Fix #3 - adding $merge

README.md

@@ -182,6 +182,12 @@ cursor.apply(function(currentData) {
 });
 ```
 
+*Merging objects*
+
+```js
+cursor.merge({hello: 'world'});
+```
+
 #### Events
 
 Whenever an update is committed, events are fired to notify relevant parts of the tree that data was changed so that bound elements, React components, for instance, can update.
@@ -549,6 +555,7 @@ The available commands are the following and are basically the same as the curso
 * `$chain`
 * `$push`
 * `$unshift`
+* `$merge`
 
 *Example*
 

src/baobab.js

@@ -30,7 +30,7 @@ function Baobab(initialData, opts) {
   EventEmitter.call(this);
 
   // Merging defaults
-  this.options = merge(opts, defaults);
+  this.options = helpers.shallowMerge(defaults, opts);
   this._cloner = this.options.cloningFunction || helpers.deepClone;
 
   // Privates

src/cursor.js

@@ -275,6 +275,16 @@ Cursor.prototype.unshift = function(value) {
     return this.update({$unshift: value});
 };
 
+Cursor.prototype.merge = function(o) {
+  if (!types.check(o, 'object'))
+    throw Error('baobab.Cursor.merge: trying to merge a non-object.');
+
+  if (!types.check(this.reference(), 'object'))
+    throw Error('baobab.Cursor.merge: trying to merge into a non-object.');
+
+  this.update({$merge: o});
+};
+
 Cursor.prototype.update = function(spec) {
   return this._stack(spec);
 };

src/helpers.js

@@ -11,6 +11,17 @@ function arrayOf(o) {
   return Array.prototype.slice.call(o);
 }
 
+// Shallow merge
+function shallowMerge(o1, o2) {
+  var o = {},
+      k;
+
+  for (k in o1) o[k] = o1[k];
+  for (k in o2) o[k] = o2[k];
+
+  return o;
+}
+
 // Shallow clone
 function shallowClone(item) {
   if (!item || !(item instanceof Object))
@@ -228,6 +239,7 @@ module.exports = {
   arrayOf: arrayOf,
   deepClone: deepClone,
   shallowClone: shallowClone,
+  shallowMerge: shallowMerge,
   compose: compose,
   getIn: getIn,
   inherits: inherits,

src/merge.js

@@ -40,30 +40,38 @@ function merge() {
 
   for (i = l - 1; i >= 0; i--) {
 
-    // Upper $set/$apply and conflicts
-    // TODO: Boooo! Ugly...
-    if (hasOneOf(arguments[i], ['$set', '$apply', '$chain'])) {
-      if (res.$set && (arguments[i].$apply || arguments[i].$chain)) {
-        delete res.$set;
-        res.$apply = arguments[i].$apply || arguments[i].$chain;
-      }
-      else if (res.$apply && arguments[i].$set) {
-        delete res.$apply;
-        res.$set = arguments[i].$set;
-      }
-      else if (arguments[i].$set) {
-        res.$set = arguments[i].$set;
-      }
-      else if (arguments[i].$apply) {
-        res.$apply = arguments[i].$apply;
-      }
-      else if (arguments[i].$chain) {
-        if (res.$apply)
-          res.$apply = helpers.compose(res.$apply, arguments[i].$chain);
-        else
-          res.$apply = arguments[i].$chain;
-      }
+    // Upper $set/$apply... and conflicts
+    // When solving conflicts, here is the priority to apply:
+    // -- 1) $set
+    // -- 2) $merge
+    // -- 3) $apply
+    // -- 4) $chain
+    if (arguments[i].$set) {
+      delete res.$apply;
+      delete res.$merge;
+      res.$set = arguments[i].$set;
+      continue;
+    }
+    else if (arguments[i].$merge) {
+      delete res.$set;
+      delete res.$apply;
+      res.$merge = arguments[i].$merge;
+      continue;
+    }
+    else if (arguments[i].$apply){
+      delete res.$set;
+      delete res.$merge;
+      res.$apply = arguments[i].$apply;
+      continue;
+    }
+    else if (arguments[i].$chain) {
+      delete res.$set;
+      delete res.$merge;
 
+      if (res.$apply)
+        res.$apply = helpers.compose(res.$apply, arguments[i].$chain);
+      else
+        res.$apply = arguments[i].$chain;
       continue;
     }
 

src/update.js

@@ -5,14 +5,16 @@
  * A handy method to mutate an atom according to the given specification.
  * Mostly inspired by http://facebook.github.io/react/docs/update.html
  */
-var types = require('./typology.js');
+var types = require('./typology.js'),
+    helpers = require('./helpers.js');
 
 var COMMANDS = {};
 [
   '$set',
   '$push',
   '$unshift',
-  '$apply'
+  '$apply',
+  '$merge'
 ].forEach(function(c) {
   COMMANDS[c] = true;
 });
@@ -92,6 +94,16 @@ function update(target, spec, opts) {
           log[h] = true;
           o[k] = fn.call(null, o[k]);
         }
+        else if ('$merge' in (spec[k] || {})) {
+          v = spec[k].$merge;
+
+          if (!types.check(o[k], 'object'))
+            throw makeError(path.concat(k), 'using command $merge on a non-object');
+
+          // Logging update
+          log[h] = true;
+          o[k] = helpers.shallowMerge(o[k], v);
+        }
         else if (opts.shiftReferences &&
                  ('$push' in (spec[k] || {}) ||
                   '$unshift' in (spec[k] || {}))) {

test/suites/cursor.js

@@ -366,5 +366,21 @@ describe('Cursor API', function() {
         done();
       });
     });
+
+    it('should be possible to shallow merge two objects.', function(done) {
+      var baobab = new Baobab({o: {hello: 'world'}, string: 'test'});
+
+      assert.throws(function() {
+        baobab.select('test').merge({hello: 'moto'});
+      }, /merge/);
+
+      var cursor = baobab.select('o');
+      cursor.merge({hello: 'jarl'});
+
+      baobab.on('update', function() {
+        assert.deepEqual(baobab.get('o'), {hello: 'jarl'});
+        done();
+      });
+    });
   });
 });

test/suites/helpers.js

@@ -51,6 +51,16 @@ describe('Helpers', function() {
     });
   });
 
+  describe('Shallow merge', function() {
+
+    it('should be possible to merge objects shallowly.', function() {
+      assert.deepEqual(
+        helpers.shallowMerge({hello: 'world', other: 'mate'}, {hello: 'Jack', one: 'two'}),
+        {hello: 'Jack', one: 'two', other: 'mate'}
+      );
+    });
+  });
+
   describe('Update API', function() {
 
     it('should be possible to set nested values.', function() {