Merge pull request documentcloud#239 from jgonggrijp/feature/atleast-atmost

containsAtLeast and containsAtMost

Author: jgonggrijp

docs/underscore.collections.walk.js.md

@@ -11,5 +11,6 @@ Documentation should use [Journo](https://github.com/jashkenas/journo) formats a
       map: function(obj, strategy, visitor, context)
       pluck: function(obj, propertyName)
       pluckRec: function(obj, propertyName)
+      containsAtLeast: function(list, count, value)
+      containsAtMost: function(list, count, value)
       _.walk.collect = _.walk.map;
-

test/collections.walk.js

@@ -21,6 +21,10 @@ $(document).ready(function() {
     };
   };
 
+  var getArrayValues = function() {
+    return ["a", "a", "a", "a", "b", "c", "d", "e" ];
+  };
+
   QUnit.test("basic", function(assert) {
     // Updates the value of `node` to be the sum of the values of its subtrees.
     // Ignores leaf nodes.
@@ -213,4 +217,20 @@ $(document).ready(function() {
     assert.equal(_.walk.map(tree, _.walk.postorder, _.identity).length, 14, 'default map still works');
     assert.equal(_.walk.pluckRec(tree, 'val').join(''), '0123456', 'default pluckRec still works');
   });
+
+  test("containsAtLeast", function(){
+    var array = getArrayValues();
+
+    equal(_.walk.containsAtLeast(array, 3, "a"), true, "list contains at least 3 items");
+    equal(_.walk.containsAtLeast(array, 1, "b"), true, "list contains at least 1 items");
+    equal(_.walk.containsAtLeast(array, 1, "f"), false, "list doesn't contain item for that value");
+  });
+
+  test("containsAtMost", function(){
+    var array = getArrayValues();
+
+    equal(_.walk.containsAtMost(array, 4, "a"), true, "list contains at most 4 items");
+    equal(_.walk.containsAtMost(array, 1, "b"), true, "list contains at most 1 value");
+    equal(_.walk.containsAtMost(array, 1, "f"), true, "list contains at most 1 value");
+  });
 });

underscore.collections.walk.js

@@ -168,6 +168,22 @@
         return visitor(subResults || leafMemo, value, key, parent);
       };
       return walkImpl(obj, this._traversalStrategy, null, reducer, context, true);
+    },
+
+    // Determine if the array contains a number of repated values
+    containsAtLeast: function(list, count, value) {
+      var filtered = _.filter(list, function(item) {
+        return _.isEqual(item, value);
+      });
+      return _.gte(_.size(filtered), count);
+    },
+
+    // Determine if the array contains a number of repated values
+    containsAtMost: function(list, count, value) {
+      var filtered = _.filter(list, function(item) {
+        return _.isEqual(item, value);
+      });
+      return _.lte(_.size(filtered), count);
     }
   };