adding includeWith, and uniqeWith functions

this allows for using custom matcher function for comparison
defaults to _.isEqual jashkenas#2311

test/arrays.js

@@ -193,6 +193,35 @@
     assert.strictEqual(_.unique, _.uniq, 'is an alias for uniq');
   });
 
+  test('uniqueWithAlias', function (assert) {
+    assert.strictEqual(_.uniqueWith, _.uniqWith, 'is an alias for uniqWith');
+  });
+
+  test('uniqWith', function(assert) {
+    var list = [1, 2, 1, 3, 1, 4],
+      kittens = [
+        {kitten: 'Celery', cuteness: 8},
+        {kitten: 'Juniper', cuteness: 10},
+        {kitten: 'Juniper', cuteness: 10},
+        {kitten: 'Spottis', cuteness: 10},
+        {kitten: 'Stripes', cuteness: 11}
+      ],
+      uniqeKittens = [
+        {kitten: 'Celery', cuteness: 8},
+        {kitten: 'Juniper', cuteness: 10},
+        {kitten: 'Spottis', cuteness: 10},
+        {kitten: 'Stripes', cuteness: 11}
+      ],
+      byCuteness = function (a, b) {
+        return a.cuteness === b.cuteness;
+      }
+
+    assert.deepEqual(_.uniqWith(list), [1, 2, 3, 4], 'can find the unique values from a non object array');
+    assert.deepEqual(_.uniqWith(kittens, _.isEqual), uniqeKittens, 'finds unique objects using _.isEqual');
+    assert.deepEqual(_.uniqWith(kittens), uniqeKittens, 'defaults to _.isEqual if nothing passed');
+    assert.deepEqual(_.pluck(_.uniqWith(kittens, byCuteness), 'cuteness'), [8, 10, 11], 'returns all, if comparator only looks at name');
+  });
+
   test('intersection', function(assert) {
     var stooges = ['moe', 'curly', 'larry'], leaders = ['moe', 'groucho'];
     assert.deepEqual(_.intersection(stooges, leaders), ['moe'], 'can take the set intersection of two arrays');

test/collections.js

@@ -430,6 +430,31 @@
     assert.ok(_.every([1, 2, 3], _.partial(_.includes, numbers)), 'fromIndex is guarded');
   });
 
+  test('includeWithAlias', function(assert) {
+    assert.strictEqual(_.includeWith, _.includesWith, 'is an alias for containsWith');
+    assert.strictEqual(_.includeWith, _.containsWith, 'is an alias for includeWith');
+  });
+
+  test('includeWith', function(assert) {
+
+    var list = [1, 2, 1, 3, 1, 4];
+    var kittens = [
+      {kitten: 'Celery', cuteness: 8},
+      {kitten: 'Juniper', cuteness: 10},
+      {kitten: 'Spottis', cuteness: 10}
+    ];
+
+    var checkCute = function(a, b) {
+      return a.cuteness == 8;
+    }
+
+    assert.strictEqual(_.includeWith(list, 4), true, 'should find the item in the list');
+    assert.strictEqual(_.includeWith(kittens, {cuteness: 8}, checkCute), true, 'should use the method passed for comparison');
+    assert.strictEqual(_.includeWith(kittens, {kitten: 'Juniper', cuteness: 8}, _.isEqual), false, 'should not find as cuteness does not match');
+    assert.strictEqual(_.includeWith(kittens, {kitten: 'Juniper', cuteness: 10}, _.isEqual), true, 'should find the obj as cuteness matches');
+    assert.strictEqual(_.includeWith(kittens, {kitten: 'Juniper', cuteness: 10}), true, 'should use _.isEqual by default');
+  });
+
   test('include', function(assert) {
     assert.strictEqual(_.include, _.includes, 'is an alias for includes');
   });

underscore.js

@@ -278,6 +278,15 @@
     return _.indexOf(obj, item, fromIndex) >= 0;
   };
 
+  _.containsWith = _.includesWith = _.includeWith = function(array, item, predicate) {
+    predicate = _.isFunction(predicate) ? predicate : _.isEqual;
+    for (var i = 0, length = getLength(array); i < length; i++) {
+      if (predicate(array[i], item))
+        return true;
+    }
+    return false;
+  };
+
   // Invoke a method (with arguments) on every item in a collection.
   _.invoke = restArgs(function(obj, method, args) {
     var isFunc = _.isFunction(method);
@@ -560,6 +569,20 @@
     return result;
   };
 
+  // Produce a duplicate-free version of the array using the passed function for comparison rather than ===
+  // comparator defaults to _.isEqual for comparison if omitted
+  _.uniqueWith = _.uniqWith = function(array, predicate) {
+    var result = [], item;
+    predicate = _.isFunction(predicate) ? predicate : _.isEqual;
+
+    for (var i = 0, length = getLength(array); i < length; i++) {
+      item = array[i];
+      if (!_.containsWith(result, item, predicate))
+        result.push(item);
+    }
+    return result;
+  };
+
   // Produce an array that contains the union: each distinct element from all of
   // the passed-in arrays.
   _.union = restArgs(function(arrays) {