CircularBuffer add in size() method (#172)

* add in size() method

* remove void

src/Featurizers/Components/UnitTests/WindowFeaturizerBase_UnitTest.cpp

@@ -201,6 +201,30 @@ TEST_CASE("CircularBuffer - Size 0 buffer") {
     CHECK_THROWS_WITH(NS::Featurizers::Components::CircularBuffer<std::string>(0), "Max size cannot be zero");
 }
 
+TEST_CASE("CircularBuffer - Size") {
+    NS::Featurizers::Components::CircularBuffer<std::string> circ_buf(5);
+    // size should start with 0
+    CHECK(circ_buf.size() == 0);
+    // size would be incremented as data are pushed
+    circ_buf.push("1");
+    CHECK(circ_buf.size() == 1);
+    
+    circ_buf.push("2");
+    CHECK(circ_buf.size() == 2);
+    
+    circ_buf.push("3");
+    CHECK(circ_buf.size() == 3);
+    
+    circ_buf.push("4");
+    CHECK(circ_buf.size() == 4);
+    
+    circ_buf.push("5");
+    CHECK(circ_buf.size() == 5);
+    // size reaches the maximum of 5 and never changed
+    circ_buf.push("6");
+    CHECK(circ_buf.size() == 5);
+}
+
 TEST_CASE("CircularBuffer - Push") {
     NS::Featurizers::Components::CircularBuffer<std::string> circ_buf(5);
 

src/Featurizers/Components/WindowFeaturizerBase.h

@@ -135,6 +135,8 @@ namespace Components {
         // ----------------------------------------------------------------------
         CircularBuffer(size_t max_size);
 
+        size_t size() const;
+
         iterator begin();
 
         const_iterator begin() const;
@@ -293,6 +295,11 @@ CircularBuffer<T>::CircularBuffer(size_t max_size) : _max_size(max_size), _start
     _data.reserve(_max_size);
 }
 
+template <class T>
+size_t CircularBuffer<T>::size() const {
+    return _data.size();
+}
+
 template <class T>
 typename CircularBuffer<T>::iterator CircularBuffer<T>::begin() {
     return begin_impl<iterator>();