the -u/--unsafe CLI option.

lib/includes.php

@@ -12,5 +12,6 @@
 require_once __DIR__ . '/phake/Node.php';
 require_once __DIR__ . '/phake/OptionParser.php';
 require_once __DIR__ . '/phake/TaskCollisionException.php';
+require_once __DIR__ . '/phake/TaskCycleFoundException.php';
 require_once __DIR__ . '/phake/TaskNotFoundException.php';
 require_once __DIR__ . '/phake/Utils.php';

lib/phake/Bin.php

@@ -7,6 +7,7 @@
 use phake\Utils;
 use phake\TaskNotFoundException;
 use phake\CycleDetector;
+use phake\TaskCycleFoundException;
 use Exception;
 
 class Bin
@@ -21,6 +22,7 @@ public function execute($args) {
             $task_names = array('default');
             $trace      = false;
             $runfile    = false;
+            $run_safely = true;
 
             array_shift($args);
             $parser = new OptionParser($args);
@@ -38,9 +40,9 @@ public function execute($args) {
                     case 'file':
                         $runfile = $value;
                         break;
-                    case 'C':
-                    case 'cycles':
-                        $action = 'detect_cycles';
+                    case 'u':
+                    case 'unsafe':
+                        $run_safely = false;
                         break;
                     default:
                         throw new Exception("Unknown command line option '$option'");
@@ -85,6 +87,13 @@ public function execute($args) {
             $application->set_args($cli_args);
             $application->reset();
 
+            if ($run_safely) {
+                $does_cycle = $this->detect_and_display_cycles($application);
+                if ($does_cycle) {
+                    throw new TaskCycleFoundException;
+                }
+            }
+
             switch ($action) {
                 case 'list':
                     $task_list = $application->get_task_list();
@@ -100,8 +109,6 @@ public function execute($args) {
                         $application->invoke($task_name);
                     }
                     break;
-                case 'detect_cycles':
-                    $this->detect_cycles($application);
             }
 
         } catch (TaskNotFoundException $tnfe) {
@@ -111,20 +118,21 @@ public function execute($args) {
         }
     }
 
-    private function detect_cycles($application) {
+    private function detect_and_display_cycles($application) {
         $cycles = (new CycleDetector($application->root()))->get_cycles();
         if (empty($cycles)) {
-            echo "No task cycles found.\n";
-        } else {
-            $num_cycles = count($cycles);
-            $pluralized_cycle_label = ($num_cycles > 1 ? 'cycles' : 'cycle');
-            echo "$num_cycles $pluralized_cycle_label found:\n";
-            foreach ($cycles as $cycle) {
-                $task_names = array_map(function ($task) { return $task->get_name(); }, $cycle);
-                echo '>> ' . implode(', ', $task_names) . "\n";
-            }
-            echo "\nTo ensure proper execution of tasks, please untangle these cyclic dependencies\n";
+            return false;
+        }
+
+        $num_cycles = count($cycles);
+        $pluralized_cycle_label = ($num_cycles > 1 ? 'cycles' : 'cycle');
+        echo "$num_cycles $pluralized_cycle_label found:\n";
+        foreach ($cycles as $cycle) {
+            $task_names = array_map(function ($task) { return $task->get_name(); }, $cycle);
+            echo '>> ' . implode(', ', $task_names) . "\n";
         }
+        echo "\nTo ensure proper execution of tasks, please untangle these cyclic dependencies\n";
+        return true;
     }
 
     private function fatal($exception, $message = null, $trace = false) {

lib/phake/TaskCycleFoundException.php

@@ -0,0 +1,5 @@
+<?php
+
+namespace phake;
+
+class TaskCycleFoundException extends \Exception {};