git checkout - working

src/commandModel.js

@@ -295,7 +295,8 @@ OptionParser.prototype.getMasterOptionMap = function() {
     },
     checkout: {
       '-b': false,
-      '-B': false
+      '-B': false,
+      '-': false
     },
     reset: {
       '--hard': false,

src/git.js

@@ -1132,6 +1132,18 @@ GitEngine.prototype.checkoutStarter = function() {
     return;
   }
 
+  if (this.commandOptions['-']) {
+    // get the heads last location
+    var lastPlace = this.HEAD.get('lastLastTarget');
+    if (!lastPlace) {
+      throw new GitError({
+        msg: 'Need a previous location to do - switching'
+      });
+    }
+    this.HEAD.set('target', lastPlace);
+    return;
+  }
+
   if (this.commandOptions['-B']) {
     var args = this.commandOptions['-B'];
     this.twoArgsImpliedHead(args, '-B');
@@ -1438,6 +1450,21 @@ var Ref = Backbone.Model.extend({
       throw new Error('must be given an id');
     }
     this.set('type', 'general ref');
+
+    if (this.get('id') == 'HEAD') {
+      this.set('lastLastTarget', null);
+      this.set('lastTarget', this.get('target'));
+      // have HEAD remember where it is for checkout -
+      this.on('change:target', this.targetChanged, this);
+    }
+  },
+
+  targetChanged: function(model, targetValue, ev) {
+    // push our little 3 stack back. we need to do this because
+    // backbone doesn't give you what the value WAS, only what it was changed
+    // TO
+    this.set('lastLastTarget', this.get('lastTarget'));
+    this.set('lastTarget', targetValue);
   },
 
   toString: function() {

todo.txt

@@ -11,7 +11,6 @@ Big things:
 Medium things:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 - gitEngine loads from tree immediately, not the weird thing we have now!
-- help better
 
 Small things to implement:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~