title: mongodb return number of matched expression
body: <p>I have many document in collection I want to run a aggregation query. Let say sample doc are like as shown below</p>
  
  <pre><code>{"A":1,"B":2, "c":"x"}
  {"A":3,"B":2, "c":"play"}
  {"A":1,"B":2, "c":"test"}
  </code></pre>
  
  <p>to these doc I want to run a OR query and also I want to return number of or condition matched.
  for example if query is</p>
  
  <pre><code>{"A":1, "A":3, "c":"test"}
  </code></pre>
  
  <p>it should return result like</p>
  
  <pre><code>[
      {"A":1,"B":2, "c":"x", "count":1}
      {"A":3,"B":2, "c":"play", "count", 1}
      {"A":1,"B":2, "c":"test", "count":2}
  ]
  </code></pre>