Adding the ability for the task queue to be cleared more programmatically via marker.

Author: cowboy

lib/util/task.js

@@ -20,7 +20,9 @@
     // Task queue.
     this._queue = [];
     // Queue placeholder (for dealing with nested tasks).
-    this._placeholder = {};
+    this._placeholder = {placeholder: true};
+    // Queue marker (for clearing the queue programatically).
+    this._marker = {marker: true};
     // Options.
     this._options = {};
     // Is the queue running?
@@ -240,6 +242,19 @@
     return {task: task, nameArgs: name, args: args, flags: flags};
   };
 
+  // Append things to queue in the correct spot.
+  Task.prototype._push = function(things) {
+    // Get current placeholder index.
+    var index = this._queue.indexOf(this._placeholder);
+    if (index === -1) {
+      // No placeholder, add task+args objects to end of queue.
+      this._queue = this._queue.concat(things);
+    } else {
+      // Placeholder exists, add task+args objects just before placeholder.
+      [].splice.apply(this._queue, [index, 0].concat(things));
+    }
+  };
+
   // Enqueue a task.
   Task.prototype.run = function() {
     // Parse arguments into an array, returning an array of task+args objects.
@@ -250,15 +265,15 @@
       this._throwIfRunning(new TaskError('Task "' + fails[0].nameArgs + '" not found.'));
       return this;
     }
-    // Get current placeholder index.
-    var index = this._queue.indexOf(this._placeholder);
-    if (index === -1) {
-      // No placeholder, add task+args objects to end of queue.
-      this._queue = this._queue.concat(things);
-    } else {
-      // Placeholder exists, add task+args objects just before placeholder.
-      [].splice.apply(this._queue, [index, 0].concat(things));
-    }
+    // Append things to queue in the correct spot.
+    this._push(things);
+    // Make chainable!
+    return this;
+  };
+
+  // Add a marker to the queue to facilitate clearing it programatically.
+  Task.prototype.mark = function() {
+    this._push(this._marker);
     // Make chainable!
     return this;
   };
@@ -273,8 +288,10 @@
       var async = false;
       // Get next task+args object from queue.
       var thing;
-      // Skip any placeholders.
-      do { thing = this._queue.shift(); } while (thing === this._placeholder);
+      // Skip any placeholders or markers.
+      do {
+        thing = this._queue.shift();
+      } while (thing === this._placeholder || thing === this._marker);
       // If queue was empty, we're all done.
       if (!thing) {
         this._running = false;
@@ -340,9 +357,14 @@
     nextTask();
   };
 
-  // Clear all remaining tasks from the queue, or a subset.
-  Task.prototype.clearQueue = function() {
-    this._queue = [];
+  // Clear remaining tasks from the queue.
+  Task.prototype.clearQueue = function(options) {
+    if (!options) { options = {}; }
+    if (options.untilMarker) {
+      this._queue.splice(0, this._queue.indexOf(this._marker) + 1);
+    } else {
+      this._queue = [];
+    }
     // Make chainable!
     return this;
   };

test/util/task_test.js

@@ -285,7 +285,8 @@ exports['Tasks'] = {
       }
     });
     task.run('a:b:c').start();
-  },  'Task#clearQueue': function(test) {
+  },
+  'Task#clearQueue': function(test) {
     test.expect(1);
     var task = this.task;
     task.registerTask('a', 'Push task name onto result.', result.pushTaskname);
@@ -305,6 +306,59 @@ exports['Tasks'] = {
     });
     task.run('a b c d e').start();
   },
+  'Task#mark': function(test) {
+    // test.expect(1);
+    var task = this.task;
+    task.registerTask('a', 'Explode.', function() {
+      throw task.taskError('whoops.');
+    });
+    task.registerTask('b', 'This task should never run.', result.pushTaskname);
+    task.registerTask('c', 'This task should never run.', result.pushTaskname);
+
+    task.registerTask('d', 'Push task name onto result.', result.pushTaskname);
+    task.registerTask('e', 'Explode.', function() {
+      throw task.taskError('whoops.');
+    });
+    task.registerTask('f', 'This task should never run.', result.pushTaskname);
+
+    task.registerTask('g', 'Push task name onto result.', result.pushTaskname);
+    task.registerTask('h', 'Push task name onto result.', result.pushTaskname);
+    task.registerTask('i', 'Explode.', function() {
+      throw task.taskError('whoops.');
+    });
+
+    task.registerTask('j', 'Run a task and push task name onto result.', function() {
+      task.run('k');
+      result.push(this.name);
+    });
+    task.registerTask('k', 'Explode.', function() {
+      throw task.taskError('whoops.');
+    });
+    task.registerTask('l', 'This task should never run.', result.pushTaskname);
+
+    task.registerTask('m', 'Push task name onto result.', result.pushTaskname);
+    task.registerTask('n', 'Run a task and push task name onto result.', function() {
+      task.run('o');
+      result.push(this.name);
+    });
+    task.registerTask('o', 'Explode.', function() {
+      throw task.taskError('whoops.');
+    });
+
+    task.registerTask('p', 'Push task name onto result.', result.pushTaskname);
+
+    task.options({
+      error: function(e) {
+        result.push('!' + this.name);
+        task.clearQueue({untilMarker: true});
+      },
+      done: function() {
+        test.strictEqual(result.getJoined(), '!ad!egh!ij!kmn!op', 'The specified tasks should have run, in-order.');
+        test.done();
+      }
+    });
+    task.run('a b c').mark().run('d e f').mark().run('g h i').mark().run('j l').mark().run('m n').mark().run('p').mark().start();
+  },
   'Task#requires': function(test) {
     test.expect(1);
     var task = this.task;