add resources to readme

Author: TusharChugh

README.md

@@ -1,6 +1,8 @@
 # cplusplus-forward_list
 Demo implementation of c++ forward list
 
+1. Two ways of implementing it: Inner class/friend class. I used friend class because it is easier to read the code separated in different files.  
+https://web.stanford.edu/class/cs107l/handouts/04-Custom-Iterators.pdf | https://stackoverflow.com/questions/7758580/writing-your-own-stl-container 
 Todo's:
 1. Add functionality to push back
 2. add const iterator

include/forward_tlist/forward_tlist.h

@@ -2,20 +2,28 @@
 #define FORWARD_LIST_FORWARD_TLIST_H
 
 #include "forward_tlist_node.h"
+#include <cstddef>
 
 namespace tlib{
     template <typename T>
     class forward_tlist{
         using iterator = tlib::forward_tlist_iterator<T>;
     public:
-        forward_tlist(): head(nullptr), tail(nullptr) {};
+        forward_tlist(): head(nullptr), tail(nullptr), size_(0) {};
         ~forward_tlist() { delete head; }
         bool empty() { return head == nullptr; }
-        void push_back(const T& element);
+        std::size_t size() const;
+        /**
+         * Prepends the given element to the beginning of the container
+         * No iterators are invalidated
+         * @param element the value of the element to prepend
+         */
+        void push_front(const T& element);
         iterator begin() { return forward_tlist_iterator<T>(head); }
         iterator end() { return forward_tlist_iterator<T>(nullptr); }
 
     private:
+        std::size_t size_;
         forward_tlist_node<T> *head;
         forward_tlist_node<T> *tail;
     };

include/forward_tlist/forward_tlist_iterator.h

@@ -16,7 +16,7 @@ namespace tlib {
 
     private:
         forward_tlist_node<T> *pointee;
-        forward_tlist_iterator(forward_tlist_node<T> *pointee): pointee(pointee) {}
+        explicit forward_tlist_iterator(forward_tlist_node<T> *pointee): pointee(pointee) {}
 
     }; //class forward_tlist_iterator
 } //namespace tlib

src/forward_tlist/forward_tlist.cpp

@@ -0,0 +1,6 @@
+#include "forward_tlist/forward_tlist.h"
+
+template <typename T>
+void tlib::forward_tlist<T>::push_front(const T &element) {
+
+}